SYNTHESIS TECHNOLOGY—MOTM SYNTHESIZER

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FIG. 1: The MOTM system encourages DIY customization. When Robert Rich’s system outgrew its original rack case, he built a wooden cabinet that holds about 40 modules, upgraded the power supply, and rewired the power distribution. (Click image for pop-up)

Synthesis Technology grades most modules by difficulty (1 is the easiest, 5 the most difficult) and, in some cases, indicates the amount of time it will take to build the module. For this review, I built the MOTM-110 VCA/Ring Modulator module, which has a difficulty rating of 2. It took me about four hours to build.

The documentation that comes with the modules is clear and precise, featuring thorough assembly and testing instructions, schematics, and calibration procedures. The kit includes everything except a soldering iron, tools, and a voltmeter. The wires are even precut, stripped, and tinned. The module worked perfectly the first time I plugged it in, and I calibrated it in a few minutes to within a millivolt of specification. Now I have a deeper respect for the thought and precision that goes into the design of this high-quality system.

Perhaps you don’t want this kind of intimacy with your instrument. Even if you choose to buy your modules completely assembled, you could find yourself getting your hands dirty: the MOTM system encourages hands-on interaction, and you’ll get better mileage from it if you have a knack for DIY (see Fig. 1).

Kicking the Tires
The various modules’ components—1/8-inch-thick aluminum faceplates, large instrument-grade knobs, high-quality Switchcraft 1/4-inch jacks, sealed Bourns pots, and low-leakage capacitors—show attention to detail throughout. The circuit boards have solid ground planes and mount to a steel backplate that helps shield against unwanted hum and noise (see Fig. 2).

FIG. 2: Synthesis Technology's attention to detail and its modules high-quality components can be seen in this view of the MOTM-300 Ultra VCO circuit board (Click image for pop-up)

Through its care in the design process, Synthesis Technology has overcome the problems that plague most modular systems. One interesting and useful design feature is the placement of the I/O jacks in the module’s lower section, which keeps the patch cords away from the controls. Synthesis Technology’s modules have a high signal-to-noise ratio, impressive thermal stability, and low leakage and hum. The sound is neither dry nor clinical; you can easily saturate the filters and make them growl, just as you can with an old Minimoog or a Sequential Circuits Prophet-5.

Synthesis Technology also has a conservative approach to design. MOTM modules will never fulfill the addiction to blinking lights that some analog junkies have; only four of the modules sport LED indicators. According to the designer, each LED adds noise to the system in the form of added current drain and switching transients. By avoiding gratuitous flashing, each module’s sonic performance is improved. It seems like a fair trade-off, but I wish a few of the modules (especially the envelope generators) gave a visual indication of activity.

The MOTM modules fit neatly into a 19-inch rack by mounting to steel brackets (available from Synthesis Technology) that horizontally span the rack rails. Each module is 5U high and comes in multiples of the 13/4-inch width: single-, double-, and triple-width. Five double-wide modules fit the traditional 19-inch rack.

The modules are less than five inches deep, so they are shallow enough to fit into a 12-space SKB pop-up mixer case. Depending on the configuration, those cases can hold 10 to 12 modules (see opening photo).

The MOTM system is continually evolving, and new modules are due for release every few months. Although the current module selection seems a bit conservative, it provides a strong foundation for a system that will grow into a monster in the near future. (Synthesis Technology says that three new modules will be shipping by the time this goes to press.)

The current module selection includes a VCO, an LFO, a sample and hold with noise, a VCA and ring modulator, an envelope generator, a voltage router, a suboctave multiplexer, and three filters.

Reprinted with permission from

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