Tweaking voltages

[mhartman]

So, on my 50w bluesmaster build, my V1 and V2 voltages are reading around 10 volts higher than what I've seen recommended. If I want to lower these voltages, where should I start and what should I be thinking (i.e., what is the strategy and typical approach for working out voltage adjustments).

Thanks in advance for any help.

Mike

[Structo]

What value plate resistors are in your amp?

What kind of voltages are you getting on V1, V2 & V3?

These ranges here will produce good tone.
V1 190-200
V2 195-210

If you have other tubes on hand you should try some others in those
positions as a 10v difference can be found among preamp tubes.

If you are very happy with the tone you are getting with those tubes then you can play with the dropping string.

I am not familiar with the BM but usually you adjust the two resistors that feed the plate resistors from the power supply.

Raising the values with drop the voltage.

[ToneMerc]

So, on my 50w bluesmaster build, my V1 and V2 voltages are reading around 10 volts higher than what I've seen recommended. If I want to lower these voltages, where should I start and what should I be thinking (i.e., what is the strategy and typical approach for working out voltage adjustments).

Mike

Keep in mind that you might switch around tubes and find either one or both tubes now 10 volts lower.

TM

[mhartman]

Thanks guys.

I'm looking at around 200v on V1 and 210v on V2 -- so just in range, but on the high side. Good advice - I'll start by swapping out the tubes, I've got dozens of 12ax7s sitting around, so maybe I'll find a good combination.

This is the standard Ceriatone Bluesmaster configuration, so the plate resistors (I think) are:

V1 - 150k, 120k
V2 - 220k, 150k
PI - 100k, 110k (with a 10k balance trim)

Thanks again, I'll do some tube swapping and report back.

[Structo]

Those resistor values are in the ball park but I have different layouts and schematics that have varying values.

I think the critical piece is the phase inverter which has the 511R bias and 9K1 tail.

I have seen some with 91K and 110K on the plates of the PI.