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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: (2) 12AX7 +(2) 12AU7 preamp making small scratching noises, then turn off, and OK for a time? posted by Nuit on August 2, 2014 at 08:22:10:
It may "sound" like the tube acting funny and deteriorating, but like it was said, check the physicals of the preamp.
If it's been a few years running, there are two things I would check: dust/dirt and oxidization. This could affect both the sockets AND the very pins of the tubes - clean both! Between the two possibilities, the symptoms you mentioned could crop up. A little contact cleaner and rubbing alcohol could easily fix these issues. Experts such as Jim McShane will attempt this FIRST before ANY other repair, even over changing a tube.
That said, I had a bad Sovtek LPS 12AX7 once that produced those same problems: sputtering, low volume (bad performance), etc. If it's been a while since you've changed tubes, it maaaayyy be time soon. But, it was a new production tube.
To further diagnose the issue, is it localized to one channel or is it occurring on both? Can you provide the exact model and perhaps a schematic for the preamp? Depending on how the stages are wired up, one problematic tube might contaminate both channels.
Good luck!
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May your tubes be lively, warm, and long-lasting. Holy be thy heater.
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Follow Ups
- RE: (2) 12AX7 +(2) 12AU7 preamp making small scratching noises, then turn off, and OK for a time? - TubeAcolyte 09:23:14 08/02/14 (1)
- RE: (2) 12AX7 +(2) 12AU7 preamp making small scratching noises, then turn off, and OK for a time? - Jim McShane 12:46:03 08/04/14 (0)
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