The amp lacks of bass tones, and the overdirve is kinda fuzzy. the volume range jumps drastically when dialed between 6-7... cleans are ok.

The tone knob is really wierd... seems to be a -10/0/10 kinda knob where turning it from one end to the other (0 to 10) the tone at 0 seems be down, then go up at the middle (5) then down again when reached 10 (dunno if i explained myself).

I've read a few other reviews were changing the speaker and tubes helped for some, but others claim that not even that helped (i don't have extra speakers nor tubes to try this out).

So basically the mods consist in providing some bass to the amp and making the tone knob work correctly.