seems like these 2 positions crap out rather frequently. my amp started to fizzle and pop and hiss. then it'll calm down a little, then surge back. i just did the little tap-test and i can hear the clink. but i don't use my amp all that often and i just changed these 2 tubes a few months ago.
what gives?
Last edited by sethp at Apr 4, 2008,
well, preamp tubes will make noise when tapped, especially the input tube. It's the power tubes that aren't supposed to make any noise when tapped. However, your symptoms do sound like a bad preamp tube. They should last at least a year or two before you notice anything audible, depending on use. Normally they are changed every other time from the power tubes. A tube can go bad anytime though, it's an old technology, they can last 5 minutes or 5 years. If you have more than one channel, is it happening on all channels?
"The fool doth think he is wise, but the wiseman knows himself to be a fool." - W.S.
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I can tell you when i got my amp a few of the preamp tubes were out that coincided with the series and parallel effects loop. I replaced them and my amp and effects were louder.

I have no idea....i dont think i helped at all.