OK,
I've made two tweaks:
1) Dropped value of 1mg bass pot to 500k by straddling a 1mg resistor across lugs 1 and 3 of bass pot. Resulting in 500k pot...Very subtle but welcome change to the way the bass knob reacts!
2) Changed coupling cap from .0047uf to .022uf between v1 and v2 of TMB channel. This effectively destroyed the beauty of the TMB channel on the sIII....there was a slight increase in bass....but it also added a raspy, fuzzy distortion that I remembered from my 18watt lite days....I immediately reverted back to the .0047uf cap and the amp is literally perfect now.
This should teach me to make one change at a time!
I made both changes at the same time and I thankfully backed out the coupling cap first...which returned me to just the sIII with the 500k bass pot.. Perfect!
This coupling cap experience actually raised an important issue that I've been constantly fighting with my lightning deluxe. As most of you know, I've fought a raspy buzzy tone in that amp for months...and I made a whole slew of changes to the preamp to get rid of it...and in some cases, reduced distortion that I otherwise would have wanted from the preamp. After hearing the coupling cap results from the sIII, the resulting sound is *very* similar to what my lightning had done...so I am tempted to revert the lightning's preamp to the amount of gain I want...and see if playing with the coupling caps will fix the problem. (granted the current coupling cap in there is on 500pf, so I can't imagine going any lower! )
I'll report more on that in the lightning forum if the changes render something worthwhile!
-Frank