Tubes Asylum: RE: NOS GE 211 tubes... Squeak on startup by miguelito

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RE: NOS GE 211 tubes... Squeak on startup

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miguelito

In Reply to: RE: NOS GE 211 tubes... Squeak on startup posted by bcowen on June 6, 2016 at 16:17:46:

The Ongaku does not push the 211 tubes very hard, idle current is about 60mA. Bias is a pain to adjust and I have only had it done by a tech - you need to put this 85 lbs amp on the side, use a high-voltage probe, etc - so only an authorized tech did this once for me. So I have not really used any worn tubes in the amp.

So couple more observations: The tubes look pristine as I said, very large getters, don't look burnt out at all. I have two other tubes which work fine: GE 211 that came with the amp, and new Kondo tubes. None of this produce the initial oscillation. Additionally the oscillation happens in the right channel even when I switch left and right tubes.

What I will try is switching around the preamp tubes (ie left to right). This is a bit harder as I have to remove the preamp tube cover, but I will try it when I have a sec.

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Topic - NOS GE 211 tubes... Squeak on startup - miguelito 14:58:45 06/5/16 ( 7)

RE: NOS GE 211 tubes... Squeak on startup - bcowen 16:17:46 06/6/16 ( 1)
- RE: NOS GE 211 tubes... Squeak on startup - miguelito 06/6/16 19:13:27 06/6/16 ( 0)
RE: NOS GE 211 tubes... Squeak on startup - Triode_Kingdom 05:38:53 06/6/16 ( 2)
- RE: NOS GE 211 tubes... Squeak on startup - miguelito 07:00:13 06/6/16 ( 1)
  - RE: NOS GE 211 tubes... Squeak on startup - Triode_Kingdom 06:09:01 06/7/16 ( 0)
RE: NOS GE 211 tubes... Squeak on startup - miguelito 04:20:18 06/6/16 ( 0)
RE: NOS GE 211 tubes... Squeak on startup - FenderLover 19:47:55 06/5/16 ( 0)