MatureWolf - 2019-12-26 2:11 PM
While I was doing this mod I wondered why Ovation would cut the output. Then, I remembered that the ADII as well as the OFC II guitars have a boost switch that 'increases' output 4 dB. I'm guessing that the 'boost switch' doesn't really boost anything. Instead it has a separate daughter board that has different values of resisters, such as those used in this mod, to remove the inhibition built into the circuit that you found.
Seems you got the point, Dan.
Supposedly, 1769 ADII has special "modified" can (=housing) + outer "Boost" switch whilst OP-Pro preamp itself is very standard.
;-)
Best,