Hissing in left channel

[bskahj]

Hi
After months of perfect tunes from my Mainline, I am sorry to say that my left channel has started to make hissing sounds (light RF like).
It only appears after the unit has gotten properly warm (about 15min).
Then slowly gets louder and louder, until its seriously disturbing.

My resistance and volts checks out, when i swap the tubes, there is no difference, still left channel. It doesn't amplify when i turn up the volume.
It gets louder and louder, then it "pops" before starting its climb again.
what am i missing?

[Paul Birkeland]

I would reheat all the joints in the channel that's making the noise.  (Don't forget the joints on the center PC board)

[bskahj]

will do, thanks PB