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Bass Trap help



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My room sorta looks like this with the total length 25'

Im getting a rather large peak at both 63 and 80hz using warble tones and a Radio Shack sound level meter. The right from the listener opens into a kitchen. Anyway. I bought 27-Owens Corning 703 2"x24"x48" panels. Surely this is enough material? Stacking the panels 3 deep for 6" deep panels, that gives me 9 panels at 24"x48". Ive been moving them around, first trying 2 in the front corners, 1 to each side of the speakers, 3 to the rear (dead behind and one to each side, and the lasy one the wall to the left of the listening position. Zero different as read before and after using my meter.

I dont understand.

Help
jim1961jr
samhar
1,048 posts
 
You might try moving your chair forward in small increments and check readings.
ngjockey
1,042 posts
 
Even DIY sealed membrane traps, using 1/4" hardboard as the membrane would have to be at least 4'X4' or 4'X6' to be effective for 63 Hz.
jim1961jr OP
9 posts
 
I found the "super chunk" article. Thanks for that. Since I already have the OC 703, ill build it from that and hope it works as well as the mineral wool material.

Thanks.
jim1961jr OP
9 posts
 
Good advice. I have tried various locations for the listening position. Going further forward makes the peak greater at 63hz, where moving back creates one at 100hz. Perhaps going back will help some given 100hz is a bit easier to manage than 63hz.

Thanks.
kevinzoe
167 posts
 
Jim,
Your resistive-type bass traps made from OC703 work best when placed out from the wall a distance equal to 25% of the offending wavelength. So, for 100, 80, and 63Hz peaks, you should experiment with an air space of 33.9", 42.4", and 53.8" respectively. Obviously this really intrudes into the room physically and visualy but it wouldn't hurt to try a little experimentation.

Try placing the traps in the 4 room corners with the air spaces as indicated above. Try a bass trap in the middle of the front and rear walls, again with the same air spaces. I found the front/rear wall absorption seemed more effective than side wall absorption for bass but that could just be my room.

If you can't tinker your way to sonic bliss with the bass traps then you'll need a parametric EQ to tame the peaks.

For what it's worth, my room dimensions are multiples of one another (a bad thing indeed) which compounded my 80Hz peak making it a 19dB peak. I reduced the 19dB peak to 2.5dB by using very thick (i.e. 27" thick including an 8" air space) bass traps of OC701 in the four room corners and some in the middle of the front and back walls. (See my System for pictures of the DIY bass traps that double as Mid/High frequency hemi-cylindrical diffusers, for what it's worth.)

You can also use 2 or 4 subwoofers to constructively reduce the peaks but is much more complicated.

Good luck and be sure to let us know how it turns out.
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