• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Critical resistors

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Feedback resistors (R17/R14) and grid stoppers will probably be as far as i would go - no point to go crazy improving this circuit.

As the quality of the voltage used for fixed bias is very audible (really marginal in this design) i would spend some some attention on it. A small choke will be very nice and probably good quality caps bypassing R29/R30.
 
Baard said:
Hello

What are the ten most critical resistors in this design?

http://www.audiokit.it/ITAENG/UpElettr/COPLCTA401/Sch401-1-1.jpg

P1-P3, and yeah anything in the signal path or that will bring down other things on faliure (open or shorted). Carbon film is fine, except for the bias pots, which should technically be something better than conductive plastic (i.e. cermet or WW), but I haven't had any problems there either.

analog_sa said:
As the quality of the voltage used for fixed bias is very audible

Huh? Howso? (Assuming the driver is something stiff like 12AU7/6DJ8/6SN7, and the grid leaks are reasonably large (100k or so).)

Tim
 
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