jtm 612

[manolis]

hello everybody, I am new here
I bought a second hand jtm 612 wich I like very much. My only problem is that it hasn't enough bass in the clean channel
can you help me solve that?
thank you

[surfnorthwest]

Many things you can do to help with that. You could try other preamp tubes in V1 as some are more bassy then others. Also it could be the speakers you are using. Another thing would be to simply add a eq to get more bass.

[Spitfire]

I used to have one of them, years ago. It was one of the best sounding amplifiers but most unreliable. A common problem with these were coldjoints or dryjoints.
This happens when one of the legs on the valve bases start to overheat and melt the soldering off.
Copper expands and contracts under heat and a printed circuit board does not like that.
These were among the first PCB mounted valve amps that Marshall built and the output tubes are mounted horisontally on a thin little pc board. Have an amp tech resolder all the valve bases's contact points on there, revalve and rebias her.
Those Marshall Heritage 65's are awesome speakers btw.

[Vinny]

They OVERheat too much!
Try too fix that like spitfire says, otherwise it can cause much damage!