FM AID_Dotcom_midFM AID is a module designed to perform through-zero linear  Frequency Modulation (FM) in the analog modular world. Any arbitrary signals can be used as a Carrier and Modulator. The module copies FM in how it is done in digital implementation, but in a completely analog circuit free of digital aliasing artifacts. Digital or software FM oscillators are mainly based on a ramp waveform which is then shaped to other waveforms. This is also represented in the FM AID module: sawtooth signal is expected on the Carrier input to give the indicated sine, triangle, sawtooth and square waveforms on the respective outputs. However the user is not limited to only use sawtooth for the Carrier and any other signal can be plugged giving many complex waveforms at the outputs.

All known FM tricks from digital implementation are also applied – you can endlessly experiment with the Carrier/Modulator frequency ratios, Modulation index (FM knob), Modulator’s amplitude shaping (CV knob), feedback FM (output is fed back to the Modulator’s input) and many other.

Carrier input has normalled connection to the Modulator’s input. This internal routing is disconnected each time a plug is inserted in the Modulator’s input. That is a handy option which allows the module to be used with only one signal source – this single signal will act as Carrier and Modulator at the same time. There won’t be any frequency differences between Carrier and Modulator in this case, but many interesting wave folding sounds will be available anyway.

Technically speaking FM AID uses Phase Modulation, not Frequency Modulation. The sonic difference is that the produces sound is brighter.

MSRP:  150 USD or 135 Euro for Eurorack version

200 USD for Dotcom version AID_silver AID_black





Carrier input level:  -5V … + 5V   (can also accept inputs ranging from

[-1V… +1V] to [-12V…+12V] / [-15V…+15V] using onboard trimmer)

Modulator input level:  preferably -5V … + 5V

CV input level:  preferably -5V … + 5V

outputs level:  -5V … + 5V

outputs impedance: 1 kOhm

module depth: 3 cm or 1,5 inches

power consumption: +45 /-45 mA  at +/-12 Vdc,
+50 /-50 mA  at +/-15 Vdc

Two simple oscillators with basic waveforms – saw, pulse, sine, triangle are used for Carrier, Modulator and CV. Also some sounds use ADSR and LFO for CV.


FM AID knobs tweaking. Mainly FM is swept from zero to max depth. Some of the sounds also have ADSR applied to CV input and tweaked too.

Great teaser videos by John L Rice

Demo by London Modular