Jomox Mod FM – 8-Voice Eurorack FM Synthesizer

The Jomox Mod FM is a fully self-contained 8-voice FM synthesizer in Eurorack format. Combining a digital FM engine with true analog filters, VCAs, and modulation capabilities, the Mod FM bridges the gap between classic FM synthesis and analog warmth.

With 4 operators per voice, 2 LFOs/VCOs, and full multitimbrality, the Mod FM delivers everything from metallic FM tones to snappy techno percussion and lush, analog-style textures. Each voice is fully independent with its own CV/Gate inputs, dedicated output, analog filter, and VCA, making it one of the most flexible FM synths available in Eurorack.

Key Features

• 8 voices, each fully multitimbral

• 4 operators per voice with full modulation matrix (26 algorithms)

• ADSR envelopes per operator, frequency modes (key-tracked or fixed Hz)

• 2 LFOs per voice (64 waveforms), switchable into full audio-range VCOs

• Dedicated analog filters per voice (SSI2140 – modern SSM2040 design)

  • 24 dB low-pass

  • 12 dB multimode LP/BP/HP with continuous crossfade (shape)

• True analog VCAs per voice for snappy response

• Metal Noise generator for extra percussive/experimental textures

• FX engine: stereo reverb + 2x delay (syncable via MIDI clock; includes flanging-style micro delays)

• Matrix interface with 16 endless encoders + dual OLED displays for fast editing

Connectivity & Control

• CV/Gate per voice

• CV modulation inputs for each operator

• Dedicated outputs for each voice + stereo mix out (odd/even split)

• MIDI I/O (TRS Type A) and USB-C (MIDI over USB)

• Full storeability of sounds, including CV amounts

• 128 presets + 118 multi sets (multi mode = independent voices with individual sounds)

Specifications

• Sound Engine: Hybrid FM (digital operators + analog filters/VCAs)

• Operators: 4 per voice, arranged in full modulation matrix

• Algorithms: 26, derived from DX9 architecture

• LFOs/VCOs: 2 per voice, 64 waveforms, switchable to audio range

• Filters: SSI2140 per voice, 24 dB low-pass + 12 dB multimode

• Envelopes: ADSR for operators + filters

• FX: Stereo reverb, dual delay (MIDI-sync)

• Displays: 2× 128×64 OLED

• Presets: 128

• Multis: 118

• Power: +12V 370 mA / –12V 170 mA (≈ 6.5 W total)

Dimensions

• Width: 56 HP (≈ 284 mm)

• Height: 3U (≈ 129 mm)

• Depth: 40 mm