Hi everyone, My GFA-555 MK2 boards are ready to go! Thanks to Jon Morris of Morris Audio in Wyoming for helping me work out the bugs and validate the design. He’s already restored a few customer’s GFA-555 MK2’s with my boards.
Adcom had a sensational success with the GFA-535 in the 80s and 90s. A great bargain! For 300 bucks, you got a true dual-mono amplifier designed by Nelson Pass. (Separate power supplies for both channels.) Conservatively rated at 60WPC, with a high-current power supply, it was a lot of amp for the money. Lots of people read this glowing review at Stereophile magazine and bought one.
I’ve rescued this beautiful Adcom GFA-555 Mark II from an amateurish repair attempt. Evidently, the amp blew its output transistors, (rare with these amps actually) and it was repaired with non-matching parts, and some counterfeit output transistors! These were mixed with good original transistors. This repair no doubt worked, but it blew out again shortly after.