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I started on this almost two years ago. As the story goes, a young man without a clue was trying to sell around town a badly abused 68 Bassman head, and a music store he tried to hawk it to gave him my number. He wanted $200 for it, but it was badly rusted, heavily and poorlly modded, and the head cab was chock full of carpenter ants. I told him I'd give him $100, and that was a risk, not knowing if the transformers were good or bad. He declined and left. About a week later, he changed his mind and I bought it for $100, although I immediately wished I had offered less.
Turns out all the trannies tested good, so I proceded to tear it down. I stripped the chassis and tranny covers to bare metal and painted. I cleaned as much rust as I dared from the laminates, and sealed with lacquer. I made new boards from grey fiber (which after time does have some conductiveness, but without any real symptoms), and used what blue mallory caps I could. I used F&T filter caps, Sprague cathode caps, Mallory 150 and silver mica tone caps, and 1 watt carbon film resistors on the board, and 2 watt metal film in the PS. I put in new sockets, jacks, pots and switches. Cleaned up the brass plate real good, put in mid controls at the back where two jacks had been added, installed a Hi/Lo power switch where the ground switch was located, and a push/pull on one of the volume controls as a channel jumper switch. I wired it as a AB165, but with AB763 style bias circuit, and the first channel having a 5F6-A tone stack, no deep switch, and bright switches on both sides.
It has a Fender branded Eminence 4 ohm 100 watt speaker, and GT branded Russian 5881WXT power tubes. This was my first tolex and grille cloth jobs as well.
I did not do the cabinetry, I supervised a friend. He used 3/4" finger jointed pine for the cabinet, and 5/8" cabinet grade baltic birch ply for the baffle.
In the end, I am quite pleased with it. This amp does not sound like any Fender I have ever played, it barks like a dog, very crunchy, but with nice articulation. It is a nice size and weight, and it's LOUD. Thanks fellows for the advice on the tweed tone stack (nice touch), and the channel jumpering. I got the switch idea from Rob Robinette's site.
Here are some photos of the process:
Turns out all the trannies tested good, so I proceded to tear it down. I stripped the chassis and tranny covers to bare metal and painted. I cleaned as much rust as I dared from the laminates, and sealed with lacquer. I made new boards from grey fiber (which after time does have some conductiveness, but without any real symptoms), and used what blue mallory caps I could. I used F&T filter caps, Sprague cathode caps, Mallory 150 and silver mica tone caps, and 1 watt carbon film resistors on the board, and 2 watt metal film in the PS. I put in new sockets, jacks, pots and switches. Cleaned up the brass plate real good, put in mid controls at the back where two jacks had been added, installed a Hi/Lo power switch where the ground switch was located, and a push/pull on one of the volume controls as a channel jumper switch. I wired it as a AB165, but with AB763 style bias circuit, and the first channel having a 5F6-A tone stack, no deep switch, and bright switches on both sides.
It has a Fender branded Eminence 4 ohm 100 watt speaker, and GT branded Russian 5881WXT power tubes. This was my first tolex and grille cloth jobs as well.
I did not do the cabinetry, I supervised a friend. He used 3/4" finger jointed pine for the cabinet, and 5/8" cabinet grade baltic birch ply for the baffle.
In the end, I am quite pleased with it. This amp does not sound like any Fender I have ever played, it barks like a dog, very crunchy, but with nice articulation. It is a nice size and weight, and it's LOUD. Thanks fellows for the advice on the tweed tone stack (nice touch), and the channel jumpering. I got the switch idea from Rob Robinette's site.
Here are some photos of the process:
Would love to hear it. It sounds like it would be simultaneously unique and familiar. A player that knows how to get the most out of an amp could really exploit it's character. I want to hear it. Hell of an effort and I'm sure well worth it. Nice job.
Start simple...then go deep!
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