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In the Forum: Analog Playback
In the Thread: The last phonocorrector: “End of Life" Phonostage
Post Subject: Filament considerationsPosted by N-set on: 11/29/2011
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Alex, have you killed your ham finally?
What was the source?
 AlexBerger wrote: |
Is the filament ground connected to the common ground?
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Of course! Otherwise the fixed bias would not work. Moreover it's connected
directly at the V2 to minimize the loop in the V2's grid created by the connection and the voltage dividers.
BTW, I tried shorting this grounding point to the input stage ground with no result.
Actually those voltage dividers and my mess around V2's grid were my first suspects, but apparently
shorting the grid to gnd with a 0.47u cap gives relatively small hum reduction, smaller than shorting the plate.
| AlexBerger wrote: |
Is the filament ripple is small?
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It is small already at the first cap behind the input choke@200mVpp.
Cheers,
Nset
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