Pimp my room! - home studio acoustics help

[Ian Savage]

[quote name='Mornats' timestamp='1374070313' post='2144961']
How thick would a basstrap have to be in the corner? Or, in other words, if I were to badger a mate into making some for me, what size should I be aiming for? If they can be portable, I can see them being much more practical.

[/quote]

Obviously a corner basstrap would have varying thicknesses as you go through the cross-section of it; it's only in any way effective on wavelengths up to around eight times its maximum depth, as a general rule. So if you want a trap to be effective down to 50Hz (wavelength of about 6.6m), you want it to be about 0.8m thick at its deepest point - enough to take a good chunk out of any room!

[lowdown]

[quote name='Mornats' timestamp='1374070313' post='2144961']
How thick would a basstrap have to be in the corner?
[/quote]

Being a Bass forum - I should imagine there would be quite a few thick Basschaps that would stand in your corner. [size=4] [/size]


[size=4]Garry[/size]

[51m0n]

It depends on the flow resistivity of the materials.

However at its most simple people make superchunk style bass traps, and they are made from triangles of rockwool (RW30 or RW45 depending on what frequency they need to control the most) stacked on top of each other (uses a lot of materials, extends quite low in frequency terms), to do this they cut a sheet of rockwool in half, and then each half diagonally in half to get 4 triangles per sheet. Each triangle then is about 2 foot across IIRC.

Those triangles are then positioned between 2 and 4 inches off the walls in the corner, the air gap increases the efficiency of the trap significantly.

However if you make a different design you can use less material and have two different densities of rock wool, the outer one (typically RW30) 4" thich (two layers) across the corner the full width of an uncut rockwool sheet, and the inner one behind it 2" further into the corner and made of a single layer of RW45 cut into a strip half width.

The trick with this design is building the frame to put the rockwool in and keep it pretty sturdy, but block as little of the rockwool edges as possible and have a nice fabric front. There are examples of this construction on the web (possible in the BBC whitepapers but I cant be sure that I'm remembering wher I got it from right).

It uses a lot less rockwool, and goes very nearly as deep as superchunks. However the framing is significantly more complex to get right.

The there are helmholtz resonators and limp mass absorbers which can be tuned very very deep and take up less space, but are again complex to make and less broadband in nature, making them good at dealling with a final problem area after the worst excesses of bass energy have been solved across a wider area.

In fact one of the best broadband bass trap absorber designs is often sited as an 18" thick 6 to 8" off the wall absorber across an entire wall of the room made of uncompressed fluffy insulation, but that takes too much of the space in most rooms! And its difficult to stop the fluffy pink insulation getting compressed too....

Edited July 17, 2013 by 51m0n

[51m0n]

In reality frequencies around 50Hz (or indeed much below 80 to 100Hz that is causing a significant issue) are far better dealt with with tuned bass traps (limp mass absorption being a favourite) since they take up hugely less space.