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- Thread starter APEMAN
- Start date
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I'm suprised at your <20% readings (17mA @ 420V B+). At idle my previous Triple Recto and current Roadster (w/Mesa GRN 6L6GC) measure 460-475V B+ (with regulated 120V supply) at 22-25mA in Bold/Diode rectifier.
There is a lot of misleading information on the net about the bias of a tube amplifier. I agree, it's not all about "warming it up to 70% MPD".
Dom
There is a lot of misleading information on the net about the bias of a tube amplifier. I agree, it's not all about "warming it up to 70% MPD".
Dom
R_ADKINS80
Well-known member
You got something wrong with your amp, IMO. I can leave my bias meter set up on top of the amp and my bias does not change with volume.......at all.
If your plate voltage is dropping like that then the bias voltage may be dropping as well, that could explain the rise in cathode current to 50mA.
Try monitoring the bias voltage on pin 5. A non-adjustable fixed bias Class AB poweramp should remain a consistent voltage throughout amp operation. I believe that in 6L6 bias mode the spec is -51V, +/- a couple V.
Dom
Try monitoring the bias voltage on pin 5. A non-adjustable fixed bias Class AB poweramp should remain a consistent voltage throughout amp operation. I believe that in 6L6 bias mode the spec is -51V, +/- a couple V.
Dom
