Axiom Home Page Forums General Discussion Advice from Axiom Owners My Superchunk Bass Trap Project, Graphs included

Take all of the following with a LARGE grain of salt...

>>1) First of all, am I correct in saying I want to leave some space behind the 703 and the wall, within the frame I build?

The space helps with bass trapping but I don't think it helps so much with absorbing higher frequencies. There was a chart somewhere with cutoff frequencies vs. thickness of 703-style fiberglass, will see if I can find it.

>>2) Also, do I want to use the FRK(scrim) on the side facing the room, or use regular 703 with no facing?

If you're talking about paper facing, I think that helps with bass trapping but reflects a lot of higher frequencies. For treating first reflections I would say "no facing".

Note that you probably want a ton of absorbtion (sp) on the left wall to balance off the fact that you have no right wall.

>>3) For those wall/ceiling treatments do most people use 2" thick or double up and use 4" thick 703?

I'm pretty sure 2" is enough for higher frequencies -- the question is whether it's worth putting more FG in there and getting more absorbtion in the lower frequencies.
I'm REALLY tempted to pick up that $150 ETF software package from Rives (also needs mic, cables and decent sound card) which indicates decay & resonances at all frequencies. That would shed a lot of light on what the room needed.


One common treatment for mixdown rooms seems to be what they call a "cloud" over the listening position, basically a big chunk of fluffy fiberglass near the ceiling with enough framing to look half-decent. Not sure if you have enough height to keep it out of the projector light cone though...

BTW I don't think bass traps at the bulkhead would be as effective as bass traps at the back wall/ceiling boundary.