O.K., these notes are aggregated from a bunch of different sources ( the MetroAmp Forum, TGP, HRI, etc; ). Like I mentioned, Mark Abrahamian was helpful and some of these quotes are directly from either Dave Friedman or John Suhr ….
Since I’m NOT a beta tester, I have no idea how the advanced parameters have changed ? And I’m not an electrical engineer either, so most of this is complete “greek” to me ( no offence indented to any Greek Axe-Fx II owners ) !
Eddie’s Plexi # 12301 after Dave Friedman’s latest restoration:
Split cathode V1a 250uF / 820,V1b .68 / 820
All coupling caps are 0.022uF, Bright channel coupling cap is 0.0022uF
bright cap on vol pot 0,005uF
470k mixer resistors
500pF mixer bypass cap
Bypass cap on V2a is .68uF
33k / 500pF tone stack combo
100k NFB resistor at 4 ohm tap
220k bias splitter resistors
uF cap on presence control
.022uf output couplers
47pf on PI
The Power Supply Sags …. In fact, Dave Friedman said that in Eddie’s # 1, the power supply “sags about 70+ volts with normal wall voltage dimmed, and 50 some volts with a variac on it” ….
B+ and Plate Voltages drop …. Mark Abrahamson ( Rockstah ) said the B+ in the amps he’s measured were around 363 dcv, and while he evidently didn’t take the 120v measurement, he estimated that they would normally run between 410 dcv and 500 dcv ?
Tube Bias drops …, which is why everyone who uses a Variac says to “crank the bias” ! Again Dave Friedman’s comment was: “Now I have said this before, the amp is biased to like 85ma with normal wall voltage and then dropped with a variac to 90 volts. This will bring the bias down to around 50ma.” Of course “the” amp he was referring to was Eddie’s # 1 ….
You shouldn’t really have to worry about Cathode Stripping because Ed’s amp at 5.5V on the heater, and running them 5 - 10% lower has been shown to increase tube life and stability. Ed’s went from 6.6 with 115VAC at normal to 5.8 at 87VAC.John Suhr said, “You also have to get into much higher plate voltages to worry about that.”
I’m guessing that the frequency response of the Power Transformer gets restricted somewhat too ? But I’ve never been able to find any specific measurements on that ?
* Finally, don’t forget that Ed used a lot of cord ( extra capacitance ) in front of the Amp, as well as an Echoplex EP-3 as a slight booster ( James Santiago’s EP-3 tonematch anyone ? ).