LocoPatrick
Member
- Joined
- Nov 5, 2024
- Messages
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Hello, Everyone,
I'm restoring a Mesa Boogie Mark IV Rev A, wired by Kaydee in June 1992. For the preamp tubes, there is one 12at7 tube, three 12ax7 preamp tubes, and one that is completely unmarked.
Questions:
1. Could someone please confirm that the unmarked tube should be a 12ax7?
2. Is 408105 the correct part number for replacement knobs with a set screw for the channel gains?
Just information here, if you are interested:
I got this amp from my uncle who didn't want it anymore. Way too loud for the place he is living, and he doesn't want to maintain it.
So far, I've cleaned all of the potentiometers--lots of contact cleaner. Seems to have worked well.
I'm replacing all of the electrolytic capacitors.
I'm replacing all of the tubes.
I've replaced the gain potentiometers for all three channels. The knobs and shafts were broken off. Since I couldn't find an adequate direct replacement with a pull-out switch, I went with Philco 500k audio taper potentiometers, and wired in separate small toggle switches to replace the push-pull capabilities.
I've played around with the amp a bit after cleaning all of the potentiometers, and it is growing on me. I'm starting to get it pretty well dialed in. When I start to turn up the volume past 3, it starts crackling pretty badly. It's most noticeable on Rhythm 1, but it seems to be happening on all three channels. I'm hoping the new tubes will fix that.
I'm restoring a Mesa Boogie Mark IV Rev A, wired by Kaydee in June 1992. For the preamp tubes, there is one 12at7 tube, three 12ax7 preamp tubes, and one that is completely unmarked.
Questions:
1. Could someone please confirm that the unmarked tube should be a 12ax7?
2. Is 408105 the correct part number for replacement knobs with a set screw for the channel gains?
Just information here, if you are interested:
I got this amp from my uncle who didn't want it anymore. Way too loud for the place he is living, and he doesn't want to maintain it.
So far, I've cleaned all of the potentiometers--lots of contact cleaner. Seems to have worked well.
I'm replacing all of the electrolytic capacitors.
I'm replacing all of the tubes.
I've replaced the gain potentiometers for all three channels. The knobs and shafts were broken off. Since I couldn't find an adequate direct replacement with a pull-out switch, I went with Philco 500k audio taper potentiometers, and wired in separate small toggle switches to replace the push-pull capabilities.
I've played around with the amp a bit after cleaning all of the potentiometers, and it is growing on me. I'm starting to get it pretty well dialed in. When I start to turn up the volume past 3, it starts crackling pretty badly. It's most noticeable on Rhythm 1, but it seems to be happening on all three channels. I'm hoping the new tubes will fix that.
