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Acoustical Treatments Master Thread - Page 220

post #6571 of 10167
Quote:
Originally Posted by SierraMikeBravo View Post

Commercial THX theater...home THX theater...what's the difference? Best wishes!

Room size, of course. But for purposes of this discussion it probably doesn't matter.

So 6dB is 4x the power. Is this really true? As pepar says, that is huge.
post #6572 of 10167
Quote:
Originally Posted by SierraMikeBravo View Post

Treat with absorption the same way you would with any front wall. How much absorption...well I'll keep that one under wraps. A girl has to have some secrets!

Commercial THX theater...home THX theater...what's the difference? Best wishes!

Thanks, Shawn.

Jeff
post #6573 of 10167
Quote:
Originally Posted by erkq View Post

Room size, of course. But for purposes of this discussion it probably doesn't matter.

So 6dB is 4x the power. Is this really true? As pepar says, that is huge.

3db increase in loudness requires 2x the power. 6db, double it again.


Bryan
post #6574 of 10167
Quote:
Originally Posted by pepar View Post

That was indeed one of the benefits as he described it; sound that would follow or be radiated by the cabinet up, down, to the side or rear would be eliminated. The THX/Procella demo, with the baffle wall, was the second best demo we heard. Harman's demo had free-standing speakers and was third. Wisdom Audio's demo was the best and theirs had in-wall speakers. I'm not saying that that was the variable that made the difference, just observing that the two best sounding demos had "flushed" speakers.

Jeff

Quote:
Originally Posted by SierraMikeBravo View Post

Yes Pepar, there is truth to this, and Audyssey has nothing to do with it! By flush mounting, you increase the sensitivity of the speaker, thereby increasing the ouput of the speaker given the same amount of wattage. So, if you increase the sensitivity by 6 dB by flush mounting, you also increase the efficiency and the ouput is equal to the increase in efficiency....therefore an output increase by 6 dB. This, of course, depends on a perfect world, and there are other factors which may cause actual values to fluctuate, etc, etc. I am sure we will here the faint whine of circular saws buzzing away way past midnight tonight as everyone rushes out to build a baffle wall. If only Home Depot was open 24 hours. P.S. Gotta razz you on the Audyssey thing now and again.

http://www.thx.com/professional/cine...d-baffle-wall/

Quote:
Originally Posted by erkq View Post

Room size, of course. But for purposes of this discussion it probably doesn't matter.

So 6dB is 4x the power. Is this really true? As pepar says, that is huge.

Hi,

Yes, in an ideal situation with an omnidirectional source and perfectly reflecting boundaries, flush mounting results in a 6 dB increase in SPL. Dr. Toole discusses this on page 184 of his book, Sound Reproduction. Likewise, positioning the source at a bi-corner produces a 12 dB increase in SPL and positioning the source at a tri-corner results in an 18 dB increase in SPL.

Quote:


The technical description of full spherical, omnidirectional radiation is that the sound source "sees" a solid angle of 4 Pi steradians. It is a full space-a "free field" with no surfaces to reflect or redirect the radiated sound. Placing the sound source on or in a large plane surface reduces the solid angle into which the sound radiates by half-2 Pi steradians-a half space. Energy that would have traveled into the rear hemiphere is reflected forward; there is a reflected acoustical "image" of the source. Additional surfaces, positioned at right angles, reduce the solid angle by half, to Pi steradians and then to Pi/2 steradians. The number of reflected images increases correspondingly. It can be seen that the sound pressure level, measured at a constant distance from the sound source in these otherwise reflection-free circumstances, goes up 6 dB for each halving of the solid angle.

On page 191 Dr. Toole specifically discusses the situation of mounting an on-wall speaker inside a cavity, both with and without fiberglass to fill the gap between the speaker and cavity. Inserting the fiberglass does improve the response due to the reduction in diffraction effects. However, flush mounting the same speaker, i.e. turning it into an in-wall speaker, provides an even smoother response than the fiberglass filled cavity. In all three of these situations we are dealing with a 2 Pi steradian solid angle so the gain of 6 dB is apparent, but as stated the real-world frequency responses are not the same.

Larry

EDIT:
It should be noted that these +6 dB increases in SPL are with reference to the 4 Pi steradians solid angle situation, which is the same as saying a comparison to a situation with no boundaries, or basically compared to outdoors.
post #6575 of 10167
Any input on where to get GOM FR701? I'm in Canada. I looked at one reseller but the online form didnt allow for Canadian addresses...
post #6576 of 10167
Quote:
Originally Posted by SUBnet192 View Post

Any input on where to get GOM FR701? I'm in Canada. I looked at one reseller but the online form didnt allow for Canadian addresses...

Was that Fabricmate? I would think they'd ship to Canada, but I don't know.
post #6577 of 10167
Back to 1" material, diffusion and the Quest PerfSorber product ... here's what can be done with 1"

 

PerfSorber.pdf 126.21484375k . file
post #6578 of 10167
Quote:
Originally Posted by Dennis Erskine View Post

Back to 1" material, diffusion and the Quest PerfSorber product ... here's what can be done with 1"

Those look pretty cool - how much do these cost? And in what sizes do they come?
post #6579 of 10167
48"x96"
Cost depends on size, 1" or 2", and fabric covered or not.
post #6580 of 10167
...and, here's what you can do in 2" (data from Riverbank). By-the-way, when you're buying this stuff (other than just normal fiberglass panels), get the certified lab test results to make certain you're really getting the claimed performance.

 

QSorber.pdf 25.1640625k . file
post #6581 of 10167
Quote:
Originally Posted by Dennis Erskine View Post

48"x96"
Cost depends on size, 1" or 2", and fabric covered or not.

A quick google search didn't produce any cost range data, regardless of size. Perhaps there is no direct sales to end users?
post #6582 of 10167
That would be correct.
post #6583 of 10167
Quote:
Originally Posted by Dennis Erskine View Post

That would be correct.

Ah, well, the search for a consumer product like that continues, then.
post #6584 of 10167
No surprises there.
post #6585 of 10167
Search for a consumer product? It is a consumer product. You just cannot purchase directly from the manufacturer. You refuse to drive a car because you cannot purchase it directly from the manufacturer?
post #6586 of 10167
Purchasing a car these days is a whole lot more transparent and consumer-friendly than deciding on and purchasing acoustical treatments or, for that matter, the services of an acoustician/theater designer. For the former, the prices are known as is what the buyer is getting for his money. For the latter, comparative testing is non-existent.

There is no correlation between performance of mutual funds and whether they are load or no-load. And I doubt that there is any correlation between performance and whether an acoustical treatment is sold as a commodity and one that is tightly controlled and sold only through gurus.

I should add that everybody has a right to make a living and even succeed wildly if they can. But caveat emptor.

Jeff
post #6587 of 10167
Jeff:

Good points. None-the-less, Caveat Emptor does apply. In the case of the Quest products the certified lab testing results are available (some have been posted here). If one is looking for simple 1 or 2" fiberglass panels, it is possible they'll do better from a price perspective by shopping online vendors. In the case of Quest, the vast majority of their products are engineered products. Several factors come into play from the perspective of the manufacturer. These include individuals purchasing certain products and then noting they didn't do such and such which, in the end turns out to be, the use of the inappropriate product for the problem, incorrect placement or mounting of the product, or use of too much of the product (yes it happens).

Controlled distribution certainly doesn't make the product perform better (or worse); but, at least there is a qualified individual working with the end user to see that the end user is getting whatever it is that is best suited for their specific application. Good bad or indifferent, there are very few items in this industry which are available directly from the manufacturer. (Controlled distribution, btw, doesn't imply controlled pricing ... and here in the U.S. that has to be true.)

Quote:


For the latter, comparative testing is non-existent.

Sad but true, that's why I've stated before, you really need to get the third party certified lab test results if you're buying a product for its acoustical properties. (In the case of the Quest materials posted here, the lab test results are included.)

Actually, truth be told, I believe the consumer is better off with the controlled distribution or dealer network model. If the manufacturer had to deal with the entire universe of end users calling up for questions, getting pricing, placing small orders, whatever, that manufacturer would have to have the staff available to handle it ... that overhead would be reflected in the price. By the same token you'd have one, and only one, source for a specific product. In the dealer model, that overhead cost is reflected in their offering price (granted they want a profit as well) but offsetting that is price competition due to multiple sources of supply. I don't think the dealer's profit margin affects the end pricing model that much either. Profits tend to be calculated as percentages thus as the overhead of the manufacturer goes up, the profit percentage may remain the same but the raw dollars increase. Oh, well, so much for this topic .... back to acoustics please (if I had wanted to be an economist, I would have taken two semesters of econometrics ... yuk.)
post #6588 of 10167
I value the expert consulting I have paid for, in setting up my theater.

In most situations, I like to do research into products and services before paying for (or even using for free) an expert's time. In this case, with this product, I couldn't find any of the basic information about use cases and pricing structures online, in order to know whether it might be right for me to pursue it a little more. I am window shopping, at this point.
post #6589 of 10167
Well, I can provide you pricing information (offline) if you'd wish.
post #6590 of 10167
Quote:
Originally Posted by Dennis Erskine View Post

Well, I can provide you pricing information (offline) if you'd wish.

Sure, please send me a PM.
post #6591 of 10167
I found these up for sale around me, and was wondering if they might help my new room in the house I close escrow in a month on? Are these like TriTraps, or specific to a specific tune?

Four 4-ft. tall ACS bass tube traps. Two are 8/9 inches diameter, and two are 11/12 inches diameter. Fabric covered tubes in a beige tweed. Perfect condition. Clean and tight. Stack them or place them individually around your space. Tune your music room - condition your acoustics! These are priced from $498-$526 EACH new!






Thanks
post #6592 of 10167
IMO, small diameter tubes like those are not very useful. They're just not large enough to absorb to low enough frequencies. However, tube traps that are 20 inches in diameter can work very well.

--Ethan
post #6593 of 10167
Quote:
Originally Posted by Ethan Winer View Post

IMO, small diameter tubes like those are not very useful. They're just not large enough to absorb to low enough frequencies. However, tube traps that are 20 inches in diameter can work very well.

--Ethan

Are 20" tube traps equivalent to filling room corners with triangles of OC703 type material? Better? Worse? It would be a lot simpler.
post #6594 of 10167
Quote:
Originally Posted by Ethan Winer View Post

IMO, small diameter tubes like those are not very useful. They're just not large enough to absorb to low enough frequencies. However, tube traps that are 20 inches in diameter can work very well.

--Ethan

Thanks Ethan,

I will keep looking.
post #6595 of 10167
Quote:
Originally Posted by erkq View Post

Are 20" tube traps equivalent to filling room corners with triangles of OC703 type material? Better? Worse?

It depends on a lot of things, such as the wall thickness in the tube traps. Generally, bass trapping is all about total surface coverage, assuming material thick enough for the job. That's why I always remind people that rectangle rooms have 12 corners, not just four. The more total corner surface you treat, the better. Always.

--Ethan
post #6596 of 10167
Don't get anything unless you can get the certified lab test results so you know what you are getting.
post #6597 of 10167
Hey guys...looking for a solution. I am in the process of putting bass traps in the corners behind the screen wall. The issue I have is this. All of the duct board I have found in Houston TX has facing due to the heat here. what are my options?

Thanks,
post #6598 of 10167
Quote:
Originally Posted by audhunt View Post

Hey guys...looking for a solution. I am in the process of putting bass traps in the corners behind the screen wall. The issue I have is this. All of the duct board I have found in Houston TX has facing due to the heat here. what are my options?

Thanks,

Owens Corning 703, no kraft paper or "facing" is recommended. Check here.

http://winroc.com/branch-locator-spi...php?id_prov=53
post #6599 of 10167
or tear the kraft paper off
post #6600 of 10167
Thanks for the quick link really appreciate it. Next question is the size triangle 1'X1'? at $1.20 sq ft the stuff is preety darn expensive
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