by WA4SWJ » Sat Mar 31, 2007 6:52 pm
Greg,
Does the pop come through the speakers or is it just the tubes making a noise? If it's just the tubes it's most likely thermal expansion as they warm up. That shouldn't be much of a problem. Most of my larger tubes pop and crack a bit, especially when I turn the amps off and the tubes are cooling down.
If it's though the speakers it could be a number of things, but I have had amps that pop occasionally (especially my 832A amp). When I look at them in the dark, I see some very small interelectrode discharges when the pops occur. Amazing but it's true. I've been very careful to put screen dampers in all of my amps to eliminate instability that can cause that, but it still seems to happen sometimes. Just some ideas. As I mentioned it could be other things like coupling caps or resistors (if the sound is coming through the speakers).
Regards,
Ed Long