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.



A small donation would show your appreciation and enthusiasm to keep this project moving along. Thank you

ALTEZA Fred Anton Corvest

Exospheric Space Simulation Processor

Download on the App Store Download on the Mac App Store
  • True stereo reverberator
  • Amazingly lush and beautiful
  • Shimmer kind effect, harmonizer
  • Two ultra low latency pitch shifters
  • All-Pass delays fine tuning of the main and feedback sections
  • Two mixable input sources for the feedback section
  • Independent Dry/Wet Control
  • External Sidechain Input and Multiple Outputs support
  • Includes various presets for inspiration
  • iOS AuV3 - Universal (iPad/iPhone)
  • macOS AuV3 - Supported by Logic Pro X, Garage Band, Hosting AU and Reaper

Main features

Designed for ethereal lush sound textures and dreamy space reflection, FAC Alteza is the perfect solution to bring your instruments to heaven in no time. Thanks to a powerful feedback section containing, inter alia, two pitch shifters, the unit is able to deliver the very typical "Shimmer" sound kind effect very much prized by musicians that are making ambient music, or any kind of music that needs to be carried by a fabulous angelic evolving choir section.

FAC Alteza is definitely not "another shimmer reverb..." effect because it comes with additional parameters that make it very versatile. A particular attention to each part of the signal path was necessary to reach this level of high-end quality.

Here some features that make FAC Alteza an outstanding unit:

Following the diagram below, the sound flows from the left to right or from the input to the output.

Input (prior the reverb)
  • Stereo In keep the input signal stereo or make it mono
  • HPF Cutoff high pass filter
  • Dry amount of dry signal
  • Wet amount of wet signal
Reverb and Modulation (Stage 1 and 2)
  • Size defines the size of the reverb, from small to big
  • Diffuse (DIFF) regulates the initial growth of echo density
  • Rate rate of the modulation
  • Depth (DPTH) level of the modulation
  • Stage the number of All-Pass delays* involved, up to 8
Feedback (Stage 3)
  • Feedback defines the amount of signal fed back to the reverb
  • Diffuse (DIFF) regulates the initial growth of echo density
  • Pitch Shifter 1 (PTS1) raise or lower the pitch
  • Pitch Shifter 2 (PTS1) raise or lower the pitch
  • Source (SRC) IN for harmonizer or RV for shimmer
  • LPF set the damping of the high frequencies
  • Stage the number of All-Pass delays* involved, up to 8
External Sidechain Control COMPLIANT HOST ONLY!
  • Duck Wet controls the threshold of the compressor. Set to OFF position to disable the ducking
  • Curve defines how fast the compressor reacts (attack and release)

*All-Pass delays or APF for All-Pass filters

💡 Diffuse (Diffusion) Parameter And Number of All-Pass delays per stage

The diffuse parameter regulates the initial growth of echo density and settles the reflection. To understand properly how the diffusion behaves, you should experiment the parameter with a very percussive sound. When the value is less than 50% the signal goes from dry to faded in, then above 50% the signal becomes much more dense and constant to finally become percussive again but with a longer tail.

The number of All-Pass delays (APF) involved in stages will also have an effect on the behavior of the diffusion. A single All-Pass delay will provide a kind of classic delay. Once again, experiment to get a good idea on how those parameters alter the signal.

Warning: the three parameters (Stage 1-3) will generate a little glitch when the value is altered, this is the expected behavior. You will probably hear it while switching the presets.

💡 Always check your audio levels

In general, use the gain and feedback in parsimony, to avoid any excessive levels that may damage your ears or your system. FAC Alteza shall not be liable for any loss or damage of whatever nature (direct, indirect, consequential, or other) to your material (software, hardware, or other).

💡 External Sidechain Control

The knobs "duck wet" and "curve" are only visible when an additional input bus is provided by the host. Beware that some hosts may provide a muted additional input bus with no support of the sidechain feature, you will see the knobs but the ducking will be ignored. In this case, set the knob "duck wet" in OFF position.

Make sure you are providing a external signal which is strong enough, this is very important to get optimal ducking. Do not forget that only the wet signal is ducked, lower the dry signal to monitor properly the ducking effect.

💡 Multiple Outputs support

An other Audio Unit extension named FAC Alteza (MULTI OUT) provides an additional output of the stage 3. Warning: to use this additional extension you need an AU host supporting multiple outputs (AUM, ApeMatrix). If not, use the regular FAC Alteza Audio Unit extension.

As with all FAC products, the interface has a unique sober look and provides a great user experience. The value of each knob can be monitored at any time. The knobs are very responsive, natural and follow a specific curve according to the parameter type.

Preset Management

FAC Alteza also comes with factory presets to provide you a source of inspiration to satisfy your needs in any situation you might require.

The preset button provides common management features: loading, organization, and saving. The left and right arrows allow fast navigation shortcuts among all the presets (factory + user), a short press on the center label provides a detailed list of all the available presets, select the one you want to work with. On the other hand a long press (hold) provides contextual operation. For factory presets it's possible to save the current preset to a user preset, for user presets it's possible to rename, save and delete the current preset.

FAC Alteza --- PromoOfficial Promo Video FAC Alteza --- Pre-Release DemoPre-Release Demo (The Sound Test Room) FAC Alteza --- AUM PreviewAUM Preview FAC Alteza --- Ken Karsh - Meditation MomentMeditation Moment (Ken Karsh) FAC Alteza --- Martin Neuhold - Ambient JamAmbient Jam (Martin Neuhold) FAC Alteza --- Maria Calfa-DePaul - Casio Mt-68 live improvCasio Mt-68 live improv (Maria Calfa-DePaul) FAC Alteza --- OSX DemoOSX Demo

FAC Alteza - AUM

FAC Alteza - NS2

FAC Alteza - Garage Band

FAC Alteza - Beat Maker

FAC Alteza - Logic Pro X

Check out what musicians think about FAC Alteza

It sounds absolutely amazing!! I love the sound and diversity of it! I have Meris Mercury7 pedal, inspired by the Bladerunner soundtrack. Your app is going into that direction too. So I’m already sold!!

Thomas Büchel

It’s immersive! I swam around in that vast effect for a good hour and never got tired...but certainly got inspired

Frederick King

With reverb like that I could play a chord, have a bath, have dinner, have 40 winks, watch a bit of telly, come back and it'll still be running


Fred Anton Corvest is simply genius. All his plugins are totally off the any scale, and this one is no different

Ray Subject

I got a big sky for my birthday last year and love all those amazing algos but you FRIGGING NAILED THE SHIMMER MAN!!!!! I haven’t heard the Big Sky coming close, it’s crazy sir!!!


This effect is incredible, and is practically an instrument all by itself!


Download on the App Store Download on the Mac App Store