Fine tuning B+4 and B+5 = 200V, how important is it?

[BobW]

I have considered adjusting the plates of V1 and V2 with an additional smaller Plate resistor and filter cap. Has anyone tried this, and are there any benefits to dialing in the plates to 200V?

present voltages using the Rp/Rk values of 220k/3.3k, 150k/2.2k, 180k/2.7k, 120k/1.8k:
V1a = 192
V1b = 207
V2a = 195
V2b = 207

[ayan]

I have considered adjusting the plates of V1 and V2 with an additional smaller Plate resistor and filter cap. Has anyone tried this, and are there any benefits to dialing in the plates to 200V?

present voltages using the Rp/Rk values of 220k/3.3k, 150k/2.2k, 180k/2.7k, 120k/1.8k:
V1a = 192
V1b = 207
V2a = 195
V2b = 207

Bob, those values seem right to me. By plate resistor do you really mean the plate load resistor? If so, I would not use that to adjust voltages, since changing the Rp will change the gain of the stage. You could, however, change the values of the dropping resistors on the power supply and see where that takes you. But, I will say it once again, your values sound fine.

Gil

[BobW]

By plate resistor do you really mean the plate load resistor?

I should have made myself clearer, this is what I meant to say. A pic = 1000 words.

thanks Gil

[glasman]

Those values look very good and they are going to vary from 5 to 10 volts depending on the tube. No reason to be exactly 200 volts. But keeping the value around the 200 (207 is fine) mark yields a nice top end wihout edginess.

[odourboy]

Ah! So are you trying to add a second, different preamp to an amp here?

My guess is it should work, but since the loads will change you're going to have to rejigger the 'upstream' power string resistors to maintain your old B+ voltages. Anyway, never done it, so it's just speculation.

[BobW]

So are you trying to add a second, different preamp to an amp here?

No. I'm just curious since one of my all time favorite tone amps is the vibrolux reverb, at least my particular amp anyway. Am considering to build another 50W dumble but w/fender tone stack based on the vibrolux. The goal is to have a cleaner and richer OD tone similar to David Lindley on "Running on Empty".