Chris Bryant wrote:
OK- sorry to wander a bit, but I have a tube preamp, '60's vintage, that hasn't been powered up in around 4 years, and at that time I know some of the capacitors were going- crackle while warming up.
My question- should I just power it up, borrow/find a variac to bring it up slowly (something I had heard about), or something else?
Typically, capacitors in solid state audio gear had a life expectancy of 30 years. Many have exceeded that rating and are still functional. Capacitors in tube gear are a different story. You may find different construction of the caps (electrolyte, barrier materials like bees wax, etc). The tube gear caps are also used at higher voltages than typical solid state gear.
Most tube gear has a value that supports the practice of replacing capacitors as a preventative measure. If the preamp is of unknown quality and you wish to make a practice run with it, a "
dim bulb tester" will let you bring up current slowly to recharge older caps. When verified the capacitors and tubes are functional, start with your audio testing. Just know that you are living on borrowed time with the caps and some make a terrible mess if they let loose.
