DIY Amp Isolation Box

daav

daav

Flailing up a storm.
Problem: Apartment living has made the sweet tone from my Blues Deluxe unatanable at reasonable volume. I need to turn this thing up!

Solution:
I built a large box (a cube about 28" per side outside diameter) out of 2x6s, 2x4 and plywood to make an isolation box. The damn amp is about 2 feet wide, and I wanted to make room for a smallish speaker cab for my humble bass rig, which is about 2 feet tall, so it is a pretty big box overall. Well i finished the major construction on the box itself last night, put the amp inside, let the tube warm up, and then turned the beast on and put the volume at about 3-4 clean, which was way loud for my apartment wihtout the box.

Problem: It sounded like i could have made the damn thing out of tissue paper. Now the box was basically untreated at first, so i didn't expect it to be hugely effective right away, but it was basically nothing. So i packed a couple old pillows around the empty spaces, put in a big comforter, and fired it back up, the highs were well muffled, but the lows go right through the box, the floor, the walls, everything.

So i am looking for suggestions, I don't know of anyplace in Vermont that sells OC 703, so it looks like i am going to have to order some of that. Also, I am thinking that i can use some old carpeting to line the inside of the box, and I am even considering building a yet larger box to further isolate, but this box is really big already, what a pain!

When i built the box, i used lap joints and rabbets, so right now the only places where there is not some overlap from board to board is with the lid. Would it be helpful to caulk the inside (or even use that spray expanding foam stuff) and built a lip on the lid to make a tighter seal when it is closed?

Any other thoughts on some good treatment options? I only have a about 2-3 inches on the back and sides of the amp when it is in there, and about 1.5 feet in front for treatment and to put a mic in. There is plent of space in the bottom and top to add treatment stuff.

Thanks for reading this book, and any suggestions are appreciated.

Daav
 
Uh, I'm no expert but let me break this down:

You built a box out of 2x6s, 2x4s and plywood? And you wanted it to be an isolation box?

I don't really see anything that you did that actually would offer any sort of sound-proofing. Is this box for recording or just jamming out?

In order to effectively "sound proof" or "sound damper" you need MASS...a sheet of plywood is not considered MASS.

There may be some other options, but I think the best would be getting some 703. It isn't going to sound proof the box completley but it will damper the sound. And that being said, the amp is not going to sound the same to your ears when it is in the box. The mic may be able to pick up the tone you're looking for, but your ears won't hear the same thing as the mic...because you'll be outside the box.
 
Nutdotnet said:
Uh, I'm no expert but let me break this down:

You built a box out of 2x6s, 2x4s and plywood? And you wanted it to be an isolation box?

I don't really see anything that you did that actually would offer any sort of sound-proofing. Is this box for recording or just jamming out?

In order to effectively "sound proof" or "sound damper" you need MASS...a sheet of plywood is not considered MASS.

There may be some other options, but I think the best would be getting some 703. It isn't going to sound proof the box completley but it will damper the sound. And that being said, the amp is not going to sound the same to your ears when it is in the box. The mic may be able to pick up the tone you're looking for, but your ears won't hear the same thing as the mic...because you'll be outside the box.
Click to expand...

Well i am never going to not say thanks for a reply. Thanks, sorry if i wasn't as detailed.

I intend to use it to mic the amp from inside, monitor when tracking via headphones. My goal is not total isolation, but to be able to crank it loud enough to get a decent tone from inside to the mic without getting me evicted (although using the tablesaw and other tools to make it probabaly was just about as bad).
I am going to have to buy a bunch of 703 anyway, and i understand it will need treating, i was just thinking that it might have helped a little more with just some blanket type batting in there. I want to make some bass traps as well, anyway. But i am hoping some folks might tell me that:
1. Sealing joints with siilicone caulk or that expanding foam stuff will or will not make a difference.
2. Similiarly, will it keep more of the sound bouncing around inside if i put a lip on the lid to tighten up that connection.
3. will lining with carpeting inside help at all, do you think?
4. Finally, has anyone else tried to do such a thing before and can tell me is it a huge waste of time, and i jsut should buy the people next door movie passes when i want to record?

Thanks
Daav
 
I certainly can't answer all those questions for you (since like I said, I'm no expert).

But no, I think you CAN do this; but you may need to rethink your approach a tad.

Blankets would help in the fact that it is mass, but keep in mind, most blankets are not very dense. It may take up a lot of space, but it's not very dense.

I perosonally don't think you need to bother carpeting the inside at all; seems like it would be more of a waste of time and $$$ then anything.

You need something dense that takes up mass (I think). The 703 would be a candidate...hopefully someone else here would have another suggestion.

Good luck bud!
 
Iso bx

I built one about a year ago for my Fender Hot Rod so I would be able to record drums and guitar without bleed and to also to be able to hear the guitar amp though my monitors without hearing the amp itself. For those two purposes, it has exceeded my expectations.
1) Did you put plywood on the inside of the box as well as the outside.
2) In between the inside and outside walls of the box, did you put insulation of any sort.
3) Did you build the cover for the top the same way or are you placing something else on in. (I use these incredibly large, dense pillow from a 20 year old couch on top that work wonderfully).
4) Is the box directly on the floor? If so it will resonate through the floor and sound loud to you. I would raise it either by adding casters or build a dolly and attach some sort of vibration absorbtion on the dolly.

I also took some left over hardwoord and attached it to the floor of the box to add mass and look.

Hope this helps.
 
I would add, is the amp sitting on the floor of the box? If it is, the lows will be hard to tame. I would build a little table, or put four little blocks under the feet, to keep the amp from physically coupling to the floor of the box as much as possible. Doesn't have to be much, little pieces of plywood with some foam will do wonders.

ps-where in VT?
 
Thanks guys.

The structure so far is essentially a rectangle with 2 sides of 2x4 and 2 sides with 2x6, with a piece of 3/4" plywood in the center, set in a 3/4" groove all around. So there is only one layer of wood in all directions. One of the things ihave been thinking about is to add a second layer with a spacer in between, and put some 703 or rockwool in between.

2) In between the inside and outside walls of the box, did you put insulation of any sort.

I guess that would be my next step, there really aren;t inside and outside walls. Woul dyou say that it would (all but) need to be two-walled to really be effective? . After doing some extensive research yesterday, i think I have actually found a place locally where i can get some dense fiberglass, the John Manville (or whatever it is called) version. This may do the trcik for me by itself.

3) Did you build the cover for the top the same way or are you placing something else on in. (I use these incredibly large, dense pillow from a 20 year old couch on top that work wonderfully).

Yeah the top is pretty much the same as all the sides and the bottom. I was thinking about putting more insulation underneath the top, and perhaps I'll take your suggestion and drape something over the top when closed as well.

4) Is the box directly on the floor? If so it will resonate through the floor and sound loud to you. I would raise it either by adding casters or build a dolly and attach some sort of vibration absorbtion on the dolly.

I actuially did think of this, right now it is on feet made of pieces of 2x4.

So i think i will skip the carpeting and sealing every joint for now, and see if this place really does have any decent noise reducing iunsulation locally. I may have this box working as designed tonight!

Daav.
 
easychair said:
I would add, is the amp sitting on the floor of the box? If it is, the lows will be hard to tame. I would build a little table, or put four little blocks under the feet, to keep the amp from physically coupling to the floor of the box as much as possible. Doesn't have to be much, little pieces of plywood with some foam will do wonders.

ps-where in VT?
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Good suggestion, i will try that too.

I live in the Burlington area. *wave*
 
I think caulking might help. I would also be worried about heat from the tubes. I don't think insulation would be much better than air, just so long as the airspace is airtight. I might be way off base there. but without getting it airtight, I don't see how it would work.
 
It sounded like i could have made the damn thing out of tissue paper.
Click to expand...
No doubt. Even 1 foot thick concrete will transmit at certain frequencies. :) The problem is an AIRGAP!! What you need is a DECOUPLED BOX WITHIN A BOX.(TWO LEAF ENCLOSURE) with at least a 4" rigid fiberglass filled airgap. You also need to line the interior box with rigid fiberlass. You can even rest the speakerbox and mic within and on the fiberglass. Personally, I'd make this a dedicated box with a caulked lid on each of the leafs, and float it on neoprene pads. Here is an ILLUSTRATION, although there are many ways to interpret this.

Actually, I wouldn't use a tupe amp because of the heat. Personally, I'd uild a speaker box as part of this. Use an XLR panel mount jack for the mic, and one for the speaker lines. That way you maintain the airtightness integrity.
fitZ
 

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Great info Rick.

That might be exactly what i do someday, or with this eventually, but for now, I think I am going to have to live with some compromise, less noise, but not quite the perfect solution. Hopefully treatment will go a long way toward doing the trick.

I am now a little concerned about the tubes after a couple comments, how hot is too hot to be in there?

Daav.
 
They don't vent amps for nothing. It'll get hot enough sizzle the tubes or other components, if not start a fire in no time. :eek: Tubes generate a generous amount of heat. At least the ones I've owned did. If nothing else, it'll worry you. :p
fitZ
 
RICK FITZPATRICK said:
They don't vent amps for nothing. It'll get hot enough sizzle the tubes or other components, if not start a fire in no time. :eek: Tubes generate a generous amount of heat. At least the ones I've owned did. If nothing else, it'll worry you. :p
fitZ
Click to expand...

Dman right that worries me, well there is a good amount of open space in there, and i just picked up my fiberglass to treat the box, so i will how it all works out, with the tradeoff of space, heat etc. I guess i will take some temps and see how much it goes up over time.

Thanks for the warnings. Got any instructions on an iso box for the air condioner i need to install in my iso box?

Daav.
 
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