FM synthesizer


FMeron is a frequency modulation (FM) synthesizer, controlled by the pitch and dynamics of your bass or guitar.


It starts with two pure sine wave oscillators which both track the frequency of the notes you play into it. One oscillator, called the Modulator, is not heard directly – instead it's used to modulate the frequency of the main oscillator, called the Carrier. This modulation transforms the pure sine tones into all kinds of clangs, bells, and intense electronic timbres.

The octave switch allows FMeron's synthesized tones to track one octave below, one octave above, or at the same pitch as your playing.


FMeron also includes an envelope generator, triggered by plucking the strings of your instrument. This envelope can be set to ramp up (Attack) or down (Decay) when triggered, and can either control the amount of FM (thus the intensity of the added harmonics over time) or the volume of the synthesizer voice, for slow-attack or percussive, plucky sounds.


FMeron is designed in collaboration with engineer Don Stavely.



Visit the Iron Ether Pedals shop



Mod Freq: Sets the frequency ratio between the Carrier and Modulator oscillators, which defines the type of harmonics generated by FM. In addition to stepping through these harmonic ratios, this special control also allows fine tuning above and below the in-tune “sweet spots” indicated by the markers 1-4 around the knob. Detuning the two oscillators farther from these sweet spots results in more atonal and bizarre timbres.

Attack/Decay: Sets the speed and direction that the triggered envelope sweeps. To the left, the envelope will start low and sweep up when triggered by a note pluck (Attack). To the right, it will start high and sweep down (Decay). Turning the knob farther from center increases the length of the envelope, so all the way counter-clockwise is a very slow Attack, and all the way clockwise is a very slow Decay.

Env Depth: Sets how strongly the envelope affects the FM amount or Synth Volume, depending on the Env switch.

Clean: Controls the level of the clean signal. 

Synth Vol: Controls the volume of the synthesized signal.

FM: Controls the amount of frequency modulation. At 0 (fully CCW), the waveform is a pure sine wave with no harmonics. As this control is turned up, the harmonic complexity increases. 

Env switch: Assigns the generated envelope to control either the FM amount or the Synth Volume (Amplitude).

Oct switch: Sets the octave of the Carrier Oscillator relative to the notes you play, one octave up (+1), one octave down (-1) or at the same pitch (=)


Low-noise, low-distortion active components chosen for excellent audio fidelity.

Measures 4.7″ x 2.5″ (12cm x 6.3cm). 

Runs on industry-standard 9 volt DC center-negative power supply. 85mA current draw.

Relay-based true bypass.

All jacks are located at the top of the pedal to save pedalboard space.

Learn more about the construction of IE pedals here.


Connect an expression pedal to the EXP jack to control the FM amount in real-time while playing. When an expression pedal is connected, the FM knob controls the maximum level of frequency modulation to which the expression pedal can sweep.