axuality

Believe it or not, I have decided that for my style, my Marshall 4x12 sounds better without a back on it. It sounds more 'open'. I would however prefer to have at least SOME of the back still on it.

Does anybody have any ideas on how much of the back can be present (like 1/2 of it, or 3/4...) and it will still sound much more like NO back than a FULL back? And should the missing part of the back be at the top or the bottom?

Thanks for any help. I have no clue. Thanks.

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JohnH

I think youll have to experiment, but keep the old back intact and get some new plywood to do it with.

If you like the fully open sound, how about a strip top and bottom, wide enough to engage at least one screw hole at the sides and use the top one to mount the jack. A factor with that though is that the centre post is then loose, and so the front baffle will resonate more. Good or Bad? I don't know.

Most semi-open backed cabs seem to have about 25% open. Avatar show pictures of some 2x12s, with the open part centred, but I cant see a picture of a 4x12.

Id guess that putting about a 3/4 back, with 25% open all at the top would work quite well, to fill the soundspace above and around the cab, and it would still engage the centre post. I might suggest running a horizontal 19x42mm batten glued and screwed across the free edge to stiffen it.

If you try something, post how it works out
John

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MartyStrat54

Since guitar speakers have a high resonant frequency, you can get by with leaving more than half of the back on and the speakers will still act as if they are in an open back. I like JohnH's idea of a top and bottom strip, sort of like what is found on a combo amp. You could also take a piece of wood and cut it in a fashion where you still have say and eight-inch wide center strip. (Think of an H on its side.) That way you could still attach the center post.

As John said, post what you did.

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axuality

Thank you guys for your input. I was kind of wondering about the center post. And you're pretty sure the 1/2 open back will sound as 'open' as a fully open back? That's interesting. I hate doing this, but sound is #1.

In case you're interested, I use my guitar amps more as P.A. Let me show you how:
I'm a TOTAL improvisationist. I haven't played songs for many years.

On stage, I make up a rhythm part and it goes into my Pod, then into my loop station, then into my Marshalls. After however long I deem the part to be, I then hit the loop station and it immediately starts repeating through the guitar amp (they're usually undistorted rhythm parts and I want them to be amplified that way-clean). Then I immediately start improvising a (usually dirty) lead melody to go over the rhythm part that of course goes into the Pod, then the looper then into the guitar amp.

If you think about it then, I can't run my guitar amp on anything but clean. It must do nothing more than amplify my rhythm clean and amplify my lead dirty.

For some reason, it all sounds better with the backs off my Marshall cabs. It seems almost irreverant to remove the backs, but...

Here's a link to an improv song called 'Tough Luck'.(I added bass and drum machine) I have a number of styles, being an improv guy, but this one is kind of bluesy rock, I guess.

http://www.axuality.com/html/songs.html

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All ad-lib guitar, all the time, including onstage.
www.axuality.com