Amp Isolation Box Build (w/ pics)

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Tims96
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Amp Isolation Box Build (w/ pics)

Post by Tims96 » Fri Sep 16, 2011 12:23 pm

I wanted to share some pics of an isolation box for amps I recently built for my studio. It wasn't that much work, and was relatively cheap to build (~$100 total). The best part is that it works REALLY well. We had a Fender Deville cranked, and got nearly no bleed at all into our drum mics, roughly 15 feet away. I have to thank Red Rockets Glare for the design, which was simple yet effective.

Here's the frame. We used 2x4 framing lumber since we knew it'd end up being pretty heavy.
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Next we attached the outer layer, which is 1/2" MDF board. This stuff is dense! We caulked the seams, though I'm not sure how much of an acoustic difference it made.
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Here's a picture of the outside of the box with the outer layer attached. Because we didn't have a table saw and had to have the Home Depot cut the MDF, our cuts were not perfect. Hence the bit of overhang. Again, we caulked the seams just in case.
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Here's a picture of the insulation we used. Pipe insulation. Not ideal right? Of course not, but I got a box of 40 4' rolls of these for $5 at a local construction materials re-use store. If we had to buy new insulation the cost for this thing may have been double what it was. We ended up unrolling these and putting about 34 rolls inside the box.
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At this point we moved the box into the garage, since it was already super heavy. You can see the two layers of insulation on the sides before we added the second layer of MDF.
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Here's the box with all insulation and MDF attached. Not pictured is the plug/door, which is Roxul cut to the exact dimensions of the front attached to an MDF board and then clasped to the box. Also not pictured is the packing blanket inside to kill internal reflections. I'll take some of those when I'm at the studio later today.
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While it looks pretty DIY, it sounds great! It's an incredibly effective way to increase the flexibility of a small one-room studio, and I'd definitely recommend it as a fun project! Ours is designed to fit many popular combo amps including Twins, AC30s, and Devilles, but of course you can go bigger or smaller depending on your needs.

More pictures soon!

-Tim

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Post by goose134 » Fri Sep 16, 2011 9:54 pm

I am well aware of how much MDF weighs. That is something I would have built about 3 feet from where it was going to live for a long time. Looks solid. Glad to hear the heavy lifting paid off.
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Post by Tims96 » Sat Sep 17, 2011 11:00 am

Yeah, with both layers of MDF and all the insulation, there's no way to pick that thing up. The only way to move it is to roll it end over end!

Here's a less than ideal phone picture of the iso box as it stands now. I've got a packing blanket in there, and on the right side you can see the plug with Roxul cut to fit. I just bought some fabric yesterday to cover up the Roxul to make it look a bit nicer, and I'm considering replacing the packing blanket on the inside with an interesting pattern. Plaid perhaps?

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Post by goose134 » Mon Sep 19, 2011 9:10 pm

Plaid? Jeesh. You don't want the fabric to be louder than the amp inside. :)
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Post by Matt C. » Sat Sep 24, 2011 5:38 pm

question for you or anyone else who's used one of these - does the recorded sound end up sounding like it was inside a box, or not so much? I'm thinking about building something like this (maybe collapsible, even though it would be harder to build and isolation would suffer a little...).

also, would there be any reason to not use it for bass too?

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Post by JGriffin » Sat Sep 24, 2011 10:54 pm

That's very cool! Wish I had the time and skills to do something like that; it would make apartment recording a bunch easier.
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Post by DrummerMan » Sun Sep 25, 2011 8:28 am

dwlb wrote:That's very cool! Wish I had the time and skills to do something like that; it would make apartment recording a bunch easier.
You could do it in some beat up old fridge like I did , even forgoing the totally unnecessary interior wood panels. requires less carpentry ability. Though if I was doing it again and had the choice of fridges I might have gone for one a little bigger.


To mattcastore:
I don't find mine particularly "boxy" sounding. Totally useable sounds once the mics are placed right. I often have two mics in there so I can do some fun things with stereo spread. The only issue is that there isn't any possibility of getting a sense of space. Everything's very close sounding. Even with a mic 2 feet away and fcing the other direction the best I get is a slightly muffled big-ish tone. I'd imagine that if it were a little bigger, I might start to have enough space to get some comb flitering and things could get boxy pretty quick. As it is now, it's just too saturated with sound to have any distinguishable reflections. So, in a nutshell: good for close sounds, nonexistent for anything else... In my experience...

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Post by Tims96 » Mon Sep 26, 2011 9:53 pm

Drummerman's experience is similar to mine. The box is big enough to get enough distance to minimize proximity effect (with certain mics), but it's definitely close micing. No sense of space at all. I found that once I dampened the high frequencies inside, I couldn't hear the effect of the box at all.

To mattcastore, you certainly could do bass tracks in one of these, but keep in mind that low frequencies are more likely to escape the box. So while you'd definitely notice some attenuation, the amount of isolation would be decreased compared to a guitar amp. Also, bass amps tend to be bigger. If anyone has an experience with a bass iso box, I'd love to know how it works!

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Post by norton » Tue Sep 27, 2011 5:04 am

Nice work! I would think these things are going to start popping up more and more. They make a ton of sense in certain applications.

One way to make this work a little better would be to isolate the box from the floor it sits on. This is basically a very small room, so the same construction techniques for rooms should be applied. To that end mass is your friend, mdf etc....but I don't think it would be any more effective than Sheetrock doubled up.

If you really want to go "all in". Making it with steel studs and or a resilient channel will help the box/room performance. The steel studs and rc channel will help make the box much lighter, along with the Sheetrock, but will also make it a less rigid structure which should make it more effective in stopping sound transmission.

Steel studs are super easy to work with, so that's a plus too.

Maybe these things should all live on damped platforms with wheels?

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Post by Tims96 » Tue Sep 27, 2011 6:48 am

Yeah, we actually put a bunch of rubber feet on the bottom of this thing, but I'm not sure how much help they are since it's so heavy. From what I've heard, rubber compresses a ton when it's supporting large masses, so it's possible they're not decoupling at all.

I would LOVE to try and build one of these with a resilient channel. If only for the practice so that when I move into a proper space I'll know what the heck I'm doing. That's a really cool idea. The room for error there is pretty low, yeah? As in, if I mess up one screw I can accidentally couple an entire side, ruining the effect of the RC.

I'm surprised at how effective this one is. I've had literally no audible bleed from amps inside to drum overheads (while the drums are playing). There's a bit that gets into my room mics, but I'm not worried about that at all. So even just going all brute force with it and adding a bunch of mass can be huge improvement over throwing an amp in the room "naked."

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Post by vvv » Tue Sep 27, 2011 6:46 pm

FWIW, I used to use a Anvil amp case on wheels. I put a small combo in it and used that combo as a extension speaker (heat is a prob with cranked Marshalls :twisted: ). I did have to cut a 1" hole for the cables.

Then I threw a cuppla leathers and quilts on top - it was cheap and easy and pretty functional.

Hanging a dynamic on the combo inside like you would on stage resulted in all speaker, no "room" or boxiness.

Now that I have a house, I just wait for times when the family is out ...

Sometimes. :lol:
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Post by BassGuy87 » Tue Nov 08, 2011 2:05 pm

My guitarist is looking at this sort of thing. Thanks for the pictures, that's a big help. The only problem is, we hate building stuff that doesn't make noise. On that note, as you all know, buying anything like this is penultimate to selling your soul to the devil. We actually considered buying a sauna box to do both things. Believe or not, that's cheaper than a lot of iso boxes, at least for vocals and speakers.
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