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Help clean up RI fender Super Reverb
Happy New Years guys. The shop owner recently sold a used but very clean lightly used Reissue Super Reverb to a studio. He brought it back and sure enough when played loud (6 ish) on channel 2 with reverb up, it had a selective crackle on some notes ( must be a clinical name for this) BUT only with reverb knob up. So I disconnected both tank jacks and still made the noise only when reverb turned up... So the distortion is somehow coming from the reverb recovery cable/stage with no signal...only gain. Just tried some tubes thursday. I will open it up tomorrow. Not sure what's up...would appreciate any suggestions. And then when it's fixed, how do I make it sound like SRV's amp? I have till Wednesday. Thanks.
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A word of caution.
These amps have the infamous Fender volume controls where the amp starts to clip with the controls at about 3-4.
So first off, make sure that you are not overdriving the amp. -
Am driving the amp hard, but the distortion stops when turning down reverb gain pot - everything else untouched. So the selective distortion is being introduced by the reverb gain stage- evn with no reverb wet signal...Comment
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Ball up your fist and whack the top of the amp. Does that make it crackle? If so, you have a loose connection.Education is what you're left with after you have forgotten what you have learned.Comment
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There was no apparent intermittent or bad connection...probed and prodded everywhere with no input and everything dimed. V4 was more microphonic than expected as were the tank jack leads to the board. So Here is what I called the solution... I put a 12AU7 in v4 as well as a 12AT7 in v2. The amp and reverb was plenty loud still with seemingly more headroom...whatever that means...but the distortion was gone and the owner was 8 pleased on a scale of 1 to 10. I kept the original tubes in a swap and the shop owner didn't have to issue a refund. Root cause of the distortion is lost for the ages...for now. Thanks.Comment
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Did you check that the plate load resistors dissipation was ok? They may draw more current than a 12AX7, especially the 12AU7.Originally posted by fredcapo View Post
0.5W is only 223V across 100k.My band:- http://www.youtube.com/user/RedwingBandComment
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Thanks for the comment re plate resistance. I did not give that consideration. What would be the permanent fix for leaving the 12au7 or possibly a 12at7 in that v4 position. Increasing the resistance value, wattage or both?Comment
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