Making the bass-trap back

Copying from the Sound on Sound article (https://www.soundonsound.com/techniques/studio-sos-building-diy-vocal-booth), I decided to make the back of the booth a bass-trap.

Basically, a 2x8 box, four feet wide and 76 inches high (inside). Back to front

Standard fire-code 3/8 sheetrock
Safe 'n Sound between the vertical supports
Hung carpet
Hung mass-loaded vinyl
Hung carpet
Acoustic fabric front

This back would be anchored by 4x4 posts that would bolt to the booth walls.

Namely because I'd already bought them (while possibly intoxicated), I decided to use tee nuts into the posts and have the side bolts anchor into them.

Base layer of carpet anchored by a 2x2. Mass-loaded vinyl (folded back to show the 2x2) is attached to the top of the 2x2 for extra support

Plan A was to use a 2x1 to attach the carpet, etc too. However, once wielding the mass-loaded vinyl, I decided there was no way it would be strong enough and swapped it out with a 2x2.

One word to the wise, while mass-loaded vinyl is heavy, that doesn't make it strong, and it tears easily.

The mass-loaded vinyl folded down with the 2x1 for mounting the front carpet piece on top.

Adding the final piece of carpet, and the thing becomes to come together.

To help with the weight of the mass-loaded vinyl, I added corner braces.

The back side of the frame with corner braces. The cavities between the wood will be filled with Safe 'n Sound and then covered by sheetrock.

Finally, the front is covered by acoustic fabric.

My hospital corners need a little work.

Moving into position I bolted the sides to prove out the concept.

Next up I'll be working on the side interiors. I'll be adding the sheetrock to last outsides last.

The T-Nuts weren't anchored securely enough to use the bolts to move the wall into position (they just pulled out) so I ended up replacing them with carriage bolts.

Finally, mounting the sheetrock to the back.

The back, with half the sheetrock attached.

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Finishing touches

The sound was a little dead, so I added perforated MDF at ear-level to help restore some high frequencies. If I'm honest, it could probably use more. Finished interior Finished door. The headphone amp I mainly added because I was no longer sitting directly in front of my audio interface and this helps to span the gap. Since StudioOne allows for remote control by app (via WiFi), the plan is to control session via an Amazon Fire tablet that can double as a lyric sheet. I'm a little disappointed by the sound isolation achieve (definitely muffled, but by no means absolute), but maybe I just had unrealistic expectations. If I had to do it again, I would probably use more seals. The next time I take it apart I will probably add a layer of isolation on top of the walls to help with the ceiling, and use seals on all joints. I finally got around to testing it by placing a mic outside the booth and playing the same (strummy) groove on acoustic guitar with the ...

Building the ceiling.

The basic idea for the ceiling was simple. Two interlocking tongue-in-groove slabs of Oriented Strong Board (OSB) with abutting sections of PSA-backed soundproofing composite attached to the underside. However, the PSA was a pain to work with, sticking to everything but the OSB (now the sheepish owner of a pair of inconveniently ass-less jeans). PSA is messy to work with. The finished ceiling.

Building the front

The front was fairly challenging, in that to keep things semi-airtight, my usual slapdash construction wouldn't do. But what the hell, it had gotten me this far. The main pickle was the fact that I needed a solid core door, and I couldn't find one less than 80” high and all the space I had to play with was 76". However, I did find one that could have two inches trimmed from there top, and two from the bottom without damaging the core. This was cutting it close, but I figured I could make up the difference, by cutting out a door-shaped hole in the bottom of the frame. As it was thoroughly summer by this time, I wasn't worried about disturbing any groundhogs, their shadow should've been vanquished by now. I opted for a variation of the superdoor design mentioned in Rod's book , but using a soundproofing composite instead of the lead sheet since this is mostly for vocals/acoustic guitar, and shouldn't have that many low frequencies to worry about. ...

DIY isobooth

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