late night thoughts about DIY vs Comercial - Page 16 - AVS Forum
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post #451 of 682 Old 03-25-2008, 04:09 PM
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Quote:
Originally Posted by Richard Mayer View Post

Hmm, probably it's just the room gain that boosts that low end, which makes it look like it doesn't attenuate with distance.

So, you're saying that the room gain in single digits is the same for a given input no matter where you sit in the room? It looks that way in my case, but wouldn't that lend to the zero attenuation thought?


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Yes, naturally low frequencies go further in distance because they will pass any objects with less attenuation than higher frequencies. But those studies mean distances in the range of miles or at least a couple hundred yards. I'm not sure if that applies to distances of 4 meters, in a room.

"Less attenuated by air and less diffracted by obstacles", the important question would be how much less, not at what distance. As you point out, if ULF is able to travel miles or hundreds of yards further than higher frequencies, the general thought is that there is virtually no attenuation at 4 meters, when clearly there is at higher frequencies, as the graph (and any graph) shows.

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Also it doesn't mean anything whether you need more output in 15-40 Hz range or not. It doesn't take away the fact that porting a subwoofer adds significant amount of gain at and above the tuning frequency. That's a great way of extracting more performance from the driver (let's keep the same 15-40 Hz range) compared to sealed enclosure. Some people with low or no space constraints and less money (or want to spend less money) may find it useful, even though it doesn't go as low (isn't practical anymore) as a sealed system can be pushed (optimally).

I'll give you 1 octave, 15-30Hz, but using the qualifying word 'performance', I'll shrink that to a much narrower range for higher excursion in the larger box just above tune, generally speaking, which will raise non linear distortions.

Still, in the case I cited, there is no viable option for a ported version of the LMS-5400-18" driver.

Bosso
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post #452 of 682 Old 03-25-2008, 07:02 PM
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Bosso,

Since you are obviously a fan of sealed subs.

What do you think about seven dual opposed subs using dual TC300015's,Acoupower 18's,AudioPulse REVO 15's,Mach5 IXL18.4,CSS SDX15,SS RL-p 15D2,Exodus Maelstrom-X(will have all these save for the Maelstrom-X within two weeks) ? Build time, 7-10 days for the cabinets.I need almost to EQ boost to have prodigious extension in my test room.

All this in a 800cu ft space. With ample power to get each to Xmax with ease(not to worry ,thermal of each driver will not be in the danger zone).

So far I have had great results with sealed in this smallish space,as the room gain is almost car like at sitting position,not boomy like a few may suspect.

Should be interesting to test the ULF response and if the extra frequency extension is worth the effort.

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
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post #453 of 682 Old 03-25-2008, 07:07 PM
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Quote:
Originally Posted by bossobass View Post

So, you're saying that the room gain in single digits is the same for a given input no matter where you sit in the room? It looks that way in my case, but wouldn't that lend to the zero attenuation thought?

"Less attenuated by air and less diffracted by obstacles", the important question would be how much less, not at what distance. As you point out, if ULF is able to travel miles or hundreds of yards further than higher frequencies, the general thought is that there is virtually no attenuation at 4 meters, when clearly there is at higher frequencies, as the graph (and any graph) shows.

The high frequency loss described here is an actual resistive loss. This is entirely different from the reduction in level over distance from a point source, as described by 20*Log (D/Di).

The loss described in your reference is air losses over larger distances which are quite identifiable in pro and outdoor applications, not in home listening rooms.

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post #454 of 682 Old 03-25-2008, 07:17 PM
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Lots of posts - thankfully a few good ones.

Quote:
Originally Posted by bosso View Post

BTW, the drone cone inverter or slave diaphragm or passive radiator is a sealed system. It's not in any way similar to the ported version.

Quote:


It's sealed, no matter how you slice it.

Umm, no? I'm assuming (hoping) you are meaning this ONLY in the fact that the enclosure is essentially air tight.

Quote:


And, you gotta be kiddin' me with the whole outperform thing. What's it, down 40dB at 10Hz??? Waste of good drivers.

While I agree that it should have been larger and tuned lower, it shows how much more benefit there is in a reflex system in terms of less distortion, better FR linearity, and plenty more output.


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Originally Posted by Richard View Post

The air spring distortion is a real thing. But it's quite hard to measure it because as you make the enclosure volume smaller, you also lose in efficiency which kinda masks the higher air spring distortion. But it's there no matter how you slice it. Whether it's a major contributor to THD is a whole another issue.

Mark confirmed the air spring distortion as well, and while nobody ever made it out to be a huge distortion, it - combined with the reduced amount of power an IB needs to achieve the same levels at low frequencies as a smallish sealed box - gets back to why I said an IB will perform similarly to a smallish sealed with less distortion in the lower frequencies. No more, no less. And this is why we CAN look at Ilkka's testing of the TC2k ported vs sealed and get a very clear picture of what a SLLT vs IB will do with minimal extrapolation required. 3 pages down the drain

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Originally Posted by Richard View Post

I would think that most of us would prefer more clean output in 15-40 Hz range than in <15 Hz range.

And I think you would be right.

Quote:


I'm thinking you are taking the Dolby's LFE spec a bit too seriously. It's ok to reach for the skies but don't use it as an excuse to dismiss every ported/PR subwoofer just because they "can't" go down to 3 Hz.

It would be one thing if a comparable design could actually get there with a linear FR, adequate headroom (120db+), and decent distortion levels, but instead, when a smallish sealed design is forced (EQ'd) to try and reach that low, it not only can't do those things, but it takes away a LOT from the reproduction of the most common bass ranges. Large and low tuned ported on the other hand basically leaves the reproduction of 35hz+ alone (intact) and slowly adds clean output as frequency decreases until below tuning. It's corny, but I'm still impressed by the concept when I think about it. So maybe the size isn't for everyone, but you can't argue with the performance advantages.

Richard, I'm by no means 'explaining' that to you, just venting I guess...pun intended. From previous discussions I'm quite aware you know all of this.


As for the IB drivers,
Acoustic Elegenace IB15 looks great in a SLLT with ~1400 liters and an 8" diameter port that is ~17" long per driver. Four drivers in that configuration will far outperform four in an IB. Posting graphs is so 2006, but what the heck.

FiCar IB18 looks nice in a SLLT with ~1750 liters and a 10" diameter port that is ~21" long per driver. I would take four drivers in that configuration vs four in an IB any day of the week, again, because of the big performance advantages.

In both comparisons, equal power is being fed to SLLT and IB, and of course, the IB reaches excursion limits sooner. For those who might look at those volumes and think they are insane, keep in mind these are not stand-alone enclosures that are built inside the listening room. The are made by boxing off a region of an adjacent space that would have otherwise been used entirely by the IB. So say if your IB rear chamber is your attic, you could section off the needed space with a few sheets of plywood.


Quote:
Originally Posted by Mark View Post

The same applies to larger sealed boxes, where an IB is just an extreme example.

Quote:
Originally Posted by Richard View Post

And yes, an IB is just like a huge sealed enclosure

ssabripo, I'm still waiting to hear how it isn't - you were adament that it isn't.


Good thread....almost like a recap of the last 3 years.
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post #455 of 682 Old 03-25-2008, 08:00 PM
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Oh, and TheEAR, something you might find pretty interesting. This isn't the first time bosso has talked about <10hz content playing a role in the audibility/enjoyability of bass in music. In fact, a few years ago, he was so adament that single digits added significantly to our perception of bass in music, even when at far reduced output levels than the fundamental bass notes in higher bass frequencies, that he felt it would easily be percievable in blind listening tests comparing music with single digits vs that same music with it filtered out.

I found this quite interesting and wanted to test it myself. Since I was skeptical, and I don't have a system capable to 3hz (ahem), I thought I would make his proposed experiment even easier by looking for music with output in the 10-20hz range at reduced levels relative to the primary, higher frequency bass notes. If people could discern when that bass was filtered out, he may be on to something. If they couldn't, and this was in the 10-20hz range, surely we can't below that. I started viewing songs with Spectrum Lab to isolate a few good samples - after literally viewing hundreds of songs, from classical to rock to vocals to jazz to techno to R&B to pop, the first thing I realized is that very, very little music has anything below 30hz. The majority of songs that did have anything below 30hz were actually from the pop genre, stuff like Gwen Stefani, Fergie, etc.

Anyway, after enough searching, I was able to finally find a few samples that met my criteria. I posted the results and offered bosso and others involved in the debate at that time access to the songs and a free program that could be used to filter out frequencies below a point of our choosing. Strangely, nobody accepted, inclusing bosso - perhaps because they realized the absurdity of the experiment and I couldn't at the time....though I certainly do now. Snapshots of the passages in question are attached by the way. I went through and did the experiment myself and could discern absolutely no difference. Some will say I was biased, and perhaps they have a point, but I heard/felt no difference, and at least I was trying it out - more than I could say for the others involved at that time.

If you are interested EAR, I would encourage you to try this on your own with your existing subs and some of your own music samples, it's really a pretty easy experiment, and it can point you in the right direction as to whether you are chasing a non-existant musical improvement or perhaps the next big thing in music. I have plenty more files too if you are interested in seeing what kind of music has some low bass.
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post #456 of 682 Old 03-25-2008, 08:30 PM
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Quote:
Originally Posted by SteveCallas View Post

As for the IB drivers,
Acoustic Elegenace IB15 looks great in a SLLT with ~1400 liters and an 8" diameter port that is ~17" long per driver. Four drivers in that configuration will far outperform four in an IB. Posting graphs is so 2006, but what the heck.

FiCar IB18 looks nice in a SLLT with ~1750 liters and a 10" diameter port that is ~21" long per driver. I would take four drivers in that configuration vs four in an IB any day of the week, again, because of the big performance advantages.

In both comparisons, equal power is being fed to SLLT and IB, and of course, the IB reaches excursion limits sooner. For those who might look at those volumes and think they are insane, keep in mind these are not stand-alone enclosures that are built inside the listening room. The are made by boxing off a region of an adjacent space that would have otherwise been used entirely by the IB.

Yep lets just ignore Mark's advise....

Quote:
Originally Posted by Mark Seaton View Post

So far as these drivers in a ported box, I personally couldn't respect myself in the morning (nor keep a straight face) in telling someone to put the effort into a >1000L (35 cu.ft.) box and only expect 105-110dB @ 1m from it. Sure, you can do it, but why? It's also pretty likely that an effort that large will face some problems with internal dimensions and interacting resonances, although those (don't) seem to get as much attention as real measurements of the boxes being built.

Quote:
Originally Posted by Steve Callas View Post

So say if your IB rear chamber is your attic, you could section off the needed space with a few sheets of plywood.

And your bachelor's degree is in mechanical engineering?....

Bracing? Bracing? SLLT's don't need no stinking bracing, they're fine with a layer of 3/4" MDF screwed to the studs.

Whoever gave Rodny the okay for this port placement and bracing should be taken to the woodshed.



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post #457 of 682 Old 03-25-2008, 08:44 PM - Thread Starter
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FiCar IB18 looks nice in a SLLT with ~1750 liters and a 10" diameter port that is ~21" long per driver. I would take four drivers in that configuration vs four in an IB any day of the week, again, because of the big performance advantages.


If you post this statement 50 more times....do you think it becomes true at some point?

The tribal wisdom of the Dakota Indians, passed on from generation to generation, says that, "When you discover that you are riding a dead horse, the best strategy is to dismount."

However, in government, education, and in corporate America, more advanced strategies are often employed, such as:

1. Buying a stronger whip.
2. Changing riders.
3. Appointing a committee to study the horse.
4. Arranging to visit other countries to see how other cultures ride dead horses.
5. Lowering the standards so that dead horses can be included.
6. Reclassifying the dead horse as living-impaired.
7. Hiring outside contractors to ride the dead horse.
8. Harnessing several dead horses together to increase speed.
9. Providing additional funding and/or training to increase dead horse's performance.
10. Doing a productivity study to see if lighter riders would improve the dead horse's performance.
11. Declaring that as the dead horse does not have to be fed, it is less costly, carries lower overhead and therefore contributes substantially more to the bottom line of the economy than do some other horses
12. Rewriting the expected performance requirements for all horses.



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post #458 of 682 Old 03-25-2008, 08:54 PM
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Steve,

I will probably just TRY the ULF for the sake of experimentation ,I have no desire to aim at a frequency range that brings only very deep rumble.Looking for musicality near DC is only for those who have invested a huge amount(time/money) into getting the audible as close as it can be to perfection with the current state of driver/cabinet and electronics.Plus have a room that is nearly flawless...very few would qualify.

The sealed subs are to fit a limited space.



Penngray,

Post of the year ! Too much this thread sure has its twists.

Your number six is a classic! LOL

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
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post #459 of 682 Old 03-25-2008, 09:00 PM - Thread Starter
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Penngray,

Post of the year ! Too much this thread sure has its twists.

Your number six is a classic! LOL

lmao, I love it but I can not take credit for it. Its been around a long time and posted on many, many sites.

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post #460 of 682 Old 03-25-2008, 09:04 PM
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Quote:
Originally Posted by Thomas-W View Post


Whoever gave Rodny the okay for this port placement and bracing should be taken to the woodshed.

I have to say the "box" looks a bit on the White Van cabinet side of well built.

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
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post #461 of 682 Old 03-25-2008, 09:33 PM
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Quote:
Originally Posted by TheEAR View Post

I have to say the "box" looks a bit on the White Van cabinet side of well built.

All I get are red X's.

YID DIY
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post #462 of 682 Old 03-26-2008, 05:50 AM
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Originally Posted by SteveCallas View Post

ssabripo, I'm still waiting to hear how it isn't - you were adament that it isn't.

LMAO!....so lets take Richard's word for it, that is definitive proof. Lets ignore the information ThomasW and goneten posted, lets ignore the info on the cult and HTS.

I'm actually waiting on you steve...

btw, I don't even know WHERE to begin replying to your post on the IB drivers on the SLTT configuration . Surely SURELY you are smarter than that...I know you are.
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post #463 of 682 Old 03-26-2008, 08:04 AM
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It's sort of like going back to pre school and telling Steve the paste is for adhesion, not for eating, but he just keeps smearing the **** on his sandwich, day after day.

Quote:
Mark confirmed the air spring distortion as well, and while nobody ever made it out to be a huge distortion, it - combined with the reduced amount of power an IB needs to achieve the same levels at low frequencies as a smallish sealed box - gets back to why I said an IB will perform similarly to a smallish sealed with less distortion in the lower frequencies. No more, no less. And this is why we CAN look at Ilkka's testing of the TC2k ported vs sealed and get a very clear picture of what a SLLT vs IB will do with minimal extrapolation required. 3 pages down the drain

Exactly how did Mark 'confirm' air spring distortion?

Ilkka's test of the ported TC2K vs what sealed? You mean the defective TC2K that has its output numbers in parenthesis? Good example.

In all your thousands of posts about comparing whatever it is you deem comparable to make whatever point it is you keep babbling about, there is not a single real comparison, driver for driver. Not one.

I challenged you to show the modeled comparison between the LMS-5400-18" sealed vs the ported version. By all means, extrapolate. I'm still holding my breath.

Quote:
It would be one thing if a comparable design could actually get there with a linear FR, adequate headroom (120db+), and decent distortion levels, but instead, when a smallish sealed design is forced (EQ'd) to try and reach that low, it not only can't do those things, but it takes away a LOT from the reproduction of the most common bass ranges. Large and low tuned ported on the other hand basically leaves the reproduction of 35hz+ alone (intact) and slowly adds clean output as frequency decreases until below tuning. It's corny, but I'm still impressed by the concept when I think about it. So maybe the size isn't for everyone, but you can't argue with the performance advantages.

Here, we have the Stevie Gems, all in one paragraph.

1) Sealed L/T has NO EQ ABOVE 35Hz. Did you get that Steve? I can repeat it until you do, if you need me to, which seems apparent that you do need me, and a dozen other people to, over and over and over.
2) Your recent favorite example, the ported TC2K: LINEAR FR?? Down 20dB at 10Hz with compression on the 105dB sweep? You're right, it's corny.
3) 120dB?? You mean 4 of them? And, 10 of them won't get you 120dB at 10Hz, your own magic number.
4) Port compression at 100dB. Wow, it's miraculous performance.
5) 100% THD at 15Hz. More miracles.
6) 16.5Hz tune. Is that the 'L'? Man, that's what, a whole 1/3 octave lower than TV's first DIY ported 12" sub. Big improvement in 9 years.
7) TV kicked that sub's tail in a smaller box, smaller driver, 1600 watts less amp, more linear response, more output, same port compression, lower extension, less THD, better driver protection, variable tune, better looking, better warranty...

Maybe you should be asking TV for pointers instead of arguing with a guy who has more clean output, 10dB more output at 10Hz and 30dB more output at 5Hz in less space than 4 of the PB-13 Ultras...for the same money.

You can't even use that TC2K ported sub for firewood where I come from, but it's a benchmark performance for Steve, as he references it every day...vs 'extrapolations'.

LMS-5400-18". LLT it and get back to me.

Bosso
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post #464 of 682 Old 03-26-2008, 08:13 AM
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Quote:
Originally Posted by bossobass View Post

Here, we have the Stevie Gems, all in one paragraph.

1) Sealed L/T has NO EQ ABOVE 35Hz. Did you get that Steve? I can repeat it until you do, if you need me to, which seems apparent that you do need me, and a dozen other people to, over and over and over.
2) Your recent favorite example, the ported TC2K: LINEAR FR?? Down 20dB at 10Hz with compression on the 105dB sweep? You're right, it's corny.
3) 120dB?? You mean 4 of them? And, 10 of them won't get you 120dB at 10Hz, your own magic number.
4) Port compression at 100dB. Wow, it's miraculous performance.
5) 100% THD at 15Hz. More miracles.
6) 16.5Hz tune. Is that the 'L'? Man, that's what, a whole 1/3 octave lower than TV's first DIY ported 12" sub. Big improvement in 9 years.
7) TV kicked that sub's tail in a smaller box, smaller driver, 1600 watts less amp, more linear response, more output, same port compression, lower extension, less THD, better driver protection, variable tune, better looking, better warranty...

you forgot a couple of big ones Bosso:

8) port resonances for the SLLT are gonna be what? anyone up for crossing at 50hz?
9) Steve modeled the "SLLT" for the fi18 at 50W, which is fine to push into them above 12Hz, with about 75-100W being the point where you start pushing mechanical limits. What happens below that?

oh the fun...
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post #465 of 682 Old 03-26-2008, 08:24 AM
 
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Quote:
Originally Posted by TheEAR View Post

Bosso,

Since you are obviously a fan of sealed subs.

What do you think about seven dual opposed subs using dual TC300015's,Acoupower 18's,AudioPulse REVO 15's,Mach5 IXL18.4,CSS SDX15,SS RL-p 15D2,Exodus Maelstrom-X(will have all these save for the Maelstrom-X within two weeks) ? Build time, 7-10 days for the cabinets.I need almost to EQ boost to have prodigious extension in my test room.

All this in a 800cu ft space. With ample power to get each to Xmax with ease(not to worry ,thermal of each driver will not be in the danger zone).

So far I have had great results with sealed in this smallish space,as the room gain is almost car like at sitting position,not boomy like a few may suspect.

Should be interesting to test the ULF response and if the extra frequency extension is worth the effort.

Ear ... One rather inportant question.

Where do you sit ?
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post #466 of 682 Old 03-26-2008, 08:48 AM
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Originally Posted by craigsub View Post

Ear ... One rather inportant question.

Where do you sit ?

In a listening "chair" . You will understand when you will see the stacks.

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
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post #467 of 682 Old 03-26-2008, 09:00 AM
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Originally Posted by TheEAR View Post

In a listening "chair" . You will understand when you will see the stacks.

Your low freq extension is bound to improve with each new sub.......... I mean your overall room volume keeps decreasing by large amounts with each new box in there.

Pretty soon car audio subs will start working well
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post #468 of 682 Old 03-26-2008, 10:02 AM
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Originally Posted by zamboniman View Post

Your low freq extension is bound to improve with each new sub.......... I mean your overall room volume keeps decreasing by large amounts with each new box in there.

Pretty soon car audio subs will start working well

Hah...clever.

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post #469 of 682 Old 03-26-2008, 10:08 AM - Thread Starter
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You can't even use that TC2K ported sub for firewood where I come from, but it's a benchmark performance for Steve, as he references it every day...vs 'extrapolations'.

dont discourage me

Im building two TC2K 15" ported subs (310L each). Im pretty sure they will still make me very happy

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post #470 of 682 Old 03-26-2008, 10:36 AM
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Originally Posted by penngray View Post

dont discourage me

Im building two TC2K 15" ported subs (310L each). Im pretty sure they will still make me very happy

Based off my experience with a pair of these with one 18" vmp radiator for each you will not be unhappy at all!!! There is always one better, louder, faster, etc. I don't think the comment was put up to say this is an under performing alignment, just that where he comes from he would not consider them a reference.

29 Litres of Infinite Baffle Bliss. Oh, and the rest of the setup isn't too shabby either!
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post #471 of 682 Old 03-26-2008, 10:51 AM
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Quote:
Originally Posted by ssabripo View Post

you forgot a couple of big ones Bosso:

8) port resonances for the SLLT are gonna be what? anyone up for crossing at 50hz?
oh the fun...

Actually, the 1st port resonances in either of those alignments would be over 300Hz.
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post #472 of 682 Old 03-26-2008, 12:50 PM
 
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Jack, you're late, as usual.

--Regards ,
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post #473 of 682 Old 03-26-2008, 01:03 PM
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Originally Posted by TheEAR View Post

Bosso,

Since you are obviously a fan of sealed subs.

What do you think about seven dual opposed subs using dual TC300015's,Acoupower 18's,AudioPulse REVO 15's,Mach5 IXL18.4,CSS SDX15,SS RL-p 15D2,Exodus Maelstrom-X(will have all these save for the Maelstrom-X within two weeks) ? Build time, 7-10 days for the cabinets.I need almost to EQ boost to have prodigious extension in my test room.

All this in a 800cu ft space. With ample power to get each to Xmax with ease(not to worry ,thermal of each driver will not be in the danger zone).

So far I have had great results with sealed in this smallish space,as the room gain is almost car like at sitting position,not boomy like a few may suspect.

Should be interesting to test the ULF response and if the extra frequency extension is worth the effort.

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http://www.youtube.com/watch?v=-DP89iMe0BY

or if you prefer, this classic:

http://www.youtube.com/watch?v=R5paXeKX-W8

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----Check my QUAD 18" Fi IB Build Thread!! (DONE) King of the 400 lb Gorilla
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post #474 of 682 Old 03-26-2008, 01:47 PM
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Quote:
Originally Posted by Willd View Post

Actually, the 1st port resonances in either of those alignments would be over 300Hz.

oh snap! a willy sighting!!!
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post #475 of 682 Old 03-26-2008, 02:41 PM
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Quote:
Originally Posted by SteveCallas View Post

Oh, and TheEAR, something you might find pretty interesting. This isn't the first time bosso has talked about <10hz content playing a role in the audibility/enjoyability of bass in music. In fact, a few years ago, he was so adament that single digits added significantly to our perception of bass in music, even when at far reduced output levels than the fundamental bass notes in higher bass frequencies, that he felt it would easily be percievable in blind listening tests comparing music with single digits vs that same music with it filtered out.

I found this quite interesting and wanted to test it myself. Since I was skeptical, and I don't have a system capable to 3hz (ahem), I thought I would make his proposed experiment even easier by looking for music with output in the 10-20hz range at reduced levels relative to the primary, higher frequency bass notes. If people could discern when that bass was filtered out, he may be on to something. If they couldn't, and this was in the 10-20hz range, surely we can't below that. I started viewing songs with Spectrum Lab to isolate a few good samples - after literally viewing hundreds of songs, from classical to rock to vocals to jazz to techno to R&B to pop, the first thing I realized is that very, very little music has anything below 30hz. The majority of songs that did have anything below 30hz were actually from the pop genre, stuff like Gwen Stefani, Fergie, etc.

Anyway, after enough searching, I was able to finally find a few samples that met my criteria. I posted the results and offered bosso and others involved in the debate at that time access to the songs and a free program that could be used to filter out frequencies below a point of our choosing. Strangely, nobody accepted, inclusing bosso - perhaps because they realized the absurdity of the experiment and I couldn't at the time....though I certainly do now. Snapshots of the passages in question are attached by the way. I went through and did the experiment myself and could discern absolutely no difference. Some will say I was biased, and perhaps they have a point, but I heard/felt no difference, and at least I was trying it out - more than I could say for the others involved at that time.

If you are interested EAR, I would encourage you to try this on your own with your existing subs and some of your own music samples, it's really a pretty easy experiment, and it can point you in the right direction as to whether you are chasing a non-existant musical improvement or perhaps the next big thing in music. I have plenty more files too if you are interested in seeing what kind of music has some low bass.

Something most of you will find boring, this isn't the first time Steve has attempted to be the world's authority on a subject that's beyond his capability and over his head.

Yes, folks, here we have the definitive study on single digits in the recorded media world. Steve scoured the earth, looking for single digit sound and found NOTHING. Or, as he puts it: non-existant.

I'm sorry I missed your most excellent experiment offer.

Maybe you can try some of these:

Big Notes Flim & The BB's DMP
Battle Music of Beethoven and Liszt Beethoven Telarc
1812 Overture Tchaikovsky Telarc
Great Fantasy/Adventure Album Erich Kunzel Telarc
Fantastic Journey Erich Kunzel Telarc
MANGER, Musik wie von einem anderen Stern, sampler
TELARC
CHESKY SACD

Maybe e-mail some of the people involved in hi rez discs and see what you might learn. Just a suggestion, FWIW.

Of course, I don't see any benefit in Steve having any of these samples, as he has no way to replay them.

Bosso
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post #476 of 682 Old 03-26-2008, 02:43 PM
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Quote:
Originally Posted by penngray View Post

dont discourage me

Im building two TC2K 15" ported subs (310L each). Im pretty sure they will still make me very happy

Of course, it was implied that you will do a much better job.

Bosso
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post #477 of 682 Old 03-26-2008, 02:59 PM
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Quote:
Originally Posted by Willd View Post

Actually, the 1st port resonances in either of those alignments would be over 300Hz.

Will,

We covered this earlier but you were AWOL ....

It appears sims don't tell the whole story....

If you read Rodny's IB to LLT conversion thread, a port resonance (at least that's want he calls it) limits his crossover point to 60Hz or lower...

Quote:
Originally Posted by Rodny View Post

The port has a resonance pass 60Hz, when I was inside of the box and you talk or scream can here a weird noise with a little echo, I think is the PVC pipe, change the crossover to 60Hz and it goes away!, I'm going to try Dynamat on the port to see if it kills the resonance, anybody with the same problem ??

To the rescue......
Quote:
Originally Posted by Steve Callas View Post

Hmm, cardboard sonotube is a naturally more damped material than pvc, I'm thinking that would play a role. To fix the issue with the pvc though, I'm thinking you would want to add more mass to the port. Strips of cloth dipped in plaster of paris and then warpped around the port perhaps?

This recommendation is interesting in light of the fact that port resonances aren't caused by the port material itself vibrating.......Doh!

IIRC, there's a simple test for a port resonance and a relatively easy fix. But unlike Mr Callas I'm not a self proclaimed "Professional Genius" so I'm probably wrong .....
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post #478 of 682 Old 03-26-2008, 03:25 PM
 
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Originally Posted by Thomas-W View Post

But unlike Mr Callas I'm not a self proclaimed "Professional Genius"....

...with a bachelor's degree in mechanical engineering...don't forget about that bachelor's degree...

--Regards,
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post #479 of 682 Old 03-26-2008, 03:37 PM
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Quote:
Originally Posted by goneten View Post

...with a bachelor's degree in mechanical engineering...don't forget about that bachelor's degree...

--Regards,

CORRECTION: not a bachelor's in Mechanical Engineering....a Bachelor in Industrial Technology, if I'm not mistaken
http://www.tech.purdue.edu/it/

not that it makes a difference though...a degree is worthless in this topic IMO.
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post #480 of 682 Old 03-26-2008, 03:48 PM
 
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Quote:
Originally Posted by Steve Callas View Post

With a powerful enough amplifier and EQ, there is no reason the cone travel in a smallish sealed box cannot match that of an IB unless the VC eventually fries.

What good is a small sealed box with a fried voice-coil ?

Quote:


Correct, but whereas you are assuming that air spring stays linear at all times[snip]

I don't think I assumed this. Or did I ?

Quote:


goneten, as to your comments regarding "using up excursion", looking back at your earlier statement I do see that you prefaced it with a fixed amount of power, so I aologize.

"Aologize" ? No need to "aologize".

Quote:


"At and around Fb" is a pretty large range then. . .[snip]

Assuming all parameters are equal. Comparing a large ported subwoofer to a "small-"ish" sealed box is not equal.

Quote:


as looking at Ilkka's testing of the ported TC2k vs smallish sealed, the ported has the clean output advantage from at least 12.5hz - 40hz.

A small-"ish" sealed box versus a large ported box. That doesn't seem like a valid comparison to me but I could be wrong.

Quote:


I would be interested in hearing how efficiency rises below resonance.

I don't think I said efficiency rises below resonance. However, all things being equal, a smaller sealed box with a higher box resonating frequency will have less efficiency in the deep bass spectrum due to the box acting like a high-pass filter at resonance.

An infinite baffle will "pull ahead" in this regard.

--Regards,
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