It's as described in Joe's notes.
First thing I noticed was that turning the master volume up past 8 caused the volume to go down rather than up. Mod 1, cutting the white/blue wire eliminated that.
Next was that there was always a midrange bump in the response. I prefer a predominantly flat response, and I just couldn't get it. Mod 2 eliminates the "always on" boost. I can still get the midrange boost if I want it, but now it goes away when I turn the midrange control to zero.
My T is one of the earliest 2G units. Still has the silver centers on the knobs instead of red. I haven't ever traced out the circuitry to determine what kind of tone controls I have. Given that it has the midrange selection switch, it's reasonable to think that it has the Baxandall tone circuit, but it's possible that it has the original tone stack. Either way, I generally prefer all the tone controls at zero. It seems to me that I get the flattest response that way.
Best I can do as far as describing the tone is that, before the mods, it sounded honky or squawky, the result of the midrange boost. That's gone, post-mod. I don't think the master volume mod changed the tone; it simply made the amp respond the way I think an amp should respond. Now, post-mod, the response is pretty flat. I rarely drive it into overdrive, but, even clean, it has a fair amount of harmonic distortion, which gives it a full, fat sound rather than a squeaky clean, hi-fi sound.