Bob Latino wrote:
I have a problem that I'm trying to diagnose -- I get a sort of oscillating ringing sound out of one tweeter.
I'm assuming it's a microphonic tube, but I'm not sure, and I'd really appreciate it if some folks here could chime in with their opinions on what it might be.
thanks in advance,
This IS probably, as you mentioned, a microphonic tube. It's more likely a driver tube than an output tube ..
Try swapping out a new tube one at a time in each driver position (in a tube amp)
Thanks. I was thinking it might be a preamp tube. I did the test of swapping the two outer tubes on the driver board, and the ringing didn't move. I just need to get a few new substitute tubes or just swap the two preamp tubes.
I was wondering also if it could be traced to the rectifier, either in the preamp or the amp.
And...sorry, I have to ask...if swapping the tubes doesn't do it, do you have any other ideas?
Oh...I have to add this...it only starts when both the preamp and amp have been on for a while.
Last edited by dougmon on Sat Jan 31, 2015 3:42 pm; edited 1 time in total (Reason for editing : clarification)