avoelp
Member
I have a Mark IV (B) that I have used regularly and that has never failed on me. Lately, I haven't used the amp for 1 1/2 years or so. After taking it out of the flight case, switching the power on, letting it warm up for about half a minute, and then switching it from standby to on, the amp makes a crackling noise and the guitar sound is thin, scratchy, and low-volume. When the amp has warmed up for another 2-3 minutes, the noise is gone, the tone is perfect, and everything is fine again.
This happens every time when I turn on the (cold) amp. None of the controls on the front panel (including the output volume pot) has any effect on the crackle, and it also does not matter whether I play in tweed or full mode, Class A or Simul Class, or in triode or pentode mode. I have removed all the tubes and cleaned the contacts, and I have also swapped the inner and outer power tubes; none of this had any effect.
Any suggestions what the cause and the cure might be?
Best, Andreas
This happens every time when I turn on the (cold) amp. None of the controls on the front panel (including the output volume pot) has any effect on the crackle, and it also does not matter whether I play in tweed or full mode, Class A or Simul Class, or in triode or pentode mode. I have removed all the tubes and cleaned the contacts, and I have also swapped the inner and outer power tubes; none of this had any effect.
Any suggestions what the cause and the cure might be?
Best, Andreas