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I'm reading this with interest, as I built two synth VCAs that use the CA3080 and I had to pick through a whole bunch of chips I originally bought way back in the '80s. All of them were working, tested devices from RS Components in the UK. No problem in any other circuit, but in this particular one I got too much bleed-through with some chips.
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Yeah, I've learned a wealth of info by repairing several issues with that amp. The different odd chips and the lack of suitable substitutes are definitely most interesting, the workarounds Enzo and Juan shared even more so.
Original repair thread is here: http://music-electronics-forum.com/t43929/Comment
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This may already be understood by those here, but note that, while they perform largely the same action as OTAs, the 3080 and 3094 are NOT the same chip and do not have the same pinout. The 3094 has an additional buffer/gain stage.
The closest thing to a 3094, still in production (or recently enough) is the LM13600 and 13700. Note that this is a 18-pin chip containing the functional equivalent of two 3094s. One could, in theory "dead bug" them as viable replacements if the exact replacement can't be sourced.
EHX also used the 3094 in many products. Their in-house part number was EH-1048.Comment
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The Stompbox Cookbook has some interesting info regarding older OTAs and subbing the LM13600 and 13700.Comment
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Get it while you can.
Superb, and good bedtime reading.
Just the kind of book Enzo should write.Comment
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