Mode Machines
OMF-1 Rack Analog Filter

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Item: N13-5466

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OMF-1 Rack Analog Filter
OMF-1 Rack Analog Filter OMF-1 Rack Analog Filter OMF-1 Rack Analog Filter


The Mode Machines ‘OMF-1’ is a Rack-Mountable Analog Filter featuring a four pole true analog filter. This is based on the famous transistor ladder filter developed by Dr. Bob Moog in the 1960s. A front panel pot controls the filter cut-off frequency, another controls the resonance. The resonance control is configured not to cause volume drop when turned up. The filter can be made to oscillate if required.

Two filter outputs are available. One is the Fizz output. This is a type of -6dB/octave filter and it gives a unique filtering effect with a real bite. The other is the Smooth output. This is a classic -24dB/octave filter, and gives a smooth warm analogue filter sound. Each filter output goes via its own reversible attenuator. This means not only can users adjust the output level, but also the phase of the output signal. This allows complex filter shapes to be made when the two outputs are mixed together in various degrees. This includes a very nice sounding band pass filter.

A wet/dry control allows the filtered audio to be mixed with the original signal. Not only is this useful in controlling the depth of the effect, but it can also create unusual phasing and vibrato type effects.

A wide range pre-amplifier is included. Users can use the OMF-1 with virtually any input from guitars to synthesizers. A peak indicator will allow users to monitor overloads, although the OMF-1 is designed to overdrive beautifully.

An inbuilt low frequency oscillator with triangle and square waveforms. The frequency can be changed from 0.05Hz (one cycle in 20 seconds) to over 50Hz. A bi-color LED gives visual indication of the speed of the LFO. Use the LFO to create auto wah and phaser type effects. The LFO can also be selected to trigger the envelope generator.

There is also on-board an ingenious dynamic envelope section that can move the filter cut off point up or down. It can be put into one of three modes at a flick of a switch. In FLR it can function as a useful envelope follower, with controllable attack and decay times. Perfect for simulating many classic dynamic follower filter boxes. Play louder and hear the filter open up. In AD it can be a standard attack-decay envelope generator. This is a type of one shot envelope, that rises and falls at the presence of an initial trigger signal. Useful for percussive type sounds. In AR it can be a standard attack-release envelope generator. This is triggered either by the LFO, external gate signal or by an automatic audio trigger circuit with a variable threshold level. Powerful for creating rising crescendos.

The final output volume can be controlled with a level control. The output circuitry is configured to drive long length cables with ease and without ground loops.

A side chain input is available. This is a second audio input that can control the main input, but is not heard directly. Use this to trigger the envelope generator, or drive the envelope follower. A common use of this is to make the main audio program respond to a drum machine’s output for syncopated effects. Use a deep rich string patch as the main input, and listen to the drum machine automatically pulse the output to the beat. Awesome!

CV and gate inputs are available for connection to a modular synth or midi-CV convertor. The CV input will control the filter frequency, and the gate control will trigger the envelope generator if selected.

With a second OMF-1 a stereo unit may be built. The two channels can either be run independently or linked together for true stereo processing. 


  • Mode Machines OMF-1 Rack-Mountable Analog Filter
  • A four pole true analogue filter based on the famous transistor ladder filter developed by Moog in the 60´s
  • Built in Wide range Pre-amplifier suitable for most audio sources
  • Side Chain Input
  • CV and Gate inputs to control the Filter Cut Off and Envelope from your Modular/Analog gear
  • Self Oscillation if desired

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  • True analog classic filter
  • 13 knobs & 4 switches for direct access to all the parameters
  • Audio In-/Out 6,3 mm Jacks
  • Dimensions: Standard 1U Rack
  • Robust metal chassis
  • Weight: 2 kg
  • PSU: 15V – 18V AC wallwart included

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