Fighting one or more issues with mine (2x12 combo).
1) At my last gig, the LSS began to jump up and down in volume, as well as sound awful, then it "corrected" itself.
At home, I noticed that random odd things were happening - jumping back and forth between channels, loud pops when switching between 5, 15 and 30 watts, etc. You could even see the channel leds flickering as it hopped back and forth.
All this "felt" like relay issues, and after looking at the Non special schematics, I am assuming there is a 12V regulator in the LSS, like the LS, which drives the relays, and also a couple of heaters on the front end 12AX7 tubes.
Started swapping out tubes, the problem "went away" even when I put back any suspect tubes. (grrr)..
2) Now a new variant (or new issue) of the problem: Squealing and fizzling noise in 5 watt mode.
So, I pulled all but the one power tube used for 5 Watt mode, and the problem goes away.
So, using that I ran each of my power tubes through that same tube socket and used 5 watt mode to check basic operation of all the power tubes I have. All seem to work ok.
Here's what's weird: when I put the other tube in (needed for 15 watt) but leave the amp set to 5 watt mode, it starts the squealing and fizzing again!
I tried a few different power tubes (both far left and far right tube sockets) and had the same result.
This is in 5 Watt mode where the other tube isn't supposed to be connected up! ??
Next steps:
I have two rectifier tubes - one was in the amp when I bought it used, and the other came as a spare. I've swapped those in and out, no effect.
It's possible both of the rectifiers are bad, so I'll probably order a NOS and see what happens next.
I'm also going to put my scope on the 12vdc output of the linear reg (assuming the LSS has one) and see if I can spot who is causing the troubles..
Love the sound, but not loving the issues. (I had to replace a smoked resistor once before..)
I've done work on tube amps before, and am an electronic engineer by day, so I'm too stubborn to pay some local tech to look at the amp for me..
Any thoughts out there?
1) At my last gig, the LSS began to jump up and down in volume, as well as sound awful, then it "corrected" itself.
At home, I noticed that random odd things were happening - jumping back and forth between channels, loud pops when switching between 5, 15 and 30 watts, etc. You could even see the channel leds flickering as it hopped back and forth.
All this "felt" like relay issues, and after looking at the Non special schematics, I am assuming there is a 12V regulator in the LSS, like the LS, which drives the relays, and also a couple of heaters on the front end 12AX7 tubes.
Started swapping out tubes, the problem "went away" even when I put back any suspect tubes. (grrr)..
2) Now a new variant (or new issue) of the problem: Squealing and fizzling noise in 5 watt mode.
So, I pulled all but the one power tube used for 5 Watt mode, and the problem goes away.
So, using that I ran each of my power tubes through that same tube socket and used 5 watt mode to check basic operation of all the power tubes I have. All seem to work ok.
Here's what's weird: when I put the other tube in (needed for 15 watt) but leave the amp set to 5 watt mode, it starts the squealing and fizzing again!
I tried a few different power tubes (both far left and far right tube sockets) and had the same result.
This is in 5 Watt mode where the other tube isn't supposed to be connected up! ??
Next steps:
I have two rectifier tubes - one was in the amp when I bought it used, and the other came as a spare. I've swapped those in and out, no effect.
It's possible both of the rectifiers are bad, so I'll probably order a NOS and see what happens next.
I'm also going to put my scope on the 12vdc output of the linear reg (assuming the LSS has one) and see if I can spot who is causing the troubles..
Love the sound, but not loving the issues. (I had to replace a smoked resistor once before..)
I've done work on tube amps before, and am an electronic engineer by day, so I'm too stubborn to pay some local tech to look at the amp for me..
Any thoughts out there?
