thank you,i was wondering about the meaning od these serial numbers

Mine is loudest when the rectifier switch in back is on number 1 labeled “Tube” and quietest when switched to 3 labeled S.S. AB2. Isn’t that backwards from what it is supposed to be? In the 2 middle position it is mid loudest too.

Just to set the record straight, the Prosonic was designed by Bruce Zinky of the Custom Shop, but none of these amps were actually built there, nor were they sold as Custom Shop amps. The “LO” prefix to the serial number indicates that the amp was made at the old Sunn Amp factory in Lake Oswego, OR. Late, production was moved to Corona, and those amps are indicated by the prefix “CR.” The Lake Oswego amps are supposed to have better-quality components than the later models, though. Fender is said to have made modifications to Zinky’s original design, but with a few circuit and tube mods, these amps go from good to really great!

Could you show the correct wiring diagram for the two 10in speakers in the Pro Sonic. I’m not getting much out of the game section at all and wonder if the wires where are installed improperly when someone put aftermarket speakers in it. I put the originals back in according to the way the wires were but not sure if they are correct. Thank you

This is good to read, Thank you. I am about to buy my friend’s Prosonic head, he bought it from Gary Hoey. ( has proof ), I have been reading all I can re: this amp. Your comments make me feel good! My plans for the amp are to use the clean channel, with pedals. That’s the way I run my ’87 Mesa Boogie Mark III, and, the way I run the amp you mentioned – Super Champ X2 ( head ), XLNT amp! It’s my new ‘church amp’, because it’s lighter than the Boogie ( duh ), anyway, the Normal Channel of the X2 is really really good IMO. I’m looking forward to the Pro Sonic, again, thanks for info, and, in my case, encouragement!