Bass Trap Design for Wall

#1

Hi Folks,

Happy New Year! Please look at these photos. Is there too much material (wood framing) on the inside? Shouldn't it just be an open box? Once filled and wrapped with fabric, I want to mount on wall not corner, with 2" gap so it is not right against the wall.

Thank for any feedback.

Howie

#2

Hello Howie. I don't see a problem with the cross-braces. You could open up the top, bottom and sides to allow more sound to enter the traps, either by drilling, routing or jigsawing holes, something like this, for example.

Also, if you have the space to increase the 2" gap to be the same as the depth as the traps then you will get better low frequency performance from them - and that is where this comes in useful: http://www.acousticmodelling.com/porous.php

#3

Are these 4x2 feet frames?

The internal cross bracing will make it more difficult to stuff with absorption, and I'm not sure what benefit it would give. I've never required it for traps of that size, getting the perimeter frame square has always provided enough rigidity. On recent builds I've used a jig to keep the corners square while putting countersunk screws in to clamp the frames together.

It's easy enough to put spacers or brackets on after fabric etc. to get it 2" from the wall. Or you could always add 2" deep vertical, horizontal, or diagonal cross braces on the back for this, also after the trap is build with fabric on.

Another way... I have a wall with french cleats for the panels, that provides a bit of a gap.

Cheers!
Jennifer

#4

Are these 4x2 feet frames?

No, they are 4’x 2’-6”. The depth is 5.5”.

if you have the space to increase the 2" gap to be the same as the depth

Unfortunately I don’t. Thank you for the calculator! It shows that I get more absorption from 200hz and below using my current depth of 5.5” with 2” gap than if I used 3.5” depth with 3.5” gap.

Thank you both! I like the idea of putting holes in the frame. It would also lighten the weight. I will also consider Jennifer your suggestion of putting cross framing outside fabric or just eliminating all together.

#5

Hello Howie, here are the clamps I use to get square corners. One at each end of the join. I placed glue along the seam, clamped the corners, lined up the edges properly, then put several countersunk screws along the seam to hold the boards together. Absolutely solid when done, and much quicker & more accurate than using brackets.

https://www.amazon.co.uk/gp/product/B001W7ARXK/

I used very good quality torx countersunk screws. They are more expensive than standard screws, but are self countersinking (?) so you don't have to pre-drill the countersunk hole. Saves a lot of time. I pre-drilled pliot holes for the screws using a drill jig - it looks a bit like a harmonica! This ensured the screws also went in properly square. If they are not square they might pull the wood off square when you tighten them.

https://www.amazon.co.uk/Big-Gator-Tool ... B00CYNOFM0

I had some photos of these in use but can't seem to upload them at the moment so have put links instead.

Cheers!
Jennifer

#6

my preference for maximizing surface exposure is to make a set of frames - 1x1 + 1x2 so edges are open. generally my clients need to "manufacture" a bunch so using some jigs to align while gluing and tacking is a good choice. see attached as examples.

#7

That's a brilliant idea Glenn, thank you for posting the plans. Some years ago I made 4" thick panels in a similar way using metal corner beading (usually used for plasterboard) for the face of the panels. The panels were completely covered with fabric, structure and all. They look really good but those metal pieces have sharp edges when cut so were tricky to work with. I was worried the sharp edges would tear the fabric when it was pulled tight over them, and filing the edges blunt and taping over them took ages.

Both faces made from wood is definitely better.

Cheers,
Jennifer

#8

the nice thing with the wood frame, you can insert the cloth wrapped insulation/mlv packs into the frame so its exposed which can add a visual interest to them. painted or stained.

#9

Glenn, you are so helpful! I just wanted to say thank you for the time and effort you put in.

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