#1
I gots a question about my 6260-212. I just got a replacement for my old Bugera that died, and they said it was one of the new ones with the fixed transformer clips or something like that. (dunno if that’s relevant to my question) But the amp is sounding great, but whenever I turn the volume right down on the guitar, about 3-7 seconds later the amp starts to crackle like I’m messing around with the patch chord and it hisses. But it still sounds good when I turn the volume back up (the crackling isn’t noticeable) It just isn’t very nice when I turn the volume back down. But when I just tap the top of the amp a bit, it goes away along with the hiss, and it gets quiet again. But after I turn it up and play then turn the volume down it does it again. The tubes look fine but I’m no expert. Is there any way to tell if I have a bad tube (power and Preamp Tubes) How could I check that there installed properly? Also, I think I heard that Bugeras aren’t biast right from the factory, so do I need to bias it? Thanks in advance!!!
Gear:

Line 6 Variax 300 (electric)
Jay Turser acoustic
A soon to be Jackson Demmelition King V

Bugera 6260-212
Vox AD30VT (for sale)
#2
sounds like a tube going microphonic. Take a pencil with an eraser, and with the amp on and no guitar plugged in, tap very lightly on the preamp tubes with the eraser end. If the amp starts crackling and making the hiss, you've found your bad tube. The power tubes should be all quiet when tapped, but the preamp tubes will make some noise when tapped, and it will get louder the closer you get to the input tube. You're looking for the crackling/hissing sound to start/change however, not just noise from tapping.
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