Selmer TnB 100 - Clipping/Overload/'Orrid Noise

[4 Strings]

Just bought a Selmer Treble n Bass 100 for the boy, desperate for a valve amp.

Works fine, sounds great, knobs quiet etc. But, if it's turned up beyond half way (which is pretty loud to be fair) there is a horrible clipping/overload sort of noise, a loud, high pitched crack sound which sounds quite destructive.

Any ideas? It's obviously 40 odd years old but has JJ EL34 output valves and electro-harmonix pre-amp valves and so these are not going to be too old. (There's another valve next to one of the transformers, can't see what that is, nor know what it does!).

Any ideas? A capacitor on the way out?

I noticed the plastic covers to the connections on the output side of the mains switch have become hot at some stage and are browned.

Apart from that it seems to be in good nick, with a Precision sounds really great!

[DGBass]

could be a multitude of different things on an amp of this age...from personal experience of using a similar style of amp( a late seventies marshall super bass 100 mkII), orrible loud cracking sounds were caused by arcing across the base of the output valve sockets and caused ultimately by poor biasing. Cap jobs are almost mandatory in an amp this age ( espesh on the power supply circuit ). It could also be a dry joint or faulty jack/pot etc. I'd recommend taking to a reputable amp tech who knows old valve amps. On another note, most old british design 100 watters do start to grind a bit once you get to four or five on the volume knob. They don't get any louder by that point, just filthier