Corner bass traps: Is shape important?

I should clarify that I'm referring to the typical triangular bass trap design that appears in room corners in numerous places all over this forum. I've noticed that they are almost always triangles, at 45 degree angles across the corners. QUESTION: Does it make a big difference to angle them at, for example, 60 degrees, or 30 degrees, instead of 45? Or any arbitrary number? (Assuming you keep the total volume the same). The reason I ask is because I'm trying to refine the design for my "really small room", and I figure I could gain a couple of inches to move the sliding doors to a better location, if I could just angle the bass traps in the rear corners a bit less. I would still have the same total volume in my bass traps, but the frontal area would increase a bit, which I guess is not a bad thing. QUESTION: Does it help if the bass traps directly face the monitors, or is that irrelevant? If I do change the angle, then the front face of the bass traps would be more perpendicular to the direct sound field from the speakers. The front face of the traps would be nearly parallel to the front face of the speaker soffits. I have no idea if that means much, but I suspect that it is probably not relevant. Worth asking, though! QUESTION: Also, would traps with rounded shape front face be better? For example, a slightly convex or slightly concave curved front surface? Or does that not make any difference? I plan to build them by cutting semi-rigid mineral wool "panels" to the correct shape, piling them up on top of each other (floor to ceiling) then covering them with cloth attached to a frame. So I can make them pretty much any shape i want. I want to get optimum performance, but I'd also like to gain a couple of inches, if possible. - Stuart -

Soundman2020 wrote:

Does it make a big difference to angle them at, for example, 60 degrees, or 30 degrees, instead of 45? Or any arbitrary number? (Assuming you keep the total volume the same).

Probably not.

Does it help if the bass traps directly face the monitors, or is that irrelevant?

Irrelevant. It's the trap's placement in the room that matters, not the relation to where the speakers are.

would traps with rounded shape front face be better? For example, a slightly convex or slightly concave curved front surface? Or does that not make any difference?

No difference. --Ethan

Great! Thanks very much, Ethan. I'll take that as a license to go crazy with my bass traps, then?! :) So, from this and from reading over your website, basically the important points are: 1) Must be in the corners (as many as possible). 2) Must be "deep". 3) Must be lots of volume. 4) Must be fiber glass, mineral wool, or best of all Real Traps. Nothing else works. :) Does that about cover it? - Stuart -

when you have a rectangular room you can use this calculator to find the best place for a trap: http://www.hunecke.de/de/rechner/raumeigenmoden.html it shows exactly where you have the max pressure points for each mode of your room. cheers mika

Thanks Mika. I don't speak German too well, but it's fairly self-explanatory! Pretty neat, actually, to get that visual representation. However, the best place for bass traps is always in corners, due to the 6 dB or 9 dB boost you get from having two or three walls in proximity, and modes area always maximum in corners. Try it out with that same calculator, and you'll see that the corners are always part of the solution. So, any give bass trap will be three or four times more effective if you put it in a corner, then if you put it at a node in the middle of the room. My question was more about the shape of the bass traps than the position. I suspected that the shape doesn't really matter, for a given volume, and Ethan has confirmed my suspicion. And Ethan is one of the real expert authorities on bass traps here! But thanks for posting that calculator! I love the 3D graphical representation. It makes it very clear and simple to understand how standing waves form in 3D in a room. Do you know if they have the same calculator in English somewhere? - Stuart -

Yes the linked site have a englisch transaltion button in the upper left. The 3D animation is very good when you want to built many tuned basstraps. So you can plan the place already in the designphase of the room. cheers mika

Soundman2020 wrote:

Does that about cover it?

Yep. :mrgreen: Related to Mika's posts: Pink noise aids placing bass traps --Ethan