Bought an Oakley Discontinuity v1 full kit from Synthcube. I had been looking for a MOTM-format module to replace one that I had sold and Discontinuity looked interesting.
Building the module
The version 1 Discontinuity uses large pots with special pot brackets. Unfortunately no pot brackets were included. Oakley MOTM format modules use these brackets to secure the pots to the PC board, and the pots mounted to the panel are the means of holding the board. Without the brackets there is no way to securely fasten the PC board. After contacting Tony Allgood at Oakley Sound Systems, I learned that the needed brackets were no longer available. But Tony sent me instructions for a small circuit modification that made an improvement. Thank you, Tony!
I then contacted Synthcube and had them send me their Stooge 4-pot bracket, which is used with many MOTM format DIY modules. I only needed to drill four mounting holes and cut off the end of the bracket, which is long.
Fortunately I had some 3/16-inch spacers that were just right for mounting the PC board.
This bracket holds the board securely and provides holes for the pots at the right spacing. I added an extra nut on the pot bushings, behind the bracket, to keep any pressure off the pot housing.
All integrated circuits are soldered in, despite IC sockets having been supplied. If a PC board is high quality, as the Oakley’s are, I don’t worry about having to replace a chip if needed, which almost never happens.
Tony designs his boards with headers for all off-board connections, which simplifies wiring up to the panel parts.
The top PC board should have the pot brackets. But since it is small and has a lot of short wires attaching to it, using the pot leads to suspend the board isn’t too risky. Notice all the MTA-100 IDC connectors. I have a tool for seating the wires in them which simplifies their assembly. The wire was included in the kit.
The front panel is the Bridechamber style, of which I have used several in the past. It’s a clean design, if somewhat different from Synthtech panels and the older Stooge panels.
Rather than use the knobs that came with the Synthcube kit, I decided to order knobs matching my other MOTM modules, i.e. TE Connectivity PKES90B1/4. Cost $3.00 apiece, but gotta have consistency!
What does it do?
Tony calls discontinuity a Waveshaper, Wavefolder, Clipper, Ring Modulator & Wavesplicer. It is a waveform modifier that works at any frequency from DC through high audio. Mostly it will be used for controlling timbre at audio rates, but it will work just fine mangling control voltages.
It has one input and three outputs (Main, Clamp, and Clip), plus four CV inputs (Threshold, Fold, Discontinuity, and Offset). All but the Offset CV have panel attenuator pots. For details and demos, I refer you again to the Discontinuity page at Oakley. I will be adding a video, but this module has too many controls to give an adequate demonstration. It’ll be just a taste.
Video Demo
For this demonstration the input comes from the triangle wave of a MOTM-300 VCO, threshold CV from the triangle wave of a MOTM-390 LFO, and fold CV from the triangle wave of a second MOTM-300.
The first part shows the Threshold value being modulated across the zero position. To the right, the threshold increases, chopping off smaller and smaller portions of the triangle wave (appearing truncated). Fully to the right, the threshold goes above the maximum positive value of the input, so we hear the original signal. To the left of center, threshold converts the input into a pulse wave, where modulation results in a PWM effect. When the modulation crosses zero, it alters between the two.
With the second VCO patched to the Fold CV, the result is four-quadrant multiplication with the input, i.e. ring modulation.
Other controls, Discontinuity, Fold, and Offset, are twiddled during the demo.
