So what about the 110mV mentioned? ie what are you measuring and how have you measured it.tedsorvino wrote: ↑Thu Sep 21, 2017 11:55 pm My bias probe is similar to this one: https://www.amazon.com/Eurotubes-Bias-P ... B019PAVXPG
My mistake. It juest measures current, no voltage. I measure plate voltage on pin 3.
Regarding the current measurements, are you sure that the meter is good? eg to verify, try measuring the current that a 220 ohm resistor pulls from a 9V battery.
When using the bias probe, are you keeping the leads and meter away from the pre-amp?
Do the readings change if the amp is operated with the tube removed from V6 LTP socket?
The issue with the diode is that as you have described things, the bias supply would created a positive voltage, rather than the negative that you have reported; so something is wonky.
Sketching out a schematic, rather than tedious, confusing and apparently erroneous circuit descriptions would save an awful lot of bandwidth.