Mod Squad: Three for Two

A trio of modules that fill 2HP gaps in your rack
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It never fails: You scrimp and save to buy your favorite Eurorack modules, only to find that a slight miscalculation has left you with a tiny unfilled space in your rig. And nobody wants that!

Until recently the solution was to use either a blank or mult panel, but I’ve found three products that will fill that 2HP hole with something far more useful and exciting.


Like its namesake, if this module were any slimmer, it would disappear. Utilizing the Analog Devices AD633 four-quadrant analog multiplier chip, the Circuit Abbey Twiggy (; $99) puts two ring modulators at your fingertips. Because the multipliers are DC-coupled, you can use them effectively with control voltages. Consequently, when dynamics control is needed, the circuits can be drafted into service as VCAs or CV-controlled attenuverters.

Meng Qi Dual Passive Lowpass Gate

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It’s not uncommon to have more modules than power-bus connectors. But before you reach for that passive mult, check out the Meng Qi Dual Passive Lowpass Gate (; $60 street). As its name implies, the DPLPG requires no power but gives you a pair of 1-pole (6dB/octave), vactrol-based LPGs/VCAs in a skiff-friendly module. According to the manufacturer, the vactrols are hand-picked for their musicality. And at this price, the DPLPG is almost an impulse buy for those who can’t get enough of that “Buchla bongo sound.”

Qu-bit Electronics Eon

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If you really want to get the most out of those two blank spaces, check out the Qu-bit Electronix Eon (; $150). It not only has three main operational modes—square wave oscillator (tracking 1V/oct), envelope (linear or exponential), and digital noise (with down-sampling capabilities)—it can produce random gates, cycling envelopes, and an LFO with a triangle waveform. The two outputs provide the added functionality based on the mode you’re in—envelope and end-of-attack gate, square wave oscillator plus triangle-wave LFO, or noise and random gate output. Eon is the kind of module you’ll use for many years to come.