• 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.

12BH7 in 12AU7 cathode follower circuit

I’m using the power supply Stephe uses in her color preamp.
 

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What I’m trying to understand, on a much more basic level, is what is causing the left/right voltage discrepancy? Going to have to look into that. As well as reducing the voltage to 300vdc from the existing 324vdc.

But I’m having to put this on hold for a couple of days, daughter’s graduation tonight and I have the kids this weekend.
 
That power supply will be OK for higher anode currents. You will only change that resistor in CRC to adjust the voltage. the power supply is not stabilized, so the voltage can change depending on the voltage in the network and the consumption of the tubes. I think you would get a better sound with a Salas SSHV2 or some similar stabilizer. And the voltage would not be variable.
 
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And here are the voltages I’m seeing. Surprised at the 324v on the power supply. Thought I adjusted that down? And I don’t understand why there is a discrepancy between the left and right channels. Something is off…. Top number is left, bottom is right.
Those numbers are almost identical, left to right. What discrepancy are you talking about?
 
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The two tubes (even two halves of a real tube) are not the same, unless you really go through a lot of them and select a pair matched with identical halves. As @Merlinb said, they are pretty close to each other.
The grid voltage on the right triode looks a bit low, it is probably influenced by the impedance of the voltmeter you are using to measure.
 
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That power supply will be OK for higher anode currents. You will only change that resistor in CRC to adjust the voltage. the power supply is not stabilized, so the voltage can change depending on the voltage in the network and the consumption of the tubes. I think you would get a better sound with a Salas SSHV2 or some similar stabilizer. And the voltage would not be variable.
I have to adjust pretty much every build as my house has a transformer right in front and I see higher than usual voltages. Ranging from 123 to 125. I’ll look into the salas
 
I’m using a Fluke 87 meter, I would hope it would be accurate?
It is not about accuracy, but about input impedance. The grid voltage is supplied via 560K R6 resistor. That will form a voltage divider with the input impedance of your Fluke. I tried to look into the datasheet but it does not state the value, which I find strange.

PS For example, my BK 393 multimeter has a 10Meg input impedance. If you look at the simulation above, you connect a 10 Meg resistor from grid to ground (my multimeter), and the grid voltage goes from 69V to 56V.
 
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