In Greek mythology Medusa was a snake-haired woman whose visage turned those who looked at her to stone. By contrast, the Mod Medusa Euclidean LFO from Shakmat is a true beauty, albeit one that will seduce you with her many many charms, yet still leave you to live out your years in your soft, human form.
While being billed as a Euclidean LFO there are more than just strictly Euclidean patterns available in the Mod Medusa, and it packs in a total of eight different tables of patterns derived from Shakmat’s Knight’s Gallop and White Gallop modules. The four output channels are congruent by default but can also be set to work independently with per-channel control over various parameters. Continuously morphable waveshaping can be applied to the signals and there are several performative controls over the patterns themselves.
Clocking in at a relatively slim 12hp the Mod Medusa boasts an intuitive and clean layout with well-labeled controls and smooth knobs, solid pots, and robust feeling jacks that give the module a premium feel. There are manual controls for pattern length [up to 16 steps long], pattern density, wave shape, and wave symmetry and there is an array of buttons surrounding the pattern length knob for tap tempo, waveform polarity, peak syncing [more on that later], a length/menu button for various shift functionality, and two shift buttons for nudging patterns left or right along the grid. To the left and right of the pattern density knob are two sets of 4 LEDs and a selection button. On the left is the selection for pattern tables as well as the clock divider settings, and on the right is a combination of correlation mode selection and the gate input function assignments. All inputs and outputs are along the bottom of the module, and in addition to the four outputs, there are inputs for clock, a VCA, reset, the assignable gate input, as well as for voltage control over the pattern length, pattern density, and waveform shape and symmetry.
While dense with options and deep in functionality, the Mod Medusa is quite easy to use and users of other Shakmat modules will find themselves right at home. Patch any or all of the four outputs to various destinations, clock the module externally, or use the tap tempo button to set an internal rate, select a pattern table, and away you go. The row of four LEDs along the top of the module provide excellent visual feedback for the activity of each output channel and exploring the interplay between the waveshaping and symmetry controls, the pattern length, and density is enough fodder for tons of patch experimentation.
The output sequences derived from Mod Medusa’s eight pattern tables can be modified by four different correlated output modes: Main, Compute, Random, and Phase. While in the Main mode the output patterns for channels 2 through 4 are derived logically from channel 1. Compute mode associates channel 1 with channels 2 through 4 mathematically, with various multiplications and divisions based off of the pattern step length and sequence cycles. Random offers varying degrees of random variations across the second through fourth channels, and the Phase mode shifts each subsequent channel by the pattern length divided by four. In addition to the four correlated output modes Mod Medusa can be put into Independent mode in which the parameters of each channel can be individually set, though the CV inputs will only affect the settings of channel 1.
Sitting unobtrusively in the top half of the Mod Medusa are two features that really combine to enhance the flexibility and fun of the module; the Uni button and the P Sync button. The LFOs generated are bipolar by default but can be switched to be unipolar with the Uni button and I found this to be a very handy feature allowing for a lot of flexibility and variation for the modulation destinations. The peak syncing feature of the Mod Medusa allows you to choose where the positive peaks of the generated waveforms will fall relative to the clock pulse. When P Sync is off, the beginning of the wave will line up with the clock. When engaged, the waveform peaks are synchronized with the clock. Playing around with P Sync in conjunction with the Shape and Symmetry controls is super interesting. With the clocked and correlated signals you are able to push and pull the generated rhythms while never going off the rails, and the interplay between peaks and troughs, waveshape, and wave symmetry is fantastic. Changing polarity and peak sync applies to all four channels when in Correlated mode, but when in Independent mode, each channel can have different polarity and peak sync status.
There is an assignable gate input that gives you access to several flavors of ratcheting as well as Track and Hold and One-Shot modes. Triggering a ratchet multiplies the cycle rate of the LFO by the selected ratio [x2, x3, x4, random, accelerando, and deccelerando]. All pretty interesting, especially when coupled with the different waveshaping tools available on the module. Track and Hold lets the LFOs cycle normally when the gate is high and will hold when the gate is low and offers some really nice variations between the cycling modulation and the intermittent, but ever changing static voltage. One-Shot mode allows for channels to be cycling only while the gate is high, always dropping to 0v as opposed to the Track and Hold’s held level. Finally, a VCA input allows for the external enveloping of the generated LFO signal outputs.
With all the functionality packed into 12hp there are inevitably key combos and shift functions, but the Mod Medusa [and Shakmat modules in general], strikes a solid balance between immediate usability and deep functionality. Will I ever remember what the different Assignable Gate options are? Probably not. Does that detract from the absolute blast that four channels of tempo-synced Euclidian patterned LFO modulation madness brings to the table? Definitely not. The module is incredibly performative and lends itself well to spontaneous patch experiments. As an intuitive and accessible way to quickly add movement and rhythmic interest to any patch it excelled. I really enjoyed using the outputs as AD envelopes, and because of the sharp trigger-like LFO shapes that can be dialed in, it can even double as a percussive trigger pattern generator. Exploring the multitude of different relationships between the four outputs via the selectable modes give it a much wider ranging suite of rhythmic options than more typical Euclidian patterning, not to mention the ability to customize each channel’s settings independently. The Mod Medusa manages to be both complex and straightforward, deep and intuitive, and above all highly musical.

12 HP +12v 55mA -12v 30mA
Price: $275

shakmatmodular.com