FAC Envolver Is A New Envelope Follower AUv3 Plugin For iOS

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FAC Envolver is a clever and easy-to-use envelope follower app for iOS with AUv3 support from Fred Anton Corvest!

Fred Anton Corvest is an iOS developer and released in the past great apps like the FAC Chorus, Maxima or the Transient, the first transient designer for iOS. He released recently FAC Envolver, an envelope follower iOS app with AUv3 support. A good feature is here the implementation of MIDI CC that allows you to use it with any kind of Synthesizer, even with hardware.


FAC Envolver is an envelope follower, this implies that it tracks the contour of the input signal and builds a corresponding envelope. Think of the envelope as the outline of the graphical representation of a rectified version of your input signal. By its very essence, it’s exactly what you get. But the process does not stop there and gives you the ability to modify the shape according to a set of provided parameters.

So it’s possible to define the rise and fall time as well as the depth of the envelope or also to invert it. Those parameters are the key to ensure the flexibility of the effect, and to meet the goal you are looking for. The previous lines are more a general presentation of what an envelope follower does, but the particularity of FAC Envolver, which makes it an outstanding and versatile tool, is that it delivers the envelope via MIDI control change messages or commonly referred to as CC.

The key is to map the CC number parameter to the volume, cutoff, resonance control of your synthesizer or effect units. By doing so you will get instant additional hands to tweak your parameters automatically depending on what you are currently playing.

The internal signal path is built around two independant channels, having one envelope circuit detection per input signal. So the left input signal is wired to the envelope one, and the right input signal is wired to the envelope two. FAC Envolver will breathe life into your sound, providing interesting natural modulation that will always be different by nature.


  • Detection of the contour of the input signal and output of the envelope via MIDI CC
  • Suitable for any situation: sidechain (VCA), wah VCF…
  • Stereo or Mono processing
  • Fine tuning of each envelope circuit; rising and falling time, depth and inverter
  • Parameterable MIDI CC number
  • Input signal can be attenuated, amplified or muted
  • Multi-waveform graph per audio channel: envelope contour layered over input signal
  • iOS Audio Unit V3 supported in compliant hosts

Available here: FAC Envolver 

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