Hello Mr Heyne!
I am looking at an original, apparently early '80s, U47 fet in Matte Black (?) finish. The seller has sent pictures but unfortunately one showing the bottom is missing (so far). Seller also reported that he doesn't remember any "-6 dB" switch. While gathering info I came across a black U47 fet for sale in California and actually the switch is not present. On this one there's a sticker on the top of the bottom half (sorry about that) that says "Circuit Diagram 08". My question is: has production evolved into different revisions of the circuit? Should I expect the black I am looking at to sound like the grey, older one I already have?
Thank you very much, Gabe