I am not satisfied with the two-stage (2nd tube) gain circuit yet. However, for traveling, I just buttoned up the amp as-is so I could take it along, and I have been exploring the nice new tones I can get with just the 1st stage, using the mods I have outlined. I'm doing it a little differently than what I described before, however.
Since I am willing to completely forgo the original negative feedback, the way is open to place a master volume control. The original volume pot stays same, but is now better labeled "gain", or "pre" perhaps. The 3M-RA pot (which I was formerly using for stage-2 gain) becomes the master volume ("M-vol"), being inserted between the plate capacitor of the final 12AX7 stage, and the grid input of the 6V6. Thus, you can turn up "gain" and keep "M-vol" low, for a little more crunch than the Champ can normally do at low volumes (still pretty clean, though: more of an "edge" than actual "crunch", at least with this Squier Strat). Or, max-out the M-vol, and then gain becomes same old "volume" control like on most Champs (still no NFB, though).
When the master volume is fitted, the 2nd-stage gain circuit can share the original volume control (now "gain") with the 1-stage circuit: so there is no "gain2" anymore. The "gain" pot is operational in 1-stage and 2-stage modes.
The "mid" EQ is as shown earlier, i.e., replace fixed 15K resistor from "bass" pot to gnd, with the 25K pot removed from the "vibro" circuit. (Wire pot so minimum resistance is at the CCW position (0, not 10).) Thus, you can get somewhat fatter mids than the regular Champ (25K vs 15K), but more interestingly, you can "scoop" the mids in a way that most Fender amps can do, but usually Champs can't, by turning the "mid" EQ down low or to 0.
Nice range of clean and almost-clean tones.
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