hi guys,
just wanted to make a small correction. the 12AX7 was used as a driver/phase splitter and was only in the original series of amps between 1974 and 1976. (I too gigged MusicMan amps, a 210 sixty-five and an HD one-thirty driving 8 EV 12" speakers during the 1970s....I was very happy with my amps and still own and occasionally use the 210 sixty-five.) Musicman amps did a fairly covert/frantic redesign of their driver section because of an inherent design problem that was causing some radical melt-downs in the amps when driven hard. They substituted a newly designed solid state PI/driver section in all new amps (and any amps that came in for warranty work also received the retrofit) sometime in 1976. Many of the old chassis with a cover placed over the hole for the 12AX7 went out of the Fullerton Factory in the last part of 1976. the preamps of all musicman amps were the "hybrid" part of the equation (5X IC 1447, I believe?)....the output section was pure tube: 6CA7 Sylvania's (EL34) and later changed to 6L6's during the 1980s. by 1984 it was all over for music man amplifiers and they slapped a padlock on the factory doors and auctioned off all the left over parts. just a little slice of MusicMan history, guys
ce blue