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Old 22nd July 2011, 10:15 AM   #1
Green77 is offline Green77  Sweden
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Default TubelabSE left 5842 drift

Hi all!

Enjoying my TSE with 300b tubes. Think after 20 h that the sound is really good I have a small problem with my left channel. Nothing i hear but i need to adjust the 175 V at 5842 tube all the time..

After 30 min it has drift +/- 10V while the right channel is steady (+/- 1V).
Maybe it is the tube. I haven't swaped them yet but maybe i do that tonight..

What can do this except for the 5842 tube?

Thanks //Daniel
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Old 22nd July 2011, 03:45 PM   #2
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Originally Posted by Green77 View Post
After 30 min it has drift +/- 10V while the right channel is steady (+/- 1V).
Maybe it is the tube. I haven't swaped them yet but maybe i do that tonight.
Both of mine drift in about 10 min. I set it at 175V at that point and it stays there. If yours doesn't drift anymore after 30min, it may be ok.
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Old 22nd July 2011, 05:55 PM   #3
Green77 is offline Green77  Sweden
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i have adjust it 5 times under 30 min..if i check it again after 1 h it has drift +- 10 v
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Old 23rd July 2011, 02:59 PM   #4
rknize is offline rknize  United States
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Keep in mind that the 5842 is not fixed bias. If it's drifting it's because the cathode bias and active plate load is compensating for changes in cathode current. It could also be the CCS that's drifting, but that is not likely. Does the CCS have an adequate heat sink?

The drift itself is nothing to worry about, but it could be a sign of some other issue.
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Old 23rd July 2011, 03:59 PM   #5
Green77 is offline Green77  Sweden
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Thanks for your answers. I use the same heatsink for both sides. And there is no drifting on the right side..
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Old 23rd July 2011, 04:44 PM   #6
rknize is offline rknize  United States
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Swap tubes. If the drifting follows the tube, you have your answer.
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Old 23rd July 2011, 06:06 PM   #7
Green77 is offline Green77  Sweden
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Thanks, will try that tomorrow..
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Old 25th July 2011, 08:30 AM   #8
Green77 is offline Green77  Sweden
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I had a spare 5842 home. Changed the tube and the problem was gone Bad tube..
Thanks all! //Daniel
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