MXR M-120 Envelope Filter



  • Threshold
    Varies the sensitivity of the filtering action; i.e. the degree of brightness obtainable from a given input level. Sensitivity increases as the control is rotated clockwise. The user may find that more subdued effects are appropriate for accompaniment textures such as rhythm guitar, while a brighter sound is suitable for solo lead playing.
  • Attack
    Varies the attack time of the filter; i.e. the time required for the cutoff frequency to reach its peak. At full clockwise position, the filter responds almost instanteously. Counterclockwise rotation of the control gradually lengthens the attack time. Longer attack times serve to create a "wa" at the beginning of each note played.


an MXR brochure

The MXR Envelope Filter is a professionally designed, competitively priced tone modifier which enables you to create a wide variety of "wa-wa" sounds. The Envelope Filter is a voltage-controlled, low-pass filter in which the upper cutoff frequency is determined by the amplitude, or level of the input signal. The louder the signal, the higher the cutoff frequency. The loudness of the signal therefore controls the "brightness" of the sound.
Two controls are provided on the MXR Envelope Filter. A Threshold control varies the sensitivity of the filtering action. An Attack control varies the attack time of the filter. At full clockwise position, the filter responds almost instantaneously. Longer attack times serve to create a "wa" at the beginning of each note played.
The MXR Envelope Filter may be used with any electric keyboard or stringed instrument, including guitar, bass, piano, and clavinet. The Envelope Filter will add variety and expression to both solo and accompanying performances.

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  • Maximum Input Level
  • Input Impedance
    150k Ohms
  • Output Impedance
    5k Ohms
  • Dynamic Range
    95dB (typical)
  • Equivalent Input Noise
  • Filter Frequency Range
    150Hz to 3kHz
  • Power Requirements
    9 volt battery, 1.3 mA
  • Power Consumption
    12 mW.


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