I've just replaced the trio of 12AT7/ECC81 tubes on my ST70 driver board because one failed. The replacements work fine and everything sounds lovely again but........................
..................When I swich the amp on all 3 12AT7/ECC81s glow very brightly, like a light bulb instead of a valve, for a second or so then settle down to the normal amber glow I'm used to. I don't remember that happening with the valves I've had to replace. Maybe that's why I had to replace them in the first place.
So I'm currently scared of using my system at all in case I blow up another £30 quids worth of new valves. Can anyone tell me if I have a fault in the amp upstream of the tubes and, if so, wot it is and how to fix it.
p.s. cracking forum. I'd be stuck without it!