CGS dual ETI 414 master mixer

Both of the mixers in the CGS dual ETI 414 master mixer started out life as the output stages of an ETI 414 master mixer, a project of the same vintage as the ETI International 4600 synthesizer. In fact there was very little difference between the 4600 equalizer and those used in the mixer.

The mixer equalizers were designed to work on a single +30 volt supply, as distinct from the +/- 14 of the International synthesizer. They also used 741's instead of 301's. The important part, the five pot-core based inductors used in each were identical.

It was a simple matter to move a few parts around on the PCB, cut a few tracks etc., to convert one circuit to the other.