overheating?
alright, so i have this problem with my tubes in my marshall overheating after playing for periods of 20 minutes. They will get really hot and almost appear to be on fire, at the same time the sound will completly drown out, or decrease in volume. my next question is what should my head and cab be set at ohm wise and stero/mono wise, assuming that i have a marshall 1960 cab and a marshall jcm 2000. like right now i have one cable going from the heads 16 ohm jack into the cabs mono/16 ohm jack, and the head is selected to 8 ohms.. my final question is, am i supposed to run two cables from head to cab and if so what is the settings on head and cab supposed to be... thanks guys for the help!
# 1
[font=trebuchet ms]I'm not familiar with Marshalls so you may want another opinion on this.
With your cab set up as a 16 Ohm load, I think your amp output should also be set at 16 Ohms.
But even that kind of mismatch would be unlikely to cause overheating as severe as you describe. It sounds to me like there is a problem with the bias circuit for the power tubes. With not enough negative voltage applied to the grids, (like if the bias supply cap starts to short out), the tubes will flow far too much current and overheat. This is a job for a competent tech to handle.[/font]
With your cab set up as a 16 Ohm load, I think your amp output should also be set at 16 Ohms.
But even that kind of mismatch would be unlikely to cause overheating as severe as you describe. It sounds to me like there is a problem with the bias circuit for the power tubes. With not enough negative voltage applied to the grids, (like if the bias supply cap starts to short out), the tubes will flow far too much current and overheat. This is a job for a competent tech to handle.[/font]
# 2