O3A Reverb

The plugins in the O3A Reverb library generate realistic 3D reverb to simulate acoustic spaces or add "magic" to a mix.

The plugins are:

  • O3A Early Reflection
  • O3A Reverb - MS3
  • O3A Reverb - MS5
  • O3A Reverb - Convolution
  • O3A Reverb - Shaped Convolution
  • O3A Shoebox

These are higher order ambisonic (HOA) VST2 and AAX plugins for macOS (10.7+) or Windows (Win7+) running on 32bit/64bit Intel. They can be hosted in some Digital Audio Workstations (DAWs) that can handle tracks with at least 16 channels. Options include Reaper, Pro Tools Ultimate, Pyramix and Max/MSP.

These plugins use the SN3D ambisonic convention, at third order, although FuMa impulse responses can be used.

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O3A Reverb


Algorithmic Reverb

There are two versions of our algorithmic reverb. The "MS3" reverb has a simple parameter set (just ten dials) whereas the "MS5" has so many that they don't all fit on screen at once! The MS5 is great when you need fine control.

Both reverbs come with presets.

O3A Reverb - MS3 Screenshot

3D Reverb

The algorithm is a true 3D surround reverb - it produces ambience all around, even above and below! The input and output of this plugin is a O3A stream, as produced by 3D tools like the O3A Core.

O3A Reverb Diagram

If you are working with other surround formats, you will need to convert to a full O3A 3D mix, perhaps by using one of the O3A Upmixer plugins, and later convert back using decoders in the O3A Core, O3A Decoding plugin libraries, or Rapture3D Advanced's AAX or VST2 plugins. There are many other good things you can do to your mix while it is O3A form.

Early Reflections

Also, it can generate specific early reflections that are literally reflections: sounds on the left can be reflected to the right and so on, and manipulated in level and time depending on the reflection's direction and distance.

Up to six reflections are provided by the MS5 reverb. There's also a separate O3A Early Reflection plugin that can be used to add just one.

O3A Reverb - MS5 Screenshot

Late Reflections

The late reflection engine can produce a rich decaying texture with many reflections spread out in space and time. It can be tuned to produce textures from rough and ringy to soft and sumptuous, and its controls can be tweaked live.

Convolution and Shaped Convolution Reverb

Convolution reverbs use recordings of real spaces ("impulse responses") to generate highly realistic reverberation.Two convolution reverbs are provided: a simple one, "O3A Reverb - Convolution" and a much more sophisticated one, "O3A Reverb - Shaped Convolution". In both cases, the impulse responses used are themselves ambisonic and contain 3D detail. These can be sourced in various ways, for instance from the Open Acoustic Impulse Response (Open AIR) library or from acoustic modelling software like CATT-Acoustic or Odeon.

O3A Reverb - Shaped Convolution Screenshot

The Shaped Convolution reverb allows the directivity of the output to depend on the directivity of the input. This solves the common problem with convolution reverbs where, after adding reverb, all sound seems to come from the same place.

This can be used to create a wide range of effects. Reverb can stay in the directions of triggering sound sources, or bloom slowly out into the whole space, all while keeping the original character of the impulse response. This plugin is often used to shape just the first part of a reverb response, leaving its tail alone.

"Shoebox" Simulation

The O3A Shoebox plugin works differently. Rather than processing a complete 3D O3A scene, this works like a surround panner, placing a single mono sound source into an acoustic simulation of a shoebox-shaped room. Of course, the output is a 3D O3A sound scene which can be processed further or added to your mix.

Up to 128 early reflections can be simulated in real-time, using dynamic surface reflections with control of acoustic absorption, and high quality delay lines. We've been uncompromising with the design and the plugin can use a lot of CPU, but we hope you'll be impressed with the results, particularly for moving sources.

O3A Shoebox Screenshot

Plugin List

O3A Early Reflection

I/O: 16 in, 16 out

This plugin simulates a single early reflection, but applies it to a complete 3D O3A audio scene.

O3A Reverb
O3A Reverb - MS3

I/O: 16 in, 16 out

This plugin adds high quality synthetic reverb to a 3D O3A soundfield. It uses the same algorithms as the MS5 reverb but has a simplified control interface.

O3A Reverb
O3A Reverb - MS5

I/O: 16 in, 16 out

This plugin adds high quality synthetic reverb to a 3D O3A soundfield using a highly configurable directionally-dependent early reflection model and a rich late reflection model.

O3A Reverb
O3A Reverb - Convolution

I/O: 16 in (but mono input to the convolution core), 16 out

This plugin performs convolution reverb based on a WAV file with up to sixteen channels.

O3A Reverb
O3A Reverb - Shaped Convolution

I/O: 16 in, 16 out

This plugin performs convolution reverb based on a WAV file with up to sixteen channels. The reverb output can be shaped by the input directivity, so the spatial output is not only determined by the WAV file.

O3A Reverb
O3A Shoebox

I/O: 1 in, 16 out

The O3A Shoebox operates like a panner, but simulates up to 128 dynamic acoustic reflections off the walls of a virtual shoebox-shaped room.

O3A Reverb

Tech Requirements

O3A Plugin Technical Requirements

Please check that everything is okay here before purchasing software.

Operating System

Supported versions of Microsoft Windows are Windows 7, Windows 8 and Windows 10. Supported versions of Apple macOS X are 10.7 or later, Intel only. The VST plugins are available in 32bit or 64bit forms on both platforms (packaged as a Universal Binary on macOS). The AAX plugins are 64bit only.

VST Host

The VST plugins require a VST 2 host with shell plugin support.

These plugins do not work with all VST 2 hosts. One reason for this is that the O3A plugins need large numbers of channels on their input or output busses. Check the individual plugins for the channel counts they need, but all of the O3A plugins need at least 16 channels on each track, and a few need more. Also note that not all VST 2 hosts can use shell plugins. In particular, at the time of writing shell plugins are not supported in Nuendo or Cubase.

AAX Host

The AAX plugins require Pro Tools Ultimate, or Pro Tools HD v12.8.2 or later.

Due to channel and stem restrictions, not all plugins are supported in AAX. Please see the documentation for details.

PC Hardware

Please check your PC meets the following requirements:

  • Intel Pentium D CPU or better.
  • 200MB of free disk space.
  • Internal network card.

Internet Connection Required

These plugins require an Internet Connection for license activation and verification. We don't really like this, but we can't think of a better way to discourage piracy! Please don't hack our code, it's taken a lot of effort to get it this far...

Successful license verification isn't required every time you use the software, but it is needed during installation and needs to succeed once every couple of weeks to keep the license fresh.

The license can be "revoked" to remove it from one machine so it can be moved on to another. You should also do this if you're updating your system in case the machine appears to have changed identity.


You'll need administrator permissions while installing on Windows. The software won't install properly using a "restricted" account.