i happen to have the mk ii with 2x10, no reverb or trem, but i am pretty sure most of the the 17s are pretty similar save some minor things like rectifier/no rect, etc. so i welcome feedback from anyone with a 17. anyway, my question is about the tone control. from what i have read and experienced playing the amp, the tone control is different from an eq adjustment. rather than cutting or adding treble or bass, it seems to affect the overdrive characteristics of the preamp and/or powertube (honestly not sure if either or both). i remember reading somewhere that it only really works if the gain is 12:00 or greater, but i can not remember the specifics. i have played around with it a lot and have found the sound i like out of it, but i am just curious to know how the tone control technically effects the circuit or at least what it is suppose to do to the output?