if i took the dimensions for a marshall 2x12 1936 and added 2 inches to the depth, would it totally screw up the acoustics?
1936-29.5" H X 23.5" W X 12.24" D
if i made it 29.5" H X 23.5 W X 14.24D would i mess it up?
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This may not be entirely helpful to you but it's the best advice I've got.

If you're really worried about it, you'll have to do some research and possibly by a book about the subject. There's a lot mroe that goes into speaker box construction than just marshall, mesa, or fender dimensions. The size and shape of the box has an effect on the sound output and you'll need to learn how to calculate that if it's that important to you. Generally, makeing the inside dimensions larger, will give you better low-end. Again, research, it's the best advice I've got.
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Probably not, why do you have to extend it by 2"?

And if you're worried, why not extend the other 2 dimensions by 2" also?
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Last edited by Stratoblaster73 at Aug 22, 2008,
^ that wouldn't compensate exactly for the added two inches in the back. Like MeanwiththeDean said, find a book with formulas or some calculation software. Your frequency response is affected by the interplay of your speakers, interior volume of the enclosure, and ports.

Will adding two inches change your acoustics? Yes. Would it be noticeable? I don't know.
I'm not sure if it would help at all, but might it help preserve the acoustics if you increased the length and width by the same percentage as the depth?

e.g. use a ratio formula to find the unknown amount of increase.

I don't know if that makes sense, but it was just a thought.
If you do change the depth a bit, it can alter the way it sounds. It'll give your speakers considerably more airspace, which is generally a good thing. It won't kill your acoustics, especially considering that it's a sealed box. For the most part, with sealed enclosures, you just need to come up with enough airspace for the given speakers, and stay away from square dimensions. By that, I mean that if you built this box as a 25" x 25" x 25" cube, you'd get all kinds of wave cancellations. The dimensions you're planning on should sound great if you build it sturdy with good materials, and make sure to seal it properly. It won't sound exactly like a 1936 (the difference might not be nearly enough to worry you), but if anything, it should sound better.