[taskerc]

Hi all,

Have been enjoying my Cornet II for nearly two years.  But recently changed my table set up and started to hear an annoying "fizz" sound from right channel.  Naturally thought it was the new table since it changed etc etc.  But on a whim bypassed Cornet II as a test and no fizzing sound.  The sound is not constant and a bit random.  Is this what a dying tube sounds like?

Chris

[poty]

It may be due to changed electromagnetic environment (new position of TT motor or electronics, new or repositioned cables, new neighboring equpment...). Of course it may be internal Cornet problems too, but as soon as the problem had appeared just after the TT change I doubt it.

[taskerc]

Hi Poty,

Thanks for the reply.  I had thought something similar so I played around with positioning etc and found the issue was the same.  I have some new tubes on the way as a backup and to test.

[richidoo]

If the Cornet uses different tubes per channel, you can swap the tubes to see if the noise moves to the left channel.   But if each tube runs two channels then this won't work. But it could be tube noise. They can fail in many different ways. A quality signal (small) tube can last 10,000 hours if it is used gently. But a defect or running hard could cause quicker expiration. Good to have some cheap spares like Sovteks for diagnostics and in case of a complete failure you can still keep the tunes flowin...

[GRD]

Could well be a tube.  I've run across some that "fizz" and "hiss".  As stated, having a few spares makes sense.

[bregez]

I rolled a weak 12AU7 tube through my Clarinet and it made some faint background white noise. 

[taskerc]

I swapped in new ax7s and an au7 and noise gone.  Now I will do one by one swaps to see which one might have been the offender.