I know this topic has been beaten to death, but I am in the process of reverse-engineering the schematic to the old 46745 Haz Labs preamps used in Spector basses back in the day.

I don't have an original unit on hand, so I've been circuit-tracing via high-res photos of circuit boards that were posted online. At this time, I think I have a valid schematic. I've also located a NOS (new old stock) source of the original LF442CN JFET opamps and bought a few dozen units so I can do test...

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