Plexi 6v6 "Bias Range"?

[mcamelo]

Hi, all.

This probably has an obvious answer but I can't figure it out myself.

I am trying to understand what the "Bias Range" point in the Plexi 6v6 layout diagram means:

https://el34world.com/Hoffman/files/Hoffman_Plexi_6V6-V2.pdf

Is that where the "Bias Tap" connects to the board? Looking at the schematic, it doesn't look like it, but I can't figure out.

Any help would be much appreciated.

-Marcelo

[sluckey]

The "Bias Range" flag is pointing to that 220K resistor. Depending on which PT you use, you may have to change the value of that resistor to get the proper adjustment range for the bias voltage.

[mcamelo]

Alright. That makes sense.

And I presume the -36V in the schematic (between R27 and R28) is the target voltage? I can get from -40 to -20, so I'll keep the 220K for now.

This amp sounds exactly as I've hoped. Great tones from cleans to fully dimed.

Thank you Sluckey for your answer.

[sluckey]

And I presume the -36V in the schematic (between R27 and R28) is the target voltage? I can get from -40 to -20, so I'll keep the 220K for now.

I'd say that's a good range.

[tubeswell]

As a general rule of thumb for 6V6s, the range of (negative) bias source voltage (prior to adjustment) wants to be at least (about) 10% of the B+ voltage. So if your B+ is 440, then your bias voltage source ideally should supply at least -44V (to be on the safe side)