[sdiy] First appearance of the CA3080?

[Michael E Caloroso]

> Can some of you imagine, why there was no synth filter until the State
> Variable Filter in the Oberheim SEM in 1974, which was based on the
> OTAs? Or were there some earlier OTA filters in Synths?

There was...

Dennis Colin developed the multimode filter using OTAs for the ARP
2500.  Patent #3,805,091 filed in June 1972, and presented an AES
paper in April 1971

MC