# FAC Envolver — FAC Fred Anton Corvest

> MIDI effect processor with envelope follower, noise gate, and trance gate for audio manipulation. (iPhone/iPad app by Frederic Corvest.)

- Source: https://appshunter.io/ios/app/fac-envolver/id1378195291 (this page in markdown: same URL + `.md`)
- Developer: [Frederic Corvest](https://appshunter.io/developer/1230164765)
- Category: Music
- Price: $9.99
- Rating: 4.90/5 from 41 App Store ratings · 14 written reviews indexed
- Age rating: 4+
- Requires: iOS 10.0 · 25 MB
- Languages: American English
- Released: 2018-05-16
- Data updated: 2026-08-15
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/fac-envolver/id1378195291/reviews.md

## What is FAC Envolver?

Being a MIDI effect in its essence, controlling your synthesizers parameters (e.g volume, cutoff, res) with MIDI CC and notes, FAC Envolver is also able to transform the input audio via two exclusive effects: a Noise Gate and a Trance Gate. This combination is the key to breathe life into your sound, providing interesting natural modulation and sequences that will always be different by nature.

Under the hood, FAC Envolver is an envelope follower delivering MIDI data generated from the contour of a signal. The source of this signal may come from two distinctive circuits: the first one is a classic envelope follower and the second one is a rythmical pattern called trigger gate. Both circuits are responsible for providing a signal envelope that can be altered by a set of parameters and delivered as MIDI control change messages (CC).

The generated signal envelope also passes through a gate detection mechanism driven by a threshold. When the signal goes above the threshold, the gate is open and when the signal goes below, the gate is closed. This open/close sequence provides a second envelope which is delivered as MIDI CC (on/off) and notes. The pitch of the note may be set within the effect or from an external value provided by MIDI input. Both may follow a particular scale progression.

The envelope follower circuit also provides a noise gate to control precisely the level of your audio signal. This uses the same open/close sequence built by the gate detection mechanism that delivers MIDI data but acts on the audio. Following the same logic, when the second circuit - the trigger gate - is engaged, the open/close sequence provides a trance gate style effect to the audio.

FAC Envolver is a stereo effect and provides two slots, one slot per channel. Both can be linked to facilitate the manipulation. The audio can also be turned to mono and the dry and wet audio can be mixed.

## Key features

- MIDI CC and note control
- Envelope follower
- Noise gate
- Trance gate
- Stereo effect with linked channels
- Adjustable pitch and scale progression

## Recent user reviews (10 of 14)

All indexed reviews: https://appshunter.io/ios/app/fac-envolver/id1378195291/reviews.md

### 5/5 — Super useful for niche cases

*2023-09-08*

I’m using this to create an audio-responsive MIDI CC values for some custom MIDI-controlled LED lights. I simply load Envolver onto an audio channel in AUM, use AUM’s built in LPF to isolate the bass, then use Envolver’s envelope follower to output MIDI CC of the volume to a MIDI out interface. It’s awesome! Thanks for the great app!

### 5/5 — Great utility

*2023-07-26*

This is a super useful utility plugin. I’m using it as an audio envelope follower in AUM which then sends MIDI cc’s based on the amplitude of the signal to my lighting rig. Easy audio-responsive lights!

### 5/5 — Great with drum triggers!

*2023-04-07*

FAC Envolver is a fantastic app that I highly recommend for anyone looking to trigger midi notes from drum triggers. The app is incredibly easy to use, and it provides a wide range of features and options to help you create unique and interesting sounds.

The app also provides a wide range of features for triggering midi notes from drum triggers. You can choose from different note values, velocities, and even select specific midi channels to trigger. This gives you a lot of flexibility and control over your sound, so you can create exactly what you're looking for.

The app is designed with a sleek, modern interface, and it comes loaded with a variety of presets and sound effects. Whether you're looking for a classic drum machine sound or something more experimental, you're sure to find what you're looking for with FAC Envolver.

Overall, I highly recommend FAC Envolver to anyone looking for a powerful and intuitive app for triggering midi notes from drum triggers. Whether you're a professional musician or just getting started, this app is a must-have for your toolkit.

### 5/5 — Yup another winner

*2022-01-27*

This developer only makes great apps.

### 5/5 — It’s Fred...

*2020-04-19*

What more do u need to know.

### 5/5 — Fabulous!

*2019-10-18*

Truly!

### 5/5 — A versatile midi power tool

*2019-10-18*

Whether you’re looking for a random midi note generator, trance gate, or creative ways to manipulate filters and effects in your favorite synth apps, this app does it all in a very easy to master and powerful interface.  Extremely highly recommended for anyone who uses midi in their studio or live environment.

### 5/5 — 5 Star App

*2019-09-25*

Like all of Frederic’s apps! BUY THEM ALL!

### 5/5 — Great app!

*2019-06-05*

Just like every FAC apps. Highly recommended for serious musicians. Makes your music sound better!

### 5/5 — Very useful!

*2019-02-07*

Envolver is the envelope follower you need to dynamically drive effects directly from sound! The inverse envelope is great for ducking other channels if you have a midi controllable mixer. The two separate followers mean you can do some very controlled mixing! I hope there’s more in the future ... like adding a pitch detector to plonk external midi notes, but this is plenty of goodness!

## Frequently asked questions about FAC Envolver

### What is FAC Envolver?

FAC Envolver is a MIDI effect processor that controls synthesizer parameters like volume and cutoff using MIDI CC and notes. It also includes exclusive Noise Gate and Trance Gate effects to add unique modulation and sequences to your sound.

### How does FAC Envolver generate MIDI data?

It acts as an envelope follower, generating MIDI data from the contour of an input signal. This signal can come from a classic envelope follower circuit or a rhythmic trigger gate pattern.

### Can FAC Envolver process audio directly?

Yes, FAC Envolver includes a noise gate to precisely control audio signal levels and a trance gate effect that applies a rhythmic open/close sequence to the audio.

### What devices is FAC Envolver compatible with?

FAC Envolver is available for iPhone, iPad, and iPod. It is a paid app priced at $9.99.

### How often is FAC Envolver updated?

The latest version, 2.3, was released on April 13, 2020. The app was originally released on May 16, 2018.

### What is the user rating for FAC Envolver?

FAC Envolver has a very high user rating of 4.9 stars based on 40 ratings, indicating strong user satisfaction.

### Does FAC Envolver have ads?

No, FAC Envolver does not contain advertisements. It is a paid application.

### Can the note pitch be controlled in FAC Envolver?

Yes, the pitch of the generated MIDI notes can be set within the effect or from an external MIDI input, and can follow a specific scale progression.

## Version history (last 5 releases)

### 2.3 — 2020-04-13

• NEW: Support of user presets saved from hosts
• NEW: Import/export of presets from/to "Files" (from the host App)
• Update of the support dialog in the host app
• Fix missing USB input interfaces in host app
• Fix Laggy WaveForm viewer on iPad Pro
• Fix minor UI issues

### 2.2 — 2019-06-05

• NEW FEATURE: Addition of different views for portrait and landscape mode (iPhone/iPad)
• NEW FEATURE: Dynamic resizing according to the size provided by the host

Hey, I'm Fred developer of FAC. We share the same passion: MUSIC. A wonderful universal language and an amazing source of happiness.

FAC is a one person business, and as you may guess designing such apps is a very long process. Want to support? Please rate and review Fac Envolver, and check out my other apps. You are my motivation, and as I’ve already tweeted, your support provides me an instant coding nitro boost. So the more you give the more you receive.

### 2.1.1 — 2018-12-22

• Consolidate view configuration management (Center View Position)
• Bug Fixes and stability improvement

### 2.1 — 2018-09-22

• Replace MIDI Note Gate chart by dashed lines
• Update rise and fall ranges
• Update some labels and colours
• Addition of a new preset (SQ BrB Tom)
• Bug Fixes, Stability And Performance Enhancements

New in 2.0
• Two circuits: Env Follower and Trigger Gate (Audio/MIDI fx)
• Each circuit provides MIDI out (CC/Note) and optional audio transformation
• Env Follower provides a Noise Gate with threshold, hysteresis and curve smoother
• Trigger Gate provides a Trance Gate Style fx with optional resolution and patterns
• Stereo/Mono processing - a slot per channel
• Fine tuning of each slot; rising and falling time, bias, depth and inverter
• MIDI IN/OUT support: CC#, channels, int/ext note pitch and scale progression
• Multi-waveform graph: input signal, env contour, gate signal and threshold
• Host tempo sync

Note: The MIDI/AUDIO combo makes FAC Envolver usable in every host, even the ones that still do not provide MIDI out support, in this case the MIDI generator is disabled and the fx can be used as standard AUDIO fx.

### 2.0 — 2018-08-03

• Two circuits: Env Follower and Trigger Gate (Audio/MIDI fx)
• Each circuit provides MIDI out (CC/Note) and optional audio transformation
• Env Follower provides a Noise Gate with threshold, hysteresis and curve smoother
• Trigger Gate provides a Trance Gate Style fx with optional resolution and patterns
• Stereo/Mono processing - a slot per channel
• Fine tuning of each slot; rising and falling time, bias, depth and inverter
• MIDI IN/OUT support: CC#, channels, int/ext note pitch and scale progression
• Multi-waveform graph: input signal, env contour, gate signal and threshold
• Host tempo sync

Note: The MIDI/AUDIO combo makes FAC Envolver usable in every host, even the ones that still do not provide MIDI out support, in this case the MIDI generator is disabled and the fx can be used as standard AUDIO fx.

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## More apps by Frederic Corvest

- [FAC Chorus](https://appshunter.io/ios/app/fac-chorus/id1230164766)
- [FAC Maxima](https://appshunter.io/ios/app/fac-maxima/id1323117302)
- [FAC Transient](https://appshunter.io/ios/app/fac-transient/id1354088081)
- [FAC Bandit](https://appshunter.io/ios/app/fac-bandit/id1458633968)
- [FAC Alteza](https://appshunter.io/ios/app/fac-alteza/id1489369665)

All apps by Frederic Corvest: https://appshunter.io/developer/1230164765

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-15.*