Guitar Amp Isolation Cabinets

[obutcher]

I'm just doing some research on how to build a decent guitar cab enclosure to be used in the studio. You know the kind, you put the cab/amp in the box with a mic on it, close the door and hopefully no sound comes out!

Has anyone had any experience building these? I've been looking around on the net and it seems that people have a few issues with getting cables in/out without wrecking the isolation and that unless you've got a metal box built like a safe (or an old safe!) you'll still get a lot of low end out of it.

Any tips would be appreciated! I'm literally starting from scratch here and still don't know how much one would cost to build as the materials seems to vary wildly in price.

[waitup]

You just need to approach it the same way you would isolate a room. The shell of the box must be very heavy and dense to be effective. I would probably build up some frames of 90x45mm pine or similar, like the way that you would frame a wall, then insulate and finish with 18mm MDF... Maybe a couple of layers if you can. As with all things isolation, you need to make it airtight, including the door/hatch.

Where the cabling penetrates the box you're probably best building a secondary small box around the penetration point (baffle) and pack that with insulation.

Ultimately what will will really screw you is the sound inside. No matter what, a box of that size is going to resonate like a bastard at frequencies well within the guitars range. Will probably sound pretty boxy... Excuse the pun.

[Wiz]

its a good point, the resultant sound.


Cause, if you think about it, you are building an isolation box, because for whatever reason (bleed, neighbours, ears) its too loud to record without the box.

So, you are eschewing DI , speaker simlators, etc, because of the tone, fair enough.

But, you are now, dependant on the box, and the tone you end up with, which in reality, is a really large crap shoot.

If this is for one amp, for say yourself, perhaps its good, and you will end up with the tone you want, at a outside the box volume thats appropriate.

But, if its for every guitar player who comes through your studio, I would reconsider.

I actually have very small tube amps for recording, and my AC30 rarely gets turned on these days...


just a thought.


I do remember a few years back there was a commercial version of a speaker in a cabinet, it was reviewed by sound on sound.

I also remember playing on a session, somewhere in the south east of melbourne, where the studio had a drawer that slid out, and you laid you amp in , on its back, it would take a quad box, and then they slid the drawer shut.

I thought it sounded like shit, and bled out anyways, would have been better off just operating differently in that situation. (my point being, that as a guitar player, there is a reason for me to stand near my amp, if I am going to be doing controlled feedback, or need to adjust the amp during the song. As soon as its in a box, or another room, I am diconnected )

There were other rooms the cabinets could have gone in anyways.



let us know how it works out.

[obutcher]

Well, the ideal situation would be to have the amp in the box, nice and isolated, so the guitarist can be in the same room as the drummer and play along live (monitoring via HP's of course). We've got the space for the boxes, but it's in one end of the live room where the drums would be located. Right now I'm just scoping out whether it's possible for this to happen to a high enough standard that we can still get good good guitar tones as well as the isolation required for drum recording.

I've seen quite a few around the internet with either MDF or plywood around the outside, with one or two more MDF/Plywood layers on the inside separated by either a heavy rubber or floor spacing material and tons of foam inside. Seems like a simple option, but I'm not convinced by a lot of their joints and seals.

Like I said, I'm starting pretty fresh with this, so keep the thoughts coming!

[Text_Edifice]

Personally, I'd use baffles, keep the guitar amp at a reasonable volume and deal with the bleed.

If isolation is absolutely critical I think you need another room for the cabinet, or DI the guitar and reamp it later.

I don't like isolation boxes and (for the reasons already stated) I'm not convinced they're a good idea.

[waitup]

Is there enough room there to just build a booth? Not much more effort and probably more useful.

[seancook]

Hey
Manyof the pitfalls of this have been discussed, I have used one of Naut from nautcases'
Isocabs which is just a speaker in a box with two mic cables going in to little stands. Anyway, I used one of them live tracking in the se rooms as drums. It sounds fine, not great, but more than good enough for vibe and sometimes I keep it.

[jkhuri44]

you could line the box with carefully cut butyl/tar compound roof underlayment, which is a cheaper version of the automotive sound deadener "dynamat".

As for box joins, i would suggest butt joins, with battens on all edges or hardwood, and if you feel like overkill, perhaps some bracing, which could actually be necessary to prevent the box from rattling.

You could go even further with overkill, and use green glue.

I would drill a hole just big enough to pass an xlr cable, then solder a connector to permanently be inside the box, pull the cable until the connector is right up against the MDF/wood, and then seal around it with silicone or what not. Yes you can cover the ugliness later on, but the point of that is to make as little air escape from the box as possible.

where the box top meets the sides, i would possibly line the junction with rubber.

The isobooth concept has always been slightly confused to me....you're putting a speaker cabinet which is designed to project LOTS of sound, and then putting it in a box which when designed properly is designed to kill sound....hrmmm. yes i know its reflections and such that are being killed, but anyway.

[Text_Edifice]

Just a thought – but I've mic'd the speaker on a rola 77 before and got a stupidly large sound, same goes for lots of small tube combos. Depends on the style of music and players but if space is at such a premium that you need a iso-box I wonder if a very small speaker and amp built into the box might give a better solution?

[waitup]

Similarly I've done some great guitars through one of those tiny toy marshalls. Wouldn't take much to isolate one of those!

[wez]

I did a punk EP with numerous big amps available... various Marshalls, Vox AC30 etc... and the sound we kept coming back to was a close mic'd pignose. It sounded huge, the client loved it.

[The Tasmanian]

Ive built a few - they work well.
A tip before working out the size of the cabinet is to make sure that your amp/speaker box can sit at a 45 deg angle inside the iso cab.
This way you dont get the paralell sound issues, and the 45 deg angle allows the mic stand feet (and boom) to fit in the box easier.

[Drumstruck]

A cheap and easy option for small amps is to use an old refridgerator or freezer .... nowhere near perfect, but provides significant reduction with almost nil effort ;-)

[obutcher]

Loving the feedback guys, thanks for the replies.

Certainly a lot for me to think about! If we do go ahead with building them, I'll let you know what we did.