SynthCase 2 Patchable Roadcase Synthesizer


This project is the second in a series of synthesizer "multi-modules" that will be built in heavy-duty equipment road cases. Check out the first SynthCase project here and the third SynthCase project here. The second SynthCase will be primarily composed of signal processing modules, with a trio of VCOs included as well.

Below is the road case chosen for this project, prior to being cleaned and prepared.

With the case looking good and ready to go, two panels of 1/8th inch aluminum plate were cut to 12 1/2 by 17 1/2 inches and mounted into the case using four "L" brackets for each panel.

The main synthcase power supply circuit was expanded to power the new modules. The updated schematic is below.

There are many great synthesizer modules with pcbs available these days, which means there were a lot of choices for modules to include in this project. There are also some interesting module designs out there without pcbs available. Below is a summary of what is included in SynthCase 2.

The first module is the Triple "Living" VCO project from J.H. Since the CV processing portion of the pcb was not going to be used in Synthcase 2, that part of the pc board was sheared off and saved for a later project. Additional waveshaping circuitry was added to each VCO using perf board, consisting of a standard sawtooth to triangle convertor and Ian Fritz's OTA Feedback Sine Shaper circuit. Next is the JH Polymoog Resonator project, followed by Ian Fritz's Double Pulse Generator. This last circuit was built up on perf board as well. Then there is Neil Johnson's 3 Pole State Variable VCF, Ken Stone's Bi-N-Tic VCF, and Thomas White's Buchla Lowpass Gate. There will be two separate switchable vactrols included for different response speeds. The first panel is finished up with two Dixon/Gallo/Irwin VCAs and two basic mixers.

The second panel begins with a J.H. Triple Chorus and then three of Ken Stone's Bandpass Filers. Next is a J.H. Tau Phaser, followed by a J.H. Variable Slope Filter/Phaser and a J.H. Interpolating Scanner. Finally, two Thomas Henry MAP VC Analog Delays, one using the original SAD4096 and the other modified to use the SAD1024. Pcbs for these were etched using the toner transfer method, and voltage controlled regeneration was added using a Ray Wilson dual VCA pcb.

Two regulator circuit boards using LM317/337 parts were built up using perf board for the pcbs that did not come with on-board regulators, one for each half of the case.

Below is the planned module layout.

Next, a 300 dpi scale drawing was created with all of the hole location markings and labeling for each panel:

The drawing files were emailed to a local printer who printed each one on to a single piece of white bond paper and then laminated them using low-gloss matte type plastic laminate.

The laminated graphics sheets were taped to the aluminum panels and all of the holes were center-punched.

Then, after removing the graphics sheets, each hole was pilot drilled, drilled to size, and deburred.

Each panel was then cleaned and the back of each graphics sheet was slightly scuffed with steel wool. The laminated graphics sheets were then attached to the panels permanently using 3M type 77 spray adhesive, and all of the holes were cut to size out of the laminate with an Exacto knife.

Here is a rear view of the two panels with all of the connectors, controls, and indicators mounted:

And here is the front view of SynthCase 2 with the hardware assembly completed:

Next up, installing and wiring up the pc boards, then testing and calibration. Here is a series of pictures showing how the work progressed on the bottom half of the wiring:

Each module was fully tested and calibrated before moving on to the next one.

Here's a larger picture of the finished bottom half, everything completed and working:

Then the top half wiring was completed module by module:

And finally a picture of the finished top half wiring:

And so the second SynthCase has been successfully completed! The mixture and quantity of new modules are a great addition to the first Synthcase, making a significant and exciting expansion to an already versatile system.

Don't forget to check out The Peasant's first SynthCase project: SynthCase 1

The Peasant has completed the third SynthCase project: SynthCase 3

The SynthCase is controlled using The Peasant's Banjo Processor

Sometimes The Electronic Peasant lets The Celtic Peasant play the SynthCase with her Keyboard Controller