Syncussion SY-1M Modifications

While building two of the Psycox Syncussion SY-1M units I thought a lot about modifications I could add to the unit. Initially I considered using the unused positions on the rotary switches to add additional modes and while I may come back to this at a later date I decided to build the units and spend a bit of time using them first.

Whilst building the first unit I realised stereo jacks had been used for the trigger and pitch and each had an unused pin. In using the first unit I decided to use thes unused pins to add two additional CV inputs to the unit. This could be done without effecting the normal operation of the synth.

After a bit of breadboard tinkering I designed a small board to go in the cludge section on the voice board. In combination with a few wires and resistors across the back of the board this added CV control of Decay time and VCO2 offset to each voice.

These additional inputs can be accessed with stereo to twin mono adaptor cables plugged into the jacks – (image to be added).


Here’s a few videos of the mod in action.

Firstly here’s a rough video of a single voice demonstrating the VCO2 tuning mod. A single note pattern is triggered via MIDI and then VCO2 is modulated by the additional CV input.

Here the two voices are being driven by my MPC via MIDI giving timing and pitch events. A collection of synced LFO’s and envelopes from my modular are fed into the additional inputs to modulate Decay times and offset of the second VCO.


Here for information purposes only is the documentation for the mod PCB’s.

Documentation for mod PCB’s

Syncussion-Add-In-Build Document