ALM Busy Circuits FMco
Compact 2-operator FM synth voice with chords in 8HP
8 HP Eurorack module
The ALM045 FMco is a compact 2-operator FM synthesis VCO and complete voice in 8HP. Its custom DSP - inspired by ALM's Akemie modules but tuned for a more immediate, modern sound - gives manual and CV control over FM index, ratio and eight operator waveforms. An 'endless' clickable encoder handles fast, accurate tuning, and a built-in decay envelope (triggered via Trig) drives both FM depth and output level so the module works as a self-contained voice. CV-selectable four-voice chords with inversion feed a stereo-widened Left/Right output.
Features
- 2-operator FM synthesis voice using a custom ALM DSP (inspired by the Akemie series, tuned for a modern sound)
- Manual and CV control over FM Index, Ratio and operator waveform
- Eight operator waveshapes: Sine, Half Sine, Rectified Sine, Pulse Sine, Alternating Sine, Camel Sine, Square, Sawtooth
- 'Endless' clickable encoder tuning with octave / semitone / cent increments
- Double-click the encoder to reset pitch to C3 (~261.63 Hz)
- Ratio control with Lock switch for free or integer-locked operator ratios
- FM Index CV input with a bipolar attenuverter
- Wave CV input with a dedicated attenuator
- Built-in decay envelope routed to FM depth and the output VCA via the Trig input
- CV-selectable four-voice chords with 17 voicings including Castle Detune
- Chord inversion via the Inv CV input
- Stereo-widened Left / Right outputs
Controls & Jacks (19)
- Freq
- Status LED
- Lock
- Ratio
- Wave
- Index
- Wave Attenuator
- Index Attenuverter
- Chord
- Decay
- V/Oct
- Chord CV In
- Wave CV In
- Index CV In
- Trig In
- Inv CV In
- Ratio CV In
- Out L
- Out R
How-To Guides
- Basic FM lead / drone
- Triggered FM pluck (self-contained voice)
- CV-morphing waveform
- Four-voice chord stab
- Inharmonic / bell timbres
Explore the interactive FMco panel on BleepDex — tap any control to learn what it does.