Electro-Harmonix Q-Tron+ Envelope Filter + FX Loop


  • Drive (Up/Down)
    selects direction of filter sweep : upwards or downwards.
  • Norm/Boost
    Normal mode allows setting the Gain control without changing the output volume.
  • Peak (Q on the Mini Q-Tron)
    Determines frequency peak of filter. Makes more "effected sound" when turned up more.
  • Gain
    Functions as both a volume control and a filter sensitivity control in boost mode. In normal mode it acts only as a filter sensitivity control, unlike the Mutron-III which also changes the unit's output volume.
  • Range (Hi/Lo)
    Emphasizes vowel like sounds in low position, overtones in high position.
  • Mode (LP/BP/HP/Mix)
    Select the filter used by the effect: Lowpass, Bandpass, Highpass or a mix of Bandpass with dry unprocessed sound.
  • Response (Slow/Fast)
    Selects either a slow, smooth, vowel-like attack or the fast, snappy response of the original Q-Tron.


Designed by Mike Beigel, inventor of the legendary Mu-Tron III envelope filter.


"The ultimate envelope follower! Same as the original Q-Tron but with added Effects Loop and Attack Response Switch. The Effects Loop lets you place an additional effect between the Q-Tron+'s preamp and filter section without changing the envelope drive. The added Response Switch lets the player choose between a slow, smooth, vowel-like attack and the fast, snaked response of the original Q-Tron."

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