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So, I left my tube amp on accidentally for about 24hrs (in standby mode). When I went back upstairs to play, I noticed I had done this and now the amp is acting very strange. There is static noise even when the guitar cable is disconnected and the volume fades in and out… The tubes seemed pretty hot… Have you ever experienced this? I turned it off this morning and hoping it acts normal when I use it again. But, I guess I will probably have to take it in for repair…
Alan
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Hi Alan
Very common occurrence among peers of tube amps. If the owner of a tube amp hasn’t left their amp on overnight, they’ve not owned their amp very long or they are OCD!! LOL
In standby mode, voltage is supplied only to the part of the tube that is known as the heater, and that is usually +6.3 volts DC. Typically damage doesn’t occur to the tubes in your amp when it’s in standby but the volume fading in and out is a classic description of a bad tube – a preamp tube would be my first guess as being the culprit.
If that happens to be the case, preamp tubes are much cheaper than power tubes so…..You didn’t mention what amp that you own so depending on brand & model, you could have 1-5 preamp tubes. If it is a bad pre tube, I would suggest replacing all of them as a precaution
Let us know how the repair goes
Keith
aka GnLguy-
Hi Keith,
It is a Fender Deluxe Reverb 68 Reissue. I turned it back on this morning after being off for about 24hrs and the volume is still way lower that normal. However, it was quieter as far as static noise. I bet one or more of the tubes has failed. I played this morning for about an hour and the lower volume doesn’t bother me too much (just turned up the volume). I guess I will start looking at buying new tubes… I replaced the pre amp tubes in one of my previous amps (Fender Blues Deluxe) and wasn’t too hard.
Alan
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Hi Keith,
It is a Fender Deluxe Reverb 68 Reissue. I turned it back on this morning after being off for about 24hrs and the volume is still way lower that normal. However, it was quieter as far as static noise. I bet one or more of the tubes has failed. I played this morning for about an hour and the lower volume doesn’t bother me too much (just turned up the volume). I guess I will start looking at buying new tubes… I replaced the pre amp tubes in one of my previous amps (Fender Blues Deluxe) and wasn’t too hard.
Yeah the pre tubes are straight forward, pins are keyed so dummies like me won’t install them incorrectly…plus they don’t need to be biased like a power tube.
A trick that SRV and others would do is to use a 5751 tube in the first position instead of a 12ax7; the 5751 has about 30% less gain than a 12ax7 and that provided more clean headroomKeith
aka GnLguy -
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Welcome to the club. Been there done that. Well worth the tube issues. Nothing like a ’68 DRRI. Enjoy.
JH
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