Building a 2x12 Cab

[vonFrenchie]

Does anyone have any tips for building a cab? I was thinking of building it out of pine. The top bottom and sides would be each a solid piece (no plywood) with a box support in the center. How should I add the grille? Should it be sealed, vented or open backed?

[billydiego]

Hey Frenchie,
A 2 X 12 cab is a great project, I have begun to amass the components to build one myself. Pine is absolutely the way to go, it's alot lighter, and over time it will dry out and take on a tone all it's own. The best method, if you don't have access to pro-level woodworking gear would be to glue and screw with 1" square pieces on the inside of each corner, so you can bevel the corners. You're gonna have to use at least one pice of plywood for the front to mount the speakers into. The grill can then be installed on a false front. That's about the simplest way. Six of one, half a dozen of the other whether it's open backed or not, Fender Bassman cabs were closed, it depends on the sound you like. Measure twice, cut once!

[RandomHero]

A closed back cab will have a lot more "oomph" than an open-backed cab, but by the same token a closed back means that "oomph" is only going in one direction!

I'd play some open and closed combos to get a feel for what I mean.

[ChrisK]

Open back and closed back are the two fundamental types of guitar speaker enclosures.

The open, or ported enclosure (an open back is a port) comes in different versions such as the bass reflex (used in hi-fi systems for rock music), the semi open back a la Mesa, and the fully open back. All of these are tuned to a particular boost low frequency whether intended or not. This boost accentuates the low end (down to this frequency) and makes the speaker "bassier", a benefit to rock music.

At frequencies below the tuned one, the drivers tend to unload (since the air within has some effect as a suspension component above the tuned frequency, but little below such). This leads to speaker damage and why most bass cabinets are of closed back design.


The closed or acoustic suspension enclosure makes full use of the trapped air within as a suspension, or spring component of the system tuning. This support extends fully downward and results in a flatter frequency response, which is why acoustic suspension cabinets are of great interest to classical musical listeners.

While the analysis of such cabinet topologies is fairly complicated (math, Thiele/Small parameters, etc.), I would suggest designing your cabinet with provisions for different backs and maybe even for a front port tube (??).

I would first go read some speaker enclosure design books at your local library or Borders/Barnes&Noble (?same thing!). Or, like search the web.

[ux4484]

I'm in the process of making a cover for the rear bottom port on my 50's Allied 2x12 bottom. After I had the speakers redone, I had put black foam strip insulation along the rear panel to seal it, and once I can match the gray pleather texture of the cabinet, I'll be able to finish the cover, it has a recessed lip that seals against the inside of the current back while the rest will seal against the inset lip of the cabinet. I plan to have it attach with toolbox type latches so I have it on for bass and quickly pop it off for guitar.

If you really want to play with making enclosures, I'd hit the thrift stores and old style music stores in the area and look for blown amps and cabinets, it's much easier to experiment with stuff that's already made than to build from scratch, and once you find your happy place, you can build it from scratch and know you will already like it.

[vonFrenchie]

Thanks for the advice. I think I'm just going to a 3/4x3/4inch square in each corner. I'll put biscuit joints w/glue and screws or nails. Then the back would be screwed on so I can add or remove a back piece. The board holding the speakers would have a slight slant on it and then a false front would have a cloth grill. It would be 30x15.5x12 in.

I tend to play more of a metal style so I think I'll start with a closed back and change it from there.

[ChrisK]

I tend to play more of a metal style so I think I'll start with a closed back and change it from there

Wander thru Mesa's site. You'll see a lot of closed backs for metal.


Here's my arc welder.

[vonFrenchie]

Your arc welder? When I hear arc welder I think flux, Miller welders, welding sticks, etc but please explain.

I've been looking at the Mesa Boogie 3/4 Backs and Roadsters and taking their dimensions and adjusting them.

[ChrisK]

I tend to play more of a metal style so

An arc welder, you know, for working on metal...... ;D ;D

[vonFrenchie]

AAAAH. Now I get it. Thats a good one. Thats really clever. Your listeners must really get a shock from that amp.

[vonFrenchie]

Hey, I'm about 85% complete. I just need to paint the baffle board, mount and wire the speakers, wrap the cab in vinyl and mount the face. Ill send pictures of in progress and finished soon.