Speaker cabinet question

[ciscokid]

Is there a formula for how much of an open backed amplifier's speaker cabinet should be closed? The cabinet in question is a V-front out of black walnut that will house two 12" speakers. It is still a WIP but, when finished, will be driven be a point to point hand wired 35 watt head that I built over the summer. Not too sure where to post this. :o My apologies if this is the wrong area. I also posted this in the musical instruments section, but you guys seem very knowledgable about cabinet theory. The cabinet is 32 inches wide by 22 inches tall and is 12.25 inches deep in the center and 10.25 deep at the edges.

Thank you!:)

[soundman]

Nope.

There is very little science involved in building most traditional gituar cabinets.

The forms of cabinet that persist in gituar amplification predate any serious research into speaker cabinet design and were originaly based on economy of construction.

What you are building sounds to be about the size of a fender twinn.
Check one of those out.

My observation is that most open backed cabs either have no back or less than half the back covered.

It is my opinion that the board that covers part of the back was originay places there to provide bracing and protection for the speakers and the exposed parts of the amp chasis, rather than to provide any meaning full acoustic effect.

I would build the cabinet allowing for a cleat to mount a full back and then trial a variety of different options.

(with spaced out voice)
Afterall gituar isn't about science.... its about your individual sound man.:cool:

cheers

[Petebass]

Nope.

There is very little science involved in building most traditional gituar cabinets.

The forms of cabinet that persist in gituar amplification predate any serious research into speaker cabinet design and were originaly based on economy of construction.

Agreed! Which explains why a large percentage of guitar and bass cabs contain 2 or 4 speakers mounted in the worst possible position for maximum comb filtering. Placing speakers horizontally was a basic mistake, one that unfortunately continues to define the norm today. Blame Leo Fender. He designed his cabs to "look" right, then Marshall became the first in a looong line of copy-cats that never stoped. Leo also invented some seriously good guitars and basses so he's almost forgiven for stuffing up decades of guitar and bass speaker cabs. :) He also pre-dated and significant scientific research on speaker cab design, so you can't really stay angry at him can you....

Similarly the open back came about because it just "felt right" as a way to make cabs that were easy and cheap to manufacture. By all means try different sized rear baffles, but I'm not sure you'll hear much difference. Even if the cab is only 1/4 open, that's still a large enough gap to disqualify it as acting as a port of any sort. As far as I'm concerned, the open back cab is little more than a speaker stand that doubles as a protective case.

[ciscokid]

Thanks for the replies. I just finished this V-front cab. Still have to get the backs done. It's black walnut so I hope it doesn't have to do too much 'protecting'.

[Petebass]

As far as I'm concerned, the open back cab is little more than a speaker stand that doubles as a incredibly beautiful piece of eye candy.

Is this version better? :)