I bought this amp a few years ago it is Jim Price's (Omega Amps) take on the #40. He built it on a Tweed Bassman narrow panel chassis. The original 4x10 cab had been cut down to a head size, but was pretty gnarly looking. After finishing up the cab for my Express I'm on a roll.
The problem was how to mount the narrow style chassis in a classic D cab? Here's what I came up with in Baltic Birch.
Pretty Slick!! ..You probably already know this but thought I would mention anyway!! Since a large surface of the output tubes (especially KT66's)are above and fairly close to the top of the head cab I would cut my tolex directly after the chassis ends and find a metal flashing to help dissipate the heat there..This will help keep the wood from burning and perhaps help keep the tolex on the top from distorting..The top of the cab will still get hot without fan.. hint!! Good luck!!
Tony
" The psychics on my bench is the same as Dumble'"
Thanks Tony - I'm thinking fan myself, but barring that I'll glue aluminum flashing to the top for shielding and heat dissipation. I also have a piece of heat proof glass I'm going to mount over the KT66's. Unless I can get some 2000 degree header tape from a local race car builder. That would be the shit right there.
Structo - I did a rabbeted tongue and dado then I glued and nailed them. It is quite strong and went together square. I made a jig for the front cut away and routed it.
Mike9 -- definitely go for the aluminum shield above the power tubes -- maybe even use Marshall-style vent material and rout a couple holes above them. I'd go something like the old Scott amps where you have a curved shield at the edges but the shield isn't anchored to the wood. Staple down some really thin roof flashing and then use a bit stouter shield piece kind of like "Z" flashing so it is snug under the chassis but makes two 90 degree bends so it doesn't touch (or rattle against) the anchored flashing. It doesn't have to be much wider than the tubes.
If I get motivated I'll tolex this one today. Tom, you can barely see the routs. I used a lock mitre bit which is a big, scary unit that ought to be on a shaper. I've got the router table set up to use the table saw fence. You run one edge flat on the table and the mating piece on edge (remember which is which and mark them). I made a jig to hold the latter firmly. When I first got this thing I was worried that the tear-out in plywood would be a mess but it plows right through cleanly as long as the butcher board isn't too ratty. A shallow and a full pass is all it takes. I used gorilla glue. Once these things are in the clamps, it squares up almost perfectly. The speaker cab in this set didn't need any cross clamps to square the dimensions.
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Thanks for the info.
Looks like a strong joint.
I'd be interested in mocking up a corner joint or even another box
and do a torture test to see just how much abuse those joints can
actually take.
So this is a special saw blade that makes that cut?
I know what Dado blades are is it similar to that?
Very nice. I've been pondering about how I could make a head cab for a plexi build I did a few years ago. I used the same type chassis that I got from Weber. I was concerned about the heat. I think I will vent the top.
It is a lock miter router bit. It has to be set-up for both height and fence depth so the horizontal piece is the mirror opposite of the vertical piece.
I mean - if you think about it you could put a silicone hot pad on top of - or under - the flashing to stop heat transfer. Either way it's nice to see others trying to make something out of narrow panel chassis lately.
Now if I could just get a template made from an empty Tweed Bassman reissue face. Beuller . . . Beuller . . . anyone???
Plan B - is to fabricate angled brackets so tube sockets are fitted to an aluminum angle attached to the chassis. Tube sockets would be attached to that to hang 90% down wired to a tube base plugged into the original socket on the chassis. That would: A - look cool as shit and B solve the heat problem. I'd just leave the preamp tubes where they are as they produce that much heat. Might as well put external bias test points and pot on the outside as well.
Nice cab. I use a lock miter all the time to build drawers.Provides alot of glue area.Makes a very strong joint.they can be a little fussy to get setup just right.
I have some boards of different thicknesses with the lock miter joint already cut.Then all i have to do is adjust the fece and bit hieght to the appropiate board.
..You probably already know this but thought I would mention anyway!! Since a large surface of the output tubes (especially KT66's)are above and fairly close to the top of the head cab I would cut my tolex directly after the chassis ends and find a metal flashing to help dissipate the heat there..This will help keep the wood from burning and perhaps help keep the tolex on the top from distorting..The top of the cab will still get hot without fan.. hint!! Good luck!!
