Synthetic Sound Labs Releases ThunDrum

Eurorack two oscillator FM percussive membrane / metal based drum voice module      05/09/21

Synthetic Sound Labs Releases ThunDrum

Synthetic Sound Labs has released its Model 2140 ThunDrum module, which they describe as a flexible two oscillator FM percussive membrane / metal based drum voice in 8 HP Eurorack width. Here's the details in their own words...

SSL experimented with hundreds of modular patch variations to get to the best combination of simplicity and tonal versatility in a reasonably priced, compact and user-friendly format.
The main Tone oscillator (VCO) has a linear control response and is adjustable from zero (not thru-zero) to several kilohertz, but the key to the 2140's unique sound is its enveloped linear FM (frequency modulation).

A secondary wide range "sine" FM oscillator output is routed thru an internal VCA (FM Amount).  As pre-patched, the modulation depth is controlled by the Envelope output.  This allows higher harmonic contents at the beginning attack of the envelope, which trail off as the tone decays.  Of course, this is entirely under your control, and you can easily patch around this normalization and create your own variations.

The main Tone oscillator is designed to "stall" (zero frequency) at the lowest settings so that you can get unique musically useful pulsing effects when modulated.

The Tone oscillator can be frequency modulated (FM) from:
    •    A secondary wide range FM oscillator with initial and external amount controls
    •    External linear CV input with attenuator for controlling the overall pitch
    •    Envelope control of pitch with (+/-) reversible attenuator

The waveform Color control goes from triangle, to pseudo-sine to rounded square waves.  Using an external filter to control the harmonics can make some really cool sounds.

ThunDrum's inputs and outputs provide a great deal of creative patching capabilities.  Features include a lighted trigger button and quality pots that allow adjustment over a wide tonal palette.
The ThunDrum employs a unique circuit that allows more natural sounding tones by preventing output clicks caused by sharp unsynchronized envelopes.

    •    Tone Pitch
    •    Tone Color
    •    External Pitch Amount
    •    Pitch Envelope Amount (+/-)
    •    FM Rate
    •    Ext FM Amount
    •    Initial FM Amount
    •    Envelope Decay Time
    •    Trigger Button (lighted)

    •    FM Amount CV
    •    Pitch CV: Bipolar +/- 5V. Roughly linear
    •    Decay / Choke CV: 0 to 5V
    •    Trigger: Logic ~1.2V threshold

    •    Envelope: 0 to ~5V
    •    Audio: AC Coupled

Frequency / Decay Ranges
    •    Tone VCO: 0 to ~9 KHz
    •    FM Oscillator: Approx. 15 Hz to 2.2 KHz
    •    Envelope Decay: Approx. .002 to 8 Seconds

SSL uses quality fiberglass-epoxy printed circuit boards, precision automated robotics combined with meticulous hand-crafted assembly assure years of trouble-free service. Synthetic Sound Labs has been in the analog synthesizer business since 1973.  The 2140 is yet another in SSL's growing line of new synthesizer modules, proudly made in the USA and available directly from SSL and through our fine distributors.

Pricing and Availability:

More information:


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