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Post by bhayn007 on Jun 7, 2014 12:28:20 GMT -7
Gigged with my Z-wreck last night. Was going great right up until last song. Someone accidentally unplugged our entire set-up (PA, amps, etc..). At the time I didn't turn the amp off (hope this wasn't a bad idea). When we plugged the extension cord back in the amp turned on, but for the last song could not get the amp back up to performing volume (1 o'clock - no attenuator). Didn't check the amp until right now and the volume drop is still really low. I'm not noticing any weird tube noise and they seem to be firing normal (from what I can tell - I'm no expert). Any ideas for what I should try first?? I'm REALLY hoping this isn't anything major as my backup amp is also having issues and I have 2 other gigs this week. Any help would be greatly appreciated. Thanks Ben
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Post by DRZ on Jun 7, 2014 13:48:07 GMT -7
From that brief description my best guess would be a bad pre-amp tube. Get a known good 12AX7 and one at a time sub it into position 1,2,and 3. See what that does. If there is no other weird noises I wouldn't suspect an output tube or a rectifier.
Z
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Post by bhayn007 on Jun 7, 2014 17:10:37 GMT -7
Thanks for the quick reply Doc!
I fired it up twice since this morning and each time the volume has been normal. I haven't tried swapping the pre-amp tubes yet, but I will pick some spares up in case it continues to act up. I hope it was something as simple as bad power from the gig. We did have a very overloaded power strip running most of the equipment. Maybe when it got unplugged the amp just didn't have time to warm-up properly before playing our last song??
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Post by digs57 on Jun 8, 2014 7:00:59 GMT -7
Good move... back up tubes are essential.
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Post by zigzagman on Jul 2, 2014 7:55:04 GMT -7
similar occurrence happened to me, but without the power failure. Sudden loss of volume. I unplugged from the amp and went from pedal board to PA direct to finish the set, then ended up changing out one bad pre amp tube during the break and all was good...(I borrowed a spare tube that our B3 player had packed away with his repair & tube kit inside his organ cabinet)... but since then pack a spare set in my gear bag...so far so good and that one replaced tube is still the only one that I've changed.
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Post by telejas on Jul 2, 2014 9:59:33 GMT -7
similar occurrence happened to me, but without the power failure. Sudden loss of volume. I unplugged from the amp and went from pedal board to PA direct to finish the set, then ended up changing out one bad pre amp tube during the break and all was good...(I borrowed a spare tube that our B3 player had packed away with his repair & tube kit inside his organ cabinet)... but since then pack a spare set in my gear bag...so far so good and that one replaced tube is still the only one that I've changed. I ALWAYS carry spare tubes with me! It doesn't matter how great an amp is built, you're still relying on tubes and tubes are unstable. Unfortunately, this sometimes reflects back on the amp maker when it's actually just a $25 tube that failed, and there's no way to predict this. It's surprising how many tube amp owners know so little about tubes (not referring to you "zigzagman"). I have a buddy retubing his 65 RI Twin this week and has no idea where to start, or even what tubes are in it (6L6), and nobody reads a manual unless they have a problem.
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