Will connecting two 36" x 12" x 4" absorbers together create an effective bass trap?

[ceemonkey]

Will connecting two 36" x 12" x 4" absorbers together create an effective bass trap?

The panels are wood-framed, and the absorption material is rigid fiberglass (I believe it's Knauf).

My concern is that having no fiberglass where the frames are joined will reduce absorption significantly.

 

[Bubba po]

You'd be better off separating them and using them to treat different corners of your recording space.

To answer your question as you asked it, the bass trap will be unaffected in its performance. If you build your bass trap properly, the insulation sits on top of the frame, not inside it. The dimensions of your frame are the same size as your insulation sheets.

 

[mjbphotos]

You'd be better off separating them and using them to treat different corners of your recording space.

To answer your question as you asked it, the bass trap will be unaffected in its performance. If you build your bass trap properly, the insulation sits on top of the frame, not inside it. The dimensions of your frame are the same size as your insulation sheets.

I disagree regarding the trap construction (but not in putting them together) - mine (and most traps I've seen) have an outside frame - usually 1" x X" wood (where X = nominal insulation thickness). But I'm not sure why someone would build 12" wide traps, as the insulation all comes in 24" (or 23" sometimes) widths.

 

[ceemonkey]

@Bubba po and mjbphotos:

Thank you both for your answers. Some additional explanations:

1. I want to join them together to create a bigger gap between the trap and the wall/ceiling corners where I am installing them. I already have two 48" x 24" x 5" rigid fiberglass bass traps in the front of the room where my listening position is (installed at ear/monitor level), and I need another set of traps behind me.

2. As for why they were built as 12" vs 24" wide traps, they were made that way to fit into a smaller space. My back wall has a door and a closet that limits how and where I can install traps. But now I realize that 12" wide traps don't provide much trapping since the trap-to-wall gap is small. Plus, I've found a way to install 24" wide traps there after researching the issue.

Based on your advice (both of you), I feel much better about joining them together. Thanks!

 

[Bubba po]

I disagree regarding the trap construction (but not in putting them together) - mine (and most traps I've seen) have an outside frame - usually 1" x X" wood (where X = nominal insulation thickness). But I'm not sure why someone would build 12" wide traps, as the insulation all comes in 24" (or 23" sometimes) widths.

That's fair enough, I got my construction from a PDF I found on the net. The explanation for it not sitting within a frame was in order that the sound waves could enter the rockwool slab via its sides along the leaves of fibre, as well as through the faces. It seemed reasonable, so that's how I've done mine.

 

[GIK Acoustics]

That's fair enough, I got my construction from a PDF I found on the net. The explanation for it not sitting within a frame was in order that the sound waves could enter the rockwool slab via its sides along the leaves of fibre, as well as through the faces. It seemed reasonable, so that's how I've done mine.

This is one method of building them. But the effect the exposed sides actually have little effect. We actually tested this exact thing - some absorption with and without a wood border in the corners of the room to see how much this actually affects bass trapping. Our tests suggests this effect is negligible, especially for bass frequencies: DIY Acoustic Panel and Bass Trap Frames -

 

[Bubba po]

This is one method of building them. But the effect the exposed sides actually have little effect. We actually tested this exact thing - some absorption with and without a wood border in the corners of the room to see how much this actually affects bass trapping. Our tests suggests this effect is negligible, especially for bass frequencies: DIY Acoustic Panel and Bass Trap Frames -

That was really interesting, and great to see actual data used to back up any conclusions. Thanks for the link!

 

[GONZO-X]

seems the border would be more useful as a structural element, if the impact of sound transmission is negligible

 

[ceemonkey]

Awesome, Alexander, thanks for the link!