kb_cheapmods
BlackTrak_OpenJacks
Here's the VCF/VCA input jacks (left) and the signal output jacks (right). Also, you can see the multiple trimmers for each of the NJM2069 Korg VCF chips.
The adaptation of the DW-6000 board to the Six-Trak required more work than I anticipated. I had to remove quite a bit of the interface circuitry that the DW-6000 used. Also, the periodic self-calibration that the Six-Trak uses doesn't JUST tune it's VCO's, it also tunes the VCFs! For some reason, the microcode in the Six-Trak would end up leaving a big DC offset in the final CV when it tried to calibrate the NJM2069, so I had "remove" it by putting an LED in series with the cutoff frequency CV, then adjusting the trimpot to scale the CV appropriately.
BlackTrak_OpenJacks
Here's the VCF/VCA input jacks (left) and the signal output jacks (right). Also, you can see the multiple trimmers for each of the NJM2069 Korg VCF chips.
The adaptation of the DW-6000 board to the Six-Trak required more work than I anticipated. I had to remove quite a bit of the interface circuitry that the DW-6000 used. Also, the periodic self-calibration that the Six-Trak uses doesn't JUST tune it's VCO's, it also tunes the VCFs! For some reason, the microcode in the Six-Trak would end up leaving a big DC offset in the final CV when it tried to calibrate the NJM2069, so I had "remove" it by putting an LED in series with the cutoff frequency CV, then adjusting the trimpot to scale the CV appropriately.