Are extra-large super chunk bass traps beneficial?
Of course, it is not a good idea to rob materials for additional traps by making one trap bigger. But assuming you have material for all traps, is there a benefit to increasing the size of a super chunk?
I ask because my room has a vaulted ceiling, rising up behind the listening position. I was planning to put a super chunk trap in the ceiling-to-rear-wall corner, composed of 24"x24"x33" triangles of Owens Corning 703, 2" thick but spread the entire width of the room. But now that I think about it, I'm not using the space up there, why not make the ceiling super chunk bigger?
I'm considering instead of cutting the 48"x24"x2" sheets of OC 703 into two unequal pieces instead of four equal pieces: one piece would still be a 24"x24"x33"x2" triangle for one of the front super chunk bass traps, and the remainder would be a polygon that is 48" on the ceiling-facing edge, reaching 24" down into the room, with the bottom edge reaching 24" into the room towards the front of the listening room before angling 33" back up to the ceiling.
This would be triple the material of a standard 24"x24"x33" super chunk trap, although not perfectly distributed into a neat triangle. (The large black thing in this next render.)
(And by the nature of my vaulted ceiling, there would be a small air gap above the trap towards the back wall, since I'd have to carve some funky angles in the 703 sheets to get them to sit flush.)
Would a massive super chunk trap like this be more beneficial than the standard 24"x24"x33" triangles?
I recommend reading up on gas flow resistivity since using a high depth of high GFR materials results in some reflection rather than just absorption. However, presenting a larger surface area of coverage of a given material will absorb more. For a really huge superchunk, you could consider low GFR materials such as attic insulation. You could also make a large surface area trap that is ~4" thick of 703 that has an air gap back to the wall.
If you are going huge, you could also consider the kind of hanging batts like in Newell's designs. Boggy also uses this kind of approach in his MyRoom designs.
Bigger is generally better, but it would be very difficult to calculate or predict a Superchunk's performance, because corner mounting is not in any of the calculators I have seen. I would base decisions more on tests in any case. Acoustics Forum • View topic - Corner Absorption Comparision test
The 703 here does well.
I and clients have built floor to ceiling Studiotips SuperChunks using 48KG fibre and Attic insulation. They all work, hard to get wrong. I wouldn't try the attic insulation with the 24 inch wide SSC, but I think they are too small to be really effective anyway. I have measured considerable absorption down at a 35Hz mode using three 48KG (703 equivalent) floor to ceiling in a small room.
One may not do as much business as you hope for.
The semirigid panel has some construction benefits, may be just right in this case. But if you intend slatting the front, i.e. a frame, attic insulation seems a better choice.
if you are intending to make the trap wider/deeper -- you could use a combination of the two (OC703 and Fluffy attic). Use the 4" of 703 as the face to get a nice flat aesthetically pleasing front and fill behind it with the fluffy stuff.
Skye - What did you end up doing? I have a very similar sutuation; Ceiling that vaults from 6'6 at the listening end up to 13' at the rear - and I'm tossing around ideas just like you were almost 2 years ago. How'd things work out for you?