I think I may be opening a can of worms, here.

What are the advantages of each?

20' x 20' room with 18' ceiling, open on one side to a large dining room and entryway. I have Klipsch RF-82 fronts, RC-62 Center, and RS-52 Surrounds, and an older JBL 150 watt 10 in sub. I was looking to get the Klipsch RW-12d, but I hear complaints of port noise, which will not do.

I have BB gift cards and rewards certificates to burn, and they sell the Martin Logan and Def Tech subs as their "high-end" subs. (sealed, right?)

On the other hand, I really like what I here about the HSU VTF 3.3. (ported)

Help.

From what I've generally heard, a sealed sub will play deeper flatter. Meaning it doesn't drop off as quickly as it approaches it's low frequency limit.
However a ported sub usually plays lower overall.
Personally I've always perfered sealed subs, to me they sound "tighter", and "faster". Both of these traits could be due to a sealed sub's increased dampening.

Anybody please correct me if any of this is wrong.

No cans of worms are open.

Sealed will go deeper given a limited volume,the roll off is gentle compared to a tuned(ported) design where the output drops like a stone below tuning point.

A well edsigned sealed will sound better compared to a well designed ported one.The gain is not major here,more for music ,for HT the quality of say a HSU VTF3HO or SVS Ultra(both ported)is A1 and more than plenty.For music a Velo DD or JL Fathom will have an advantage in sound quality.

With a tuned design you pay less for more output,always. Take HSU and SVS versus JL and Velodyne DD series.


Overall a well designed tuned or ported sub will do,in the end a matter of budget,room size and listening preferences.

And no a sealed is not faster. Just tighter,more controlled.As the internal air pocket in the sub acts as a natural damping(air spring).To replicate this in a ported would force you to use a very(extreme) stiff spider on the driver and an amp with extremly high damping.And you may get close.

I think another way to say tighter or more controlled is that it has a starting point and stopping point, no lag. This is how you get more definition, you don't miss any notes.

Some ported subs make Boooeeeen Noises! whenever you turn them up too high.

So, why is it then, that my Aerial sub sounds so much better than my Servo 15? The Aerial is ported, whereas the Servo isnt. The Aerial goes much lower, and is more musical, so, wouldnt design of the sub account for much of the characteristics, as opposed to just a general statement that "sealed subs are more musical", or "ported subs "arent as controlled, or as fast" I personally think it all comes down to who has designed the sub, what parts are used, and how well the sub was thought out. I can also say that I have never heard a Boooeeeen? noise from the Aerial? Not really sure what that is even.
Both subs (sealed, or ported) can be musical, tight, play low, etc. etc. it all comes down to how much thought has been put into the design.
I also have an NHT SW12i, that is pretty decent for what it is, but even being a sealed design does not have any advantages over the Aerial, or for that matter the Paradigm, my point being, its the design, not just sealed, or ported.

my point being, its the design, not just sealed, or ported.

True. There are certainly bad sealed designs that sound, well, bad. I have a SVS cylinder with three huge ports and it sounds pretty good.

But all things being equal sealed does have an advantage. Properly designed they can sound tighter and more musical. But there are ported designs that are quite musical as well. You just don't see many of them since most people use ported subs for SPL.

[Partial thread hijack] Does anyone know, is a sub with a passive radiator still considered sealed?

[Partial thread hijack] Does anyone know, is a sub with a passive radiator still considered sealed?

They are actually more closely related to ported subs. Except for the lack of port noise, a passive radiator acts a lot like a port and is tuned to a frequency.

So, why is it then, that my Aerial sub sounds so much better than my Servo 15? The Aerial is ported, whereas the Servo isnt. The Aerial goes much lower, and is more musical, so, wouldnt design of the sub account for much of the characteristics, as opposed to just a general statement that "sealed subs are more musical", or "ported subs "arent as controlled, or as fast" I personally think it all comes down to who has designed the sub, what parts are used, and how well the sub was thought out. I can also say that I have never heard a Boooeeeen? noise from the Aerial? Not really sure what that is even.
Both subs (sealed, or ported) can be musical, tight, play low, etc. etc. it all comes down to how much thought has been put into the design.
I also have an NHT SW12i, that is pretty decent for what it is, but even being a sealed design does not have any advantages over the Aerial, or for that matter the Paradigm, my point being, its the design, not just sealed, or ported.

I have the Aerial SW12,JL Audio f113,Paradigm Servo 15 v.2 and a Velo HGS18 among others.

The Aerial is one of the very best ported subs on the market,I would say outstanding as far as ported subs go.To compare this compact sub properly you would have to take a Fathom f113,an outstanding sealed compact sub.

Here the f113 has an edge in output,extension and very slight in sound quality. Where the Aerial has the edge is cabinet built,it is what some DIYers will build when attempting an all out sub(braced all around and constructed from thick panels).

The Paradigm Servo is cleaner than the Aerial and JL ...IMO of course.This could be verified in testing and often to our ears it sounds artificial to some degree.As it stands I prefer the JL and Aerial to servo subs as there is no limiting felt unless the subs are being pushed and stop going louder(never during any normal and abnormal listening).

On paper servo subs will always look better in THD measurments,when the servo is doing its job.This limits the subs dynamics(most of the new designs,this is very minor).The HGS18 series sounds a bit better than the Servo thanks to its larger piston and being capable of more SPL with the same cone travel.

Also a factor is your room,the reverse could be noted in another room.I found subwoofer A may sound better to my ears in room 1 and then come in second or further down when moved to another room.Interaction with the listening space is a big factor when comparing speakers/subs.

I am going to go out on a limb here and say that you can't tell by listening to a sub alone whether is ported or sealed.

Having owned both I can have that opinion. There are differences in the way they handle the rolloff. To quote TheEar: "the roll off is gentle compared to a tuned(ported) design where the output drops like a stone below tuning point."

There are, however, so many other factors that contribute to a sub's sound as to mask the differrences between ported and sealed.

If you do not aggree, go to a store that has an assortment of ported and sealed subs and ask to hear three of them without knowing what they are and then single out which are ported or not.

If you hit three out of three you could prove me wrong.

A well edsigned sealed will sound better compared to a well designed ported one.
But all things being equal sealed does have an advantage
Let the stereotypes live on :rolleyes:

I am going to go out on a limb here and say that you can't tell by listening to a sub alone whether is ported or sealed.

Having owned both I can have that opinion. There are differences in the way they handle the rolloff. To quote TheEar: "the roll off is gentle compared to a tuned(ported) design where the output drops like a stone below tuning point."

There are, however, so many other factors that contribute to a sub's sound as to mask the differrences between ported and sealed.

If you do not aggree, go to a store that has an assortment of ported and sealed subs and ask to hear three of them without knowing what they are and then single out which are ported or not.

If you hit three out of three you could prove me wrong.

No I probably would not hit three out of three.So I agree with the above.

Listening last night to the Aerial SW12 and switching to the Fathom f112,I could not tell there was one ported and one sealed.Must be two well designed subs.

Only my observation so far the sealed subs I have would rank higher in sound quality compared to ported,nothing major here.


You made valid points,I will listen/compare more this weekend.

Let the stereotypes live on :rolleyes:
dont waste your time with him.....it's like trying to make Bush understand Thermodynamics.

fsullivan3,
there are advantages and disadvantages in each alignment, but know that there are great subs in both alignments and some that leave much to be desired. The correct implementation of a sealed or ported sub will result in deep, accurate bass with nominal amounts of headroom.

if at all possible, you should try to audition some of the subs mentioned in this subforum, and you will get to hear some of the pros and cons in each.

dont waste your time with him.....it's like trying to make Bush understand Thermodynamics.


You compliment your president well!

You compliment your president well!
http://forums.offtopic.com/images/smilies/ugh2.gif

http://forums.offtopic.com/images/smilies/ugh2.gif

Superb repply

Taking yourself for a scientist and audio great! :rolleyes: I will sure seek enlightement from an audio maverick like you. :o

Ear out,have fun.

blah blah blah, yada yada yada
Ear out,have fun.
thank god....hopefully nobody else will get infested with your continuous absurd facade.... at least in this thread. :rolleyes:

dont waste your time with him.....it's like trying to make Bush understand Thermodynamics.

fsullivan3,
there are advantages and disadvantages in each alignment, but know that there are great subs in both alignments and some that leave much to be desired. The correct implementation of a sealed or ported sub will result in deep, accurate bass with nominal amounts of headroom.

if at all possible, you should try to audition some of the subs mentioned in this subforum, and you will get to hear some of the pros and cons in each.

Is there anywhere you can audition an HSU VTF 3.3?

I also have an NHT SW12i, that is pretty decent for what it is, but even being a sealed design ...

The SW12 is not sealed. ;)

I have/had a DLS-5000R, but I blew it yesterday. It's pretty good, but I auditioned a Sunfire True Sub EQ.. Very different tones and sound. I really like the extra punch the Sunfire seemed to have, and the low end rumble had a very powerful feel, something my 5000R lacked. I also like the fact that there is no port noise and the sound seems much more defined.

Is there anywhere you can audition an HSU VTF 3.3?
where r u located?

where r u located?


Oklahoma.

Oklahoma.
hmm.....dunno anyone personally with an HSU in OK, but there has to be a couple close by. According to this:
http://www.frappr.com/hsuowners/map

there are a couple of owners in KS and TX. Also, consider that you can always order one and return it if you dont like it....ID subs selling model is that you can try them at home and return them in case they dont fit your bill.

Mark,SW2Si, sorry, I mistyped.. its sealed. Didnt spell check!

it's like trying to make Bush understand Thermodynamics.

He graduated from yale...

...with a C average and he was guaranteed entry as a legacy of a fairly well known graduate. Do you actually have a point?

He graduated from yale...

...and buys into the theory of "Intelligent Design". :rolleyes:

...and buys into the theory of "Intelligent Design". :rolleyes:

I take exception to your use of "theory"--you needed quotation marks.

...and buys into the theory of "Intelligent Design". :rolleyes:
Is that how you measure intelligence based on if someone buys into some theory or not? Strange :rolleyes:

...and buys into the theory of "Intelligent Design". :rolleyes:
I suggest some homework on Sir Isaac Newton and Albert Einstein and what they bought into? I wouldn't however use these names and Bush in the same sentence though :D except for what they believed in.

This is not a potitical forum, but let's just say that I do question the intelligence of anyone who buys into the theory Intelligent Design.

This is not a potitical forum, but let's just say that I do question the intelligence of anyone who buys into the theory Intelligent Design.
Agreed on the former. Disagree on your opinion on the latter. You are not alone, just that you and I are in a different camp. Best not to bring religion and politics in here. Now back to sealed vs ported.

I prefer sealed with an LT.The secret is multiple drivers.Don't let that one get out or the commercial world may actually build something that resembles reference bass.Sans the Genelec.

KG

Best not to bring religion and politics in here.

I definitely agree with that and I apologize for allowing myself to get so far off topic.

Let's get back to bass-ics! :)

I think I may be opening a can of worms, here.

What are the advantages of each?

20' x 20' room with 18' ceiling, open on one side to a large dining room and entryway. I have Klipsch RF-82 fronts, RC-62 Center, and RS-52 Surrounds, and an older JBL 150 watt 10 in sub. I was looking to get the Klipsch RW-12d, but I hear complaints of port noise, which will not do.

I have BB gift cards and rewards certificates to burn, and they sell the Martin Logan and Def Tech subs as their "high-end" subs. (sealed, right?)

On the other hand, I really like what I here about the HSU VTF 3.3. (ported)

Help.
This is a difficult question but I will take a shot at it. Not to complicate things, but I think it might help to consider a couple of other designs too. So let's briefly consider sealed (otherwise called acoustic suspension), ported (bass reflex), passive radiators (middle ground between sealed and ported) and horns. Horn loaded subwoofers are usually very large and anyone worried about size can easily rule this design out. In general, it is easier to achieve higher SPL with ported and horn designs as they are very efficient. It is harder to achieve similar higher SPL with sealed subs, unless the driver is very well engineered and you have whopping power behind it to drive it to limits you would like. So why would a designer choose a sealed one against a ported one, if he can achieve higher SPLs? One quick answer is that with sealed subs you get better accuracy more easily than ported designs. That does not automatically imply that ported ones are less accurate. It boils down to what is easier to achieve. WIth ported, higher SPL is easier to achieve where as SQ is harder. With sealed it is vice versa.
Subs with passive radiators are a good compromise between the two. Having owned one in the past with a passive radiator and seeing how well it performed, I wonder why there are not that many passive radiator subs these days.
My experience with horns is a Danley DTS-20. The design is very much like a big band-pass box but there is a lot more cleverness in this design. The sheer size makes it unsuitable for most homes. I finally settled with dual JL audio f113 subs. Amazing sound both in terms of quality and quantity, for such a small box. One advantage I readily found with a small sealed box is placement. Unlike ported ones, you don't have to worry too much about how much breathing room you have to give for the ports. Also, you don't have to worry about port chuffing. Small stackable sealed boxes, potent to the core, is a very good choice.
I hope more designers and manufacturers will consider passive radiators especially if cost is an issue. With cost no object, sealed all the way. I hope this helps.

This is a difficult question but I will take a shot at it. Not to complicate things, but I think it might help to consider a couple of other designs too. So let's briefly consider sealed (otherwise called acoustic suspension), ported (bass reflex), passive radiators (middle ground between sealed and ported) and horns. Horn loaded subwoofers are usually very large and anyone worried about size can easily rule this design out. In general, it is easier to achieve higher SPL with ported and horn designs as they are very efficient. It is harder to achieve similar higher SPL with sealed subs, unless the driver is very well engineered and you have whopping power behind it to drive it to limits you would like. So why would a designer choose a sealed one against a ported one, if he can achieve higher SPLs? One quick answer is that with sealed subs you get better accuracy more easily than ported designs. That does not automatically imply that ported ones are less accurate. It boils down to what is easier to achieve. WIth ported, higher SPL is easier to achieve where as SQ is harder. With sealed it is vice versa.
Subs with passive radiators are a good compromise between the two. Having owned one in the past with a passive radiator and seeing how well it performed, I wonder why there are not that many passive radiator subs these days.
My experience with horns is a Danley DTS-20. The design is very much like a big band-pass box but there is a lot more cleverness in this design. The sheer size makes it unsuitable for most homes. I finally settled with dual JL audio f113 subs. Amazing sound both in terms of quality and quantity, for such a small box. One advantage I readily found with a small sealed box is placement. Unlike ported ones, you don't have to worry too much about how much breathing room you have to give for the ports. Also, you don't have to worry about port chuffing. Small stackable sealed boxes, potent to the core, is a very good choice.
I hope more designers and manufacturers will consider passive radiators especially if cost is an issue. With cost no object, sealed all the way. I hope this helps.


Hi joe

According to Tom Nousaine, it all comes down to 3 things: extension, THD, and flat frequency response. 2 HSU VTF-3MIIIs for $1,600 will kill just about anything out there. For about 30% of the cost of 2 F113s, anyone can get as much bass as they need for rooms up to 6,000 cubic feet.

Hugs and Kisses

Hi joe

According to Tom Nousaine, it all comes down to 3 things: extension, THD, and flat frequency response. 2 HSU VTF-3MIIIs for $1,600 will kill just about anything out there. For about 30% of the cost of 2 F113s, anyone can get as much bass as they need for rooms up to 6,000 cubic feet.

Hugs and Kisses
If all about subwoofers comes down to just extension, THD and flat frequency response, this subject will not need a separate area in this forum ;). You are probably right about getting as much bass for 30% of the cost but I don't know how it would translate if we take SQ into the equation. WHat you indicate was top on my list. Who knows, someday I may decide to try out the HSUs. Yeah, I will take the hugs, kisses, back off :D LOL

WIth ported, higher SPL is easier to achieve where as SQ is harder. With sealed it is vice versa.
Based on what exactly? Sound quality is a moving target from person to person, and the more GTGs I go to the more I realize that most people don't like accurate bass. The term sound quality is basically useless if we want to make frame of reference comparisons - accuracy is a much better measuring stick. If people don't like the sound of accuracy, that's their call, but it's the only way to make useful comparisons. Flat FR, deep extension, low distortion, and headroom is what it comes down to. If we are comparing two subs using the same driver and power, a ported will have a naturally flatter FR, lower distortion, and more headroom. The sealed will extend deeper due to its shallower rolloff. At the point the low end output of the sealed exceeds the ported, you are likely going to be at least -10db from higher bass frequencies.

That's what it boils down to.

Based on what exactly? Sound quality is a moving target from person to person, and the more GTGs I go to the more I realize that most people don't like accurate bass. The term sound quality is basically useless if we want to make frame of reference comparisons - accuracy is a much better measuring stick. If people don't like the sound of accuracy, that's their call, but it's the only way to make useful comparisons. Flat FR, deep extension, low distortion, and headroom is what it comes down to. If we are comparing two subs using the same driver and power, a ported will have a naturally flatter FR, lower distortion, and more headroom. The sealed will extend deeper due to its shallower rolloff. At the point the low end output of the sealed exceeds the ported, you are likely going to be at least -10db from higher bass frequencies.

That's what it boils down to.
The point I am trying to convey is this. Numbers say only so much and not everything can be measured. So confining a subs performance to just a set of numbers is meaningless. The numbers are guidelines, beyond that comes actual user experience. Psycho-acoustics is yet another dimension. If someone says that THD, flat FR and extension is all there is, then they are over simplifying reality.
Don't get me wrong. I am one of those, who is obsessed with numbers .
But they are not everything!

..with a C average and he was guaranteed entry as a legacy of a fairly well known graduate. Do you actually have a point?

Wow, and before, Liberals were whining about how out of touch Bush was because he went to an "elite" school.

but let's just say that I do question the intelligence of anyone who buys into the theory Intelligent Design.

And a universe blowing itself out of nothing and forming life from a lightning bolt in some mud is more "intelligent"?

OMG Where's this thread headed? :confused:

OMG Where's this thread headed?

OK, ignore my posts. :(

;)

And no a sealed is not faster. Just tighter,more controlled
I think for all practical purposes, when describing a subwoofer fast and tight can be synonymous. The ability to start and stop quickly, more dampening.

Hi joe

According to Tom Nousaine, it all comes down to 3 things: extension, THD, and flat frequency response. 2 HSU VTF-3MIIIs for $1,600 will kill just about anything out there. For about 30% of the cost of 2 F113s, anyone can get as much bass as they need for rooms up to 6,000 cubic feet.

Hugs and Kisses


Spyboy....please buy a 3.3 and do your OWN testing and stop quoting Tom Nousaine for every verification you try to give for the 3.3.

Is it a great sub...YES.....will it KILL all other subs for $1600....that is up to the user because everyone likes different sound!!

Advice....I've learned the hard way that you have to get out there and listen and do your own testing before people will give you respect and credit (which makes sense). I've really tried to listen to a variety of SVS subs and now I've had the pleasure of hearing the 3.3 with turbo live an in person.

Quoting numbers and words from someone you don't know from some testing that was conducted over and over again really doesn't help.

I'm not trying to come across mean or anything.....just trying to help man!! we all have to start somewhere and the more you can get out there and listen for youself the better.

Thinking out loud :D
Why not compressed nitrogen in sealed subs? Maybe one of the DIYers can lead the way.
Larger molecules prevent leaks, moisture-free, non-flammable. Wouldn't this make a sealed sub more efficient due to elastic properties of compressed medium.
Stupid idea?

I don't think any kind of compressed gas would be a good medium inside a sealed sub. I think you need to have a pressure that is nearly equal to the atmosphere otherwise high pressure inside the box would cause the woofer at rest to be in a "pushed-out" position. That can't be good.

Thinking out loud :D
Why not compressed nitrogen in sealed subs? Maybe one of the DIYers can lead the way.
Larger molecules prevent leaks, moisture-free, non-flammable. Wouldn't this make a sealed sub more efficient due to elastic properties of compressed medium.
Stupid idea?
Or should I say rarefied nitrogen with lesser pressure than ambience.

I don't think any kind of compressed gas would be a good medium inside a sealed sub. I think you need to have a pressure that is nearly equal to the atmosphere otherwise high pressure inside the box would cause the woofer at rest to be in a "pushed-out" position. That can't be good.
The sag (example from downfiring subs) "equilibrium position" can be compensated right?

Why not put this debate to some testing.

http://www.avsforum.com/avs-vb/showthread.php?t=824418


I'd like to see SEALED and PORTED owners read and contribute to this detailed thread. The more data we have the better, plus I spelled it out for everyone! :D

I knew I was opening a can of worms, just didn't know what kind of worms, I guess.

I appreciate everyone's diverse opinions on politics, scientific theory, and subwoofers.

So let me get this right - to decide which sub will work better for me, I need to demo as many as I can, sitting in my living room, hooked up to my receiver, and sitting on my couch where I like to watch movies and listen to music, and then make a decision?

In general, are sealed subs better for music and ported/passive for movies? Is that at least true?

The sag (example from downfiring subs) "equilibrium position" can be compensated right?

There I think you have a good point. From the standpoint of practicality, however, what would it take to maintain a perfectly sealed box like that for many years.

There I think you have a good point. From the standpoint of practicality, however, what would it take to maintain a perfectly sealed box like that for many years.
Solvable. Maybe maintain them like tires which are subject to much harsher conditions. But having a lesser pressure inside the unit will require more energy to move the cone out. However the cone can come back to equilibrium faster. I am treading on thin ice here. Will stop now before I make more absurd comments and wait for the experienced to chime in.

So let me get this right - to decide which sub will work better for me, I need to demo as many as I can, sitting in my living room, hooked up to my receiver, and sitting on my couch where I like to watch movies and listen to music, and then make a decision?

Yes, that's what I would do. But to do that you want to narrow your choice down to about 3, so it is more practical.

What would the sonic effect of needing more energy for a positive excursion than for a negative excursion? I would think that if they are not pretty much the same, it would result in severe distortion.

I knew I was opening a can of worms, just didn't know what kind of worms, I guess.

I appreciate everyone's diverse opinions on politics, scientific theory, and subwoofers.

So let me get this right - to decide which sub will work better for me, I need to demo as many as I can, sitting in my living room, hooked up to my receiver, and sitting on my couch where I like to watch movies and listen to music, and then make a decision?

In general, are sealed subs better for music and ported/passive for movies? Is that at least true?

I think the sealed versus ported discussiion has been debated before, and it has always tended to get a little testy. :)

Ultimately, you will need to decide which subwoofer is going to work for you. One thing that has not entered the discussions is the issue of cost. For retail subs (I'm excluding DIY from this statement), a sealed subwoofer will almost always cost more to achieve similar SPL and extension to a ported / passive radiator sub.

What would the sonic effect of needing more energy for a positive excursion than for a negative excursion? I would think that if they are not pretty much the same, it would result in severe distortion.
A sealed sub since it does not have ports will not move air during negative excursion, hence this should be a non-issue.

In general, are sealed subs better for music and ported/passive for movies? Is that at least true?[/QUOTE]

I have owned several sealed subs and ported, and for my 2 channel music system, I am using a ported sub. Compared to the others, it just sounds the best to me, although the consensus is that for music, a sealed sub is better, but I really think it is the quality and design that is a bigger factor then wheather it is ported or not. The ported sub is just as tight, and quick as my sealed.

The point I am trying to convey is this. Numbers say only so much and not everything can be measured. So confining a subs performance to just a set of numbers is meaningless. The numbers are guidelines, beyond that comes actual user experience. Psycho-acoustics is yet another dimension. If someone says that THD, flat FR and extension is all there is, then they are over simplifying reality.
The frequencies reproduced in the subwoofer range (assuming an 80hz crossover) are not directional, and the RB and LFE are combined into a single channel, so you can eliminate imaging and soundstage as variables like they would be in speakers. Baffle shape doesn't really play any role for subs like it does in speakers. There is no crossover in a sub like there is in speakers. There are lots of variables for percieved sound quality in speakers, not too many in subs. "Numbers" correlate well for subs.

In general, are sealed subs better for music and ported/passive for movies? Is that at least true?

That is the general perception but as you can tell from reading through this and other threads, not a universal truth.

Not to get on a soap box on this but in my early days of researching AV systems, I recognized the foolishness of asking general subjective questions on Forums. Instead I read a lot and PMed individuals whom I felt would give the best advice. Most were willing to give me their opinions as long as I asked specific questions and respected their time.

A sealed sub since it does not have ports will not move air during negative excursion, hence this should be a non-issue.

Not true. The negative excursion is still responsible for forming the negative half of the wave cycle. It's just as important as the positive excursion. A full wave is formed by the front of the woofer and a full wave is formed by the back of a woofer, just out of phase. Part of that wave from the back is what makes it into the port which is tuned in such a way as to correct the phase and so it combines with the front wave for added SPL.

Based on what exactly? Sound quality is a moving target from person to person, and the more GTGs I go to the more I realize that most people don't like accurate bass. The term sound quality is basically useless if we want to make frame of reference comparisons - accuracy is a much better measuring stick. If people don't like the sound of accuracy, that's their call, but it's the only way to make useful comparisons. Flat FR, deep extension, low distortion, and headroom is what it comes down to. If we are comparing two subs using the same driver and power, a ported will have a naturally flatter FR, lower distortion, and more headroom. The sealed will extend deeper due to its shallower rolloff. At the point the low end output of the sealed exceeds the ported, you are likely going to be at least -10db from higher bass frequencies.

That's what it boils down to.

Steve knows exactly what he is talking about. Flat FR, deep extension, low distortion, and headroom are as much as you need to know. You do not have to audition every subwoofer you are considering buying. Ported subs sound great. If there is any difference in SQ between ported and sealed subs it is of no consequence if you have a sufficiently capable ported sub.

Hugs and Kisses

Steve knows exactly what he is talking about. Flat FR, deep extension, low distortion, and headroom are as much as you need to know. You do not have to audition every subwoofer you are considering buying. Ported subs sound great. If there is any difference in SQ between ported and sealed subs it is of no consequence if you have a sufficiently capable ported sub.

Hugs and Kisses


LOL.
:rolleyes: :rolleyes: :rolleyes: :rolleyes: :rolleyes:

I'm suprised you didn't reply with the usual:

" An HSU VTF-3MK3 with the Turbo attached will do a record breaking 112 db at 20Hz.

Best Regards"


But your post is equally laughable. :p

This is a difficult question but I will take a shot at it. Not to complicate things, but I think it might help to consider a couple of other designs too. So let's briefly consider sealed (otherwise called acoustic suspension...

Sorry but sealed and acoustic suspension are not the same. Sealed designs have been around since the invention of the loudspeaker.

Acoustic supension was invented by AR (Acoustic Research) in the mid sixties, if my memory serves me right. A specially designed woofer with very loose suspension is placed in an air-tight chamber. The chamber acts as the "suspension" for the driver instead of the spider-cone surround combination of regular woofers. The cabinet had to be kept small, by design, because it needed to provide the woofer the necessary amount of resistance. This design enabled them to produce a small bookeshelf that produced real deep bass. The caveat was they were very inefficient.
The AR-1 was their very first speaker followed by the AR-2 and AR-3.

Wow, and before, Liberals were whining about how out of touch Bush was because he went to an "elite" school.

You just have a bad memory. Going to an elite school is indisputably a good thing. Being intellectually (rather than hereditarily) qualified for such is even better, and that's where the problem with this guy lies. But that's not the issue back to sealed vs. ported, a few random misconceptions I think should be cleared up.

A few points I think are relevant to this thread and things that have already been posted.

First, listening to a few commercial subwoofers and trying to generalize about ported vs. sealed is a waste of time. Most expensive commercial subs will be sealed or passive radiator, for size/packaging reasons. (Making, shipping, and selling a 3 ft^3 box is much easier and cheaper than doing the same for a 12 ft^3 box.) Many cheap subs will be ported, but tuned high because they still have to fit in small boxes. Moreover, a subwoofer cannot be considered in isolation. It needs to be tailored to its positioning and the space around it. Just as an off-the-rack suit (even something impeccably made, such as an Oxxford or Kiton) is never going to look right on anyone without some alterations, a subwoofer needs "alteration" in the form of EQ to integrate it better into the system and the room. Some commercial subs have good EQ built in. (I use a Velodyne SMS-1 in my system, which is the standalone version of the EQ in their DD subs.) Most do not. So for most people, assuming the sub is capable of enough output, a better upgrade would be something like an SMS-1 or BFD with appropriate other tools. Likewise, even once altered that Kiton is always going to be inferior in fit to good bespoke, and by the same token a well-designed bespoke (DIY) sub, designed expressly for the room in which it sits by someone with a solid understanding of what goes into a good subwoofer and then further tailored with appropriate EQ, is the ultimate level of subwooferdom.

Second, it's been said a few times that a sealed box acts as an air-spring. While that can be true, it does not have to be. "Sealed" and "acoustic suspension" have the same relationship as "rectangle" and "square;" all of the latter are the former, but all of the former are not the latter. Point of fact, in the sealed enclosures generally considering "best sounding" (those with Qtc values of around 0.5) have little to no air-spring effect. One could, in fact, argue that a passive radiator box that's undersized and tuned really low has more of an air-spring effect than a good sealed box.

Third, it's been claimed that sealed go lower, and ported get louder. Sometimes, but one can't generalize. Yes, the ultimate rolloff of a closed (2nd order) system will always be half the ultimate rolloff of a vented (4th order) system. However, corner frequency matters, too. An EBS (which is the accepted term for what's been called "LLT" on this forum) vented sub with a corner frequency at 16Hz will have more output everywhere it matters than the same driver in a sealed enclosure, where its corner frequency is likely to be an octave or more higher (mid 30's). True, the sealed one might have more output at 3Hz, but that is hardly relevant to anything even if the sub is multiple long-throw 18's. For a given driver, ported get louder is always true in some area of the spectrum, simply because the backwave is exploited rather than wasted. Because of that, the heat shrugged off by the voicecoil is generally lower in a ported subwoofer than a sealed one, and the attendant lower power compression is a point in the ported sub's favor.

Fourth, anyone who really wants to claim that SPL and extension are all that matters are fooling themselves. For one thing, inductance (Le) matters. Lower is better, and linearity is mandatory. A subwoofer driver that does not have a Faraday ring in its motor to linearize inductance is one that a serious musicphile should never consider no matter how long its throw may be. In general, low-inductance woofers sound better than high-inductance woofers, though one may also argue that low-inductance is simply a proxy for good motor design. One notable exception is the Peerless XLS12, which is widely regarded as one of the top medium-throw subwoofer drivers on the market. It has a very high inductance, though the motor design and build quality are excellent. Group delay is something else that has been shown to correlate with good-sounding bass. Sealed systems have lower group delay than ported systems, so that is a point in their favor.

As for me, I've used ported, sealed, and PR subs. My current subs are ported (HT) and PR (home office). I'm considering replacing the 6 cubic foot vented sub with an 18" woofer in my HT with a 4 cubic foot sealed (Qtc=0.55) sub with a 15" woofer. I don't need the extra output the ported sub offers, and I want to build a more attractive cabinet. I may also do some experimenting with Geddes-style bandpass and Danley-style tapped horns in the near future, too.

A sealed sub since it does not have ports will not move air during negative excursion, hence this should be a non-issue.

What??????? :rolleyes:

So it clips the negative side of the input signal? :eek:

You really meant something else. Right?

Group delay is something else that has been shown to correlate with good-sounding bass. Sealed systems have lower group delay than ported systems, so that is a point in their favor.





Why is that important if you have a current receiver? You can (must) adjust for differerences in group delay quite easily these days!

Why is that important if you have a current receiver? You can (must) adjust for differerences in group delay quite easily these days!


Hi

I am waiting for my Denon 5803A to be delivered. Supposed to be delivered on 4/4/07. It has an adjustable subwoofer groop delay function. Some people say it doesn't mean anything.

All the Best

Sorry but sealed and acoustic suspension are not the same. Sealed designs have been around since the invention of the loudspeaker.

Acoustic supension was invented by AR (Acoustic Research) in the mid sixties, if my memory serves me right. A specially designed woofer with very loose suspension is placed in an air-tight chamber. The chamber acts as the "suspension" for the driver instead of the spider-cone surround combination of regular woofers. This enabled them to produce a small bookeshelf that produced real deep bass. The caveat was they were very inefficient.
The AR-1 was their very first speaker followed by the AR-2 and AR-3.

Hi John

I had an AR4-X, and an AR-2Ax. Sold them for a mint condition pair of the original Bose 901s that cost $400. Lost $25 when I sold the Bose 901s. I got tired of hearing the piano coming from the ceiling.

Kind Regards

Hi

I am waiting for my Denon 5803A to be delivered. Supposed to be delivered on 4/4/07. It has an adjustable subwoofer groop delay function. Some people say it doesn't mean anything.

All the Best



Actually, you have to delay all the other speakers relative to the subwoofer in that the subwoofer has the longest group delay of all your speakers (in general). You don't wat to "delay" the subwoofer.

Then again, some manufacturers use words that are misleading (like "adjustable subwoofer groop delay function"). I will have to read the instruction book for that specific Denon unit!

Why is that important if you have a current receiver? You can (must) adjust for differerences in group delay quite easily these days!
Actually no. Usually group delay rises towards the lower frequencies, and receiver can only add or reduce (by delaying the other speakers) a constant value in the subwoofer pass band. So the delay settings do not reduce the group delay difference between different frequencies i.e. make the phase response flatter. If you want to make your system's group delay lower/flatter, you have to EQ your frequency response flatter.

What??????? :rolleyes:

So it clips the negative side of the input signal? :eek:

You really meant something else. Right?
Sorry but sealed and acoustic suspension are not the same. Sealed designs have been around since the invention of the loudspeaker.


I said a "sealed sub does not move air during negative excursion". I did not say it clips the negative side of the input signal. The negative side of the input signal moves the woofer to the negative position from equilibrium and rarefies the air. When I say does not move, I mean does not compress. Clear?

There are several indications on-line where sealed and acoustic suspension are used synonymously. As long as you understand what I mean, that's what matters.

Not true. The negative excursion is still responsible for forming the negative half of the wave cycle. It's just as important as the positive excursion. A full wave is formed by the front of the woofer and a full wave is formed by the back of a woofer, just out of phase. Part of that wave from the back is what makes it into the port which is tuned in such a way as to correct the phase and so it combines with the front wave for added SPL.
I agree it is as important as the positive excursion. Again, we are talking about sealed subs in that reference. YOu mention "port". There is no port in a sealed sub.

Actually no. Usually group delay rises towards the lower frequencies, and receiver can only add or reduce (by delaying the other speakers) a constant value in the subwoofer pass band. So the delay settings do not reduce the group delay difference between different frequencies i.e. make the phase response flatter. If you want to make your system's group delay lower/flatter, you have to EQ your frequency response flatter.


That is somewhat true. Why do people keep trying to bring "flatness" into almost every issue related to subwoofers? Flatness was not being discussed. Perhaps the FR curve will be flatter, perhaps not. It all depends on the speakers in question.

I for one was not talking about "the group delay difference between different frequencies i.e. make the phase response flatter". That can not be heard, so it means nothing much at all.

The thinking behind this is to minimize the differences in group delay BETWEEN DIFFERENT SPEAKERS playing the same frequency at the same time. This issue is very important if you have "large " speakers running along with a subwoofer!

I for one was not talking about "the group delay difference between different frequencies i.e. make the phase response flatter". That can not be heard, so it means nothing much at all.

So you're saying that one can not hear if the 20 Hz signal delayed by say 100ms compared to the 100 Hz signal? That's already 2 cycles at 20 Hz.

So you're saying that one can not hear if the 20 Hz signal delayed by say 100ms compared to the 100 Hz signal? That's already 2 cycles at 20 Hz.



100% correct for a single speaker (absolute basis). When you come right down to it I am not sure if I can hear 20 Hz at normal (or any???) playback levels anyhow.

On a relative basis (simultaneous bass from two speakers), yes you can hear (or feel) the difference if there is a major difference in group delays between the two (or more) speakers and you do not compensate for this difference.

Some discussion on how audible is group delay for bass frequencies.

http://www.trueaudio.com/post_010.htm

Hi John

I had an AR4-X, and an AR-2Ax. Sold them for a mint condition pair of the original Bose 901s that cost $400. Lost $25 when I sold the Bose 901s. I got tired of hearing the piano coming from the ceiling.

Kind Regards

OMG! you are as old as I am! :D

I agree it is as important as the positive excursion. Again, we are talking about sealed subs in that reference. YOu mention "port". There is no port in a sealed sub.

I didn't mean to imply that a sealed sub had a port, but rather that in the case of a ported sub, it isn't the negative excursion any more than the positive excursion which results in the sound reinforcemnt which comes out of the port. It's both excursions, but 180 degrees out.

Hi guys,

This discussion has been headed out towards left (right?) field from the get go, but let's get back to the core question of what is important.

Execution is everything.

I guarantee you can make any and every design type sound like doo-doo if you try hard enough. :rolleyes:

So far as the "best" design method, I don't believe there is one. Only after we start defining the application and practical limitations do some designs begin to step forward as more attractive for a particular use, application, or set of performance targets. Those who are most adamant about one design being superior usually already have in their mind a well defined concept of what is "enough" and ideal. Only with many hard questions answered are there any obvious choices.

When I talk with those whom I consider to be the most knowledgable in their area of audio, there are recurring topics of discussion. The first to run through is usually poking fun at what "everyone else" is doing, and how many basic operational characteristics are ignored to persue the ultimate in one specific quality. After some good laughs and frustrations the topic usually moves on to what is the next unknown or uncertainty that they want to further explore. Almost to a rule, the more experienced the practitioner, the longer the list of things to still explore.

I'm not saying we don't have a very good working knowledge of what characteristics we can subjectively react to. We do(as an industry/community), and I myself have very specific performance targets I want to achieve with each design. That isn't the same as being able to combine every possible characteristic and environment (the room) and tell someone with 100% confidence, exactly what will be heard, and what will sound better.

I'd like to add another point that hasn't been touched on yet.

Let's for a moment not worry about which sounds "better," but instead consider where differences lie between the various design types.

While most models make general assumptions of ideal linearity over some operating range for drivers and other parts of the system, this is a gross simplification. Many characteristics of devices change significantly in operation. It is commonly overlooked that such changes in devices will have very different effects on different design types and even subsets of each type. More than a few well intentioned audiophile wives tales arose from co-incidences with certain design choices, although often annother innocent factor received the blame.

1a. Ported subs are resonant systems. The latent release of stored energy is audible and measurable.

1b. Other forms of self noise are also less audible in a sealed sub.

2a. The dual knee curve with 4th order roll off of the EBS ported sub in no way can be construed as 'flatter' than the low Q, single knee, with a 2nd order roll off curve of the sealed sub.

2b. A sealed sub with a system Q of .5 does not have the requirement of being larger than a sealed sub with a properly designed air spring.

2c. The transient response of the sealed sub is better than the ported sub, which is the only evidence required to prove the claim of 2a.

3. The sealed sub offers lower extension than even the lowest tuned EBS ported sub by orders of magnitude. Just click on the graph posted below and realize that only the 2nd order filters at 3Hz in the player (not employed in the chain that generated the graph) and amp limit the response to DC, which extension is not possible with a ported sub.

Arguments as to whether or not the extension/roll off is an audible improvement assume that one has (a) the capability to reproduce the extended response and (b) has compared the two curves being discussed under proper conditions. ;)

4. The sealed sub occupies much less real estate, especially in the case of lower and lower tuning of an EBS ported sub. This makes the single driver comparisons irrelevant. Why impose restrictions on one alignment, but none on the other? The debate is as to which alignment performs best, not it's size and/or driver/amplifier compliment.

6. The ported sub unloads below tune, generating very unmusical noise at levels that vary in direct proportion to the frequency response of the upstream electronics, up to and including driver failure. This can be remedied by use of a HP filter, which has it's added performance negatives.

7. Headroom is a non issue, as it's assumed that the correct number of subwoofers is employed to suit the application.

The disputes over the above facts in these forums are legendary, but do not change the facts.

Bosso

7. Headroom is a non issue, as it's assumed that the correct number of subwoofers is employed to suit the application.



...Assuming price is no object.

1a. Ported subs are resonant systems. The latent release of stored energy is audible and measurable.

1b. Other forms of self noise are also less audible in a sealed sub.

2a. The dual knee curve with 4th order roll off of the EBS ported sub in no way can be construed as 'flatter' than the low Q, single knee, with a 2nd order roll off curve of the sealed sub.

2b. A sealed sub with a system Q of .5 does not have the requirement of being larger than a sealed sub with a properly designed air spring.

2c. The transient response of the sealed sub is better than the ported sub, which is the only evidence required to prove the claim of 2a.

3. The sealed sub offers lower extension than even the lowest tuned EBS ported sub by orders of magnitude. Just click on the graph posted below and realize that only the 2nd order filters at 3Hz in the player (not employed in the chain that generated the graph) and amp limit the response to DC, which extension is not possible with a ported sub.

Arguments as to whether or not the extension/roll off is an audible improvement assume that one has (a) the capability to reproduce the extended response and (b) has compared the two curves being discussed under proper conditions. ;)

4. The sealed sub occupies much less real estate, especially in the case of lower and lower tuning of an EBS ported sub. This makes the single driver comparisons irrelevant. Why impose restrictions on one alignment, but none on the other? The debate is as to which alignment performs best, not it's size and/or driver/amplifier compliment.

6. The ported sub unloads below tune, generating very unmusical noise at levels that vary in direct proportion to the frequency response of the upstream electronics, up to and including driver failure. This can be remedied by use of a HP filter, which has it's added performance negatives.

7. Headroom is a non issue, as it's assumed that the correct number of subwoofers is employed to suit the application.

The disputes over the above facts in these forums are legendary, but do not change the facts.

Bosso
The way this is worded sounds like a patent application :). Very well said.

But mostly incorrect or misleading. I guess he wants to do this YET AGAIN. For anyone interested, search for ported vs sealed and judge for yourself if Bosso's claims stand up in the previous debates.

1a. Ported subs are resonant systems. The latent release of stored energy is audible and measurable.
Audible with <15hz tuning? Meaning you can hear ringing occuring for the reproduction of say 5hz material? You must have superior hearing to common folk like me.

1b. Other forms of self noise are also less audible in a sealed sub.
Maybe, if you like to sit 6" from your sub's port.

2a. The dual knee curve with 4th order roll off of the EBS ported sub in no way can be construed as 'flatter' than the low Q, single knee, with a 2nd order roll off curve of the sealed sub.
So which one of these is flatter?

http://gallery.avsforum.com/data/507/RedSLLT.jpg

If you picked blue, you picked ported ;)

2c. The transient response of the sealed sub is better than the ported sub, which is the only evidence required to prove the claim of 2a.
Hmm, a bit misleading. The transient response is better when frequencies near and below tuning of the ported sub are played. At about an octave above tuning, they are near identical in equally sized enclosures. When the ported sub uses a muh larger enclosure than the sealed, the ported will be even better in this regard in higher bass frequencies.

So, you have to ask yourself, what's more important - less group delay in the infrasonic range where bass is tactile and not audible, or more clean headroom with a naturally flatter FR in that same region? If you picked the latter, you picked ported again ;)

I bought my Cerwin-Vega HT-12 PWR after reading the review of 10 different subs by Tom Nousaine. The top rated sub was a $900, 12 inch HSU. The 2nd highest rated sub was the Cerwin-Vega. I am very very happy with it, especially with remote volume control for $378 delivered. It did 105.9 db from 25-50Hz in the test by Nousaine. I have enough confidence in the reviews by Tom Nousaine to have bought the C-V without ever hearing it.

If money were not an object, I would get 2 Velodyne DD-18s in Maple. Still, I decided to save $4,000 and get 2 HSU VTF-3HOs plus Turbos. They are set at one notch above minimum on the gain control. I have considered adding the Velodyne SMS-1, however, instead of that, I would get the HSU MBM-12, for an extra 10 db of headroom in the 50-80Hz range. Takes too much time to explain how an MBM-12 can substitute for a Velodyne SMS-1.

I think that Steve got it right: flat FR, low distortion, deep extension, and high headroom.

All the Best

2b. A sealed sub with a system Q of .5 does not have the requirement of being larger than a sealed sub with a properly designed air spring.


Curious, Do you say this because filters can be used to adjust the system Q?

Dr V

1a. Ported subs are resonant systems. The latent release of stored energy is audible and measurable.

Sure it is. It audibly extends the low-end. :)

1b. Other forms of self noise are also less audible in a sealed sub.

Maybe, maybe not. Motor noise generally isn't an issue in either ported or sealed systems, except for types that are if anything more common in sealed systems such as voice-coils bottoming out or the hollow thwack that sometimes comes from issues with the currently-fashionable spun metal dish cones. Self noise (assuming well-designed woofers with lots of ventilation) is really only a problem in dipole or U-frame subs.

2a. The dual knee curve with 4th order roll off of the EBS ported sub in no way can be construed as 'flatter' than the low Q, single knee, with a 2nd order roll off curve of the sealed sub.

Sure it can. It depends on the bandwidth over which it is used.

2b. A sealed sub with a system Q of .5 does not have the requirement of being larger than a sealed sub with a properly designed air spring.

How do you figure that? Please provide a real world example of a system with an F3 of at least 40Hz and a box requirement that's no larger for a Qtc=0.5 than an acoustic suspension (as defined in Dickason) enclosure. You may well be right, but I've never seen such a thing, so I'd be interested in doing so.

Unless, of course, you're writing about a Linkwitz Transform. But if you're inveighing against use of highpass filters on ported boxes, surely you wouldn't suggest such a processed solution as an LT. Moreover, with one exception (using JBL's phenomenal W15GTi woofer with its dual-coil/dual-gap DDD motor) I've never found LT'ed systems to be as satisfying as systems in natively low-Q enclosures and just FR equalization to bring the low end up to the same levels as the upper bass. The big issue with LT's, of course, is power compression. Sure, one can use multiple LT'ed subs, but the point of an LT is to save space so that's counterproductive. Also, drivers cost much more than wood does.

2c. The transient response of the sealed sub is better than the ported sub, which is the only evidence required to prove the claim of 2a.

Depends on what you mean by "transient response," I guess. Also, the bandwidth over which one expects the sub to operate.

3. The sealed sub offers lower extension than even the lowest tuned EBS ported sub by orders of magnitude. Just click on the graph posted below and realize that only the 2nd order filters at 3Hz in the player (not employed in the chain that generated the graph) and amp limit the response to DC, which extension is not possible with a ported sub.

Technically true, but entirely irrelevant. Assuming you don't go completely insane, (http://www.danleysoundlabs.com/matterhorn.htm) domestic subwoofers are limited in SPL down low by their volume displacement. Because of the limits of the human bass reception system (face and chest, not ears), most even remotely practical domestic subwoofers - even the multi-driver I-B manifolds - are useless below ~12Hz. Certainly, over an operating range of 16-80Hz it is not only possible but easy to get higher low-end output from an EBS-style ported sub than a sealed one.

4. The sealed sub occupies much less real estate, especially in the case of lower and lower tuning of an EBS ported sub.

Nope. Low end efficiency is a function of box volume. Take any given box volume, and add a low-tuned passive radiator, and you will get more low end efficiency.

This makes the single driver comparisons irrelevant. Why impose restrictions on one alignment, but none on the other? The debate is as to which alignment performs best, not it's size and/or driver/amplifier compliment.

Who's imposing "restrictions" on anything, exactly?

6. The ported sub unloads below tune, generating very unmusical noise at levels that vary in direct proportion to the frequency response of the upstream electronics, up to and including driver failure. This can be remedied by use of a HP filter, which has it's added performance negatives.

Yes, unloading below tuning frequency is an issue, but high-pass filters can easily fix it.

Also, of course, a sealed sub that is overdriven can fail just as readily as a vented subwoofer used poorly. Moreover, because of its lower efficiency, a sealed sub will suffer from greater power compression than a vented subwoofer.

I'd say in this debate I'm more a slut than a partisan. :) I've used both ported/PR and sealed alignments, and I'm interested in experimenting with tapped horns and bandpass boxes. I recognize that each type has its advantages and disadvantages. Much more the issue than the ultimate bass alignment, I think, is integration with the mains. That's one area where I do think ports hurt matters. (So do high-Q midbass sealed subsystems, a la the KEF/BBC LS3/5a.) Not ports on the sub(s), mind, but ports on the mains. When I'm having trouble getting a stereo to sound with one voice, one of the first things I do is plug the mains' ports. Often, that makes things a great deal easier.

1a. Ported subs are resonant systems. The latent release of stored energy is audible and measurable.

1b. Other forms of self noise are also less audible in a sealed sub.

2a. The dual knee curve with 4th order roll off of the EBS ported sub in no way can be construed as 'flatter' than the low Q, single knee, with a 2nd order roll off curve of the sealed sub.

2b. A sealed sub with a system Q of .5 does not have the requirement of being larger than a sealed sub with a properly designed air spring.

2c. The transient response of the sealed sub is better than the ported sub, which is the only evidence required to prove the claim of 2a.

3. The sealed sub offers lower extension than even the lowest tuned EBS ported sub by orders of magnitude. Just click on the graph posted below and realize that only the 2nd order filters at 3Hz in the player (not employed in the chain that generated the graph) and amp limit the response to DC, which extension is not possible with a ported sub.

Arguments as to whether or not the extension/roll off is an audible improvement assume that one has (a) the capability to reproduce the extended response and (b) has compared the two curves being discussed under proper conditions. ;)

4. The sealed sub occupies much less real estate, especially in the case of lower and lower tuning of an EBS ported sub. This makes the single driver comparisons irrelevant. Why impose restrictions on one alignment, but none on the other? The debate is as to which alignment performs best, not it's size and/or driver/amplifier compliment.

6. The ported sub unloads below tune, generating very unmusical noise at levels that vary in direct proportion to the frequency response of the upstream electronics, up to and including driver failure. This can be remedied by use of a HP filter, which has it's added performance negatives.

7. Headroom is a non issue, as it's assumed that the correct number of subwoofers is employed to suit the application.

The disputes over the above facts in these forums are legendary, but do not change the facts.

Bosso

It is doubtful that anyone in these boards has built and tested as many different designs as has Bosso. Three years ago, I was firmly in the ported subwoofer camp.

After dozens of blind tests, in which sealed subwoofers have been better sounding than ported and/or PR subwoofers, I am in agreement with Bosso.

The one "however" is this: For state of the art, nothing beats multiple sealed subs, or multiple drivers in a sealed box. The sealed option WILL cost more than its ported counterpart.

DS-21 ... If you look around the DIY section here, the popular alignment is an EBS with 240 liters as a minimum for net volume and a single driver ... and they go up to about 650 liters with a single driver.

Take the same cabinet, and place 2-4 drivers in a sealed alignment, and it will be audibly superior to the ported design. It will also cost more to build.

To some, dollars per dB is the barometer. To others, it dB per square foot, cost no object.

Take the same cabinet, and place 2-4 drivers in a sealed alignment, and it will be audibly superior to the ported design. It will also cost more to build.
correct. However, as you mentioned, it will cost multiple factors to build it (multi-drivers, more power, possible LT for added extension). One of the reasons, IMO, that IB is such an attractive alignment is that your only real cost increase is the drivers; no real estate impact, slight increase in power consumption, sealed characteristic. The cabinet at this point is out of the picture.

To some, dollars per dB is the barometer. To others, it dB per square foot, cost no object.
I can agree to this.

I said a "sealed sub does not move air during negative excursion". I did not say it clips the negative side of the input signal. The negative side of the input signal moves the woofer to the negative position from equilibrium and rarefies the air. When I say does not move, I mean does not compress. Clear?.

Kinda, maybe. :rolleyes: Moving and compressing are two different things. If a driver literally does not move air then it is effectively eliminating that part of the signal, which is why I used the electrical term clipping.

There are several indications on-line where sealed and acoustic suspension are used synonymously. As long as you understand what I mean, that's what matters.

Sorry, but this is not going to fly. Acoustic suspension is a patented design in which the woofer compliance and enclosure volume are crtitical for it's functioning. I don't know what the "several indications on line" are, but the're just not very precise or even factual.

People on this board are entitled to factual information, so it is not whether I understand it or not that matters . It's an issue of providing accurate information.

Sorry, but this is not going to fly. Acoustic suspension is a patented design in which the woofer compliance and enclosure volume are crtitical for it's functioning. I don't know what the "several indications on line" are, but the're just not very precise or even factual.

People on this board are entitled to factual information, so it is not whether I understand it or not that matters . It's an issue of providing accurate information.
If you don't know, here are a couple. If the terminology bugs you, write to them and ask them to not call sealed/closed boxes as acoustic suspensions.

http://en.wikipedia.org/wiki/Loudspeaker_enclosure
http://electronics.howstuffworks.com/speaker9.htm

Agreed, people here are entitled to factual information. What are you insinuating?

If you don't know, here are a couple. If the terminology bugs you, write to them and ask them to not call sealed/closed boxes as acoustic suspensions.

http://en.wikipedia.org/wiki/Loudspeaker_enclosure
http://electronics.howstuffworks.com/speaker9.htm

Agreed, people here are entitled to factual information. What are you insinuating?

No insinuation. The information you provided is NOT accurate. Sealed and acoustic suspension are not the same thing.

If you look carefully at the Wikipedia site you will see tah acoustic suspension and IB are in two different parragraphs. A sealed enclosure can be IB or acoustic suspension. But they are not the same thing.

Kinda, maybe. :rolleyes: Moving and compressing are two different things. If a driver literally does not move air then it is effectively eliminating that part of the signal, which is why I used the electrical term clipping.
No it does not eliminate the negative part of the signal. Depends on what direction it is moving. IN the negative cycle, the volume inside the sealed box reduces, pressure increases (Boyles Law). It is not compressing air outside the box yet. In a way stored as potential energy inside the box, to be released when the driver moves out and compresses.

No insinuation. The information you provided is NOT accurate. Sealed and acoustic suspension are not the same thing.
Not what I provide, then it is the links that they provide. As I said, write to them if it bugs you as not being "ACCURATE".

Not what I provide, then it is the links that they provide. As I said, write to them if it bugs you as not being "ACCURATE".

What are you a politician?

What bugs me is people like you providing misleading and inaccurate information and then trying to weasle out of it.

What is so hard to understand that closed baffles are of two types:
1) IB
2) Acoustic suspension

And that they are different and not interchangeable. No matter what technobable website you get your information from!

Is there a problem with the water or air in Oregon?

What are you a politician?

What bugs me is people like you providing misleading and inaccurate information and then trying to weasle out of it.

What is so hard to understand that closed baffles are of two types:
1) IB
2) Acoustic suspension

And that they are different and not interchangeable. No matter what technobable website you get your information from!
No weasling out here. I have a fundamental problem here and that is your logical reasoning.

There is a Class A and it has two types, type X and type Y.
I can refer to type Y as Class A because it belongs to the set of Class A.
Just because I say type Y is class A, does not negate type X also being class A. Also just becuase I don't enumerate both type X and type Y and distinguish them, does not making call type Y as Class A misleading.
My problem with people like you is that you have a set way of thinking. Anything outside that, and you think it is wrong or incorrect. Worse, you correct people based on your poor reasoning skills.
Now talking normal language. If a sealed box can be an acoustic suspension or IB, there is nothing wrong or misleading in calling a sealed box an acoustic suspension.
I don't understand why something this trivial should lead to such stupid arguments when we can all learn something more keeping the topic at hand being discussed in mind.
Not a politician. Just a mad scientist :D.

John, for our purposes I think we can safely consider sealed and acoustic suspension to mean the same thing. When we refer to "sealed", I believe it to mean that the enclosure is small enough to provide some sort of dampening of cone movement while IB if sealed, is so large as to have an insignificant effect on cone movement. Your argument seems to be one of semantics.

John, for our purposes I think we can safely consider sealed and acoustic suspension to mean the same thing. When we refer to "sealed", I believe it to mean that the enclosure is small enough to provide some sort of dampening of cone movement while IB if sealed, is so large as to have an insignificant effect on cone movement. Your argument seems to be one of semantics.
Thank you Mike. I feel I was wasting my breath. Let's move on..

I'd say in this debate I'm more a slut than a partisan. :) I've used both ported/PR and sealed alignments, and I'm interested in experimenting with tapped horns and bandpass boxes. I recognize that each type has its advantages and disadvantages. Much more the issue than the ultimate bass alignment, I think, is integration with the mains. That's one area where I do think ports hurt matters. (So do high-Q midbass sealed subsystems, a la the KEF/BBC LS3/5a.) Not ports on the sub(s), mind, but ports on the mains. When I'm having trouble getting a stereo to sound with one voice, one of the first things I do is plug the mains' ports. Often, that makes things a great deal easier.



I agree with that. I am glad that my mains are acoustic suspension type of design. Or are they sealed???

No problem with the water, but the pollution from Cali is starting to infiltrate our state!

The acoustic suspension principle revolutionised the loudspeaker industry in the late fifties. Based on a mathematical model of woofer behaviour in tandem with the air in a speaker cabinet, it provides a way to design a small speaker system (as opposed to the refrigerator sized monsters previously used to get halfway decent bass) with effective, linear low frequency response.

Acoustic Research, Inc. (“AR”) was founded in 1952[1] and incorporated on August 10, 1954 by audio pioneer, writer, inventor, researcher and audio-electronics teacher Edgar Villchur and his student, Henry Kloss. AR was established to produce the $185 model AR-1, a loudspeaker design incorporating the acoustic suspension principle based on patent US No. 2,775,309, granted to Edgar Villchur and assigned to Acoustic Research in 1956.

Those that wish to remain ignorant may ignore the facts.

The acoustic suspension principle revolutionised the loudspeaker industry in the late fifties. Based on a mathematical model of woofer behaviour in tandem with the air in a speaker cabinet, it provides a way to design a small speaker system (as opposed to the refrigerator sized monsters previously used to get halfway decent bass) with effective, linear low frequency response.

Acoustic Research, Inc. (“AR”) was founded in 1952[1] and incorporated on August 10, 1954 by audio pioneer, writer, inventor, researcher and audio-electronics teacher Edgar Villchur and his student, Henry Kloss. AR was established to produce the $185 model AR-1, a loudspeaker design incorporating the acoustic suspension principle based on patent US No. 2,775,309, granted to Edgar Villchur and assigned to Acoustic Research in 1956.

Those that wish to remain ignorant may ignore the facts.
John,
For the record, I already know what you mentioned about AR.
This is a matter of semantics as Mike said. You contribute some good information from what I know about you in past threads. Leave this behind. Seriously, this is not a big misleading issue. Can we move on?
Thanks,
-Jai

BTW, just for the record wikipedia should NOT be a reference for anything. Anyone can put anything in there that may or may not be even losely related to facts.

http://www.danleysoundlabs.com/images/Matterhorn%20Finished.jpg
W-O-W :eek: :eek: :eek:

First time I have seen that project. 105db from 250 meters away, solid to 12hz.....nice.

Not to get on a soap box on this but in my early days of researching AV systems, I recognized the foolishness of asking general subjective questions on Forums.
Nah.....thats what makes reading this stuff fun.

Sorry but sealed and acoustic suspension are not the same. Sealed designs have been around since the invention of the loudspeaker.

Acoustic supension was invented by AR (Acoustic Research) in the mid sixties, if my memory serves me right. A specially designed woofer with very loose suspension is placed in an air-tight chamber. The chamber acts as the "suspension" for the driver instead of the spider-cone surround combination of regular woofers. The cabinet had to be kept small, by design, because it needed to provide the woofer the necessary amount of resistance. This design enabled them to produce a small bookeshelf that produced real deep bass. The caveat was they were very inefficient.
The AR-1 was their very first speaker followed by the AR-2 and AR-3.
Wrong. Sealed and "Acoustic Suspension" are exactly the same thing.

Just because Henry Kloss called his sealed enclosures "acoustic suspension" doesn't mean they are different things.

Granted some possibly unique engineering goes into a true acoustic suspension speaker, such as the loose or floppy woofer you mentioned earlier, to achieve high excursion. It is still a sealed box.

As for the argument about IB speakers.....2 woofers sitting on a baffle in the trunk of a car against the rear seat qualifies as a IB. Because the trunk of a car is definitely not ported I guess you'd have to say it's sealed.

At what size point does the box transition from acoustic suspension to sealed and finally to IB?

Wrong. Sealed and "Acoustic Suspension" are exactly the same thing.

See how you are? Now that's just gonna cause John to use fonts that are even bigger and bolder than before! ;)

Sorry Jai, John is right.

It really only boils down to what you define as a sealed box.

All acoustic suspension designs are forms of sealed box designs.

All infinite baffle designs are forms of sealed boxes.

An acoustic suspension design is, by the vast majority of conventional definitions, not an infinite baffle design.

So, a sealed design is not always an acoustic suspension design.

As I recall previous texts on the topic and the AR patent define acoustic suspension as a design where the compliance (stiffness) of the box is dominant over that of the driver suspension. As a rule of thumb, that's a point where box volume is less than 1/3rd Vas. Note that Vas is a lumped parameter of compliance and cone area. Larger boxes are of course still sealed designs, but do not fit the classic definition of acoustic suspension.

Note that the definition of IB has also become more fuzzy over time. Early texts simply define all sealed enclosures to fit into two subsets. The first being acoustic suspension as I noted, and then all larger enclosures to be of the "infinite baffle" type. This is why you will occasionally see older sealed speakers referred to as "infinite baffle." Only more recently in communities like the Cult of the Infinitely Baffled has the implied definition of IB come to be a box that is >10x Vas. This is in fact the opposite of acoustic suspension, where the compliance of the box becomes insignificant as compared to that of the driver. Inbetween these two cases lie a range of sealed boxes where the driver and box both contribute to the total compliance.

See how you are? Now that's just gonna cause John to use fonts that are even bigger and bolder than before! ;)
I know that was odd. I've never seen someone "yell" like that before here on AVS forums. :p

The one "however" is this: For state of the art, nothing beats multiple sealed subs, or multiple drivers in a sealed box. The sealed option WILL cost more than its ported counterpart.

DS-21 ... If you look around the DIY section here, the popular alignment is an EBS with 240 liters as a minimum for net volume and a single driver ... and they go up to about 650 liters with a single driver.

Take the same cabinet, and place 2-4 drivers in a sealed alignment, and it will be audibly superior to the ported design. It will also cost more to build.

To some, dollars per dB is the barometer. To others, it dB per square foot, cost no object.

Great summation craig. While probably heresy for me to claim considering I have a potent sealed sub, but I'm not of the thought that multiple sealed drivers will be the absolute best sounding design, but they are at the top of the list and are easier to make perform well than other competing options.

I can also say that when people have asked me what would be an ultimate sound quality and performance subwoofer system, a ported design is not at the top of the list of options I'd consider. That is not to say that a well designed ported sub can't be made to sound extremely good, but rather I see it as a value/performance choice best suited to larger enclosures with lower power density (SPL/box volume).

At what size point does the box transition from acoustic suspension to sealed and finally to IB?
common practice it to go 10x the Vas value of the drivers.

DS-21 ... If you look around the DIY section here, the popular alignment is an EBS with 240 liters as a minimum for net volume and a single driver ... and they go up to about 650 liters with a single driver.

Take the same cabinet, and place 2-4 drivers in a sealed alignment, and it will be audibly superior to the ported design. It will also cost more to build.

Four of the same drivers drivers, probably. Two, debatable. Maybe less so if one mounts them push-pull to cancel out some driver nonlinearities. Of course, the aesthetics of multiple drivers are an issue, too. A single driver gives one much greater flexibility in terms of cabinet shape and finishing. But frankly, having read through the DIY section on occasion I've found most of the recommended subs really don't have much to do with anything but getting the lowest F3 on a graph. One can do just fine with smaller enclosures, provide one knows what s/he's doing. Not to mention that often a very low modeled F3 leads to excessively boosted bass in a real room. Not that one can't use EQ to dial it down, and certainly too much low end capability is better than not enough. Still, I prefer to design my ported subwoofers to have a shallow "knee" in the response that correlates with room measurements. Here's (http://www.audioheritage.org/vbulletin/showthread.php?t=7365) an example, a thread about my old pair of subwoofers.

To some, dollars per dB is the barometer. To others, it dB per square foot, cost no object.

And to everyone but the richest or most simpleminded, it's more complicated than that: best sonic performance per square foot and/or cubic volume per currency outlay by aesthetic impact. The relative weights of each differ from individual to individual.

But more to the point, what most people consider "subwoofer sound" is really just integration between subs and mains. In my experience, neither sealed nor ported subwoofers have an advantage in that respect. What very clearly do have an advantage in integration ease (the Peerless XLS being a curious exception) are low-inductance subwoofers. I never understood why everyone went gaga over the first several rounds of overhung TC Sounds woofers. (Mostly sold through Stryke Audio and the car-fi firm Eclipse.) Yes, they looked kind of cool. Yes, they could good extremely low extremely loudly, with excursion figures that nobody else at the time (except for Aura, with the expensive 1808/Seismic 8196) could touch. Yet every time I heard one it sounded truly awful, and both of the ones I measured had off-the-charts inductance values. IMO, the first listenable overhung TC woofer was the TC2+. And what changed with the TC2+? Inductance, reduced by a factor of more than four compared to some 3HP motor Stryke HE15's I've measured thanks to the insertion of copper Faraday sleeves into the motor. My point here is that integration should come first, and what has mattered IME for integration are tuning skill and motor design. Enclosure type, assuming competent modeling and post-listening tweaking, does not seem to be a factor.

Sorry Jai, John is right.

It really only boils down to what you define as a sealed box.

All acoustic suspension designs are forms of sealed box designs.

All infinite baffle designs are forms of sealed boxes.

An acoustic suspension design is, by the vast majority of conventional definitions, not an infinite baffle design.

So, a sealed design is not always an acoustic suspension design.

Agreed. John is right about the definitions, wrong about saying that I am posting inaccurate information.
Sealed design is not always an acoustic suspension, but an acoustic suspsension is always sealed right? Vast mojority of sealed are acoustic suspensions, so it is still ok to use them interchangeably unless someone is trying to distinguish between each of the sealed designs. That is not what I was trying to do.
We are getting too much hung up with terminology here.

Agreed. John is right about the definitions, wrong about saying that I am posting inaccurate information.
Sealed design is not always an acoustic suspension, but an acoustic suspsension is always sealed right? Vast mojority of sealed are acoustic suspensions, so it is still ok to use them interchangeably unless someone is trying to distinguish between each of the sealed designs.

It depends. Do you call every rectangle you see a square? If so, feel free to call every closed box you see an AS.

Also, most closed boxes one sees are not AS. In fact, AS enclosures are relatively rare, and most of the woofers built and sold today are not designed for them (by "designed for them" I mean loose suspension, very high compliance, etc.) The last commonly-available long-throw woofer I can recall that was really designed for AS use was the NHT1259.

Agreed...
Sealed design is not always an acoustic suspension, but an acoustic suspsension is always sealed right?

Right.


Vast mojority of sealed are acoustic suspensions, so it is still ok to use them interchangeably unless someone is trying to distinguish between each of the sealed designs. That is not what I was trying to do.
We are getting too much hung up with terminology here.

Terminology and vocabulary are what allow clear communication. A large percentage of confusion and banter here comes from people inferring different meanings to terms that should have fairly clear definitions.

It is incorrect or in no-way certain to say that the vast majority of sealed boxes are acoustic suspension per earlier definition. This is especially true with many commonly available high excursion drivers. My own perogative is that the only reason to use the term acoustic suspsension is to call attention to the box's dominance over the compliance; otherwise it's just another sealed box.

Agreed. John is right about the definitions, wrong about saying that I am posting inaccurate information.
Sealed design is not always an acoustic suspension, but an acoustic suspsension is always sealed right? Vast mojority of sealed are acoustic suspensions, so it is still ok to use them interchangeably unless someone is trying to distinguish between each of the sealed designs. That is not what I was trying to do.
We are getting too much hung up with terminology here.

Wrong again! The vast majority of sealed designs are not acoustic suspension.
Quoting Mark Seaton: "It is incorrect or in no-way certain to say that the vast majority of sealed boxes are acoustic suspension per earlier definition." So it is not OK to use them interchangeably. You are wrong but are too thick headed to admit it.

http://www.lolimacyb.org/upload/files/1/GIFs/vault%20fault.gif

Right.



Terminology and vocabulary are what allow clear communication. A large percentage of confusion and banter here comes from people inferring different meanings to terms that should have fairly clear definitions.

It is incorrect or in no-way certain to say that the vast majority of sealed boxes are acoustic suspension per earlier definition. This is especially true with many commonly available high excursion drivers. My own perogative is that the only reason to use the term acoustic suspsension is to call attention to the box's dominance over the compliance; otherwise it's just another sealed box.
In the context of what I was talking about, there was no confusion. Acoustic suspension was used in brackets (post #35) and someone just decided to nit-pick on it. It was not used to explain anything later, just in that post until it was picked on. Many a times people refer to sealed and acoustic suspension interchangeably. That is the only reason I used it.

Wrong again! The vast majority of sealed designs are not acoustic suspension.
Quoting Mark Seaton: "It is incorrect or in no-way certain to say that the vast majority of sealed boxes are acoustic suspension per earlier definition." So it is not OK to use them interchangeably. You are wrong but are too thick headed to admit it.
OK! So you don't want to let this go. How many types of sealed boxes are there?
Let's see who has a thick head and who has a tough neck. I admit when I am wrong and I have been in the past. In this context, you are making a mountain of something very small. Let's break this down logically and investigate.

alright...we need to settle this terminology in VERY simple terms for future reference.

I propose a step-by-step breakdown:











































http://i156.photobucket.com/albums/t25/messy0786/dickinabox.gif






:p

but seriously, lets get back to topic here.

alright...we need to settle this terminology in VERY simple terms for future reference.

.....
:p

but seriously, lets get back to topic here.
My hope too :p . Maybe I should simply ignore stupid comments about "acoustic suspension" blah blah blah yada yada yada... you are inaccurate, you are blah blah blah.

Funny thing is, I doubt we all could agree as to what the definition of a subwoofer is. When exactly is a woofer not just a woofer, but a becomes a subwoofer.

The comments about performance per dollar and cost no object are plain BS. If somebody really approached building a subwoofer with a cost no object mentality, then size would never be an issue either, as they could just build an addition to their house to use as a discrete enclosure for 50 18" drivers or so. And their home theaters wouldn't look like they did either if cost was no object. It's a lame excuse at covering up the WAF they have to put up with. Everybody is looking for the most performance per dollar.

The comments about performance per dollar and cost no object are plain BS. If somebody really approached building a subwoofer with a cost no object mentality, then size would never be an issue either, as they could just build an addition to their house to use as a discrete enclosure for 50 18" drivers or so. And their home theaters wouldn't look like they did either if cost was no object. It's a lame excuse at covering up the WAF they have to put up with. Everybody is looking for the most performance per dollar.


True,cost not being an object,size constraints are gone. WAF...throw this out the window.

I must respectfully disagree, for many performance is actually low on the list. Looks and brand recognition as well as what the installer suggests are bigger factors when we are talking "no budget" in the real world which does not live here in AVS.

I also don't see how cost is related directly to size - just because I can afford a $100,000 subwoofer does not mean I am willing to make other sacrifices or need to. Perhaps my design goal is best output possible from a 1'x1' box and the budget is unlimited to hit that goal.

OK! So you don't want to let this go. How many types of sealed boxes are there?
Let's see who has a thick head and who has a tough neck. I admit when I am wrong and I have been in the past. In this context, you are making a mountain of something very small. Let's break this down logically and investigate.

I've said enough. You have exposed yourself as a missinformed, cementheaded technobable and have done so all by yourself. There's nothing to "break down logically and investigate" since you are neither logical nor want to search the truth.

The comments about performance per dollar and cost no object are plain BS. If somebody really approached building a subwoofer with a cost no object mentality, then size would never be an issue either, as they could just build an addition to their house to use as a discrete enclosure for 50 18" drivers or so. And their home theaters wouldn't look like they did either if cost was no object. It's a lame excuse at covering up the WAF they have to put up with. Everybody is looking for the most performance per dollar.

Discussion of "cost-no-object" concepts tend to be pointless because any REAL situation will face some practical limits to the space occupied, physical size and aesthetic of the various parts and pieces. Without a context of application and use, you can't pin down the relative value of various characteristics.

I've built a couple of IB's as well as ported boxes built into crawl spaces, attics and un-stair cavities, as well as building subs specifically to use the particular space available. Utilization of space is always the biggest battle and one where people need to get creative. For any given design type, box size can trump power and driver technology in getting lower, louder, or cleaner.

Sure, you can "fit" HUGE enclosures in a room, or even stacks of smaller boxes of the same total size. That is not to say that we will WANT to do that. The ultimate point of reconing comes when you have two designs next to eachother and one is 1/4 the size of the larger, and they perform very similarly. You guessed it, the smaller box will be more expensive if from the same maker. The choice of if you save the money on the larger sub, save space with the smaller sub, or buy 2 of the larger subs instead of one of the smaller, is a very personal decision which has many influences, WAF influenced or not, and that answer will vary greatly from one person to the next.

The choice of if you save the money on the larger sub, save space with the smaller sub, or buy 2 of the larger subs instead of one of the smaller, is a very personal decision which has many influences, WAF influenced or not, and that answer will vary greatly from one person to the next.

Words of wisdom here. I just "upgraded" not to something bigger, louder or even better, but smaller. It was not the wife, but I that was tired of looking at big black boxes (and tubes) all over the family room.

I've said enough. You have exposed yourself as a missinformed, cementheaded technobable and have done so all by yourself. There's nothing to "break down logically and investigate" since you are neither logical nor want to search the truth.
If I start calling names, it will get ugly, so I will still tackle this logically.
There are 2 commonly used types, namely 1. IB and 2. Acoustic suspension.
I was not talking about large IBs in our discussion. I was referring to small ones. If they are not called acoustic suspensions, then they don't have a name of their own. You can simply call them sealed subs but which sealed sub (IB or AS?).
John, those were some pretty rude comments, not called for. Since you could not argue with valid logical points you are resorting to calling names. I don't want to call you a loser since you may not be one in real life. But don't behave this way.
After all this is a box we are talking about. So cool down ;). We can agree to disagree.

Great summation craig. While probably heresy for me to claim considering I have a potent sealed sub, but I'm not of the thought that multiple sealed drivers will be the absolute best sounding design, but they are at the top of the list and are easier to make perform well than other competing options.

I can also say that when people have asked me what would be an ultimate sound quality and performance subwoofer system, a ported design is not at the top of the list of options I'd consider. That is not to say that a well designed ported sub can't be made to sound extremely good, but rather I see it as a value/performance choice best suited to larger enclosures with lower power density (SPL/box volume).

Mark ... It will be fascinating and fun to finally get to hear the BMF you are designing for AV123. Heck, it will be fun to read about the manufacturing process ... even though it is a relatively large enclosure for a commercial sub, it packs a 15 inch active and three 18 inch passives into one enclosure. Plus, of course, the amp has to go there, and the mounting internally for the 15 ...

You have heard the mule, and liked the results. Having watched enough designs take shape from the prototype to the finished product at my brother's place, the manufacturing of your brainchild should be something to witness.

You are correct, of course ... a ported sub can sound excellent.

Can of worms? What can of worms?

Perhaps my design goal is best output possible from a 1'x1' box and the budget is unlimited to hit that goal.
If the budget is unlimited, why would one be constrained to such a set of circumstances to begin with? The reason is because the budget is NOT truly unlimited.

Many CUSTOMERS want high output, some want real depth, some want musicality (low distortion, etc) but many, many want (or need) small enclosures , and they are willing to pay lots for it....most here know that if you don't mind a big ported box, you can get high output at low frequencies fairly inexpensively, but when you get enough money to properly decorate and entertain, the water heater may have to move elsewhere.

No matter what budget there is only so much air a very small sub can move.All small subs are major sacrifices,some better hidden than others.

JL simply maximised the quality and quantity of bass at the expense of higher THD,THD that does not bother human hearing unless very high(refers to deep bass here).

Velo DD series trade extra output for low distortion. And the best compact subs no matter how high end will be compromised.

With all this in mind the compact sub is here to stay.As performance has reached quite high.

Many CUSTOMERS want high output, some want real depth, some want musicality (low distortion, etc) but many, many want (or need) small enclosures , and they are willing to pay lots for it....most here know that if you don't mind a big ported box, you can get high output at low frequencies fairly inexpensively, but when you get enough money to properly decorate and entertain, the water heater may have to move elsewhere.
You're missing the point entirely. Why do these people need small subs to begin with? If they truely had an unlimited budget, they could build a dedicated HT room with built in space for massive subwoofage. Since they don't, and they are likely using a living room, basement, or recreation room as their home theater space - and many have to do what their wife tells them - they find themsleves having to compromise on size. So the fact of the matter is that "cost no object" is BS, and enthusiasts are trying to get the most performance for their dollar, whether they are comparing small subs or large subs. Large subs just happen to have the advantage of being able to offer more performance.

You're missing the point entirely. Why do these people need small subs to begin with? If they truely had an unlimited budget, they could build a dedicated HT room with built in space for massive subwoofage. Since they don't, and they are likely using a living room, basement, or recreation room as their home theater space - and many have to do what their wife tells them - they find themsleves having to compromise on size. So the fact of the matter is that "cost no object" is BS, and enthusiasts are trying to get the most performance for their dollar, whether they are comparing small subs or large subs. Large subs just happen to have the advantage of being able to offer more performance.
so what you saying is.......

You're missing the point entirely. Why do these people need small subs to begin with? If they truely had an unlimited budget, they could build a dedicated HT room with built in space for massive subwoofage. Since they don't, and they are likely using a living room, basement, or recreation room as their home theater space - and many have to do what their wife tells them - they find themsleves having to compromise on size. So the fact of the matter is that "cost no object" is BS, and enthusiasts are trying to get the most performance for their dollar, whether they are comparing small subs or large subs. Large subs just happen to have the advantage of being able to offer more performance.

Talk about missing the point! Did you bother to read tweeterex's post? You seem to think that anyone unwilling to have a huge cardboard tube wrapped in carpet in their HT/living space is wupped. Perhaps when you grow up (seems unlikely at this point), get a good paying job and move out of the apartment, you may think differently. Not wanting one of those hideous looking creations in the home is not a WAF issue; it is a MAF (My Approval Factor).

Let's play nice. :)

I agree with the MAF factor. I am sure I am not in the majority, but I would rather not see my sub. I like to have it as small as possible and/or tucked away and not a piece of furniture or obtrusive object. I will gladly pay more for a smaller sub even if there are some sacrifices that have to be made.

Talk about missing the point! Did you bother to read tweeterex's post? You seem to think that anyone unwilling to have a huge cardboard tube wrapped in carpet in their HT/living space is wupped. Perhaps when you grow up (seems unlikely at this point), get a good paying job and move out of the apartment, you may think differently. Not wanting one of those hideous looking creations in the home is not a WAF issue; it is a MAF (My Approval Factor).
so Rob, what you saying is........ :p

so what you saying is........ :p

What he is saying is there is no one way to do things right,and gigantic carboard tubes are not the best way to go for everyone. :p


The way some hard core DIY people go you would need a dedicated room with an all out IB system,making even your giant tubes perform poorly in comparison!

Take a few dozen massive 18" woofers,build a structure as inert as possible to mount them,reinforce the room to eliminate wall,floor and celling flex and you are almost there. Very very practical if your budget is ...Gates like.Not many here did this,not even in the Poupon 20K forum! That is how realistic it is.

After add as many fan subs as it takes to have perfectly linear response down to 1Hz all this with a celling of at least 130dB to please the future hearing aid club members! Voila

The performance of a sealed system has little more to do with size than the drivers selected for the design.

Take the TCSounds TC3K driver. It's designed for a small box. Will you get more from them by putting them in a bigger box? No. You'll maybe gain a dB or 2 of output below 20Hz, but the price is losing the excursion protection of a smaller box and the extra output is not clean output.

Brian Ding has written some great info on excursion curve optimization that's worth reading. This is best achieved by manipulation of the input signal in careful design with the driver, box and amplification parameters.

WAF has little to do with the subs I use in my HT. My wife digs low end (she married a bass player...duh) and couldn't care less what system I employ to achieve it. OTOH, she certainly wouldn't appreciate car rug as a finish material, especially if you're talking a LOT of it. Neither would I.

The bottom line is that you simply don't need an extremely large box to achieve great low freqs to VLF. In fact, it can be easily achieved using relatively very small boxes.

As far as the alleged huge difference in price, you simply double the driver compliment and double the available amp power and you not only match the ported sub's output at tune, you add 6dB of headroom everywhere else in the sub's BW and 2 additional octaves of in-room extension.

If you design for a dual opposing driver configuration, you have the added benefit of a huge reduction in sympathetic resonant distortions.

What does that add to the cost? $500.00?

I've chosen to add a custom electronics path of very high quality that adds the benefits of flexibility in adapting the sub to the system and room as well as the sources being reproduced.

I also refuse to have a subwoofer system that looks like crap. This means added cost in finish materials and industrial design, but the added cost of an electronics path and exotic ID and materials is optional.

So, to put it into perspective, to achieve the output I have in a single, dual opposing driver, sealed system with 3KW amplification in 3 1/2 cubes, I'd have to trade for a box that's 4 times the size using a single driver with 1500 watts in a resonant system.

In the trade, I'd lose 6dB of headroom for music transients and lop off 2 octaves of low end, in-room extension, as well as settle for poorer GD and TR, not to mention the ability to have selectable tunes and Q, on-the-fly.

Arguing the audibility or non-audibilty of the differences in extension, GD and TR is a waste of discussion. Just ask yourself...which would you rather have? Better TR performance or worse TR performance? Extension to 10Hz, or extension to 3Hz? 7ms of GD or 50ms of GD? Case closed.

$500.00 for the added benefits seems like a bargain to me, but as I've said many, many times...price is irrelevant. A sub is worth what someone is willing to pay for it.

Bosso

Talk about missing the point! Did you bother to read tweeterex's post? You seem to think that anyone unwilling to have a huge cardboard tube wrapped in carpet in their HT/living space is wupped. Perhaps when you grow up (seems unlikely at this point), get a good paying job and move out of the apartment, you may think differently. Not wanting one of those hideous looking creations in the home is not a WAF issue; it is a MAF (My Approval Factor).
Clearly I'm not getting through, so let me try again. I'm not saying everyone has to build a giant tube sub - I don't think anything approaching those words came out of my mouth. I'm saying that if one's budget was truly unlimited, size would never be a contraint. If you don't want to have a big sub in your room, that is fine, you could build an adjacent room to use as the enclosure, line the connecting wall with drivers, and cover them with a cloth grill. It would be less intrusive than even the smallest box sub, as nothing is physically in the room. People don't do that however (royal device room aside), therefore claims that budget is unlimited or cost is no object are BS.

If I start calling names, it will get ugly, so I will still tackle this logically.
... Since you could not argue with valid logical points you are resorting to calling names. I don't want to call you a loser since you may not be one in real life. But don't behave this way.
After all this is a box we are talking about. So cool down ;). We can agree to disagree.

My points were very logical. What's ilogical about stating you were wrong when you posted that: "So let's briefly consider sealed (otherwise called acoustic suspension..."

So now for pointing out you made a mistake you are calling me a loser?

Let me sum this up: Hardly any sealed designs are acoustic suspension Whereas all acoustic suspension have to be sealed. You tried to convey that sealed and acoustic suspension were one and the same.

With me so far?

Rather than admitting you made a mistake you tried:
1) Quoting Wikipedia.
2) Saying they are almost the same.
3) We are talking only about a box.
4) We can agree to dissagree. (an original, no doubt)
and last but not least:
5) "...maybe I should simply ignore stupid comments about "acoustic suspension" blah blah blah yada yada yada... you are inaccurate, you are blah blah blah."

So the insults were started by you when you called my coments stupid. Which has made this already ugly.

The bottom line is that you simply don't need an extremely large box to achieve great low freqs to VLF. In fact, it can be easily achieved using relatively very small boxes.

Not really.

So, to put it into perspective, to achieve the output I have in a single, dual opposing driver, sealed system with 3KW amplification in 3 1/2 cubes, I'd have to trade for a box that's 4 times the size using a single driver with 1500 watts in a resonant system.

And you get ringing from the high-Q enclosure (LT or not, the natural state of the enclosure is high-Q, and electronic band-aids cannot entirely mitigate acoustic reality. Motors better than TC's - the Hyperdynamics dual-gap/dual-coil design called "DDD" by JBL, Aura's underhung NRT's, for instance - do seem to perform better in high-Q enclosures than conventional overhung motors, but they still sound better in naturally overdamped enclosures), and you lose considerable output due to power compression. If sonic performance is the primary goal - which, to be sure, it absolutely is not for most people - then large boxes and minimal voicecoil heating is the way to go.

Extension to 10Hz, or extension to 3Hz? 7ms of GD or 50ms of GD? Case closed.

Sorry, but with 2 TC3k's in 3.5 cubes the only perceivable output you will get at 10Hz, let alone 3Hz, is distortion products.

And you get ringing from the high-Q enclosure (LT or not, the natural state of the enclosure is high-Q, and electronic band-aids cannot entirely mitigate acoustic reality.
Not really. The enclosure itself does not ring, it's the frequency response that rings.

Not really.



And you get ringing from the high-Q enclosure (LT or not, the natural state of the enclosure is high-Q, and electronic band-aids cannot entirely mitigate acoustic reality. Motors better than TC's - the Hyperdynamics dual-gap/dual-coil design called "DDD" by JBL, Aura's underhung NRT's, for instance - do seem to perform better in high-Q enclosures than conventional overhung motors, but they still sound better in naturally overdamped enclosures), and you lose considerable output due to power compression. If sonic performance is the primary goal - which, to be sure, it absolutely is not for most people - then large boxes and minimal voicecoil heating is the way to go.



Sorry, but with 2 TC3k's in 3.5 cubes the only perceivable output you will get at 10Hz, let alone 3Hz, is distortion products.two things...one i believe i remember talking to Brian about the high Q/LT enclosure and he said something to similar effect...that some high Q characteristics would persist...i did'nt press him further on details so i'll defer to Bosso as i've not heard a high-Q/LT enclosure...i do believe that one moves closer to ideal with a larger enclosure...however

point two...i have a dual 2x15 tc3k and a 1x15 tc3k...the dual in 5.4ft3 and the single in 3.6ft3 and i assure you that they both respond to 10 Hz with ease...as one system, they play to about 109 dB at 3.5 meters with THD ~10-14% and f3 at 8 Hz...

My points were very logical. What's ilogical about stating you were wrong when you posted that: "So let's briefly consider sealed (otherwise called acoustic suspension..."

So now for pointing out you made a mistake you are calling me a loser?

Let me sum this up: Hardly any sealed designs are acoustic suspension Whereas all acoustic suspension have to be sealed. You tried to convey that sealed and acoustic suspension were one and the same.

With me so far?

Rather than admitting you made a mistake you tried:
1) Quoting Wikipedia.
2) Saying they are almost the same.
3) We are talking only about a box.
4) We can agree to dissagree. (an original, no doubt)
and last but not least:
5) "...maybe I should simply ignore stupid comments about "acoustic suspension" blah blah blah yada yada yada... you are inaccurate, you are blah blah blah."

So the insults were started by you when you called my coments stupid. Which has made this already ugly.
Almost everyone but you think sealed and acoustic suspension are identical.
Case in point this link:http://www.humanspeakers.com/whatis/AS.htm
Its not Wikipedia.
Or this one:http://macro.lsu.edu/russo/QuAdvent/QuAdvent.htm

Almost everyone but you think sealed and acoustic suspension are identical.
Case in point this link:http://www.humanspeakers.com/whatis/AS.htm
Its not Wikipedia.
Or this one:http://macro.lsu.edu/russo/QuAdvent/QuAdvent.htm

Mark Seaton doesn't think so either.
Quoting Mark Seaton: "It is incorrect or in no-way certain to say that the vast majority of sealed boxes are acoustic suspension per earlier definition."

So it matters not if there's a whole bunch of missinformed people claiming that they are the same or that the world is flat for that matter.

If you would spend a little time reading the link you just sent me you will learn a thing or two.

I quote from YOUR link: "An acoustic suspension, or "sealed box," design, usually employs a woofer with very soft, compliant suspension components, and uses the air sealed inside the cabinet as a spring to control the system resonance."
This is not how the majority of sealed enclosures work. They do NOT use a woofer with "very soft, compliant suspension components". They rely on the woofer itself to provide the compliance not the box.

How does a horn designed sub fit, is it ported, sealed or different?

point two...i have a dual 2x15 tc3k and a 1x15 tc3k...the dual in 5.4ft3 and the single in 3.6ft3 and i assure you that they both respond to 10 Hz with ease...as one system, they play to about 109 dB at 3.5 meters with THD ~10-14% and f3 at 8 Hz...

Those are very specific claims. Is that 109dB measured or modeled? (I'm not at a PC right now, and Unibox doesn't play well with Macs, so I can't run a model for myself.)How are you measuring THD? What is the spectral content of the distortion?

109dB at 10Hz (assuming a sine wave; square waves are a different story) is probably (but just barely) perceivable. But the distortion products will dominate what you actually hear if you played a 10Hz wave at 109dB in that system. And drop 5dB of output and distortion will be all that you hear.

Those are very specific claims. Is that 109dB measured or modeled? (I'm not at a PC right now, and Unibox doesn't play well with Macs, so I can't run a model for myself.)How are you measuring THD? What is the spectral content of the distortion?

109dB at 10Hz (assuming a sine wave; square waves are a different story) is probably (but just barely) perceivable. But the distortion products will dominate what you actually hear if you played a 10Hz wave at 109dB in that system. And drop 5dB of output and distortion will be all that you hear.don't deal with models...this is a 3x15" system based on the tc3000 drivers...measured at 3.5 meters in 1800ft3 with 5.5 kW of power...made with ecm8000 and trueRTA...http://i40.photobucket.com/albums/e216/kramskoi/3x15_10Hz_spl.jpg

I'm saying that if one's budget was truly unlimited, size would never be a contraint.

Think Condo.

Really, let's not say TOTALLY unlimited, let's say that we aren't going to do mods to the framework of the house/condo/apartment, and we don't want a whole lot of ugly in a finite space...that being said a couple of the new JL's or DD's aren't too big, nor too expensive (as compared to home modification..

don't deal with models...this is a 3x15" system based on the tc3000 drivers...measured at 3.5 meters in 1800ft3 with 5.5 kW of power...made with ecm8000 and trueRTA...http://i40.photobucket.com/albums/e216/kramskoi/3x15_10Hz_spl.jpg



Kind of a lot of high level harmonics there. 1st, 2nd, 3rd, and 4th harmonics are only down 20 dB from teh primary 10 Hz signal.

Kind of makes me wonder what good is 10 HZ bass reproduction with all those harmonics that can be heard instead of being felt!

Mark Seaton doesn't think so either.
Quoting Mark Seaton: "It is incorrect or in no-way certain to say that the vast majority of sealed boxes are acoustic suspension per earlier definition."

So it matters not if there's a whole bunch of missinformed people claiming that they are the same or that the world is flat for that matter.

If you would spend a little time reading the link you just sent me you will learn a thing or two.

I quote from YOUR link: "An acoustic suspension, or "sealed box," design, usually employs a woofer with very soft, compliant suspension components, and uses the air sealed inside the cabinet as a spring to control the system resonance."
This is not how the majority of sealed enclosures work. They do NOT use a woofer with "very soft, compliant suspension components". They rely on the woofer itself to provide the compliance not the box.
You don't have to use Seaton as your defence. Mark Seaton may not have had the time to read through all the meaningless exchanges involving the context in which I was talking and the context in which you started picking on what I was saying.
You quote Mark on
"It is incorrect or in no-way certain to say that the vast majority of sealed boxes are acoustic suspension per earlier definition."

Re-read it again. It says, "per earlier definition". I was not using that definition and hence not incorrect. Not using that definition is not wrong because a lot of people use sealed and acoustic suspension synonymously. It is "common lingo". Bottomline is this. That definition brings into the discussion a certain class of subwoofers that neither fall under the category of IB, nor AS. And that class has no specific name except that it falls under the category of "sealed subs in general". You/Mark/Several others pay a lot of attention to compliance determining the definition of AS. There is nothing wrong in that. However, there is also nothing wrong in calling small sealed boxes (not IB) AS.

Someone else here questioned me elegantly unlike the way you lashed out..

"It depends. Do you call every rectangle you see a square? If so, feel free to call every closed box you see an AS"

A square and rectangle have very precise definitions. In the absence of a clear definition for a square, it translates into the definition of a rectangle.
Similarly, there is no clear definition for a box that is not an IB and not an AS. So it translates into an AS.
There are issues with such translations too. Let's face it. English is not as precise/accurate as mathematics. So there is always ambiguity when definitions are not precise. In your mind this maybe a clear cut definition. In my mind it is not. Hence the disconnect and disagreement. In my mind, it is not, because the way you strictly refer to AS is not how a lot of people converse. As I said earlier, as long as I am able to communicate without ambiguity then it is ok. In the context I was describing, usage of AS did not shroud the discussion.
This argument is wasted time. We could all be doing something better.
Enough said.
If you drill on this more, I will lose all respect for your completely. Just to let you know, I still hold some respect for you, based on past posts and brief communication on the forum. You probably don't care about my respect for you, that's ok. Just thought I would let you know.

so Rob, what you saying is........ :p

I though that was very clear Shervin but just in case I was a bit too vague, I think all of the large tube subs are hideous ... except of course your Twin Towers which are finely crafted and a manly testament to the DIY art. :)

Now that I think about it, I have to look at my speaker manuals to find out if my non-ported speakers are called Acoustic Suspension speakers, or are they just sealed speakers.

I have always thought that speakers were either ported or sealed (AKA acoustic suspension). Not that it is worth arguing about since I do not design speakers.

I hope this is not one of those patent issues (like time aligned speakers) in that you must pay to use the term acoustic suspension speaker because someone owns the rights to the term.

I for one never knew that most sealed speakers are not acoustic suspension speakers. Now that I think about it more, it does not matter much either!

Anyone want to argue about whether whether Dolby Surround Sound is encoded with a Dolby Surround Encoder or a Pro-Logic Encoder????

.....5) "...maybe I should simply ignore stupid comments about "acoustic suspension" blah blah blah yada yada yada... you are inaccurate, you are blah blah blah."

So the insults were started by you when you called my coments stupid. Which has made this already ugly.

Not true. Post count #119 of yours says this..
.. You are wrong but are too thick headed to admit it.

My comment, was post #124. So who insulted who first?
It still does not justify me calling your comments stupid. I usually refrain from using words like that unless I am attacked first. Anyways, I am sorry for saying that.

\
Someone else here questioned me elegantly unlike the way you lashed out..

"It depends. Do you call every rectangle you see a square? If so, feel free to call every closed box you see an AS"

A square and rectangle have very precise definitions. In the absence of a clear definition for a square, it translates into the definition of a rectangle.
Similarly, there is no clear definition for a box that is not an IB and not an AS. So it translates into an AS.

I was with you from when you complimented me until your last sentence. :)

The point that several of us are making is that AS is a very small subset of all closed boxes, that meets very specific conditions. There's no malice stated or implied in that or any other basic correction of the factual record.

If you want to discuss closed boxes that are neither I-B (suspension ueber alles) nor AS (compliance ueber alles) then there is an standard way to do so: by their Qtc values. You could talk about a given driver in a Qtc=0.707 box vs. that driver in a Qtc=0.577 box, for instance. Yes, T/S is a simplified model, and it certainly does not account for everything. However, it is well-represented in the literature and provides a handy basis for discussing sealed boxes.

And you get ringing from the high-Q enclosure (LT or not, the natural state of the enclosure is high-Q, and electronic band-aids cannot entirely mitigate acoustic reality. Motors better than TC's - the Hyperdynamics dual-gap/dual-coil design called "DDD" by JBL, Aura's underhung NRT's, for instance - do seem to perform better in high-Q enclosures than conventional overhung motors, but they still sound better in naturally overdamped enclosures), and you lose considerable output due to power compression. If sonic performance is the primary goal - which, to be sure, it absolutely is not for most people - then large boxes and minimal voicecoil heating is the way to go.

As Richard said above, the box doesn't ring, the FR does.

I've put the same drivers into 4 different sizes of box and run the tests, objective and subjective, but the first thing you need to realize is that dual TC3Ks in 3.5 cubes does not yield an underdamped alignment. In fact, it's closer to critically damped.

Please explain how a dual gap or an underhung motor (both of which I have here, BTW) is 'better than TC's' in a high Q enclosure :confused:

It's always nice to be corrected by a casual reader who hasn't built or heard such a system and A/B'd it to other configurations. Reminds me of some of Steve Callas' banter :rolleyes:


Sorry, but with 2 TC3k's in 3.5 cubes the only perceivable output you will get at 10Hz, let alone 3Hz, is distortion products.

Once again, without having done the testing to make such an absurd claim, I just don't get the point in discussing it further. I assure you that 108dB at 10Hz vs no output at 10Hz is perceptible. When you quadruple the system, you perceive the bottom octaves.

And, what distortion products do you 'perceive' from 3Hz? Second order? Third order? Fourth order? Fifth order? Sixth order? We're still below audibility at that point, eh?

Don't take my word for it and don't run to the virtual library or your modeling software...try it yourself and report back...you'll be met with much more respect that way.

Bosso

I though that was very clear Shervin but just in case I was a bit too vague, I think all of the large tube subs are hideous ... except of course your Twin Towers which are finely crafted and a manly testament to the DIY art. :)
:D :p

Kind of a lot of high level harmonics there. 1st, 2nd, 3rd, and 4th harmonics are only down 20 dB from teh primary 10 Hz signal.

Kind of makes me wonder what good is 10 HZ bass reproduction with all those harmonics that can be heard instead of being felt!

You are seeing about 108 dB being reproduced @ 10 Hz ... look at the lower of the 2 numbers in the upper left ... I am saying 108 dB because the harmonics are adding slightly to the total.

We then have:

- 25 dB ... or about 5.6 % @ 20 Hz
- 24 dB ... or about 6.7 % @ 30 Hz
- 27 dB ... or about 4.1 % @ 40 Hz
- 27 dB ... or about 4.1% @ 50 Hz

Overal ... quite a solid performance.

Clearly I'm not getting through, so let me try again. I'm not saying everyone has to build a giant tube sub - I don't think anything approaching those words came out of my mouth. I'm saying that if one's budget was truly unlimited, size would never be a contraint. If you don't want to have a big sub in your room, that is fine, you could build an adjacent room to use as the enclosure, line the connecting wall with drivers, and cover them with a cloth grill. It would be less intrusive than even the smallest box sub, as nothing is physically in the room. People don't do that however (royal device room aside), therefore claims that budget is unlimited or cost is no object are BS.

I think that Steve knows what he is talking about.

Regards

You are seeing about 108 dB being reproduced @ 10 Hz ... look at the lower of the 2 numbers in the upper left ... I am saying 108 dB because the harmonics are adding slightly to the total.

We then have:

- 25 dB ... or about 5.6 % @ 20 Hz
- 24 dB ... or about 6.7 % @ 30 Hz
- 27 dB ... or about 4.1 % @ 40 Hz
- 27 dB ... or about 4.1% @ 50 Hz

Overal ... quite a solid performance.if, per the TRW article, all we need is 100 dB @ 10 Hz then these distortions would be even less at less than insane levels...thanks C... ;)

Yo Martin -

http://www.acc.umu.se/~zqad/cats/1174329819-ridindirtay.jpg

As Richard said above, the box doesn't ring, the FR does.

Except...the underlying acoustic facts do not change, nor does the band-aid completely cover them. And power compression, which isn't nearly as much of a factor in low-Q sealed or EBS alignments, rears its ugly head. Nor, for that matter, can electronic band-aids compensate for the sky-high inductance of the TC3k. That is perhaps marginally easier to integrate into a good-sounding system that TC's nasty old 3HP (especially allowing for TC's appalling quality control in those days) and TC9 motors, but not much more so. The best-sounding TC drivers that I've heard were the underhung ones Rudi Blondia used to sell and the TC2+/TC1k. None of the others have impressed me, though I've not heard an LMT-based driver. Remember that the top octave a sub reproduces is, perceptually, far more important than the bottom octave it reproduces. It also doesn't matter if a sub has all the deep bass in the world if it has inductive peaking/rolloff in said top octave that makes integration into a good-sounding audio system a trial at best and an impossibility at worst.

I've put the same drivers into 4 different sizes of box and run the tests, objective and subjective, but the first thing you need to realize is that dual TC3Ks in 3.5 cubes does not yield an underdamped alignment. In fact, it's closer to critically damped.

Perhaps we have different definitions of "critically damped." Mine is Qtc=0.5. Modeling the TC3k, I get box volume of 93L per driver, with minimal fill, for a critically-damped enclosure With the ~51L Vbox/driver one gets a Qtc of 0.693, which is more overdamped than any subwoofer I would ever design for anyone else or use for myself.

Please explain how a dual gap or an underhung motor (both of which I have here, BTW) is 'better than TC's' in a high Q enclosure :confused:

Honestly, I can't explain it. I'm only going by what I've heard. And also, all dual-gap motors are not alike. The XBL^2-style dual gap motor, which is most of 'em out there, doesn't have the same braking effect that the Hyperdynamics-style motor does. Maybe that has something to do with it. Or maybe the current Hyperdynamics patent-based drivers are just so superbly engineered that they work better. I don't know.

To borrow a phrase, try it yourself and report back...you'll be met with much more respect that way. (Or perhaps you've played with such a thing, I don't know and unlike some wouldn't deign to put words in your mouth.)

It's always nice to be corrected by a casual reader who hasn't built or heard such a system and A/B'd it to other configurations. Reminds me of some of Steve Callas' banter :rolleyes:

How, pray tell, do you know what I've built? I'm certainly no Danley, Geddes, Seaton, etc., but I've been doing this stuff for long enough to have tried basically everything except for bandpass, acoustic lever, and tapped horn. That means LT, low-Q sealed standalone, I-B, EBS vented and PR, QB3 vented, dipole, cardoid (well, U-frame and "pull-pull", neither one of which is 100% cardoid), and probably some others I can't recall.

Once again, without having done the testing to make such an absurd claim, I just don't get the point in discussing it further. I assure you that 108dB at 10Hz vs no output at 10Hz is perceptible. When you quadruple the system, you perceive the bottom octaves.

Please read what you're replying to rather than making assumptions based on a false guess of what might have been on the screen in front of you. I never wrote that 109dB at 10Hz was imperceptible. (At 3Hz, it certainly would be.) What was actually on the screen in front of you was the following sentence: "109dB at 10Hz (assuming a sine wave; square waves are a different story) is probably (but just barely) perceivable."

Regardless, the primary perceptible components in a system as outlined above are distortion and not fundamental. I'm not casting aspersions on kramskoi's sub with that remark, mind. Quite the contrary, in fact. The number of individuals in the world who can claim to have a bass subsystem in their personal audio systems that clean at that frequency/SPL probably number less than 200. A lot less. But simply by reading the graphs, anyone with basic acoustic literacy will realize that the ~80dB 3rd, 4th, and 5th order distortion components will swamp the fundamental from a human perception standpoint. Perhaps you need to investigate the peer-reviewed literature on audible thresholds of very low frequencies and get back to us.

(Damn you, you two have put into my head a new idea for a subwoofer subsystem. The Hsu VTF3HO corner/MBM12 nearfield but more fun, with twin push-pull TC3k's in the corner and twin push-pull JBL 2235H's or B&C 15TBX100's in the nearfield for the top octave. With maybe ~400W on top and a couple kW on the bottom. I might just do that...)

Don't take my word for it and don't run to the virtual library or your modeling software...try it yourself and report back...you'll be met with much more respect that way.

Again, what makes you think that I haven't? Regardless, I think we're done here. There's no point trying to talk sense to a fundamentalist ideologue.

Perhaps we have different definitions of "critically damped." Mine is Qtc=0.5. Modeling the TC3k, I get box volume of 93L per driver, with minimal fill, for a critically-damped enclosure With the ~51L Vbox/driver one gets a Qtc of 0.693, which is more overdamped than any subwoofer I would ever design for anyone else or use for myself.

Err, with no fill the Ti TC-3k needs under 3ft^3 to be critically damped...Thats under 85 liters.

Oh, and Kramskoi's dual is around 5.4ft^3 IIRC... thats a Q of under .5 with NO fill using the newer TC-3k.

A pair of last generation TC-3ks would yield a Qtc of around .566 without fill in a box that size...That is essentially what kramskoi is working with. Although I am very sure he added fill until Fs bottomed out.

Err, with no fill the Ti TC-3k needs under 3ft^3 to be critically damped...Thats under 85 liters.

Um, here's what I was replying to: "the first thing you need to realize is that dual TC3Ks in 3.5 cubes does not yield an underdamped alignment. In fact, it's closer to critically damped."

Dual TC3Ks in 3.5 cubes. Perhaps he meant 3.5 cubes each, in which case the claim would still be inaccurate, as shown below. But if that is indeed what was meant, then the lesson here is the one MS brought up earlier in this thread: clarity in writing is a necessary condition for intelligent, reasoned dialog.

Beyond that, Unibox gives significantly different numbers from what you posted. I didn't save the driver file last time, so I think I made a type in entering its parameters to generate the numbers I posted above. (And on this post, before editing.) Unibox calculates that a critically-damped (Qtc=0.500) enclosure would need to be 132.4L, with no fill. That's what, about 4.5-5 cubes per driver?

But there's another elephant in the room that pretty much trumps everything with the TC3k. Because of the ridiculously high inductance of the its motor, there is a 15dB peak in the modeled response, centered at around 50Hz. My experience with other high-Le drivers is that Unibox is accurate or maybe a little optimistic about inductive peaking, so the real peak might be anywhere from 15-18dB. (My experience with TC is also that they've underquoted inductance before, but let us assume that their QC has improved markedly since the days of Stryke Audio.) So move air it might, but hi-fi it certainly ain't. Complaining about the sonic impact of venting is really quite silly, in the context of all that Le. Personally, I'd rather have 30dB less output at 10Hz and a clean response in the useful passband.

Except...the underlying acoustic facts do not change, nor does the band-aid completely cover them. And power compression, which isn't nearly as much of a factor in low-Q sealed or EBS alignments, rears its ugly head. Nor, for that matter, can electronic band-aids compensate for the sky-high inductance of the TC3k. That is perhaps marginally easier to integrate into a good-sounding system that TC's nasty old 3HP (especially allowing for TC's appalling quality control in those days) and TC9 motors, but not much more so. The best-sounding TC drivers that I've heard were the underhung ones Rudi Blondia used to sell and the TC2+/TC1k. None of the others have impressed me, though I've not heard an LMT-based driver. Remember that the top octave a sub reproduces is, perceptually, far more important than the bottom octave it reproduces. It also doesn't matter if a sub has all the deep bass in the world if it has inductive peaking/rolloff in said top octave that makes integration into a good-sounding audio system a trial at best and an impossibility at worst.




Perhaps we have different definitions of "critically damped." Mine is Qtc=0.5. Modeling the TC3k, I get box volume of 93L per driver, with minimal fill, for a critically-damped enclosure With the ~51L Vbox/driver one gets a Qtc of 0.693, which is more overdamped than any subwoofer I would ever design for anyone else or use for myself.



Honestly, I can't explain it. I'm only going by what I've heard. And also, all dual-gap motors are not alike. The XBL^2-style dual gap motor, which is most of 'em out there, doesn't have the same braking effect that the Hyperdynamics-style motor does. Maybe that has something to do with it. Or maybe the current Hyperdynamics patent-based drivers are just so superbly engineered that they work better. I don't know.

To borrow a phrase, try it yourself and report back...you'll be met with much more respect that way. (Or perhaps you've played with such a thing, I don't know and unlike some wouldn't deign to put words in your mouth.)



How, pray tell, do you know what I've built? I'm certainly no Danley, Geddes, Seaton, etc., but I've been doing this stuff for long enough to have tried basically everything except for bandpass, acoustic lever, and tapped horn. That means LT, low-Q sealed standalone, I-B, EBS vented and PR, QB3 vented, dipole, cardoid (well, U-frame and "pull-pull", neither one of which is 100% cardoid), and probably some others I can't recall.



Please read what you're replying to rather than making assumptions based on a false guess of what might have been on the screen in front of you. I never wrote that 109dB at 10Hz was imperceptible. (At 3Hz, it certainly would be.) What was actually on the screen in front of you was the following sentence: "109dB at 10Hz (assuming a sine wave; square waves are a different story) is probably (but just barely) perceivable."of course integration will depend on the capability of your mains...and i'll say that it's not a problem with 8" drivers that reach down to 45 Hz with 96 dB of sensitivity...this is a meaningful argument only if you're using smallish satellites...

The audibility of 10 Hz is'nt so much the issue here...a better question is what tactile augumentations it brings to the presentation as a whole...it's feeling more than hearing and these ELF's do make themselves noticeable...

According to the affixed threshold chart, it seems that 95-100 dB is the threshold point for 10 Hz, so there's room for less distortion of the fundamental.

of course integration will depend on the capability of your mains...and i'll say that it's not a problem with 8" drivers that reach down to 45 Hz with 96 dB of sensitivity...this is a meaningful argument only if you're using smallish satellites...

Turns out that by my standards, both of us are running smallish satelites in our HT's. Eight-inch bookshelves are smallish speakers to run below 100Hz or so. At least if your standard is the ease and quality with which energy-dense passages such as massed strings or voices in large-scale symphonic works are reproduced.

But I just looked yours up. Given the specs you quoted, I was expecting a much larger cabinet. A bookshelf speaker with an 8" woofer that reaches down to 45Hz and has 96dB/w/m sensitivity? Something seems fishy there. I would believe mains with 8" woofers two of those other three things (45Hz F3, 96dB sensitivity, 19 x 9.25 x 10.8 cabinet) but not all three of them together. My guess, based on my measurements of speakers that are similar in size and claimed (as well as measured) extension (Tannoy System 8 NFM II studio monitors, which I use as mains in my HT) that the sensitivity spec is off by at about half. That would be consistent with the laws of physics. It would also be consistent with the Stereophile measurements of another model in the same line, the RB15, (http://www.stereophile.com/budgetcomponents/204klipsch/index1.html) which they found to have half the quoted efficiency. It measured at 90dB/w/m despite being spec'ed at 93dB/w/m.

(I know that's off topic, but Klipsch's specs pegged my BS-meter so I had to investigate a little bit more carefully.)

The audibility of 10 Hz is'nt so much the issue here...a better question is what tactile augumentations it brings to the presentation as a whole...it's feeling more than hearing and these ELF's do make themselves noticeable...

"Audibility" in the case of deep bass isn't hearing, but feeling. I think the "mechanical crossover" between the ears and the bones of the face and chest has a corner of around 45Hz. Or thereabouts.

According to the affixed threshold chart, it seems that 95-100 dB is the threshold point for 10 Hz, so there's room for less distortion of the fundamental.

Your numbers are off from what I've read by over 5dB. The curve fit has to fit the data. :)

Mark Seaton doesn't think so either.
Quoting Mark Seaton: "It is incorrect or in no-way certain to say that the vast majority of sealed boxes are acoustic suspension per earlier definition."

So it matters not if there's a whole bunch of missinformed people claiming that they are the same or that the world is flat for that matter.

If you would spend a little time reading the link you just sent me you will learn a thing or two.

I quote from YOUR link: "An acoustic suspension, or "sealed box," design, usually employs a woofer with very soft, compliant suspension components, and uses the air sealed inside the cabinet as a spring to control the system resonance."
This is not how the majority of sealed enclosures work. They do NOT use a woofer with "very soft, compliant suspension components". They rely on the woofer itself to provide the compliance not the box.
?????? Can you read English?
The link proves YOU are wrong.
Reread it........slooooowwly if necessary.

Based on the graph as shown here, a 100 SPL level at 10 Hz is appx. the same in audibility as is 80 dB @ 40 Hz. Kramskoi's sub, when delivering the 108 dB max @ 10 Hz, will have appx. 81 dB of harmonics @ 40 Hz, 6 dB below the same perceived values at 10 Hz.

It is pretty clear that 100 dB @ 10 Hz is noticeable. Yates tests also confirm this.


http://hyperphysics.phy-astr.gsu.edu/hbase/sound/imgsou/eqlou.gif

Thanks craig,

Someone is making sense here. :D

Except...the underlying acoustic facts do not change, nor does the band-aid completely cover them. And power compression, which isn't nearly as much of a factor in low-Q sealed or EBS alignments, rears its ugly head. Nor, for that matter, can electronic band-aids compensate for the sky-high inductance of the TC3k. That is perhaps marginally easier to integrate into a good-sounding system that TC's nasty old 3HP (especially allowing for TC's appalling quality control in those days) and TC9 motors, but not much more so. The best-sounding TC drivers that I've heard were the underhung ones Rudi Blondia used to sell and the TC2+/TC1k. None of the others have impressed me, though I've not heard an LMT-based driver. Remember that the top octave a sub reproduces is, perceptually, far more important than the bottom octave it reproduces. It also doesn't matter if a sub has all the deep bass in the world if it has inductive peaking/rolloff in said top octave that makes integration into a good-sounding audio system a trial at best and an impossibility at worst.

I'm not citing the TC3K as the end-all driver, but trying to convince me that it will suffer from power compression in a small box to excess compared to a larger box is...well, since you're so sure of the fact, maybe you can show some comparative graphs.

Truth is, under normal use, compression (and, I assumed you meant thermal compression, not power compression) is not an issue with a huge overhung motor. If you indeed meant power compression, I would suggest a better use of a power plant in your design.

You might also note that all of TC's latest drivers employ shorting rings. Alas, I haven't seen a graph of the 3K, but WillD measured his 2K which measured quite flat out to 500Hz. IOW, apparently, a big improvement over the older TC drivers.

BUT...to try to get back to the point...you claim that EQ doesn't eliminate ringing. Now, your claim is modified to doesn't mask it 'completely'.

I'm sorry to ask you to please be more specific. Do you have any measurements that show excessive ringing in a smaller L/T'd system vs the same system without L/T in a larger box? Or, do you have a formula for the ratio of ringing before L/T and after L/T to better assess your claim?

Perhaps we have different definitions of "critically damped." Mine is Qtc=0.5. Modeling the TC3k, I get box volume of 93L per driver, with minimal fill, for a critically-damped enclosure With the ~51L Vbox/driver one gets a Qtc of 0.693, which is more overdamped than any subwoofer I would ever design for anyone else or use for myself.

I wouldn't use minimal fill. In fact, I apologize for not knowing what that means, exactly. I haven't used the 3K (yet), so I'll yield a bit here, but I suspect a lower Q than .7. Kram's 3.6 (single driver) box yielded a measured .427. 3.5 cubes will yield an apparent 4.4ish cubes, properly filled. Take it from there. If your software tells you .693, I would suggest a different software.

Honestly, I can't explain it. I'm only going by what I've heard. And also, all dual-gap motors are not alike. The XBL^2-style dual gap motor, which is most of 'em out there, doesn't have the same braking effect that the Hyperdynamics-style motor does. Maybe that has something to do with it. Or maybe the current Hyperdynamics patent-based drivers are just so superbly engineered that they work better. I don't know.
To borrow a phrase, try it yourself and report back...you'll be met with much more respect that way. (Or perhaps you've played with such a thing, I don't know and unlike some wouldn't deign to put words in your mouth.)

:)

How, pray tell, do you know what I've built? I'm certainly no Danley, Geddes, Seaton, etc., but I've been doing this stuff for long enough to have tried basically everything except for bandpass, acoustic lever, and tapped horn. That means LT, low-Q sealed standalone, I-B, EBS vented and PR, QB3 vented, dipole, cardoid (well, U-frame and "pull-pull", neither one of which is 100% cardoid), and probably some others I can't recall.

Regarding single digit response, it's obvious what you've built. Still, feel free to post graphs that you've made of some of the single digit capable systems you've built (a prerequisite, no?, since we're talking about inaudible freqs), and explain the A/B comparos you've conducted that have led you to preach single digit response from the pulpit.

None of the alignments you mention are capable of single digits except for the sealed (L/T, IB). Now, just fill in the details of those systems you've built and I'll be a happier reader.

You see, on one hand you are quick to condemn, then you guess that there are far less than 200 people on earth who have such a system. That number would certainly be whittled down quite a bit if you include only those who have done accurate measurements of their system.

Please read what you're replying to rather than making assumptions based on a false guess of what might have been on the screen in front of you. I never wrote that 109dB at 10Hz was imperceptible. (At 3Hz, it certainly would be.) What was actually on the screen in front of you was the following sentence: "109dB at 10Hz (assuming a sine wave; square waves are a different story) is probably (but just barely) perceivable."

No need to dodge. 'Probably, but just barely perceivable' qualifies my response. Your reading lesson aside, I haven't been convinced otherwise.

I also would like to know how you became certain that 3Hz @ 109dB isn't perceptible?

Perhaps you need to investigate the peer-reviewed literature on audible thresholds of very low frequencies and get back to us.

I would be happy to. Care to point me to one? Also, would you please be more specific as to what I'll be looking for...perceptibility or audibility? And, will these studies be extrapolations based on single sine waves or more recent studies that involve real sounds through capable systems?

Again, what makes you think that I haven't? Regardless, I think we're done here. There's no point trying to talk sense to a fundamentalist ideologue.

You're right. I shouldn't have deduced as much as I did, but this is supposed to be a thread about the merits of sealed vs the merits of ported subwoofers, and, as I explain above, it's obvious to me when someone has a single digits capable sealed system (and equally obvious when he doesn't), by reading his posts.

I don't know what a fundamentalist ideologue is, so dumb that one down for me, 'cause I ain't lookin' it up.

Bosso

Turns out that by my standards, both of us are running smallish satelites in our HT's. Eight-inch bookshelves are smallish speakers to run below 100Hz or so. At least if your standard is the ease and quality with which energy-dense passages such as massed strings or voices in large-scale symphonic works are reproduced.

But I just looked yours up. Given the specs you quoted, I was expecting a much larger cabinet. A bookshelf speaker with an 8" woofer that reaches down to 45Hz and has 96dB/w/m sensitivity? Something seems fishy there. I would believe mains with 8" woofers two of those other three things (45Hz F3, 96dB sensitivity, 19 x 9.25 x 10.8 cabinet) but not all three of them together. My guess, based on my measurements of speakers that are similar in size and claimed (as well as measured) extension (Tannoy System 8 NFM II studio monitors, which I use as mains in my HT) that the sensitivity spec is off by at about half. That would be consistent with the laws of physics. It would also be consistent with the Stereophile measurements of another model in the same line, the RB15, (http://www.stereophile.com/budgetcomponents/204klipsch/index1.html) which they found to have half the quoted efficiency. It measured at 90dB/w/m despite being spec'ed at 93dB/w/m.

(I know that's off topic, but Klipsch's specs pegged my BS-meter so I had to investigate a little bit more carefully.)



"Audibility" in the case of deep bass isn't hearing, but feeling. I think the "mechanical crossover" between the ears and the bones of the face and chest has a corner of around 45Hz. Or thereabouts.



Your numbers are off from what I've read by over 5dB. The curve fit has to fit the data. :)of course these are'nt my numbers...well, iirc, both Mark Seaton and Ed Mullen have commented on the appropriate threshold levels for VLF in this region and how it affects the overall presentation...iirc, they both demoed the Thigpen Rotary Sub...

so now you're going to tell me that my Klipsch RB-35's roll off at 100 Hz?...if you have problems integrating your mains that is your issues but your posts are beginnning to smack of presumptions, generalizations, extrapolations, etc. etc. etc...i guess next you'll tell me how similar our rooms are? or how similar the rolloffs of our inner ear apparatus?...speak for yourself my friend...just buy a pair of Klipsch RB-35's and test to your hearts content...meanwhile i'll enjoy the mating between my subwoofer and its counterparts...

?????? Can you read English?
The link proves YOU are wrong.
Reread it........slooooowwly if necessary.

I can read and write three languages fluently, have an IQ of 140.

How about you?

I think you are referring to the "acoustic suspension also know as selaed box" line to challenge my knowledge of the English language.

Let me restate again. All acoustic supensions are sealed. Not all sealed designs are acoustic suspension.

You don't have to use Seaton as your defence.........

It is spelled defense, I believe. And I don't need "defending". He posted that on his own and I was quoting him. The part that you seem all too oblivious to understand is that I am old enough to have been raised on tube gear and sealed boxes. And I remember very well when AR came out with Acoustic Suspension as a totally new and different way of driver and cabinet design. It was sealed, yes, but so were all other non-ported designs. Acoustic suspension (and I know I am repeating myself here) was a totally new approach that required special drivers and a small enclosure of specific volume to provide the needed "springiness" to the woofer.


...If you drill on this more, I will lose all respect for your completely. Just to let you know, I still hold some respect for you, based on past posts and brief communication on the forum. You probably don't care about my respect for you, that's ok.....

Ok so now you resort to threats? OMG my knees are shaking now!
I am going to drill on this till oil comes out.

In any event you are right on that one. I don't need respect from people like you.

Man, this thread is getting CRAZY! :eek:

Man, this thread is getting CRAZY! :eek:

watch out for the flying pee-pee. :D

watch out for the flying pee-pee. :D

You aint a kiddin' :D

Come on guys. Let's just agree to disagree. :o

It is spelled defense, I believe.
You have a serious issue. "Defence" is also correct. It is the British way of spelling it.
I can read and write three languages fluently, have an IQ of 140.

For someone who "claims" to have the capability to read and write three languages fluently, and claiming an IQ of 140 , I am surprised you don't know this.
Do you know "color" and "colour" are both correct spellings?
Thank goodness, now it is clear that I have been wasting my time with you on "AS" and "sealed" debate.
I wouldn't be surprised if you start another rant that people here should use only American English spellings.
Ok so now you resort to threats? OMG my knees are shaking now!
I am going to drill on this till oil comes out.

In any event you are right on that one. I don't need respect from people like you.
Keep drilling and you will expose yourself of being naive, like what you just did in trying to correct my spelling. You won't get any more of my respect here and I am sure you lost your credibility here with quite a few with your meaningless rants.
Goodbye! My time is better spent with real intelligent people.

You have a serious issue. "Defence" is also correct. It is the British way of spelling it.

So maybe I can start spelling in French now.


For someone who "claims" to have the capability to read and write three languages fluently, and claiming an IQ of 140 , I am surprised you don't know this.
Do you know "color" and "colour" are both correct spellings?
Thank goodness, now it is clear that I have been wasting my time with you on "AS" and "sealed" debate.
I wouldn't be surprised if you start another rant that people here should use only American English spellings.

That's a great idea (in the right forum). This is the USA and thank goodness it is. Colour would be correct in GB. Not here! In GB is lense here is lens.
You apparently LOVE waisting your time. Me too! I love a good fight.

Keep drilling and you will expose yourself of being naive, like what you just did in trying to correct my spelling. You won't get any more of my respect here and I am sure you lost your credibility here with quite a few with your meaningless rants.
Goodbye! My time is better spent with real intelligent people.

You love to rant, but cannot deliver the goods.
How are you going to take away respect?
And who are you to speak for others?
Go and find your "intelligent people". See if they have some for sale. You could certainly use it.

Let the free for all continue.

Some interesting arguments where given by both sides(when not spilling into insults).

Yoy, I hope that is over. :)

So, which is it sealed or ported? :D

Truth is, under normal use, compression (and, I assumed you meant thermal compression, not power compression) is not an issue with a huge overhung motor. If you indeed meant power compression, I would suggest a better use of a power plant in your design.

Power compression is the commonly-used term in the literature for this phenomenon, as well as in quasi-technical documents such this JBL whitepaper. (http://www.jblpro.com/pub/technote/tn_v1n18.pdf) If you're going to pick nits, at least have some bloody sense about it! Like calling me out when I mistakenly wrote "overdamped" instead of "underdamped" in a post above...

You might also note that all of TC's latest drivers employ shorting rings. Alas, I haven't seen a graph of the 3K, but WillD measured his 2K which measured quite flat out to 500Hz. IOW, apparently, a big improvement over the older TC drivers.

I am aware that most of TC's drivers have shorting rings now (the TC9 and perhaps one or two others don't.) However, numbers don't lie. The TC2k has a claimed inductance of 2.45mH, which is similar to the old TC2+ and entirely consistent with response out that far. The TC3k has a claimed inductance of 9.2mH. That puts it in league with the really horrible TC motors of ca. 5 years ago, such as the 3HP motor. Shorting ring or not.

BUT...to try to get back to the point...you claim that EQ doesn't eliminate ringing. Now, your claim is modified to doesn't mask it 'completely'.

I assume that when you re-read your words you will realize that my two statements are entirely consistent with each other. Both point out that an LT does not magically imbue a too-small box with the properties of a properly-sized one.

I'm sorry to ask you to please be more specific. Do you have any measurements that show excessive ringing in a smaller L/T'd system vs the same system without L/T in a larger box? Or, do you have a formula for the ratio of ringing before L/T and after L/T to better assess your claim?

Not on me right now.

I wouldn't use minimal fill. In fact, I apologize for not knowing what that means, exactly.

It means about a half pound of polyfill per cubic foot.

If your software tells you .693, I would suggest a different software.

Are you claiming that Unibox is inaccurate? I doubt it, but it may be the case. Plug the numbers into your modeling program of choice and tell me what you get.

Regarding single digit response, it's obvious what you've built. Still, feel free to post graphs that you've made of some of the single digit capable systems you've built (a prerequisite, no?, since we're talking about inaudible freqs), and explain the A/B comparos you've conducted that have led you to preach single digit response from the pulpit.

Um, I'm not the one preaching about the need for response in a frequency range that's captured on few if any disks. I'm pointing out that perhaps one should concentrate on things that actually matter, such as integrating between subs and mains.

None of the alignments you mention are capable of single digits except for the sealed (L/T, IB).

That is, of course, retarded. It is entirely possible to build a vented system with response into the single digits, if one is so inclined. In fact, a vented system will always have more output around the tuning frequency than a closed one, so if it's really stuff that doesn't matter you care about, you should build vented boxes tuned to those frequencies.

I would be happy to. Care to point me to one? Also, would you please be more specific as to what I'll be looking for...perceptibility or audibility? And, will these studies be extrapolations based on single sine waves or more recent studies that involve real sounds through capable systems?

At extreme LF, audibility [i]is[/ii] perceptibility! And if you're talking about "real sounds through capable systems," what you're asking for is the audibility of distortion products. I think we agree that they are audible.

So, which is it sealed or ported? :D

Yes. :p

so now you're going to tell me that my Klipsch RB-35's roll off at 100 Hz?...

Please go back and re-read. To amplify, I don't doubt their small signal performance is as claimed. What I do know as true is that no 8" woofer, by itself without benefit of waveguide loading etc., has the cojones to do justice to musical passages with very high upper bass energy density, such as massed strings or choral works. Or exceptionally well-mastered piano recordings. If your system is used more for "Stupid S--t Blowing Up III" than Mahler 8, you might not care. Nor for that matter, if you're doing what I'm doing right now, listening to Thievery Corporation at low volumes at work on a pair of decent-but-not-exceptional minimonitors (KEF RDM one). But the reproduction of complex, large-scale music at concert-hall levels needs cone area and volume displacement. And not just (or even primarily) in the deep bass.

ust buy a pair of Klipsch RB-35's and test to your hearts content...meanwhile i'll enjoy the mating between my subwoofer and its counterparts...

I've heard them. They're perfectly OK, an awful lot of speaker for very little money. And I'm glad you like them, but they're not my cup of tea.

I think I may be opening a can of worms, here.

What are the advantages of each?

20' x 20' room with 18' ceiling, open on one side to a large dining room and entryway. I have Klipsch RF-82 fronts, RC-62 Center, and RS-52 Surrounds, and an older JBL 150 watt 10 in sub. I was looking to get the Klipsch RW-12d, but I hear complaints of port noise, which will not do.

I have BB gift cards and rewards certificates to burn, and they sell the Martin Logan and Def Tech subs as their "high-end" subs. (sealed, right?)

On the other hand, I really like what I here about the HSU VTF 3.3. (ported)

Help.

Post #1 above.

I don't think people understood this thread. They looked at the sealed vs. ported title and went on a runaway train fest.

You are asking about a few commercial products, which one to snag. Has anyone really gave you any advice on each of those products?

lol..............

So maybe I can start spelling in French now.

That's a great idea (in the right forum). This is the USA and thank goodness it is. Colour would be correct in GB. Not here! In GB is lense here is lens.
You apparently LOVE waisting your time. Me too! I love a good fight.

You love to rant, but cannot deliver the goods.
How are you going to take away respect?
And who are you to speak for others?
Go and find your "intelligent people". See if they have some for sale. You could certainly use it.
No problem. I can read French too if that would "fermi votre bouche" :D.
Oh this is the USA, thanks for the news, I didn't know. Video engineer ha? Maybe you should stop using greek letters in maths (oops, should I say math) equations (if you know any).

Is that how "waisting" is spelled? I am not a shipping company to deliver goods :). Is that correct English? Why ship goods? There is no ship involved. Intelligent people are already here, just that there are some bad bad apples or should I say rotten eggs. Is some of your 140 IQ for sale?
You picked the wrong guy for this fight :mad:

Please go back and re-read. To amplify, I don't doubt their small signal performance is as claimed. What I do very much doubt is that any 8" woofer, by itself without benefit of waveguide loading etc., has the cojones to do justice to musical passages with very high upper bass energy density, such as massed strings or choral works. Or exceptionally well-mastered piano recordings. If your system is used more for "Stupid S--t Blowing Up III" than Mahler 8, you might not care. Nor for that matter, if you're doing what I'm doing right now, listening to Thievery Corporation at low volumes at work on a pair of decent-but-not-exceptional minimonitors (KEF RDM one). But the reproduction of complex, large-scale music at concert-hall levels needs cone area and volume displacement. And not just (or even primarily) in the deep bass.



I've heard them. They're perfectly OK, an awful lot of speaker for very little money. And I'm glad you like them, but they're not my cup of tea.

i guess the sarcasm escapes you...well i'm pretty sure you have'nt heard the RB-35's in my room, with a sub-critical Q system backing them...but please, by all means, continue postulating...as i'm never more than 2-3 meters from the mains, the sound level is more than adequate...when i feel that i need more, i'll have more...my room has a very unique shape, and i'll leave it at that...

" But the reproduction of complex, large-scale music at concert-hall levels needs cone area and volume displacement. And not just (or even primarily) in the deep bass."

hmmmm...okay i get it...wait...oh your're the quy that dropped the $20K on the Magico-minis i was reading about...good for you... :rolleyes:

please, spare me the diatribe about cone area and displacement...you're preaching to the choir...

"If your system is used more for "Stupid S--t Blowing Up III" than Mahler 8, you might not care."

if all i wanted was low frequency rumble, i'd just roll on down to the local Best Buy, blindfold myself and play pin-the-tail-on-the-sub... :rolleyes:

OMG, what the hell is happening in this thread?!?!! :confused:

i know more than you know
i know more than you know
i know more than you know
and
and
my dog is bigger than your dog
so
there.

i know more than you know
i know more than you know
i know more than you know
and
and
my dog is bigger than your dog
so
there.

:eek: That about sums that up! :D

there's so many boxing matches in here you don't know who to watch. literally a frikkin riot.

Those must be some fantastic subs to make the Klipsch tolerable .... ;)

Those must be some fantastic subs to make the Klipsch tolerable .... ;)

Just a minute here I have Klipsch speakers and many Klipsch from small to large.They are very tolerable and even very smooth providing you use quality amplification and not listen to top 40 crap polluting the air waves.

I also have Dynaudio(many many..many Contour range old and new),Paradigm(Ref and Signature)Totem(ROKK,Tabu) and larger Cerwin-Vega(yes rated class AAA in Stereophile's guide to heavy metal).

Klipsch will expose the garbage receivers and low end amplification.

Ok fellow warriors time to listen to some good music and relax....

Tommy Emmanuel playing here...Guitar Boogie...

there's so many boxing matches in here you don't know who to watch. literally a frikkin riot.
Sad thing is, I have missed out on all the good discussions since I got side-tracked by BS because some guy decided to pick on my definitions and my language. Makes me more mad when I think of wasted time. Didn't learn one bit through all those stupid arguments. I have to blame myself for stooping that low :o . Yet, I am all fired up to get the sting out of this *****. Sorry, I contributed to messing up this thread by reacting to stupid comments. I tell you, if this freak stops bugging me, I will stop. He started it. It was not me.

Um, here's what I was replying to: "the first thing you need to realize is that dual TC3Ks in 3.5 cubes does not yield an underdamped alignment. In fact, it's closer to critically damped."

Dual TC3Ks in 3.5 cubes. Perhaps he meant 3.5 cubes each, in which case the claim would still be inaccurate, as shown below. But if that is indeed what was meant, then the lesson here is the one MS brought up earlier in this thread: clarity in writing is a necessary condition for intelligent, reasoned dialog.

Beyond that, Unibox gives significantly different numbers from what you posted. I didn't save the driver file last time, so I think I made a type in entering its parameters to generate the numbers I posted above. (And on this post, before editing.) Unibox calculates that a critically-damped (Qtc=0.500) enclosure would need to be 132.4L, with no fill. That's what, about 4.5-5 cubes per driver?


Yeah, I didn't realize what you were responding to, my apologies.

Well, comparing our numbers is moot...without sharing all of the parameters entered (leaks, etc). Also sometimes people have different values entered for additional resistance due to other components/wires etc (RS)..and don't realize it. Those numbers IMO are irrelevant to real world comparison because the resistance in everyone's system is dependent on so many variables.

So for this reason I assume 0 interactions from external components, that should have been specified originally. I always Assume Rs to = 0 for my simulations. No leaks, no fill, a Qtc of .5 according to Unibox requires a Vb of 78.6 liters. Yes, I am also well aware that the actual real world Qtc would be higher than .5...for other reasons.

Let's see if we can't get a reasonable consensus answer to the original question, absent the schlong-swinging all too evident on this thread:

Ported/passive radiator/TL subwoofers will always give more output within their passband a sealed subwoofer using the same driver and box volume. (Even I-B, really, though I don't know if I've ever heard of a vented I-B in real life.) Said passband is essentially whatever the sub's designer wants it to be; there's nothing stopping one from tuning a vented sub to 60Hz, and nothing stopping a tuning frequency of 6Hz for a PR or vented sub, either. (Even in a very small box, the vent can snake outside of it, or a PR can be used. However, a vented subwoofer will also have higher group delay than a sealed sub, group delay is thought to be deleterious to subjective bass quality, and electronics cannot ameliorate that physical reality.

A closed-box subwoofer will always be less efficient in the passband than a vented subwoofer, assuming the same box volume. However, it will roll off at a more shallow rate (exactly how much more shallow depends on its Qtc, though the terminal rolloff is 12dB/oct) than a vented subwoofer below the passband, and depending on how the comparison vented box is tuned may or may not offer more output in the extreme LF. A sealed subwoofer will have lower group delay than a vented subwoofer. The efficiency penalty of a sealed box vis a vis sealed can be mitigated by adding more drivers, though if the volume per driver gets too small then there will be sonic penalties from having a high-Q resonant system compared to building the box to the right size in the first place, even with electronic band-aids.

Well-deployed EQ is also highly necessary in both cases for optimal results.

Lastly, far more important than output below 20Hz is response in the two octaves from 40-160Hz. (Assuming an 80Hz crossover, that's an octave above the passband.) That is dependent more on driver quality and sub placement/room treatments/EQ than box alignment, though a ported system with low tuning may have port resonances that affect performance in this crucial octave. A good subwoofer needs to have a well-engineered motor with low inductance linearized by a Faraday ring to handle this range well.

Any real objections to those statements?

That is, of course, retarded. It is entirely possible to build a vented system with response into the single digits, if one is so inclined. In fact, a vented system will always have more output around the tuning frequency than a closed one, so if it's really stuff that doesn't matter you care about, you should build vented boxes tuned to those frequencies.
And this is what he has the hardest time understanding. Porting can always give you more clean headroom - whether you want it at 30hz or 3hz, you just need to go about it properly. A sealed sub's response will eventually drop off in room, even with EQ, that is where the port can help. Recently a fellow on another forum sectioned off his IB space into a large enclosure and gained an additional 10db or so of clean output centered around 11hz which keeps him flat in room to ~9hz compared the previous rollof from the IB at ~19hz. What did he find more audible and preferable, the shallower rolloff in the single digits or the additional clean headroom from 9-19hz that kept him naturally flat? The additional clean headroom of course.

But then now we get back to hearing about I want my sub to be 1 cubic foot, etc. (or else my wife will send me to the doghouse :rolleyes: ) That's fine, just realize you are sacrificing performance.

When you say "clean" are you really only refering to harmonic distortion?

I think most of the sealed vs reflex battle is rooted in the fact that the sealed box has higher harmonic distortion than a reflex box. Sealed camp should agree but note that these harmonics, if heard, aren't detrimental to the enjoyment of the sound. Reflex camp states the fact that reflex has lower harmonic distortion at Fb (clean?) due to the lowered driver excursion. Downside is group delay is smeared down low. Reflex camp states its not detrimental to the enjoyment of the sound.

Here you have one major tradeoff for another. Which is preferable seems to be very debatable. From those I talked to, musicians for the most part do not complain of the sound from a reflex box. Most studio monitors are reflex. Here's two professional groups of people who are dead serious about sound. Most self proclaimed audiophiles prefer sealed. And from a scientific standpoint, it would atleast appear sound eminated from a single source (driver) with no delayed resonant band output overlapping the drivers output would be superior if harmonic distortions are suppressed and excursion can makeup for the lack of a box resonance. Of course there are other minor issues with each design I have'nt touched on.

I see the logical arguments on each side and think everyone just needs to listen to as many as possible and develop a personal pref. Maybe someday the aliens will introduce us to some technology that makes both sealed & ported rediculously inferior!

Dr V

If nothing else, we have learned that Mr. Callas and DS-21 don't mind calling others retarded. This is not a surprise, but worth noting.

Let's see if we can't get a reasonable consensus answer to the original question, absent the schlong-swinging all too evident on this thread:

Ported/passive radiator/TL subwoofers will always give more output within their passband a sealed subwoofer using the same driver and box volume. (Even I-B, really, though I don't know if I've ever heard of a vented I-B in real life.) Said passband is essentially whatever the sub's designer wants it to be; there's nothing stopping one from tuning a vented sub to 60Hz, and nothing stopping a tuning frequency of 6Hz for a PR or vented sub, either. (Even in a very small box, the vent can snake outside of it, or a PR can be used. However, a vented subwoofer will also have higher group delay than a sealed sub, group delay is thought to be deleterious to subjective bass quality, and electronics cannot ameliorate that physical reality.

A closed-box subwoofer will always be less efficient in the passband than a vented subwoofer, assuming the same box volume. However, it will roll off at a more shallow rate (exactly how much more shallow depends on its Qtc, though the terminal rolloff is 12dB/oct) than a vented subwoofer below the passband, and depending on how the comparison vented box is tuned may or may not offer more output in the extreme LF. A sealed subwoofer will have lower group delay than a vented subwoofer. The efficiency penalty of a sealed box vis a vis sealed can be mitigated by adding more drivers, though if the volume per driver gets too small then there will be sonic penalties from having a high-Q resonant system compared to building the box to the right size in the first place, even with electronic band-aids.

Well-deployed EQ is also highly necessary in both cases for optimal results.

Lastly, far more important than output below 20Hz is response in the two octaves from 40-160Hz. (Assuming an 80Hz crossover, that's an octave above the passband.) That is dependent more on driver quality and sub placement/room treatments/EQ than box alignment, though a ported system with low tuning may have port resonances that affect performance in this crucial octave. A good subwoofer needs to have a well-engineered motor with low inductance linearized by a Faraday ring to handle this range well.

Any real objections to those statements?

No objections, though you did leave out a few things. When going the DIY route, watts and drivers are fairly inexpensive. Take a 60 x 24 x 24 inch box, and model out at single driver, ported subwoofer with a high output 18 inch driver... say the new Soundsplinter.

Now take the same box, and put 4 drivers, 2 on opposing sides, and model it.

It will be about $1300 additional for the extra drivers and, say, 2 Behringer EP-2500's.

The other point is in the listening. The most vocal of the "ported rules" guys have never heard a properly done, high end sealed subwoofer set up.

The $1300 for the subwoofer I describe above will, in the same amount of room space, make for a far superior system to the single driver, ported unit.

But then now we get back to hearing about I want my sub to be 1 cubic foot, etc. (or else my wife will send me to the doghouse ) That's fine, just realize you are sacrificing performance.
The 1 cubic foot arguement is, perhaps, an extreme, as is a water heater sized sub, but I don't strictly measure a subs performance based on how low and how much output. It has to have some of those elements, certainly, but also needs to integrate well with the other speakers musicly and sound respectable in it's higher octaves. While most people don't need it to be teenie-tiny, most don't want the water heater either, wife or no wife.

The $1300 for the subwoofer I describe above will, in the same amount of room space, make for a far superior system to the single driver, ported unit.
Yes , but just as we won't tolerate the water heater or a sub that doesn't blend well musically , they can't part with the extra cash.

I love how everything is always black or white, left wing or right wing! :rolleyes:

BOTH offer advantages and disadvantages! what's so hard to comprehend about it. 7 pages of name-calling and pissing contests, and nothing has been resolved, not even a "both offer excellent performance when done right".

A properly done 18" ported sub will out do a dual 18" sealed if not executed properly.
A dual 15" sealed can out-perform a pair of 15" ported subs if not designed properly.

its simple....you have choices, and not all those choices have to do with price, size, WAF, etc. The Devil is in the execution. You need more drivers and power for sealed, you need more real estate for ported.

.

Yes , but just as we won't tolerate the water heater or a sub that doesn't blend well musically , they can't part with the extra cash.

How to respond to this ... ??? I did mention it would be about $1300 more for the three drivers and the extra amp. I thought people could figure out on their own that this meant a higher budget. Perhaps I was wrong ... :p

And yes, there are always choices to be made. But ... when looking at a given size enclosure, and going under the idea (I know this is radical, Sherv) that if one can build a competent ported sub, one will also build a competent sealed sub, a sealed enclosure will allow for a better overall performer, but with the requirement of the spending more money.

If someone looks at the examples I gave regarding a single ported 18 Vs. Quad sealed 18's in a similar sized box, the question is: "Is the $1300 extra worth it to me for far superior performance?"

If not, build the big ported. If it is, build the big sealed.

And yes, there are always choices to be made. But ... when looking at a given size enclosure, and going under the idea (I know this is radical, Sherv) that if one can build a competent ported sub, one will also build a competent sealed sub, a sealed enclosure will allow for a better overall performer, but with the requirement of the spending more money.

If someone looks at the examples I gave regarding a single ported 18 Vs. Quad sealed 18's in a similar sized box, the question is: "Is the $1300 extra worth it to me for far superior performance?"
actually, here another radical one for you craig:

if one can spend $1300 extra in 3 more drivers and an extra amp on the same big box, surely nobody will dispute the performance advantage. But if you had $1300 on the table, what would one do? go out and buy the 3 extra drivers and extra amp, and slap it on the big box? how about this:

buy two more drivers and two more amps, and build two other big boxes for the $1300........now who has the advantage? ;)

the constraints are different for different people. Some people, like Steve for example, would always go for the large boxes/ported. Many others would go with your suggestion on how to invest the $1300 and get more drivers/amp and make the original platform (one big box) better.


and yet, still there are options: Ol' Sherv would scratch the box altogether, and mount all 4 drivers onto the attic, and EQ + LT, and I'm golden!! both ported/sealed would have a hard time at that point ;) If no attic, then I would probably go individual sealed cubes, and work on location and best FR in room. If not enough power (my house would require $2000 in electrical mods to rewire the room for more power unfortunately....thank you florida builders! :mad: ) available to run 4 18" sealed with their amps, etc, as is the case currently, then my other alternative is what I have: 2 18's in big boxes/tubes. Finally, if this is not possible due to size, etc, then yes, a big box with multiple drivers + power would be better than a single large ported.

at the end of the day, one has to see their constraints, and see what makes more sense. If there was a universal answer then we would all have drivers mounted on an attic :p

If nothing else, we have learned that Mr. Callas and DS-21 don't mind calling others retarded. This is not a surprise, but worth noting.you noticed that too... ;)