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This is my first post on this excellent electronics forum! Hi!
I got this Blackface bassman head for a good deal, but it has been severely modded. There may be some of you out there who are aware of certain techs who used to turn them into (I say "used to" hoping they're more sensitive to originality) multi-gain stage "Marshall-like" guitar heads.
Well, this one has had one of the tone controls replaced with a push-pull pot/switch which sounds like it is adding another gain stage. Further, the 2 second-channel jacks had one pot and another push-pull pot installed. They're another master volume circuit. Then the infinitely wise (foolish, actually) replaced the tubes with EL34s. So there's some wiring changes on the amp, to say the least.
Still, all the major components are original, and it still has the original faceplate and box. I've been scouring the 'net, found this forum, and joined it, and have been looking for a topic with instructions or at least diagrams and schematics of an original AB165 Bassman, so I can put this back to original with the assistance of my tech friend, who has over 50 years experience as a TV repairman, tube radio and amp repairman, etc. He asked me for the circuit diagram and I provided that. But I want to find good info on wiring the amp back to stock and what replacement components might be necessary. I have seen topics where they're rewiring it and they may be using parts of both the AA864 and the AB165 amp, the "best of both worlds".. I play the drums, and synth, but a family member plays guitar and I would like to show him an example of a properly-working Bassman and how it can sound good. As it is right now, the amp works, but it is noisy and is what I can only refer to as "sick"--but not in a good way..
Any info or comments are appreciated! Help me restore this into the tone machine it deserves to be! BTW Don't worry, not planning on selling it, but even if I was, I would fully disclose any and all work that has been done thus far and in the future.
I got this Blackface bassman head for a good deal, but it has been severely modded. There may be some of you out there who are aware of certain techs who used to turn them into (I say "used to" hoping they're more sensitive to originality) multi-gain stage "Marshall-like" guitar heads.
Well, this one has had one of the tone controls replaced with a push-pull pot/switch which sounds like it is adding another gain stage. Further, the 2 second-channel jacks had one pot and another push-pull pot installed. They're another master volume circuit. Then the infinitely wise (foolish, actually) replaced the tubes with EL34s. So there's some wiring changes on the amp, to say the least.
Still, all the major components are original, and it still has the original faceplate and box. I've been scouring the 'net, found this forum, and joined it, and have been looking for a topic with instructions or at least diagrams and schematics of an original AB165 Bassman, so I can put this back to original with the assistance of my tech friend, who has over 50 years experience as a TV repairman, tube radio and amp repairman, etc. He asked me for the circuit diagram and I provided that. But I want to find good info on wiring the amp back to stock and what replacement components might be necessary. I have seen topics where they're rewiring it and they may be using parts of both the AA864 and the AB165 amp, the "best of both worlds".. I play the drums, and synth, but a family member plays guitar and I would like to show him an example of a properly-working Bassman and how it can sound good. As it is right now, the amp works, but it is noisy and is what I can only refer to as "sick"--but not in a good way..
Any info or comments are appreciated! Help me restore this into the tone machine it deserves to be! BTW Don't worry, not planning on selling it, but even if I was, I would fully disclose any and all work that has been done thus far and in the future.
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