[jk@home]

Has anyone here with corner bass traps behind their panels, experimented adding plastic or craft paper to the trap face, to reduce the amount of HF absorption? At first thought, styrofoam diffusers would be better, but I would think that much material would effect the performance of the trap.

[josh358]

I wouldn't use Kraft paper, you'll hear the resonances. Plastic maybe, depending. Styro diffusers might work, it's transparent to bass. I suggest you ask this on the acoustics forum, those guys should know a lot more about what will work for this.

[Elizabeth]

I use the natural stuff in my apartment. My Magnepan speakers are 42" out in front of a very large picture window, with heavy curtains drawn to sides.. (they actually are nearly to the side wall)
Then to each rear side, tucked tightly into corner, i have homemade floor to near ceiling shelving units (25" and 37" wide ..  they were not made just for this application, but were useful for it) filled with DVDs in half thickness cases. (so they are denser, and save space)
This is the sum total of my corner bass traps.

I am satisfied, and they fulfill my desire to use natural furnishings to do what little adjustments I have made for room correction. Plus they assist in keep the media storage out of the way.. in part.

[mg3720]

I have in each corner of my theater, 8 foot tall corner bass traps (two 4 foot stacked).  In front I have a pair of Magnepan MG20.7 speakers, 4 feet from the wall.  The corner traps made a remarkable difference in the overall sound quality of the room.  Each room is unique, but I have not felt I needed to affect HF absorption.  I also have bass traps behind my surrounds, MG3.7s, necessary because the are closer to the wall, about 30 inches.  The side bass traps dramatically improved the bass response of the MG3.7s.

[berni]

I have four of them made by myself. Two on each side stacked in total 8 feet high.
The 20.1 are some 7 feet out from the wall, the traps in both corners.
The traps are made so that 1/2 of the outer diameter is covered with an reflective layer and 1/2 not. So by turning you get absorbtion or difusion(reflective layer on curved trap) all covered with black cloth and some mesh.
look here, the final pictures on side 2 , don't try to understand the language 
http://www.audio-kontakt.com/forum/viewtopic.php?t=1672&postdays=0&postorder=asc&start=0

[jk@home]

Thanks for all the input. Berni your 1/2 reflective design sounds similar to that commercial round trap, nice job. My traps are just the standard Owens Corning 703 in a diy frame style, 6" thick, designed to sit diagonal in the corners. Made them 7' tall to fit under the 45 degree wall to ceiling transitions in the room. Went with this design vs something like Super Chunks, due to attic doors and windows that are butted up to corners in the room (in other words, portability). Here they are, sitting patiently in storage (literally for years  ), waiting for me to finally get around and cover them:



It wouldn't be too hard to drag them out, dust them off, and set them up "raw" in the room. I can then try with and without plastic sheeting. As set up, the rear output my tweeters shoot almost directly into the corners, so the traps may make a big difference with the HF.

One thing I do have behind the MMGs now are faux ficus trees. Not "proper" diffusion though. If there's room, I will try to retain these in front of the traps, if nothing else, for the decor. I do plan to later add diffusers in the room, it's a man-cave, so anything goes...

[DTB300]

I have a total of 23 (2x4) absorption traps in my room, and 4 (2x4) Diffusers.   All 4 corners have traps floor to ceiling (4").  I have 2" traps on front wall behind speakers and at first reflection points, and 4" traps with diffusers in front of them on the back wall.

I had tried plastic over the 4" panels in the rear of the room, but over time and testing, I preferred the diffusers in front of these panels to give me the best results.

[jk@home]

Hey DT, do you have a web link of the diffusers you used?

[berni]

Art Noxon about tube traps.
http://www.dagogo.com/View-Article.asp?hArticle=919

[josh358]

JK, if you're looking for styrofoam diffusers, check out the GIK gridfusors. I have some to experiment with, they're very lightweight and I wanted to see if they'd help tame the problem I have with my fireplace mantle. They're designed for use in drop-in ceilings but have a removable piece so they can be joined into standard 2 x 4 panels. Another possibility would be to get some foam from Home Depot and use one of the online QRD calculators.

[DTB300]

Hey DT, do you have a web link of the diffusers you used?

I got my 2'x4' QRD1 EPS Diffusers from PI Audio. 
http://www.audiocircle.com/index.php?topic=100858.0

GIK has EPS 2'x2' GridFusor if you want a smaller form factor.   
http://www.gikacoustics.com/gik_gridfusor_acoustic_diffusors.html

I have also figured out a way to mount them in front of a GIK 244 Absorption Panel without damaging either the 244 or the diffuser.

[josh358]

I got my 2'x4' QRD1 EPS Diffusers from PI Audio. 
http://www.audiocircle.com/index.php?topic=100858.0

GIK has EPS 2'x2' GridFusor if you want a smaller form factor.   
http://www.gikacoustics.com/gik_gridfusor_acoustic_diffusors.html

I have also figured out a way to mount them in front of a GIK 244 Absorption Panel without damaging either the 244 or the diffuser.

Do you know how much they charge for unpainted 2x4 QRD1's? I could only find information for the finished ones. Also, have you seen any specs?

[S Clark]

I've got rolls of fiberglass insulation in the corners with Dave Ellidges styrofoam diffusers in front, sort of hiding them.  I've been pleased with the bass absorption and the extra imaging when using LS 9 speakers.  These line source speakers are magnificent, but sort of a PITA to get right in a room.

scott

[jk@home]

Thanks for the links, guys. Guess that makes it easy, I will just cover the traps as normal, and get diffusors later. Think I will post over at the acoustic thread, for good measure.

[DTB300]

Do you know how much they charge for unpainted 2x4 QRD1's? I could only find information for the finished ones. Also, have you seen any specs?

Dave is the moderator over at the PI Audio forum and should be able to give you pricing/information.

[josh358]

Thanks, DTB.

[jk@home]

Hey Josh. If I were to use the GIK diffusor, do you think one 2 x 2 panel per "location", centered at the listening height would be sufficient. Or should I get 2 per side, to cover at least a 2 x 4 area, to catch more of the speaker's output? (yeah, thinking about the $$$ )

[josh358]

The GIK's are sold in lots of four, so you can try it both ways. 2 x 4 should be somewhat more effective particularly at lower frequencies, but whether it will make a significant audible difference I don't know, it's on my own list of things to try.

[rw@cn]

Hey Josh. If I were to use the GIK diffusor, do you think one 2 x 2 panel per "location", centered at the listening height would be sufficient. Or should I get 2 per side, to cover at least a 2 x 4 area, to catch more of the speaker's output? (yeah, thinking about the $$$ )

The folks advised me that one pair of their QRD diffusors was sufficient for Magnepan 1.7s and advised 2 pairs for Magnepan 20.7s. I didn't see what your speakers are, but this should be helpful as a guide.

I use two since I had planned to upgrade to the 20.7s, but this has been postponed (shelved really).

[SteveFord]

rw@cn,
Why for you shelve the 20.7 idea?
I don't have the room for them so it wasn't really too much of a consideration on my end.