Few questions about insulating an iso space for a guitar cab

telecast

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Ok, I'm going to move forward with creating an iso space for a guitar cab. It's a space under the stairs in my basement. 2.5 feet wide, 7.5 feet deep, 6 feet high at it's highest point. It's under the stairs, so the top angles down from 6 feet at its opening down to the floor.
The floor is poured concrete (that plywood is just a loose piece). Isolated on both sides. The stairs are in the middle of the basement, so the crawl space was created by the drywall used on both sides of the stairs.
My plan is basically to treat it like a big iso box. I'm not making it 'soundproof', I just want to cut down on weird reflections getting into the mic.
I like the idea of using this space because it's right next to the space I want to use as a mixing space, and it's convenient.
I'm considering putting roxul safe and sound between the joists, simply because that's what I can get from Lowe's. If that's not enough, maybe I'd add Auralex all around on top of the safe and sound for added deadening. The auralex would be mounted on the edge of the joists that would peak out between each piece of roxul. The auralex wouldn't compress the roxul down, it would just be another layer of absorbtion material.
For the top, I'm thinking of using rigid fiberglass board from ATS Acoustics. I'd surround it in burlap (also from ATS), put velcro on the burlap, and velcro it to the bottom of the stairs, following the downward angle of the stairs. I'd like all of this to be easily disassembled so I can take it with me when I move.
If I need more on top, I can add velcro on to the face of the 'panel' and velcro more auralex on to that.
I'm stumped about what to do with the floor. Any suggestions?

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spence

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If you're just going to close mic your cab, then just deaden the space as good as you can. All you need to do is stop reflections from entering the mic. I'd start by stuffing it with the Roxul, then recording a passage to see if you hear anything weird. Find a piece of carpet to put over the concrete floor, and get the cab up off the floor. I wouldn't waste the money on Auralex. Is the top covered with drywall, or are the steps open underneath?
 

telecast

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Is the top covered with drywall, or are the steps open underneath?

The steps are open underneath.
Should the roxul along the sides be faced or non faced? I'm assuming faced so I can staple the facing into the joists?
 

spence

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1,726
If you buy faced, you may get some reflections off the paper. I'd leave the sides non faced, then staple some burlap or other porous material over top. As far as the steps, you could probably get away with just tacking (or gluing) pieces of carpet to the underside of the steps. Heck, if you get some old carpet, you could tack or glue strips on the sides between the studs first, then stuff it with roxul, then cover with burlap. I'd also buy a roll of non faced R-16 pink insulation, and just set it where the steps meet the floor. That will help with low end build-up that may happen in that corner. If you have enough carpet, put 2 layers on the floor.
 

spence

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1,726
Before you lay carpet on the floor, you could always get some caulk and seal up the whole room - anywhere sound can escape out. Even the smallest hole or space can let out a lot of sound. Doubling up the drywall inside would help too. If your mix room is right beside the iso room, you might as well try to soundproof it the best you can. It will make recording a lot easier too. Is there a door leading into the iso room?
 
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telecast

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Excellent suggestions! I was considering doubling up on the drywall, and I like the idea of caulking. There's no door, the opening is wide open to the rest of the basement. That's something I have to think about. I have to look at it more closely to see which options would work.
 

Crowder

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That's a perfect space for this project...pretty much useless for anything else it would seem!

I have some Safe N Sound from Lowe's and I would caution you not to expect too much from it. I made some gobos from it and they were useless. I have used the rest between studs around my music room and it is so-so. Like others have said, sound has a way of getting around things, through gaps, etc, so making the space airtight is job one before you attack resonances from the wood, drywall and any baffles you add.

For the floor, a cheap solution would be getting bags of cement mix to go under your cab. That stuff is dense. If you wipe the bags with towels you should be able to get all the extra dust off of them. Another option would be paving stones. You could even build a small floating floor with those cinderblock risers meant for deck posts.

For the walls and ceiling I would think layers with gaps between them. There's lots of good info on the greenglue site. Some things you THINK would work do not work as well as some things you THINK wouldn't work well at all.
 

spence

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1,726
Without a door on there, there's no use sealing up the room with caulk. In your original post you said you weren't worried about soundproofing. You just want to deaden the room reflections. In that case, you could just hang a heavy blanket over the door opening. If you're going to have your mix room right beside the iso room, you're going to have trouble monitoring with that loud guitar blaring out. If that doesn't bother you, then just deaden the inside of the room with carpet and insulation, covering up the hard surfaces. Don't worry about the studs. They won't affect anything. Just cover all the flat surfaces. You wouldn't even need to use the burlap unless you want to 'pretty' it up in there. If you can find an old exterior door with a threshold, put it on there, and caulk the inside of the room to seal up any areas where sound can leak through. Glue another piece of carpet on the inside face of the exterior door. You'll never keep all of the sound from getting out, especially the low end, but it may work well enough to make monitoring easier. If you end up sealing the room, try to get as much insulation in there that you can to absorb the lows. Rigid fiberglass panels work great and take up much less space than the fluffy stuff, but it can be cost prohibitive. Try to find used stuff on Craigslist, or your local Habitat for Humanity store, Goodwill for carpet, etc. Oh, and one last thing, make sure there's nothing loose in that room that will rattle, vibrate, or buzz when you crank things up - no loose drywall screws, or creaky steps.
 
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telecast

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Let me check out the rigid fiberglass panels rather than the safe and sound. I'll start by pricing it out on ATS Acoustics. An exterior door on the opening is a great idea. I'll see what I can find. I think this might be a project where I have to experiment a bit to see what works. Thanks all!
 

spence

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1,726
If you can, see if there's a place locally that sells Owens Corning or Johns Manville rigid panels, and make your own. If you make portable panels, you can move them to your mix room after you track the guitar. Better yet, just use fluffy pink insulation and old carpet in your iso room, and make some nice looking rigid panels for your mix room. Here's a homemade panel with pine boards and trim from Lowes, with burlap on the front.

 

telecast

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I have some Safe N Sound from Lowe's and I would caution you not to expect too much from it.

Crowder, was it ineffective in terms of deadening the sound for the sake of the mic in front of the cab, or was it ineffective in terms of soundproofing?
 

Crowder

Dang Twangler
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19,089
Crowder, was it ineffective in terms of deadening the sound for the sake of the mic in front of the cab, or was it ineffective in terms of soundproofing?

One layer of it built into a gobo was almost completely ineffective in reducing sound transmission at any frequency. It's clearly meant to be used as part of a wall and stud system, and it is probably good at dampening the vibrations those components would normally exhibit. But if you put a source in one side of a layer of SnS and your ear on the other, won't notice any difference.
 

spence

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1,726
This thread is getting a bit confusing to some. I think the OP just wants to deaden reflections, not soundproof, and I think he wants to use the space under the steps, not build an iso cabinet. The space is there, so use it! Here are the basics:

Deadening the space under your stairs without a door, but not soundproofing (all you're doing is taming reflections) -

1. Just use pink insulation between the studs.
2. Thick carpet over the concrete floor
3. Carpet, or any absorbent material on the underside of the steps.
4. Big thick blanket hung over the entrance.

Soundproofing the space (it won't be perfect unless you go to extreme expense, but it'll make recording easier) -

1. Check for any loose construction inside the space and screw it and glue it to eliminate buzzing or rattling.
2. Seal up any cracks or spaces with a silicone based caulk.
3. Double up the drywall and use green glue if you can (Google it).
4. Thick carpet on the floor.
5. Line your walls with as much insulation as you can. Heck, put as much insulation in that space as you can fit. That will help with the low end, which is the main culprit in this project. Lay it loose - DON'T stuff
it. Fill the area where the floor meets the steps.
5. Put on an exterior door with a threshold. Put a thick piece of carpet (or better yet, a thick rigid fiberglass panel) on the inside face of the door. Caulk the threshold along the floor so sound can't escape.

You'll need to put a speaker jack on the wall (or run a speaker wire through the wall). You can use expanding foam in a can to help seal it up inside the wall, or silicone around the speaker cable where it enters the wall - on both sides of the wall.
ANY little crack or hole will let a lot of sound out, so make that space airtight.
 
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telecast

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548
Yup, that's a good plan. I think whether I try to soundproof or just go for a deadened iso space will depend on what I end up doing for a door. If I can find a good exterior door at the right dimensions that isn't too much money, then I'll definitely try soundproofing it as well as creating a deadened iso environment. Even if it's not 'perfect' at being soundproofed that's fine. It will still likely help with monitoring since my mix space will be right near the iso space.
I really appreciate all the suggestions and the help! This will be a project I work on over the course of the next few months (dealing with medical issues at the moment) but I'll try to post reports as I make progress. Thanks!
 




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