First time cab build - looking to build a 1x15 / 1x10 cab for bass

[MikeH]

So, I've built a head cab for an amp chassis, which I did using dovetails. And I have a circle jig for my router which I have used to make a replacement baffle for a combo amp. But I've never made a cab from scratch. I have one 15" and one 10" bass speaker kicking around my workshop just getting in the way, so I figured I'd build a cab for them.

Here is my question(s) - No idea where to look for dimensions on such a cab. Especially the depth. If I lay it out carefully, I could fit both speakers on a 25" x 25" baffle. Could maybe cut it down to 2' by 2' depending on what sort of joints I go with.

Which brings me to the next question- I was thinking of just going with basic rabbet joints. I can do them well, they are simple and strong. I'd probably mess up any sort of tongue and groove attempt - any other suggestions? I guess the type of joint will also depend on the material I go with.

Which brings me to my third question - Material choice? I know MDF will make a decent sounding bass cab; I'm concerned with router blowout using MDF though.

Any and all suggestions appreciated! Thanks!

Mike

[J M Fahey]

Routers love MDF, so that's not the problem, but I'd build an internal division and acoustically separate the 10" from the 15".
I would even go as far as tuning the larger section to the 15" and leaving the 10" in a closed (non vented) baffle.
As of measures, copy some commercial working cabinet.

[Mike Burgundy]

It all depends on what you have, and what you want. Which speakers *exactly*? If you want to have a good chance of ending up with a good sounding cabinet that won't kill the speakers, you'll at least need the Thiele/Small parameters for the speakers, learn a bit about loudspeaker cab design (it's fun, really) and do the math, or get someone to do it for you. If you "tune" the box wrong, you can get anything from lack of power and bass (too small a cab) to muddy, woofy sound to speakers killing themselves with excessive and uncontrolled cone excursion. Slapping a 15" into a cab that wasn't designed for it is a crapshoot, basically. There's a lot of difference between different speakers (although not as much that you wont be near the ballpark if you copy an existing cab exactly). Some speakers are suited for use in a vented cab, some are suited for use in a non-vented cab. Switching these doesn't work well and may damage the drivers. As JM said, it's not a good idea to mix them both (edit: the 10 and the 15) in the same cab, if you want to be sure to get a good sound out of it.
But it's not too hard, really.
Vance Dickason's Loudspeaker Design Cookbook is brilliant.
With that book I've designed and built Eminence Kappa based 1x15" and 4x10" cabs which I'm very, very pleased with. They're bigger than the industry standard, but weigh a lot less and go lower.
MDF is the industries choice because it's cheap, and stiff and heavy which helps in keeping the cab from vibrating, sucking power and adding unwanted resonance. It doesn't help your back.
When youre building your own, you can employ techniques that would be impossible for (affordable) mass production.
I used birch ply, 12mm if memory serves, but internally braced all panels and put 3-dimensional bracing inside the cab so everything is connected to everything, basically. Yes, it's thin, but with that bracing knocking the side panels sounds dead, like it's 30mm MDF. This adds immensly to the stiffness of the cab, while it's still quite easy to lift the 4x10 onto the 1x15 and I'm a small guy.