tomas
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Posts: 22
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Post by tomas on May 11, 2016 6:58:42 GMT
I think it comes down to thickness and something about dense material not working as well at greater than 8" - that's where less-dense starts to shine. So what's the proper material for early reflection panels and for bass traps? I still don't understand why should dense material be in the early reflection place when it's better in low frequentions than in mid-high.
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Post by Rock on May 11, 2016 12:40:22 GMT
Here's my understanding of the density issue. I believe it's a matter of diminishing returns. For thin absorbers less than 4 to 6 inches, higher density is significantly more effective than lower density. As the thickness gets greater than 6 to 8 inches, the greater effectiveness of the higher density becomes less of a difference than lower density. But, you will always get better performance from denser material so if cost is not a factor and ultimate performance is, denser is the choice. On the other hand, if cost/performance is a consideration, using lower density for thicker absorbers is cheaper and works almost as good.
And just to be clear, the thickness regardless of density determines the lower useable frequency of the absorber due to the 1/4 wavelength
Again, this is what I have gathered from what I have learned and I do not have data to support this so we need to verify this if we want to "take it to the bank" but I'm pretty sure this is the main idea.
Cheers, Rock
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tomas
New Member
Posts: 22
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Post by tomas on May 11, 2016 16:33:41 GMT
Here's my understanding of the density issue. I believe it's a matter of diminishing returns. For thin absorbers less than 4 to 6 inches, higher density is significantly more effective than lower density. As the thickness gets greater than 6 to 8 inches, the greater effectiveness of the higher density becomes less of a difference than lower density. But, you will always get better performance from denser material so if cost is not a factor and ultimate performance is, denser is the choice. On the other hand, if cost/performance is a consideration, using lower density for thicker absorbers is cheaper and works almost as good. And just to be clear, the thickness regardless of density determines the lower useable frequency of the absorber due to the 1/4 wavelength Again, this is what I have gathered from what I have learned and I do not have data to support this so we need to verify this if we want to "take it to the bank" but I'm pretty sure this is the main idea. Cheers, Rock Thanks! Great answer. Anyway my question is whether it is more effective to use lower density material as an early reflection panel as far as the early reflection panel is dealing with mid-high frequencies instead of low frequencies. And we all know that lower density materials are more useful in the higher frequencies than more dense materials. Bass traps - different story - as thick as possible and the densier the better.
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Post by Rock on May 11, 2016 17:44:01 GMT
Thanks, but If you didn't get what I was trying yo say, I guess is was not such a great answer;(
What I was trying to say is that MORE dense at thinner thicknesses (under 4") is better. Not because it will change the frequency range absorbed, but because MORE of that frequency range is absorbed. Please re-read my answer and I think (hope) you will understand what I was trying to get across. But remember, this is only my regurgitation of what I have learned here and not my own research...I however do believe it is correct.
Thanks, Rock
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Post by Hexspa on May 12, 2016 2:34:07 GMT
Rock, that was a good answer - thanks.
Tomas, if I may say again: to start, simply, use 4" rigid panels everywhere.
If you really want to make diffusers and mess around with different types of absorptive material then ok but it's only going to get exponentially more hairy.
Best,
-m
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tomas
New Member
Posts: 22
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Post by tomas on May 23, 2016 9:44:03 GMT
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Post by Rock on May 23, 2016 13:00:48 GMT
I believe it's the other way around: Rather than denser not working as well at greater thicknesses, I believe it's lower density (fluffy) not working as well at lesser thicknesses. I'm pretty sure the main idea about using fluffy, less dense for thicker traps is because of the diminishing returns from the more expensive denser materials where the cheaper fluffy works only nearly as good, in those thicker traps, the benefit being cost savings at only slight reduction in performance with dense. I've inferred this from various other discussions on this matter but I do not have any test data to support this. That said, I'm pretty sure this is the case.
Cheers, Rock
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Post by Rock on May 23, 2016 13:03:19 GMT
Sorry about the above post, I was responding to a post on page 1...Opps
Cheers, Rock
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Post by Rock on May 23, 2016 13:09:16 GMT
OK, here is but one quick idea: Use a grid at the old flat ceiling level to create a "false" ceiling and fill the perimeter with FRK and the interior with non faced. If you follow all the threads here, Ethan recently illustrated a similar suggestion.
Cheers, Rock
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Post by Ethan Winer on May 23, 2016 17:14:35 GMT
Rock's suggestion is a good one, and made even better by piling foot-thick fluffy insulation on top of the rigid fiberglass in the grid at the height of the former ceiling. If you'd rather enjoy seeing the larger height, which is not unreasonable, you still need thick FRK material around the perimeter. You may or may not need RFZ absorption, depending on the angle. If the angle is at least 35 degrees reflection will go over your head toward the rear of the room. Of course, you'll then need to handle them there. It never hurts to have thick absorption on the entire ceiling either.
--Ethan
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