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Bass Wall traps: To FRK or not
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4 the Max
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#1
1st April 2012
Old 1st April 2012
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Bass Wall traps: To FRK or not

While Glenn of GIK recommends (in the GS forum) that RFZ be non-FRK,
any advice on whether the other non-corner (wall and ceiling) bass trap panels should have FRK?

(N.B. Please correct my summary if necessary.) Thanks.

References:
Rigid fiberglass density tests
what is and is not a bass trap ....
Difference Between Owens Corning 703 & 705 | eHow.com
PME Records Broadband Absorber Construction
Acoustics Forum • View topic - Studiotips Corner Absorber
Acoustics Forum • View topic - Types of Treatment


Densities:
703 - 3 lbs/sq ft
705 - 6 lbs/sq ft
FRK stands for Foil Reinforced Kraft paper.

Walls and ceilings:
Thickness vs. coverage
1. a)it's better to more thinner panels spread more completely around the room than less thicker panels covering less total surface area
b) wall panels should be 4" or 6" thick (6" is better)

Mounting:
c)For walls and ceilings, mount the panel 2" off the wall with air space behind it instead of flush mounting

Density:
d)Density appears to become less important when the panels are made thicker
e) Use OC 703 instead of 705 (see ehow article)
f) Use NON-FRK for first reflection zone as it will reflect High Frequiencies (HF)
g) for ceiling or other wall areas use FRK or NON-FRK depending on what you want to accomplish; FRK for more low frequency (LF) absorption

2. corners
a) triangles filling the corner (superchunks) is better than straddling flat panels.Take of the FRK on the faces between the stacks. The FRK should face the

room, not each triangle.
b) FRK Improves bass absorption. Use it on the corners
c) if your using the straddling approach,have the rear of the panels touch the walls instead of mounting the entire panel off of both walls

cover the rear of the panels with acoustically transparent fabric (you breathe through it. Make it flame ******ant with borax)
#2
4th April 2012
Old 4th April 2012
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Little Difference

I tested FRK vs none on Cloud and Side reflection traps.
Probably different from your question, the FRK was on the surface NOT facing the room, but there was a considerable airgap, say 6 inches.
Decay in the 80Hz area dropped from 0.3 to 0.2.
OC 703 FRK... to foil or not to foil????
FRK is probably more effective again on the side facing the room. It will also bounce HF back at you to some extent. Whether the HF is wanted or not is another matter, but such panel traps can be angled to prevent HF flutter.

Not sure what to say about the summary. Thickness, density, and airgaps are all dealt with by Andre in the Q4Avare thread.

DD
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4th April 2012
Old 4th April 2012
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Lightbulb

Quote:
Originally Posted by 4 the Max View Post
any advice on whether the other non-corner (wall and ceiling) bass trap panels should have FRK?
Here's my logic: Corners are not usually at direct refection points, so those should always be FRK. The front wall is behind the speakers, so unless you have dipole speakers that send sound equally front and back, those too should be FRK. The rear wall behind you can be FRK or not. If the wall is closer than about ten feet from your ears, I would not use FRK. If it's farther, I'd probably use alternating vertical "stripes" of FRK, plain, FRK, etc. I use ten feet as the cut-off because closer than that and those reflections are "early."

--Ethan

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3rd December 2012
Old 3rd December 2012
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So if I had the choice to put FRK on my cloud facing the ceiling should I? My room is small 13x13x8 foot ceiling? Will it help substantially with low end absorption?
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3rd December 2012
Old 3rd December 2012
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Quote:
Originally Posted by npatro22 View Post
So if I had the choice to put FRK on my cloud facing the ceiling should I? My room is small 13x13x8 foot ceiling? Will it help substantially with low end absorption?
If the cloud is in the early reflection area then no you would not want to use FRK on the fronts.
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Built in Slat design (Scattering/Diffusion) on all Bass Traps click here
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4th December 2012
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Quote:
Originally Posted by Glenn Kuras View Post
If the cloud is in the early reflection area then no you would not want to use FRK on the fronts.
+1
The exception would be:
Unless you had a tall enough ceiling to angle the cloud in such a way as to deflect the sound beyond the listening position.
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4th December 2012
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Quote:
Originally Posted by npatro22 View Post
So if I had the choice to put FRK on my cloud facing the ceiling should I? My room is small 13x13x8 foot ceiling? Will it help substantially with low end absorption?
Yes, if the FRK is facing up it will absorb more bass than non-FRK, but will still absorb mids and highs fully as if there was no FRK.

--Ethan
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7th December 2012
Old 7th December 2012
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Thank you everyone
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1st February 2013
Old 1st February 2013
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Quote:
Originally Posted by Ethan Winer View Post
Here's my logic: Corners are not usually at direct refection points, so those should always be FRK. The front wall is behind the speakers, so unless you have dipole speakers that send sound equally front and back, those too should be FRK. The rear wall behind you can be FRK or not. If the wall is closer than about ten feet from your ears, I would not use FRK. If it's farther, I'd probably use alternating vertical "stripes" of FRK, plain, FRK, etc. I use ten feet as the cut-off because closer than that and those reflections are "early."

--Ethan

The Acoustic Treatment Experts
I assume you are saying to face the FRK to the room, there has been talk of facing the wall.
Thanks
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1st February 2013
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I'm trapping a 4x6x7.5 room. I'm pretty much straddling all corners with 703 in 4" thick panels. I did not opt for frk bc its a small room.. I straddled the ceiling to side wall junctions with full 24x48x4 panels leaving a 1' or so air gap behind the panels in the corner space. According to glens calculators on the site I found I need about 56 sq ft of coverage.. Am I good to go with my 703 all over? Thanks you guys are so helpful I've read countless posts by you all.
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1st February 2013
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And there are a couple of panels on the ceiling too
Attached Thumbnails
Bass Wall traps: To FRK or not-imageuploadedbygearslutz1359735492.395761.jpg  
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1st February 2013
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Originally Posted by Hyder boy View Post
I assume you are saying to face the FRK to the room, there has been talk of facing the wall.
Exactly. If the FRK is facing the wall, it might as well not be there at all.

--Ethan
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1st February 2013
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Quote:
Originally Posted by Ethan Winer View Post
Exactly. If the FRK is facing the wall, it might as well not be there at all.

--Ethan
Thanks
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1st February 2013
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Damp

Quote:
If the FRK is facing the wall, it might as well not be there at all.
Of course, unless there is a thermal or vapour reason to have it there.

But remembering, if there is an air gap, then there is a small increase LF absorption.

DD
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1st February 2013
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Quote:
Originally Posted by DanDan View Post
Of course, unless there is a thermal or vapour reason to have it there.

But remembering, if there is an air gap, then there is a small increase LF absorption.

DD
That's what I was getting at.
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24th April 2014
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I'm dong 4" 703 bass traps straddling the corners of my small room. Do I want to use frk on these if my room is only 12'x11'? Thanks.
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24th April 2014
Old 24th April 2014
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Quote:
Originally Posted by mookmoof View Post
I'm dong 4" 703 bass traps straddling the corners of my small room. Do I want to use frk on these if my room is only 12'x11'? Thanks.
Yes because it is in a corner and not in the early reflection area.
Video Early or First Reflection Points - GIK Acoustics
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24th April 2014
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#19
2nd May 2014
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Not trying to hijack the thread, but would you say I'm better off treating an 18 x 20 room with 15 two inch 4'x2' Owens-Corning 705s or 4" thick ones? I'm mixing AND tracking in the same room.
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2nd May 2014
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Thicker is always better. Always.

--Ethan
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