Cabinet Design Question

[GregS]

I built a 2 x 12 cabinet where the width and height dimensions were exactly the same (i.e. baffle board perfectly square). The speakers were mounted in a diagonal arrangement. I later read that you should avoid having 2 dimensions exactly the same as it can promote strong standing waves that can make the cabinet resonate and sound boomy. The cabinet I built does not have this problem. Maybe because of the diagonal arrangement in which each speaker is not symmetrically located inside the cabinet this doesn't happen? Could it be the space the cones occupy don't allow standing waves to be set up between the walls? Or did I just get lucky with the particualr speakers I used?

I'd like to do the same design but with different speakers now and am wondering if there's any possibility I might get this unwanted resonance with the different speakers. I could make one dimension slightly larger but my present dimensions are ideal for minimizing wood wastage.

I have not been able to find any more information anywhere on this "2 dimensions the same" resonance problem so if anyone here could shed some light on this issue it would be much appreciated.

Thanks,

Greg

[Steve Conner]

A Marshall 4x12 has two dimensions exactly the same. You don't hear people going on about how crap they sound.

Laney also used to make a square 2x12 with diagonal speakers, just like you described.

If a cabinet has bad standing waves, it'll have them no matter what speakers are in it. It's not like only certain brands of speakers excite them.

There really isn't a great deal of science in guitar speaker cabinet design. It's more like cooking.

[mooreamps]

There really isn't a great deal of science in guitar speaker cabinet design. It's more like cooking.

Steve makes an interesting point.. I built a prototype 2x12 awhile back with length and width the same for a square footprint on stage, and it don't sound half bad.. For a guitar speaker, maybe those "HiFi Speaker rules-ole-thumb" maybe just don't matter that much...

-g

[GregS]

Thanks for the replies. The square cabinet I already built is fine also. I just wanted to be sure that wouldn't change with different speakers.

Greg

[mooreamps]

Just use really good guitar speakers. Use the one's you know and trust...

[Chuck H]

My educated guess is that any low frequency resonance due to symmetry in cab of that size is below the range of your average guitar and amp. As Gary mentioned, this may be more of a hi fi (sound reproduction) rule. Lots of square guitar cabs around. My amps are built just like yours. 2x12's diagonal in a square cabinet with a head to match the width. Like a baby half stack. Looks great, sounds great.

[Steve Conner]

I think it's the opposite, the standing wave resonances in a guitar cabinet are in the lower midrange, and people probably feel that they enhance the sound. A bit of midrange honk can help the guitar cut through the band and project better. I've tried stuffing guitar cabinets with acoustic wadding before, and you can try that too if you feel that your cabinet design might be suffering from standing waves. But every time I tried it, it sounded worse than an empty cabinet with bare wooden walls.

Again, in hi-fi design you have the ideal of a flat frequency response to aim for, but in homebuilt amps, you just need to make a sound that pleases you, the measured performance means nothing. A guitar cabinet is not a hi-fi speaker, it's part of your instrument, a resonator in its own right, like the body of an acoustic guitar or double bass or whatever. The peaks and dips in the cabinet's frequency response are part of the instrument's character.

[GregS]

Good to hear. I'll stick with the square design. It's also a very convenient size for loading into a car.

Greg

[mooreamps]

I'm going to do a 4x15 come next summer... I'm considering my current 2x12 prototype downrev by now, and I want to try something new. It will also give me a project for doing the dovetail joints on the cab. Besides, I have to pull one of the 12's from my cab for my new 9 watt SE / 36 watt P/P Jazz Master Combo build... ;]

-g

[cminor9]

I built a square cab, 24" x 24" x 12". I agonized (in hindsight, unnecessarily) over the cab dimensions and chose the square with speakers offset rather than a low, squat cab because it would simply lift one of the speakers off the ground a bit more. And I didn't want to put rubber bumpers on the bottom and on the end so that I could sit it on its end because I think that would look cheesy.

I put two 12" Warehouse speakers in it, a Reaper (like a greenback) and a Veteran 30 (like a Vintage 30). I think it sounds great! I have not noticed any boominess to it, but I think that might have a lot to do with speaker selection, too. The speakers are fantastic.

I finger jointed and doweled the box, and put some 1.5" strips on the front side to mount the baffle.

2x12 black tolex | Flickr - Photo Sharing!
2x12 black tolex | Flickr - Photo Sharing!

I agree with other posters here. Building a box is like cooking. Use good ingredients, take the time to do it right, and go for it. If it sounds good it is good. Build that sucker!