JOMOX / Mod FM

Mod FM is a self-contained 8-voice FM synth-voice module in Eurorack format. It provides quick access to the desired FM sound without complicated patching or setup.

Mod FM has four operators and two LFOs/VCOs per voice; the FM engine is of course digital, but each voice has two analog filters and an analog VCA to add analog warmth and depth to Mod FM.

Each voice has individual CV/GATE inputs and outputs. There is also a MIX OUT for separate even/odd output, which can be used to mix and output internal effects such as delays and reverbs. It also has a variety of external CV inputs for modulating each operator individually or controlling the FM envelope.

In addition to the CV/GATE controls, the instrument has a Type-A format TRS MIDI in/out and a USB Type-C connector that can also handle MIDI.

In addition, Mod FM allows multi-timbral playing. In multi-mode, each voice can play a different sound. Up to eight single presets can be combined and stored as a multi preset.

Mod FM offers a hybrid approach of modular synthesis flexibility and preset reproducibility.

Feautures
Matrix FM
Four operators are arranged in a matrix, with each operator (= sine wave oscillator) modulated by the other three. Sixteen potentiometers in the matrix adjust the amount of modulation (FM amt) and the frequency of the fundamental for each operator. The frequency of the bass note for each operator can be set with the knobs located diagonally from the top left corner.

There are several Overtone modes that set whether the operator is controlled by a keynote (or CV) or locked as an overtone of a particular operator.

Each operator has an ADSR envelope. This envelope can also be used for frequency modulation of the operator.

Algorithm.
Mod FM has 26 algorithms derived from the 4-operator DX9 algorithm.

The frequency mode of each operator can be changed to a fixed frequency that does not track to keynotes. Frequencies can be set in 1Hz increments, which is useful when creating sounds such as percussion instruments.

LFO/VCO
Two LFOs per voice can modulate the frequency (FM) or amplitude (AM) of the operator; the LFOs have 64 different waveforms, which are shown on the OLED display display.

The LFO can be switched to a VCO that covers the entire audio range; the VCO can be tracked to keynotes or mixed into the signal path. in VCO mode, the FREQ parameter is changed to a detune parameter The FREQ parameter can be used to control the sound of the keyboard. This can be used to create classic sounding square wave/saw wave analog bass or string pads.

Filters
Each voice is equipped with an analog filter using the SSI2140 from Sound Conductor. This is a modernized version of the SSM2040 designed by Dave Rossum and used on the Oberheim synthesizer and early SCI Prophet-5.

The filter has a classic 24dB output and a 12dB state variable multimode filter output. 3 filter characteristics (LP/BP/HP) can be continuously crossfaded with the SHAPE parameter. 24dB/12dB filters are The outputs can be mixed.

The ADSR envelopes of the filters operate with a quick response. The filter section also features an LFO with 64 different waveforms.

The VCAs are the same high-speed transistor VCAs used in all Jomox drum products, perfect for creating crisp drum and percussion sounds.

The analog voice board features another sound source, Metal Noise. It can be mixed into the filter independently of the digital FM engine to create strange sounds.

FX
Mod FM also features a FX section with reverb and two delays. These are applied only to the stereo mix output. Delays can be tempo-synced via MIDI. Very short delay times in the millisecond range can be used to create flanging effects.

Specifications
8 multi-timbral FM synth voices
4 operators per voice
Full modulation matrix / 26 algorithms
2 LFOs/VCOs per voice
CV/Gate input for each voice
CV input for operator modulation
Individual and mixed outputs for each voice
Onboard analog filter/VCA
24dB low-pass filter
12dB state variable multimode filter
MIDI TRS Type-A input/output
USB Type-C connector
Digital reverb, stereo delay x2
Fully storable, even CV-amounts can be saved
128 presets, 118 multi-preset
Two 28 x 64 px OLED displays

Width 56HP
Depth 40mm
Current consumption +12V : 370mA
-12V : 170mA