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post #181 of 1010 Old 08-10-2015, 08:18 AM
 
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Originally Posted by beastaudio View Post
. As far as ported not being "tight" like sealed, that isn't entirely true when either of the subs are designed proper. You can get what you are looking for in either alignment. What you need to look into are the differences you are giving up with either alignment

Ported - Take up more space, give you more output, but only down to what the sub is tuned to, you need to cut off the freqs below that with a High pass filter...
Sealed - Smaller/easier to design around, full extension into the bottom octaves, no need for a HPF.

This is not 100% true, but it's mostly accurate ^

Ported inherently has a poor transient response compared to sealed. Transient response is often responsible for the "tight" people describe with bass. You will read a lot of stuff about it has to do with moving mass, motor strength, inductance, and an entire host of things, and it will get complicated quickly. This is the part of what I agree with you on, if it is designed right, the problems can be minimized or managed.

In basic terms "transient response" is how fast a speaker starts, and how fast it stops in reaction to a given input signal. It is a measurement that includes an element of time, and isn't generally popular to talk about or post about. That's why you see a ton of ported Marty boxes with SI HT18's in them an everyone saying how awesome they are... I tried to warn people in the Marty thread here many, many months ago: https://www.avsforum.com/forum/155-di...l#post33566729

That in a nut shell is the problem with ported subs, and why they are often considered "sloppy"

Most don't know and most are not designed very well. The design has more to do with choosing the right driver, not the actual box design. You need a happy marriage between those two things. Some drivers just are better suited to a ported box than others.

A lot of it has to do with driver QTS and QES: http://www.loudspeakersplus.com/choo...t_speaker.html


You should not ever port drivers with a QES less than 0.4. because they will behave poorly in the time domain and have a poor transient response. This isn't new info, I learned it back in my car audio days in the 1990's and physics has not changed since then.

Simple: Sealed when Qes > 0.45, Ported when Qes < 0.45.

Many of the designed out there for ported subs are not ideal, even some popular MFG made models and popular options like the SI HT18/marty cube. So while it's not actually true 100% of the time, there is enough real world examples in reality to propagate the myth and stereotype that sealed subs are tighter.

I think when you start to port into the ULF (sub sonic) your sensitivity to transient response is less, because human hearing is less acute at low frequencies. But even a port tune of like 16hz or 17hz will extend up to 32 or 34hz where you might hear some of what I am talking about on tight acoustic music or fast electronic music. The tune generally effects the octave above it, so only port tunes near 10hz would ideally be not heard at all, but felt as pressure, with the main effected area being under hearing.

Inherently ported subs have a poor transient response, because they use both the back rear wave, and the front wave of the driver to reproduce the sound, whereas the sealed only uses the front wave. It's basically common sense that when impulse stops the sealed will have a better transient response. The way ported works means you generally need a motor that can control the cone well, because you can't rely on the acoustical suspension of the driver to stop or control it, that built up energy will be what creates the poor "sloppy" bass. Better motors cost $$$, people seem opposed to paying for it. So cheap woofers work better in sealed or IB. Expensive woofers are more appropriate for horns and ported boxes.

You don't see people using expensive drivers for the reason they are expensive, and many MFG will also compromise to hit a price point. People are essentially buying output for the dollar at that point, which can be a great deal if you only look at dollars to SPL ratio. But if you look at some of the other fine details you'll see you sometimes get what you pay for too.
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post #182 of 1010 Old 08-10-2015, 08:21 AM
 
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BTW if you are space limited, sealed is the choice. Stop. Ported gets better when it gets bigger. (sealed does too but can be smaller in general).
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post #183 of 1010 Old 08-10-2015, 08:42 AM
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Originally Posted by Mfusick View Post
This is not 100% true, but it's mostly accurate ^
That's why I said "Not entirely true." Group delay, transient response/phase shift, are pretty far ahead in this journey for Waterboy, who we are just starting to school some basics like HPF to

All that said, and with the info posted, it's all accurate and exactly why I personally have multiple sealed. Another nice advantage with multi sealed is it yields itself the best possible alignment for scale-ability. Start with two, decide if you have enough output. No? Buy two more and some additional amplification... Still not enough? Get 4 more and then you start looking like me and few others around here

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post #184 of 1010 Old 08-10-2015, 10:38 AM
 
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I think that I generally believe sealed will be tighter, it's a very rare exception that's not true. I can agree with your assessment. Baby steps !
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post #185 of 1010 Old 08-10-2015, 10:48 AM
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Heh. Sealed subs have just as much chance of not sounding "tight". In fact, I've heard several flabby sounding sealed subs. I've heard some very tight sounding resonant systems. It's all about the alignment of the system and it's integration into the room.

Low Qes/Qts helps with that sound too.

Resonant systems only have bad group delay around tune and most systems we talk about here are tuned <25hz at which point that higher than normal group delay will be inaudible.

My first ever DIY project was a 15" subwoofer that was tuned to 15hz. That was the tightest sounding system I had heard (at the time) that also could do deep bass.


Anyway, don't let "sounds tight" be the deciding factor for sealed or resonant because it's an irrelevant thing when really you should think SPL and bandwidth. Those are the worthy considerations for either sealed or resonant. Not, "tightness".
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post #186 of 1010 Old 08-10-2015, 11:46 AM - Thread Starter
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Quote:
Originally Posted by beastaudio View Post
That's why I said "Not entirely true." Group delay, transient response/phase shift, are pretty far ahead in this journey for Waterboy, who we are just starting to school some basics like HPF to

All that said, and with the info posted, it's all accurate and exactly why I personally have multiple sealed. Another nice advantage with multi sealed is it yields itself the best possible alignment for scale-ability. Start with two, decide if you have enough output. No? Buy two more and some additional amplification... Still not enough? Get 4 more and then you start looking like me and few others around here
YES you guys are certainly schooling me.....THANK YOU
There you go again.... 2 subs lead to 4, lead to 8..... And here I thought one 15" was crazy town..... now I am considering 4

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Originally Posted by Mfusick View Post
I think that I generally believe sealed will be tighter, it's a very rare exception that's not true. I can agree with your assessment. Baby steps !
BABY STEPS, you got that right..... and here you go adding more acronyms into the mix ..... thanks for the well written explanation

The use of the term "tight" was the best I could think of without knowing the proper terms..... hey I am trying to learn and appreciate it all

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post #187 of 1010 Old 08-10-2015, 12:00 PM
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Originally Posted by Waterboy77 View Post
YES you guys are certainly schooling me.....THANK YOU
There you go again.... 2 subs lead to 4, lead to 8..... And here I thought one 15" was crazy town..... now I am considering 4



BABY STEPS, you got that right..... and here you go adding more acronyms into the mix ..... thanks for the well written explanation

The use of the term "tight" was the best I could think of without knowing the proper terms..... hey I am trying to learn and appreciate it all
We can get you where you need to go, but don't let us, or yourself get out of control...Haha. It happens all too often around here.

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post #188 of 1010 Old 08-10-2015, 12:17 PM - Thread Starter
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We can get you where you need to go, but don't let us, or yourself get out of control...Haha. It happens all too often around here.

LOL ya I hear that

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post #189 of 1010 Old 08-10-2015, 12:19 PM
 
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Sealed is small, cheap and easy to build. It's a good choice as a starter IMO. But you end up needing to add MOAR ! That's ok...
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post #190 of 1010 Old 08-10-2015, 01:39 PM - Thread Starter
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Originally Posted by Mfusick View Post
Sealed is small, cheap and easy to build. It's a good choice as a starter IMO. But you end up needing to add MOAR ! That's ok...

MOAR Subs..... 15" with a Qes>0.45 in sealed enclosure
Doing a quick search came up with THIS Woofer.... seams pricey but it meets the >0.45 and the sealed volume at 1.27ft3 looks nice


http://www.diysubwoofers.org/definitions.htm

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post #191 of 1010 Old 08-10-2015, 06:01 PM
 
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For sealed its tough to beat the SI HT18. Put it into 4.5 or 5 cube box. Excellent value. Great performance to dollars.

They had some b stock 15" leftover recently for a really great price. Also there is a bunch of decent car audio subs that sell for low prices and work in sealed. You want a low fs and good extension though, most HT subs dig lower becuase lower is good for HT.
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post #192 of 1010 Old 08-10-2015, 06:45 PM - Thread Starter
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Well I just measured the inside dimensions of the column staying away from the metal pole...... 12.5" wide x 11" x 52" height. So that's not going to work for 15" subs.... darn it...... should have known as I was the one to build it but that metal pole in the one corner is eating up more space than I thought. Not even sure if a 12" will work.... thoughts?

It the column that is the closest in this picture




There's no way the "boss" is going to let me increase that as I already did once that was difficult.

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post #193 of 1010 Old 08-10-2015, 08:44 PM
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I spent a few minutes throwing together a sim in winisdpro. I'm not as familiar with the drivers around here as some of the guys are, but the UM12-22 got some good press on some professional reviews I read, and seems a decent 12" sub for excursion and price. So I started there - there might be better 12" subs for the money. I'm not the guy to ask.

With what you've said about not really needing a ton of bass - a 12" in each column, would be an okay start, but frankly it may leave you wanting. As you'd still be a good 10dB below reference with a couple 12" ported subs. (not counting for distance or boundary gain) A couple 12" in a couple columns would be smoothing bass only IMO. For this sim, You could buy a couple Dayton UM12-22 and port them to 15hz and feed them about 450 watts to them to get a max SPL of about 107 to 108dB SPL at 1 meter. That's in a 6cubic foot cab with 4 ports. You could basically turn your whole column into a subwoofer cab to get the 6 cubic foot of volume pretty easily I think. I suppose you could repeat for all four columns but if they aren't equal distance from the listening position you are going to get into phase misalignments (timing/distance settings) - which is definitely correctable through the iNuke DSP software, but requires measuring equipment like the omnimic or REW and some tinkering time. Depends on if you are up for the task or not?!?!

An Inuke DSP 3000 would do the trick for 2 column subs as far as power and DSP.

The iNuke's do a real good job with voltage limiting (watt limiting basically) You choose the power you want the driver to get, and it soft limits the driver. It won't make any bad noises when it hits the limits - it'll just not get louder and the clip lights will display. So that 450 watts will keep the cone excursion under control, and they'll do real nice until about -10dB on the AVR.

If you want more volume than that you'll either have to raise the ported tune. (yuck), or get bigger drivers. a 12" subwoofer can only do so much. Remember that when you calculate displacement a speaker is a lot more than just a couple inches smaller. Because we are calculating the surface area in total - a larger woofer has much more surface area than a couple inches would lead you to believe. For instance - a friend of mine recently told me his two 5.25" woofers should be about the equivalent of my 10" woofer. I said no. I showed him the math. It's really only the equivalent surface area of about 1/2 my 10" woofer for two 5.25" drivers. Using a simple math calculator for circles which discounts the surround and basket space - a 12" diameter's circle's surface area is about 113", for a 18" diameter's circle the surface area is about 254.5". So two 12" woofers have less surface area than a single 18" woofer - not to mention the larger woofers typically have more xmax (excursion) so that allows them even more displacement, and the surround takes up less space on a single 18" vs. two 12" further favoring the 18"
http://www.calculatorsoup.com/calcul...ane/circle.php

Truly - bigger is better when it comes to subwoofer displacement.




You could put a couple 18" up front for a bit more SPL. Either ported or sealed. (I like a good strong ported sub up front, but prefer sealed nearfield directly behind my seat when possible) If size wasn't an issue and you only wanted two subs I'd port for 15hz-16hz personally, or get about four 18" sealed instead at minimum. (I thought my two JTR captivators (ported 4000 watt variants) bested 4 sealed Um18-22 and 4 sealed SI 18HT subs. When I did the comparison in two different rooms on two different dates - 6 was about equitable - eight - then the decision went to the eight sealed.

Here is some info on the Dayton Audio UM subs.

18"
http://www.daytonaudio.com/index.php...ms-per-co.html
12"
http://www.daytonaudio.com/index.php...-per-coil.html


I've attached the winisdpro sim for you to take a look at.
Download the tool here:
http://www.linearteam.dk/?pageid=winisdpro

Play around with it.

Pay attention to several things
SPL
Cone Excursion
Frequency Response
If you are making a ported box you'll need to look at air velocity too from the ports. You don't want much over low 20's on that number - otherwise the ports will chuff (sound like wind is forcibly being pushed through them)
If I'm forgetting anything I'm sure one of the guys will let me know...
see the attached pictures for some examples...









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File Type: zip WinISDpro Project file UM12-22.zip (306.1 KB, 31 views)

Archaea's 9.8.4 Home Theater Room
(13) JBL CBT 70j-1 | Denon x7200wa | Sherbourn PA 7-350 amplifier | (8) Ultimax 18" sealed subwoofers | (4) iNuke DSP 6000 amplifiers | (4) MB Quart 12" subwoofers mounted direct mounted to Berkline theater chairs BOSS style | Epson 5040UB Projector | Jamestown 144" acoustic transparent 2.35:1 screen w/ Seymour XD fabric

Last edited by Archaea; 08-10-2015 at 08:55 PM.
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post #194 of 1010 Old 08-11-2015, 07:57 AM
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A couple of HST-11's could maybe fit into the columns if you are on the ragged edge of width requirement. Those are some pretty potent little guys for sure.

I will say, as Archaea kinda touched on, I would use columns for room smoothing subs only. Once your space is complete, it will be some trial and error to find where the best place in the room to put the subs will be. It could be possible the columns could be the absolute best place, but also the absolute worst. You don't want to handcuff yourself in most cases to a single "built in" location, especially away from the front wall. At least with the front wall, your subs are relatively close to the mains and somewhat/usually (I say that with quite a few caveats) easier to get incorporated with your mains.

Is there any reason you can't do standalone subwoofer enclosures that can be placed strategically in the right places in the room?

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post #195 of 1010 Old 08-11-2015, 08:16 AM - Thread Starter
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Quote:
Originally Posted by Archaea View Post
I spent a few minutes throwing together a sim in winisdpro.

WOW and WOW, Thank you very much, very well written. For sure I will be downloading and playing with the software I probable won't understand much of it to start but I am learning.


Ported...... interesting.... My brain was leaning toward sealed due to the cubic feet needed and at 6ft for the 12" woofer.... unfortunately I don't have the height, there is a Volt 6 going in above limiting the sub enclosure height to 52". (I will have to get some updated picture posted tonight)


Does the ported give that much more power when doing a one to one comparison to a sealed unit?


Just looking at the physical dimensions of the UM12-22, I might be still in trouble...... its outside diameter is 12 3/8"..... this would require the sides of the box to be right up against the inside diameter of 11 1/4"..... not sure if this is an OK practice.
A while back @deewan also talked about using the entire column with the pole through the one corner of the enclosure, this would give me more base area to work with and could limit the over all height. I was hoping to make a moveable enclosure to try on different areas but that might not be an option now....


Stupid question.... when looking a the volume of an enclosure (say 6ft3).... does the displacement of the driver (say 1ft3) result in the physical volume being larger (7ft3)


????? crazy thought .... does it matter if the woofer is pointing a couple of inches toward a solid wall and the ports are pointing the opposite way?

Quote:
Originally Posted by beastaudio View Post
Once your space is complete, it will be some trial and error to find where the best place in the room to put the subs will be. It could be possible the columns could be the absolute best place, but also the absolute worst. You don't want to handcuff yourself in most cases to a single "built in" location, especially away from the front wall. At least with the front wall, your subs are relatively close to the mains and somewhat/usually (I say that with quite a few caveats) easier to get incorporated with your mains.
Ya great explanation of why I would prefer to have moveable

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Is there any reason you can't do standalone subwoofer enclosures that can be placed strategically in the right places in the room?
I am trying for the "stealthy" look with all gear hidden away.... well except the 122" screen

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post #196 of 1010 Old 08-11-2015, 10:02 AM
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I wrote up a real long response for the last 30 minutes over my lunch break and it got erased when I pushed something on my keyboard and the browser went back a page unintentionally.


I lack the motivation to write it again.


Suffice to say - with a driver that can handle both ported and sealed --- in correctly appropriated boxes - the driver in the ported will have nearly a 10dB advantage around port tune over the same driver in a sealed box. At the upper bass frequencies the drivers will be pretty much equitable, but that deep bass advantage is significant for ported.


There are a WHOLE lot of caveats here --- that's what I wrote out. But some other time perhaps.

Archaea's 9.8.4 Home Theater Room
(13) JBL CBT 70j-1 | Denon x7200wa | Sherbourn PA 7-350 amplifier | (8) Ultimax 18" sealed subwoofers | (4) iNuke DSP 6000 amplifiers | (4) MB Quart 12" subwoofers mounted direct mounted to Berkline theater chairs BOSS style | Epson 5040UB Projector | Jamestown 144" acoustic transparent 2.35:1 screen w/ Seymour XD fabric
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post #197 of 1010 Old 08-11-2015, 11:08 AM - Thread Starter
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I wrote up a real long response for the last 30 minutes over my lunch break and it got erased when I pushed something on my keyboard and the browser went back a page unintentionally..
I hate it when that happens.... done it a couple times myself

Quote:
Originally Posted by Archaea View Post
Suffice to say - with a driver that can handle both ported and sealed --- in correctly appropriated boxes - the driver in the ported will have nearly a 10dB advantage around port tune over the same driver in a sealed box. At the upper bass frequencies the drivers will be pretty much equitable, but that deep bass advantage is significant for ported.

There are a WHOLE lot of caveats here --- that's what I wrote out. But some other time perhaps.

Thanks you, a 10db difference is pretty significant

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post #198 of 1010 Old 08-16-2015, 11:45 AM - Thread Starter
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Electrical Rough in mostly complete.... a couple of wires between lights on done..... waiting till drop ceiling installation in for final light locations

A lot of wires in the far column as this is the main switch "control" center, 6 zones in total



Here you can see the 12 romex bundled to try and keep as far away from the speaker as possible
Rear right speaker on a shelf placing about 2 feet above seated ear position, turned to face MLP
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post #199 of 1010 Old 08-16-2015, 12:06 PM - Thread Starter
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House Ethernet and coax relocation was completed yesterday. Moved all from the mechanical room to the rack.
So where a real pain as they were stapled in requiring coax connections to be cut off first

Before I pulled all the wire out I built a scrap lumber wire tray.... worked out better than I imagined for a bunch of scraps

The assembly before installation, made of 3/8" plywood, 3"x8". Put a nail at one end to help prevent wires falling off the end. This is also nice because I can lift one wire over it if needed
A lot more still to go on it


Installed with the exiting wires in the home rerouted


Back of rack..... got to say I am loving the Velcro straps

Upper portion bundled up


All terminated to the patch panel, wire chase really helps keep it clean..... well when the doors are closed
Patch panel hinges down and there is good slack for the cable to rotate with it
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One day I will start the new theater....... one day..... THAT DAY HAS ARRIVED
"If the women don't find you handsome, they should at least find you handy." Red Green
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post #200 of 1010 Old 08-17-2015, 01:29 AM
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sweet!
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post #201 of 1010 Old 08-20-2015, 07:13 PM - Thread Starter
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Got the speaker wire yesterday and installed it tonight..... love the new wire tray... super easy to install
Two 500 foot boxes of 14 awg made it easy to run two pair at a time.
Also ran a CAT5e and CAT6 from the rack to behind the screen.... hey you never know and I had it lying around




I have also been playing around with the WinISD software.....


Question, what is vent length and end correction?
For example in your ported sample @Archaea it shows 4 - 4 inch diameter vents with a vent length of 97.98inches and an end correction of 0.732


And the volume, is that with or without the driver?



One day I will start the new theater....... one day..... THAT DAY HAS ARRIVED
"If the women don't find you handsome, they should at least find you handy." Red Green
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post #202 of 1010 Old 08-20-2015, 07:42 PM
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Talking

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Originally Posted by rippmaster13 View Post
sweet!
"What does mine say?"
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post #203 of 1010 Old 08-21-2015, 12:20 PM
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@LTD02

Help!

I'm calling on an expert.
I'd be guessing on both questions.

My guesses - I doubt the driver's volume matters enough to really effect the sim terribly on a big ported box.
The port needs to be outside the box or accounted for in the volume calculation - especially with ports that long. (up and down the length of the box one time each x 4 )

Archaea's 9.8.4 Home Theater Room
(13) JBL CBT 70j-1 | Denon x7200wa | Sherbourn PA 7-350 amplifier | (8) Ultimax 18" sealed subwoofers | (4) iNuke DSP 6000 amplifiers | (4) MB Quart 12" subwoofers mounted direct mounted to Berkline theater chairs BOSS style | Epson 5040UB Projector | Jamestown 144" acoustic transparent 2.35:1 screen w/ Seymour XD fabric

Last edited by Archaea; 08-21-2015 at 12:40 PM.
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post #204 of 1010 Old 08-22-2015, 04:54 AM
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Quote:
Originally Posted by Mfusick View Post

Ported inherently has a poor transient response compared to sealed. Transient response is often responsible for the "tight" people describe with bass.
...

Inherently ported subs have a poor transient response, because they use both the back rear wave, and the front wave of the driver to reproduce the sound, whereas the sealed only uses the front wave.
what do you mean by transient response?

if you meant impulse response (time domain behavior), that is mostly a function of inductance and filtering.

for example, here is the impulse response of the b&c sw115 in a 4 cubic foot sealed and an 8 cubic foot ported tuned to 20hz.

the red line is the sealed.

the black line is the ported.

'port ringing' at 20hz is not an issue.

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post #205 of 1010 Old 08-22-2015, 05:05 AM
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Quote:
Originally Posted by Waterboy77 View Post
Question, what is vent length and end correction?
For example in your ported sample @Archaea it shows 4 - 4 inch diameter vents with a vent length of 97.98inches and an end correction of 0.732

And the volume, is that with or without the driver?
vent length is of course the length of the ports.

the key point is to try to keep the "first port resonance" out of the pass band. 120hz or higher is probably ok, but 140hz is about what I would suggest just to be on the safe side when using an 80hz 4th order low pass bass filter.


end correction is a complicated topic that has to do with how the vent terminates into the surround space. a port on the center of the cab will function a little differently from a port on the bottom for example. BUT if you calculate the port length correctly, the end correction isn't terribly important to be familiar with.

halfway down this post:
https://www.avsforum.com/forum/155-di...l#post23711347
is an explanation and some links on end correction if you really want to learn more. ;-)

the "volume" is the NET enclosure internal space. it does not include the driver, the port, the bracing, the cab construction or any of the rest of it. all of those must be ADDED to get to the final external size.

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post #206 of 1010 Old 08-22-2015, 05:32 AM
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not sure how far along you are on the baffle wall, but i would suggest making it modular (it looks like more of a fixed install in the o.p.


in that big room, you want 4 x 18" ported for a good effect. something in the spirit of four of these behind the screen (though they don't have to be quite that large).








four Dayton 460ho cabs tuned to about 16hz. ~10 cubic feet net internal with slot port that is 2.5" tall x about 20" wide x about 44" long. that will keep air speed reasonable. first port resonance out of the pass band. note: actual cab tuning will come in a little less than winisd projects. the actual measured port length would be a little less than 44" also. something around 42" as measured from end to end down the center of the slot port.


such as system will provide about 125db of output down to 15hz or so in 2pi space and even more in room. 125db is about "worst case scenario" (full output with all channels of bass redirected to the subs).


max spl of such a system with 1250 watts per driver.


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post #207 of 1010 Old 08-22-2015, 08:20 AM - Thread Starter
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Hi LTD02, thank you for looking in on my build.

Quote:
Originally Posted by LTD02 View Post
the key point is to try to keep the "first port resonance" out of the pass band. 120hz or higher is probably ok, but 140hz is about what I would suggest just to be on the safe side when using an 80hz 4th order low pass bass filter.
So.....ummm..... ..... huh?
Sorry but I am really new to this and on a very steep learning curve... I'm trying
Looking in WinISD, I did not see any place that displays "first point resonance", but is probably just my NOOBNESS

Quote:
Originally Posted by LTD02 View Post
end correction is a complicated topic that has to do with how the vent terminates into the surround space. a port on the center of the cab will function a little differently from a port on the bottom for example. BUT if you calculate the port length correctly, the end correction isn't terribly important to be familiar with.

halfway down this post:
https://www.avsforum.com/forum/155-di...l#post23711347
is an explanation and some links on end correction if you really want to learn more. ;-)

the "volume" is the NET enclosure internal space. it does not include the driver, the port, the bracing, the cab construction or any of the rest of it. all of those must be ADDED to get to the final external size.
Great thank you.


Quote:
Originally Posted by LTD02 View Post
not sure how far along you are on the baffle wall, but i would suggest making it modular (it looks like more of a fixed install in the o.p..
Rough in framing is complete. I have 24" from 2x4 to 2x4 behind the false wall. So depending on the wall finishes and treatments it could be down to ~19-20" (1/2 drywall and 4" lincoustic?)
This is the view from the right side..... the mackies will be on / over the bottom screen 2x4 as the screen will actually be forward of the front wall. Also the front wall will be solid.... 1/2 or 3/4" ply with faux rock on it



Modular is exactly what I want to do plus in stages.... that's where part of the challenge comes in. The thought was to build smaller subs that could fit into the side columns (going for stealthy).... this would provide the flexibility to place them there or move to a location that sounds better. However dimensionally
this is a struggle and a 12" sub is the largest. Preliminary numbers also look like ported might be out.... but I am still figuring.... thus the port length question.

Quote:
Originally Posted by LTD02 View Post
in that big room, you want 4 x 18" ported for a good effect. something in the spirit of four of these behind the screen (though they don't have to be quite that large).

four Dayton 460ho cabs tuned to about 16hz. ~10 cubic feet net internal with slot port that is 2.5" tall x about 20" wide x about 44" long. that will keep air speed reasonable. first port resonance out of the pass band. note: actual cab tuning will come in a little less than winisd projects. the actual measured port length would be a little less than 44" also. something around 42" as measured from end to end down the center of the slot port.

such as system will provide about 125db of output down to 15hz or so in 2pi space and even more in room. 125db is about "worst case scenario" (full output with all channels of bass redirected to the subs).

max spl of such a system with 1250 watts per driver.
OH Man that does look sexy in that sketchup ..... In my complete ignorance my original (way back) thinking was 1.... maybe 2 12" subs if I was feeling CRAZY...... that doesn't seam crazy at all now more like punny and inadequate.... That's where the phasing comes in as I don't really know how much I need / want

One day I will start the new theater....... one day..... THAT DAY HAS ARRIVED
"If the women don't find you handsome, they should at least find you handy." Red Green
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post #208 of 1010 Old 08-22-2015, 08:36 PM - Thread Starter
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Sound Transfer Baseline

Last weekend while my wife and daughter were away I decided it was a great time to do a little baseline sound transfer testing.
The space is open..... wide open and is directly below... well most of the house. The theater area is directly below the living room and front entry.
As I am doing drop ceiling, I know that that will not prevent much sound from transferring up to the main floor.
I do plan on doing insulation between the joists in the entire basement and am debating on doing drywall between the joist also.
Foot fall with everything open right now is terrible

In this post I want to document the baseline results that I got and how I did the test so that I replicate in the future when materials have been added

I set up my AVR with my Anthana speakers set to the image below
Downloaded a white noise track from http://www.audiocheck.net/testtones_whitenoise.php
Did three measurements with my radio shack db meter. volumes on the AVR where Off / -10 / 0
I got to say that white noise at 0 is damb annoying!!!



They way the equipment was set



I choose white noise for it "flat" frequencies


Results of Tests
With everything off and no one home:
MLP = 31db
Just outside theater pocket doors = 32db
Mid upstairs living room = 30db

So pretty quiet in general

At -10 on the AVR with white noise track
MLP = 81db
Just outside theater pocket doors = 58db (-23)
Mid upstairs living room = 46db (-35)

At 0 on the AVR with white noise track
MLP = 88db
Just outside theater pocket doors = 71db (-17)
Mid upstairs living room = 58db (-30)

I find it interesting that with an 7 db rise at MLP that the reduction in sound is not linear to that..... I'm sure there is a good explanation.... its just not what I was expecting.
Thought I would see the living room closer to 53db.....

If there is better way that I should have done the test PLEASE let me know before I get to far ahead and can't retest baselines

I was wearing earplugs during this cause it damb loud and annoying, but I took them out briefly to "subjectively" see what it was like at MLP and upstairs...... yes is was quieter upstairs but still to loud for my liking.

So this leads me back to my thoughts on installing drywall and green glue between the floor joists to try to aid in the sound transfer not only footfall but sound going up also
Now is the time to do it as I am almost ready to install the insulation
What are peoples thought on this?
My thought was to do the area above the theater.... not the entire basement, this would require ~9 sheets of drywall and 9 tubes of GG, estimated cost per layer is $300
I know there is flanking to worry about also but to do the entire basement would be stupid in cost and labor..... plus there are cold air returns and HVAC that is in the way

My theory is that if you put anything in the way of a sound wave it is going to help.... how much depends on the material and where you are measuring.
Example if I do between the joist only above the theater and measure directly above the theater there should be a measurable difference...... right?

If I yell at some one 10 ft away and then do it again with a wall in the way the yell is reduced.... yes sound travels around the wall also but it is reduced

I guess I am trying to figure out if the cost and effort is worth it when only part of the ceiling is being done??????

Found it interesting that solution three at the Sound Proof a Ceiling link (insulation, double drywall, GG and clips) gets a 6 star rating when adding 1 layer between the joists goes to 8 and two between joist to 9


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One day I will start the new theater....... one day..... THAT DAY HAS ARRIVED
"If the women don't find you handsome, they should at least find you handy." Red Green
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post #209 of 1010 Old 09-01-2015, 06:09 PM - Thread Starter
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Nothing to exciting to report from the week end, Installed 3 bags of Roxul insulation in the ceiling above the none theater area and just cleaned up a couple of loose ends on the framing and electrical.
electrical rough in is now complete and the framing also except for the couple of fake columns after drywall is up

Still on the fence with the drywall between the joist above the theater side and as a result has slowed my progress with anything ceiling related there.....

I did notice a fair bit of sound coming through the cold are return ducting to one of the main floor bedrooms not really surprising as there is nothing covering the ducts yet Might have to measure to see how much it might improve.

One day I will start the new theater....... one day..... THAT DAY HAS ARRIVED
"If the women don't find you handsome, they should at least find you handy." Red Green
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post #210 of 1010 Old 09-18-2015, 06:58 AM - Thread Starter
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Progress update:
ZIP, ZERO..... NADA
UGH, between life and a heck of a "Man Cold" (2 bloody weeks) it has been frustrating and depressing
Hoping next week to get back at it


I guess I did manage to get 4 more bags of Ruxol and at $20/bag it was a really good deal.... so far I have managed to get 10 bags for $20 each.... I like deals


Still unsure of the cost verse potential benefit of drywall between the joist only above the theater area..... would love some feedback


Thanks

One day I will start the new theater....... one day..... THAT DAY HAS ARRIVED
"If the women don't find you handsome, they should at least find you handy." Red Green
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