You could click on any of the links from "ChristianG's Corner Traps" on down at:http://www.bobgolds.com/
Similarly on this pagehttp://www.bobgolds.com/AbsorptionCoefficients.htm
any of the links between "Jon Risch's Absorbers" and "David French's absorption cloud design with aluminum guttering material"
should give you construction ideas.
And there's also ---k--- 'shttp://racarris.com/HT/Corner%20Trap/
(with some text about it atAVS Thread: Upgrades, Treatments & fun w/ ETF
I think he ended up making three short corner traps and was reasonably content that he had done so. The reason I reference this thread, even though you asked not to, is you wrote
I can not run the corner trap from the floor to the ceiling. It sits on a carpeted riser and has to terminate below the crown moulding.
and ---k--- both did that, and posted a bunch of good observations both human and ETF5 graphed.
I am getting ready to build two bass traps for the front corners of my theater.
In an otherwise untreated room, I believe corner traps are an excellent LF bang for the buck/effort. All modes are active in tri-corners, so that's a good spot to put an absorber. (there are other alternatives to corner traps, but I'm unsure how to discuss them without using the temporarily evil 'Sabin' word.)
I want to build corner traps that have two layers of unfaced oc705. The top bottom and sides will be made from 3/4" mdf. I am treating the trap as if it were a pressurized vessel. That is, the seams will all be caulked and care will be made to ensure that the foam is held tightly against the box.
Don't go gung ho on the sealing. If it has to be portable then simply glue and screw the wood (skip the acoustic caulk).
I don't want to have to build this piece again! It would be much easier to frame out the drywall (single 1/2" layer) so that the oc705 would be held against the frame. I would then forget about the top and bottom also.
Sounds a bit like the Dave Portocarrero corner trap at http://www.bobgolds.com/TrapDave/home.htm
(bottom two pictures).
Based on current knowledge (the referenced thread insists that the bass traps must be held in proximate contact with the walls and the top and bottom must be in place to maintain the spring constant (at maximum) How does this type of trap really need to be fabricated???
Don't bother going gung ho sealing the edges. Just keep the absorber touching the sides if you can. If there's a 1/4" gap some places, don't worry about it. (A 2" hole is just being lazy - fix it).
And of course, last but not leastStudiotips Corner Absorber
Anyway, building a corner trap is not rocket science. The main points are:
a) put 4" of rigid absorption on 2' diagonal as tall as you can and in as many corners as you can and touching the drywall.
b) Cover it with something fire retardant that'll keep the fibers in place when the wind blows on them. If your room has lots of HF absorption already consider something HF reflective, otherwise something you can breath through.
c) any framing you might do is simply to hold (a) and (b) in place.
If you can make observations of what you hear that's different, that's great.
We want pictures!