Looking for info on Klein+Hummel Model OY monitor speakers. The units are around 40 years but the one that's working sound excellent. I need a schematic for the preamp section in particular. There is a canister type device I take to be a filter of sorts with 8 leads coming out of it, but no markings. all leads are the same color, so as to be really helpful.
The manufacturer & their dealers' sites as well are of no help...guess they don't care about supporting anything of that vintage.
Any & all help is appreciated.