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post #1471 of 1483 Old 07-11-2015, 07:57 PM
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Thanks granroth.

How does this compare with the rattle test results you collected when you tested your sand-filled stage? I didn't see where you ever posted frequency information to go along with your observations of rattles around your house. That is to say, do you think your walls do a reasonable job of containing subwoofer rumble above the wall's resonant frequency?

Obviously, that's a more complicated issue - especially given the potential flanking paths present. I'm just really hoping that I can keep my house from rattling too much. If the wall construction is the limiting factor in a well-considered installation (with minimal/zero flanking paths) do you think it's reasonable to expect reference or near-reference level containment above the resonant frequency of the wall?
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post #1472 of 1483 Old 07-12-2015, 09:25 AM
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Quote:
Originally Posted by TMcG View Post
Rough calculations will put each box right around 315 pounds empty, with bracing. Add in 10-15 pounds of polyfill and the 115 pound driver and I think the whole thing is going to come close to 450 pounds per box.

what the . . . seriously? you guys are so hardcore here. i can't even wrap my head around all the sub and low end talk. that is nuts.

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post #1473 of 1483 Old 07-12-2015, 10:50 AM
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True ^. But it's also fun to see the passion. Passion and motivation are the two requirements for a diy theater. Without them you have no chance.

I'd point out it might be irrelevant though because you can treat for issues in bass response with treatments and also electronically.
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post #1474 of 1483 Old 07-12-2015, 12:41 PM
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Quote:
Originally Posted by HopefulFred View Post
Thanks granroth.

How does this compare with the rattle test results you collected when you tested your sand-filled stage? I didn't see where you ever posted frequency information to go along with your observations of rattles around your house. That is to say, do you think your walls do a reasonable job of containing subwoofer rumble above the wall's resonant frequency?

Obviously, that's a more complicated issue - especially given the potential flanking paths present. I'm just really hoping that I can keep my house from rattling too much. If the wall construction is the limiting factor in a well-considered installation (with minimal/zero flanking paths) do you think it's reasonable to expect reference or near-reference level containment above the resonant frequency of the wall?
The short answer is that no, I didn't see any concentration of rattling around any specific frequency, nor did I see an elimination of rattling above any obvious frequency. For instance, here are some of the observations:

Pictures on one side of a hallway: 22.4Hz - 28.0Hz (meaning: started rattling at 22.4hz and stopped entirely at 28.0Hz)
Pictures on other side of hallway: 28.0Hz - 32.0Hz
Hanging metal decoration in hallway: 41-45Hz, 54-59Hz, 76Hz
Lights in master bathroom: 32.0Hz
Master bedroom door: 30Hz
One of the windows in far room: 31.3Hz - 32.0Hz

A lot of the buzzing was around 20-32Hz, but that seemed more a property of the individual items that were buzzing than anything else. Note how the metal decoration buzzed on multiple (likely harmonic) frequencies.

This is also a very truncated list as later on, I enlisted the help of my son to find vibrations and he found them all over the house and at pretty much every frequency to 120Hz.

One of the things this shows me is how the stock equations for calculating things like resonant frequency are fun (and appeal to my geeky side) but they might not have very much relevance in the real world, since there are so many variables that come into play. For example, identical picture frames in the same hallway vibrated at distinctly different frequencies, depending on which wall they were on. Clearly the construction of those walls very notably affected the intensity of the vibrations at different frequencies.

But... even with all that, I wouldn't expect that lowering the resonant frequency to something really low like 15Hz would still result in fantastic bass containment. All transmission loss graphs show how the performance of any wall gets worse and worse the lower the frequency. Looking the highest performing double wall tested by the NRC (TL-93-283; STC 69), I see a transmission loss of 85.6dB at 1250Hz but only 26.7dB at 50Hz with a resonant frequency below their lowest testing point. It's a pretty smooth line going down, too, all well above the resonant frequency. So... if I lower the resonant frequency of my wall, then I'm going to see MORE sound loss at any given bass frequency, but it's still going to be a decently small improvement. For instance, looking at TL-93-224, I see a resonant frequency of 63Hz. That worsens the performance at all given frequencies, so now I only see 13.6dB loss at 50Hz -- notably worse. If we had a 100dB LFE push at 50Hz, then the better wall would still let out 73dB (very audible) compared to the worse wall's 86dB ("loud").

So that's my personal takeway on all this. Lowering your wall's resonant frequency is great because it increases your performance at all frequencies (up until the coincidence frequency), but it's all RELATIVE. Nothing short of six-foot thick solid concrete walls is really going to completely tamp very loud LFE.
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post #1475 of 1483 Old 07-12-2015, 12:51 PM
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Well, that's a little disappointing, but makes sense. Thanks for the follow up. I'll continue to cross my fingers.
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post #1476 of 1483 Old 07-12-2015, 07:34 PM - Thread Starter
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I just finished cleaning up after a major amount of progress the last two days. I'm beat. Unfortunately it's late and I need to shower and get a few things done for my real job since I'm wheels up at 06:15A tomorrow morning. I'll put together a progress update later this week when I have the time.
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post #1477 of 1483 Old 07-13-2015, 10:20 AM
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Hey Mike,

Final sub box dimensions are 32" wide x 48" high x 20" deep. The driver will now be centered in the box in both dimensions.

I will need four full 40" x 48" pieces to cut in half lengthwise. Two pieces will be ripped in half to make four 20" x 28" pieces for the side panels. Two pieces will be ripped in half and then cut to length to make four 20"x32" pieces for the top and bottom. The back and two front baffle pieces will all be 32"x48", so here is an opportunity to use a full 48" height sheet that may have already been cut down a bit from its original 40" width.

So that's how I came up with 5 pieces per box....three for the back and double front baffle, one ripped lengthwise to form the two sides and one to form the top and the bottom. Nice and simple. I will probably use 1" Poplar dowels glued and screwed for the interior bracing of the box. I was going to ask for enough of the offcuts from these sheets (even the circular cutouts from the driver) to form a small 5-sided box to seal the inside part of the speaker binding post location.

Sound good? Let me know your thoughts. This is why I say the sub box cuts are no big deal and shouldn't take any time at all. Running 4 full pieces at the exact midpoint and another three so the width is precisely 32". Two set ups. Easy peasy.
I don't see any glaring problems. One thing to consider is the width of the blade kerf- if you start doing stuff like taking exact 48" and splitting it to be 24" or exact 40" to be two 20" you end up with something like 23 7/8" or whatever because you lost some to the blade kerf.

And that's perfectly ok- just mentally account for it. It's totally acceptable to make a box that is 31 and 7/8" instead of 32"- it means nothing to the actual performance.

On thing I do generally is I slice up the MDF sheets with the track saw, into the rough dimensions I want. I find this easier because chopping up a full sheet with a table saw just sucks, even if you have a helper. You can substitute a basic hand circular saw too if you don't have a track saw, but it might be worth using a straight edge guide. Otherwise, you can skip that but make sure for step #2 you use the factory edge against the fence. I cut everything about 1/4" large, or at least error on the side of not being exact or too small.

Then I set the TableSaw fence for the exact final dimensions I want, and I rip every peice with that dimension through at the same time, making them all identical. I do that for every dimension. The result is absolutely perfect cuts and identical pieces, making for a perfectly square box. If you want me to chop up your sheets for a flat pack I can give it a shot. It's honestly not a ton of work, but it's nice when you get to 48" pieces to have a helper to grab the outfeed sometimes. I can sucker my dad, if you bring him a 6 pack when you pick up. He likes Michelob Ultra.

I am not sure you need the poplar dowels. Looks like extra work to me. What you do use a mortising machine? Or just drill it out with something like a forstner bit ? The extra work to measure and get the dowels aligned might not be worth all the trouble. With a full 1.5" width x say 4" or more for a brace that is a ton of surface area for glue joint. Using something like PL premium that joint will be excessively strong as it is. Your weak spot is your actual material in this case, the MDF itself is your weak link. I would save the trouble. Just make the braces snug and fit tight, and shoot a single brad in from the outside to hold it while it dries. THE END.

I'll look at your internal volume on the next post.

-

"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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post #1478 of 1483 Old 07-13-2015, 10:36 AM
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http://www.hometheatershack.com/foru...me-calculator/

32W
48H
20D
Material Thickness 1.5"
bracing volume 800 inches squared (I just guessed)
Port volume = 0
Driver volume= .70 ft^3. The motor displaces about 0.4 and the massive cone takes up the rest
# of drivers = 1

11.676 cubes.

If you heavier on bracing, take a little off. One thing to consider- do you want to do the design so the double front baffle takes away volume? Or add to the dimensions ? This would matter a little on the exact internal volume. It changes the exact sizes of your panels too.

For example- sometimes the front baffle sits inside the side walls, sometimes it sits on top. If it's on top, it won't take away volume, but add 1.5" to the depth (assuming driver faces forward). If you do the other way it takes away 1.5x32x48" of volume which is 2304 inches^3. Does this matter to you ?

That driver should fine in 10 cubic feet and the small changes don't matter too much. The biggest difference is the power handling or power requirement on the really low stuff. I doubt it is a serious concern if you otherwise power them properly (they take literally thousands of watts) and considering you have the (4) UXL18's too, by definition your system is overkill. You have a zero chance probability at effective sound containment at full tilt. Thinking otherwise if futile, save the trouble.

http://stereointegrity.com/product/h...specifications

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post #1479 of 1483 Old 07-13-2015, 10:43 AM
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http://www.linearteam.org/download/winisd-07x.exe

I don't actually have an accurate file for the 24" I don't think. Let me check what I have. I might be good to use the values that @Ricci measured at DATA-BASS.COM.

Quote:
TS Parameters (Measured by Data-Bass.com)
Qts 0.52
Qes 0.54
Qms 13.8
Fs 18.1 Hz
Res 3.38 Ω
Le 1khz 3.3 mH
Sd 0.2 m2
Vas 647.5 liters
Mms 664.1 grams
Cms 116 μm/N
BL 21.77 Tm
BL2/Res 140.2 N2/W
L/R Time Constant 0.98 milliseconds
SplSens 90.38 dB
versus:


Quote:
HS24 Dual 2 ohm voice coils HS24 Dual 1 ohm voice coils
Re 3.7 ohms Re 1.77 ohms
Fs 20 Hz Fs 18 Hz
Qes 0.57 Qes 0.45
Qms 12.2 Qms 7.99
Qts 0.55 Qts 0.43
Le 3.79 mH Le 2.1 mH
Sd 212943.8 mm^2 Sd 212943.8 mm^2
Vas 595 L Vas 721 L
Bl 23.6 Bl 17.31
Mms 671 g Mms 671 g
Cms 92.3 Cms 111
Sensitivity (1w/1m) 91 db Sensitivity (1w/1m) 91.6 db
Xmax 36 mm Xmax 36 mm
?? I might ask in the DIY forum if someone has a good accurate file, otherwise I can just use those specs to model it. It would be close enough.

-

"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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post #1480 of 1483 Old 07-15-2015, 06:35 AM - Thread Starter
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Originally Posted by Mfusick View Post
One thing to consider- do you want to do the design so the double front baffle takes away volume? Or add to the dimensions ? This would matter a little on the exact internal volume. It changes the exact sizes of your panels too.

For example- sometimes the front baffle sits inside the side walls, sometimes it sits on top. If it's on top, it won't take away volume, but add 1.5" to the depth (assuming driver faces forward). If you do the other way it takes away 1.5x32x48" of volume which is 2304 inches^3. Does this matter to you ?
This is why I was thinking of adding a 3/4" dado to all the outer edges except the top piece of the front baffle. I'd pick up 3/4" in the recess at the front and 3/4" at the back, saving 1.5" in overall box depth. If Dado'd, the internal dimensions would be 18.5" deep by 30.5" wide and 46.5" tall. I wouldn't have nearly 800 cubic inches of bracing, just a handful of 1" dowels in both directions for a touch of extra stability / peace of mind.

Creating the dado edge would only be one setup, which again makes things very easy. I'd use a 1 1/8" Forstner bit to recess the dowels by 1/2" into each surface for extra strength and stability.
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post #1481 of 1483 Old Today, 02:41 PM - Thread Starter
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Despite having two 44U Middle Atlantic MRK racks, I knew I was going to be very tight on rack space given how my system has grown.

Attached is my revised racking plan as things stand today. There is uncomfortably little ventilation and I had to consolidate two Sonance 2120T sub amps to a 2RU QSC 4-channel amplifier to save space. I've also had to pull ALL of the equipment for my family room system out of these racks. If I need any more room, the Synology NAS is the next thing to get relocated out of the rack.

Suggestions always welcome.
Attached Files
File Type: doc Stonewater Cinema Middle Atlantic Rack.doc (37.5 KB, 6 views)
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post #1482 of 1483 Old Today, 02:55 PM
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I thought you had a bunch of matrixed switching going around in here somewhere. I wouldn't have thought you really needed separate receivers for the bonus room and lounge. Obvs, I don't know much about that - it just looks redundant.
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post #1483 of 1483 Old Today, 03:40 PM - Thread Starter
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I thought you had a bunch of matrixed switching going around in here somewhere. I wouldn't have thought you really needed separate receivers for the bonus room and lounge. Obvs, I don't know much about that - it just looks redundant.
The Savant matrix switchers are located at the top of the first rack. The 3220 is a 32 in x 20 out audio matrix switch for the distributed audio system and the SLN-88BT is an 8x8 HDBaseT HDMI matrix switch for all the display locations.

For the receivers, I have 14 gauge speaker wire running from the speaker / sub locations in these two rooms back to the rack since no equipment is planned to be in these rooms except for the speakers, in-wall subs and the TV. When finished I will have 4 theaters in the house - the main front projection theater, family room, bonus room and a basement hangout area.
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