goldenGeek
Member
- Joined
- Feb 27, 2015
- Messages
- 16
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Hello
I am currently trying to figure out a Subway Blues thats humming too much. I have read some posts about the .01uf mod (replace with .68uf), but I think the problem with this amp is earlier in the path. I will replace the cap anyway, but heres the problem:
There is a loud static that gets louder with the volume knob. If I pull tube V1 the hum goes away so I think the problem must be in the first two gainstages - probably between input and before V1b. The volume pot is also scratchy. Theres also some trouble with te reverb but I'll fix that later since the noise goes away with reverb at 0. Does anybod have any clues what to check first? Replace the volume potmeter? Capacitors? Resistors? I have replaced the V1 tube with a couple of other known working ones but they were actually worse than the one originally present when I got it. I can of course replace the whole circuit up to V1b, but if anyone has any experience with this amp I'll be glad to hear from you Oh, by the way, this is probably a newer one, it doesnt have the "mojo module" installed, all the components are visible. Serial number in the 17xx-range if I recall.
I'm going to trade this amp for a MK3 black stripe thats absolutely amazing so I really need to get this amp in better shape ASAP 8)
I am currently trying to figure out a Subway Blues thats humming too much. I have read some posts about the .01uf mod (replace with .68uf), but I think the problem with this amp is earlier in the path. I will replace the cap anyway, but heres the problem:
There is a loud static that gets louder with the volume knob. If I pull tube V1 the hum goes away so I think the problem must be in the first two gainstages - probably between input and before V1b. The volume pot is also scratchy. Theres also some trouble with te reverb but I'll fix that later since the noise goes away with reverb at 0. Does anybod have any clues what to check first? Replace the volume potmeter? Capacitors? Resistors? I have replaced the V1 tube with a couple of other known working ones but they were actually worse than the one originally present when I got it. I can of course replace the whole circuit up to V1b, but if anyone has any experience with this amp I'll be glad to hear from you Oh, by the way, this is probably a newer one, it doesnt have the "mojo module" installed, all the components are visible. Serial number in the 17xx-range if I recall.
I'm going to trade this amp for a MK3 black stripe thats absolutely amazing so I really need to get this amp in better shape ASAP 8)