AM8319

Replica of the early 1970s Korg diode ring filter

This 12HP wide module has at its core a diode array that uses the original CA3019 diode ring array chip. This provides either a 12dB low pass filter or a 6dB high pass filter with a front panel push button switches between the two modes. The filter has two signal inputs, one that can be controlled in level by the SignalA control potentiometer and one that goes straight to the filter core.

The Frequency can be controlled via the large 20mm diameter front panel knob and via a direct CV signal and a level controlled CV signal. The resonance of the filter can be varied by the Peak control and the filter will oscillate at maximum settings. This VCF replicates the sound of the early Korg VCF’s found in the Traveller.

This module is a replica of the Diode Ring filter developed by Korg in the early 1970’s and used in various analog synthesizers including the:

Korg 700, 700S, 800DV, 900PS and MS-50.

Korg initially used matching diodes in the TS-201012 sub module with a transistor based circuit but then moved onto using the CA3019 Diode Array chip with Op Amps. It is this later design I have replicated.