Effective Width? - OC 705 corner trap

NKOTB · « **on:** 15 Mar 2005, 02:11 am »

My fiberglass is on the way, but I need some help... Due to aesthetics & space constraints, would I be shooting myself in the foot if I bridged the vertical(v) corners with 1' wide sections, and tri-corners(c) and 1'x1' squares, but made them 4" thick?

Like this: http://www.realtraps.com/install_mt.htm
(4th image down, on the left side - Thanks Ethan!), but just 1' wide(v) or square(c) instead of 2' wide(v) or square(c) ?

My room's only roughly 14'X14'x8'. Though not a perfect square, it's close.

Thanks Ya'll,

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David
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Ethan Winer · « **Reply #1 on:** 15 Mar 2005, 03:59 pm »

David,

> would I be shooting myself in the foot <

Yes, I think so.

Acoustic treatment, and especially bass trapping, is all about coverage. I recently tested almost exactly what you're asking - I compared 12 panels 3 inches thick versus only 6 panels a full 6 inches thick. Having more surface coverage (12 thinner panels) was much more effective than half as many panels that were twice as thick. I'm sure the same applies for covering your corners with only 1 foot wide versus 2 feet wide. If you really can't bear to look at panels two feet wide, I suggest you compromise and make them 1-1/2 feet wide. But 2 feet is still better.

--Ethan

NKOTB · « **Reply #2 on:** 16 Mar 2005, 03:32 am »

Ethan,

Thanks so much for the response... If you would indulge me, I have 10 pieces of 2"x2'x4' 705 to work with. Going with your advice & train of thought, and let's assume I can do the 2' wide panels: Should I:

1: Go floor to ceiling in the vertical corners, but with only a single panel thickness (2")?
or
2. Double up 8 of the panels so I have four 4"x2'x4' panels and use up the remaining two sheets by:
a: cutting them in half to make four 2"x2'x2' panels for the tri-corners?
or
b: cutting them in half to make four 2"x2'x2' panels for the tri-corners,
then add a second 2" layer of 703 to make em' 4" thick
(which side should face the room?)
or
c: cutting them like a:, and then again on the diagonal to make four 4 inch thick triangles for the tri-corners?

Thanks for your help with this,
David

Red Dragon Audio · « **Reply #3 on:** 16 Mar 2005, 03:51 am »

what's happening newkidsontheblock,

You should go with your first option which will only use 2 full panels per corner so you'll have a
2"x2'x8' panel of 705 in each corner. (that's 8 panels used of your 10)

Then take your two extra panels of 705 and experiment with placing them on the wall directly behind your speakers (space them out 2-6" away from the wall).

...or you can place them to either side of the listening position up in the corner where the ceiling meets the wall.

NKOTB · « **Reply #4 on:** 16 Mar 2005, 03:54 am »

Oh, oh, o, oh, oh, oh, oh, o, oh... the right stuff!

Thanks Ryan!

Let's see if Ethan concurs...

David

Red Dragon Audio · « **Reply #5 on:** 16 Mar 2005, 04:10 am »

NKTOB,

You could do this too:

Ethan Winer · « **Reply #6 on:** 16 Mar 2005, 04:30 pm »

David,

> assume I can do the 2' wide panels: Should I ... <

All of those choice will work, but it's difficult for me to predict which will be best. What you really should do is buy twice as many panels so you can have all of them, and also have them be 4 inches thick.

There are two competing goals here: having enough panels and having them be thick enough. If you're not willing or able to get more material, I agree with Ryan to leave them at 2 inches and cover more total corner surface. Cutting some in half for tri-corners makes sense too.

--Ethan

NKOTB · « **Reply #7 on:** 19 Mar 2005, 04:12 am »

OK Ethan. I found another ATL distributor that stocks 705 and equivalent competing brands. I will do as you recommend... Just a couple more questions, Foil or Kraft faced? I know faced is said to be more effective on the low freq's, but I've never seen an absorption coefficient comparisons on equal thicknesses of faced vs. unfaced corner traps for under 125 hZ. What actually happens from 125 on down? Got any graphs? Second, I saw you recommended alternating faced & unfaced in the corners to keep some reflectivity - what alternating patterns do you recommend? Faced above unfaced, vise versa, or all faced in one corner, and all unfaced in the opposite corner. etc...

Thanks again,
David

Ethan Winer · « **Reply #8 on:** 19 Mar 2005, 04:39 pm »

David,

> Foil or Kraft faced? I know faced is said to be more effective on the low freq's, but I've never seen an absorption coefficient comparisons on equal thicknesses of faced vs. unfaced corner traps for under 125 hZ. What actually happens from 125 on down? Got any graphs? <

You bet I have graphs!

Look HERE.

> I saw you recommended alternating faced & unfaced in the corners <

No, use the faced type in all corners, with the facing towrd the room for better performance at bass frequencies.

As for the rest of the room, this depends on how live a sound you want and what furnishings are already present.

--Ethan

NKOTB · « **Reply #9 on:** 19 Mar 2005, 11:55 pm »

Thanks Ethan! That's just what I needed. You are the man!