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I finished installing the bias circuit. I did the procedure as indicated in TUT 2. The issue I am having is with the power tubes pulled I am measuring pin 2 of the el84 tubes, with the bias all the way to "x". In TUT it says to measure pin 5 which I believe would be the control grid of an el34 octal tube.
The voltage from chassis to pin 2 of el84 there is no DC voltage present with bias all the way to x.
I put in the tubes and I notice the bias range goes from around 42mV and all the way up to 100mV. The other tube there is no change in current when I turn its respective bias pot. The stock resistor of 150R has not been changed yet but at least it should be working?
I drew up a layout (I apologize for the lack of neatness) going off the schematic.
Edit: I didn't read your previous message carefully regarding the push pull circuit. Essentially it is dialing the currents per tube but pushing and pulling as you mentioned. Previously I had installed sv1 raw bias supply and this seems to work differently. The previous build I can dial in the current without affecting the range of the other tube.
I didn't answer your previous question. The amp doesn't seem to have a feedback loop.
I did manage to balance the hum. The only issue now is the MV is always open now as the grounding reference is at the wiper of the bias pot. I must have misunderstood the wiring and not correctly. But you mentioned that it now has to be referenced and isolated back to zero volts via another set of coupling caps. I'm not sure how to do this visually. Do I just wire in coupling caps from the wiper back to the ground?
The voltage from chassis to pin 2 of el84 there is no DC voltage present with bias all the way to x.
I put in the tubes and I notice the bias range goes from around 42mV and all the way up to 100mV. The other tube there is no change in current when I turn its respective bias pot. The stock resistor of 150R has not been changed yet but at least it should be working?
I drew up a layout (I apologize for the lack of neatness) going off the schematic.
Edit: I didn't read your previous message carefully regarding the push pull circuit. Essentially it is dialing the currents per tube but pushing and pulling as you mentioned. Previously I had installed sv1 raw bias supply and this seems to work differently. The previous build I can dial in the current without affecting the range of the other tube.
I didn't answer your previous question. The amp doesn't seem to have a feedback loop.
I did manage to balance the hum. The only issue now is the MV is always open now as the grounding reference is at the wiper of the bias pot. I must have misunderstood the wiring and not correctly. But you mentioned that it now has to be referenced and isolated back to zero volts via another set of coupling caps. I'm not sure how to do this visually. Do I just wire in coupling caps from the wiper back to the ground?
