How big do corner bass traps need to be?

Rich_S

Rich_S

Member
Background: Mrs_S and I just moved to our "forever" home, downsizing from 2,100 to 1,400 sq ft. I put off doing any serious room treatment at our old house, because I knew we'd be moving in a few years. Now, I've settled into my new space, and we ain't NEVER moving again. My "studio" isn't much, but it's all I'm allowed to have: a 10' x 11' bedroom to serve as my home office and studio. It's sub-optimal, but I'm not planning on track much "in the room", it will mostly be used for mixing plus the occasional voice or acoustic guitar. I get stems from other players and record my electric guitars direct through a cab-sim and load box.

I know a room this small is going to be problematic in the low end. I'll be doing some actual measurements in the coming weeks but for now I'm just planning ahead. I have a lot of stuff I want to hand on the walls: my guitars for one thing, a few posters, and some other music-related "art". Unfortunately, these will be competing with the acoustic treatment for wall space. I'm kinda figuring bass traps are going to be priority #1, followed by 1st-reflection absorbers on the walls and ceiling if I can fit them all in.

How big do corner bass traps need to be? Most of the DIY videos on YouTube show them 24" x 24", because it's easy to cut 2' x 4' rock wool panels into 24" triangles. In practical terms, it I put 24" traps in my corners. it would use up nearly 40% of my available wall space. Not to mention pushing all the furniture toward the center, to the point where there'd be no room for me.

Would 9-inch triangles be effective? (I say 9" just because there's one particular corner where anything larger than 9" would prevent the door from opening all the way.) As long as we're discussing down-sizing the traps, what does making them smaller do to their effect on the acoustics? Does it change the frequencies at which they work? The amount of attenuation?

Finally, are corner traps supposed to be solid, or should they have air space behind them? (Sort of the triangular version of the air gap behind flat panel absorbers?)

I'm looking forward to spending more time here as I try to make the most of this little room.

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The simple answer is make them as big as the space allows. You will get better results using the pink stuff sealed in plastic behind a 2 to 4" thick panel that isn't sealed.
From my understanding the theory of 'air-gap' behind any absorption panels has been proven not worthy. Most effective is to have the low density fluffy stuff instead of a gap. Rockwool is somewhat reflective.
 
With such a small space (my last room was that size), you want to get as much trapping in place as you can. But for mixing purposes, you also want things to be as symmetrical as possible (assuming you will be using monitors). Those mirror doors are not a good start and with an adjacent window... Maybe you could make some floor-to-ceiling panels on wheels for that back wall (assuming you keep your desk with speakers where it is now, as the 'front'). You could make them 2' wide X just less than ceiling height, using 4" thick OC703, cloth wrapped, with frames - all hinged together, or separate, and each with a little 'foot' to keep them standing upright.
 
The mirrored closet doors are going to get gone. I think I'll replace them with normal wood sliding doors and hang an absorber panel on the outer one. Opening the inner door will expose the "diffusers" hidden behind (i.e. plastic tubs of cables and stomp boxes, and overflow from my wife's clothes closet).
 
Safe’n’Sound comes in 15” width (3.5” thick and 4’ long) to sit between 16” wall studs. I used that in double thickness for my corner/bass traps. My room is 11’x11’ and I don’t think they take up any space that would serve any purpose except possibly allow me to accumulate [even more] crap I don’t really need.

I only have 3 in the room because the entry door is in the 4th corner. A 12-pack of those 4’ pieces made my 3 floor-to-ceiling traps. Got mine at a local Lowes.
 
keith.rogers said:
Safe’n’Sound comes in 15” width (3.5” thick and 4’ long) to sit between 16” wall studs. I used that in double thickness for my corner/bass traps. My room is 11’x11’ and I don’t think they take up any space that would serve any purpose except possibly allow me to accumulate [even more] crap I don’t really need.

I only have 3 in the room because the entry door is in the 4th corner. A 12-pack of those 4’ pieces made my 3 floor-to-ceiling traps. Got mine at a local Lowes.
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Is the Safe N Sound stiff enough to stand on its own just wrapped in fabric, or does it need to be framed?
 
Yeah, "Rockboard" is the Rockwool/Roxul rigid material. (I couldn't find that or OC703 locally at the time I was building my treatment.)

If you're building reasonably thick bass traps of any material and they're 8' tall - you either need to fasten them permanently or put them in frames IMO. Actually, I have 2ea 4' framed traps in the corners that are fastened together. I couldn't reasonably have built 8' tall ones in the garage and gotten them up the stairs into my room, so I stacked them and fastened them together in place. I don't have them attached to the walls, but have some egg-crate foam (in muslin) stuffed into the small space between the ceiling and upper trap so there's no risk that any kind of bumping or moving will cause some kind of domino disaster :). (Dense material to trap bass is *heavy*.)

p.s. (edit) went back to that "let me see your studio" thread and found my post - it no long had a picture attached, but a dead link called "attachment.php" so I updated it with a slightly newer photo I found, though it has stuff that's no longer there, so not current. Traps shown are still in place though, and you can see one of the corner traps.

 
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