|This page describes support for Audio Unit effect plug-ins in Audacity. Audio Units is a plug-in architecture developed by Apple and is only supported in Audacity on Mac OS X / macOS.
Audio Unit support
In a new installation of Audacity, Audio Units already existing on the system are not enabled by default, but can be enabled in Audacity's Plug-in Manager. To install newly obtained Audio Units into Audacity, please see this page in the Manual.
Audio Unit "MusicEffects" are supported. This class of Audio Unit supports audio input like pure "Effect" AU's but has the ability to use MIDI input to set effect parameters. Audacity doesn't yet accept MIDI input, so although MusicEffects should work fine as audio effects, parameters need to be set manually. Examples of MusicEffects are all those from DestroyFX, Ohm Force and SFXmachine, plus FXpansion Snippet, Tobybear MadShifta and u-he MFM2.
Like VST plug-ins in Audacity, Audio Units display their full GUI interface by default, where one is provided. If interface difficulties arise with any particular effect, click its "Manage presets and options" button, then "Options...", uncheck "Enable graphical interface" and restart the effect. This limits that effect to a tabular interface with sliders.
Antares Auto-Tune Evo
This plug-in only has a tabular interface which is apparently a problem in some other Audio Unit hosts also.
Apple AU GraphicEQ
AU GraphicEQ has an inherent limitation that it cannot be resized in use, so that if more bands are selected than fit on the screen, not all the selected bands will be accessible. As a workaround, close the plug-in with the required number of bands selected, then re-open it. All the selected bands will now be accessible.
Apple AU MatrixReverb
AU MatrixReverb only outputs in stereo and needs a stereo track to work on, so cannot be used on a mono track. It seems to be the only one of the built-in Audio Units plug-ins that has this limitation. For a workaround, select the track by clicking in its Track Control Panel above the Mute/Solo buttons, then. Click on the dropdown arrow in the Track Control Panel of the upper track > . After processing with AU MatrixReverb, click the arrow again > , click the arrow once more in the upper track and make it Mono, then delete the lower track by clicking on the [X] in the Track Control Panel.
Slow launch in older versions of Audacity
Prior to Audacity 2.0.5, Audacity loaded all detected AU plug-ins on launch. This could cause Audacity to take several minutes to launch or to be slow to quit if older AU plug-ins were found or if the user had a large number of AU plug-ins. Audacity 2.0.5 onwards only loads AU plug-ins when they are requested from the Effect Menu, so if you experience slow launch or slow quit, upgrade to the latest Audacity version from http://audacityteam.org/download/mac.
Plug-in crashes while Audacity is open
If Audacity crashes when an Audio Unit is launched from the Effect Menu or applied to the audio, you can restart Audacity then try disabling the effect in the Plug-in Manager. This effect will then not be available in Effect Menu.
If Audacity crashes immediately after you enable one or more Audio Units in Plug-in Manager, the effect(s) that crashed should be disabled next time you launch Audacity. They will be relisted in Plug-in Manager as "New" rather than "Disabled".
Alternatively if the same plug-ins also misbehave in other audio applications you can move them from <Your Home>/Library/Audio/Plug-Ins/Components or /Library/Audio/Plug-Ins/Components which will cause them to be listed as "Disabled" in Plug-in Manager after you restart Audacity.
If preferred, you could restart Audacity then disable all AU effects in Audacity in Effects Preferences, which again removes them from Effect Menu.
Crash or hang on launch
In the unlikely event that an AU plug-in crashes or hangs Audacity on launch, you can look in the Mac Crash Report to find the AU plug-in that caused the problem. You can capture the crash report if required by clicking in the report, COMMAND + A to select all, then COMMAND + C to copy. Alternatively you can find the crash reports in the system logs. Open Finder, then chooseand type:
or on OS X 10.10 Yosemite:
If you are on OS X 10.4 or 10.5, type:
Then move the offending plug-in(s) from the Components folder as above.
If crashes or hangs on launch persist after moving individual plug-ins, you can disable all AU support in Audacity by using the audacity.cfg settings file. Force-quit Audacity if it is still running (Option - Command - Esc). In Finder, use ~/Library/Application Support/audacity/. Look in that "audacity" folder for audacity.cfg.then type in
Open audacity.cfg in TextEdit. If Audacity has never quit cleanly, you may need to create audacity.cfg by usingin TextEdit.
To disable Audio Units, edit (or add) an "AudioUnits" entry to audacity.cfg so it looks like this:
If you are creating audacity.cfg from scratch, enter all these lines:
Then save the changes to audacity.cfg and restart Audacity. If Audacity still hangs then the problem could be with VST Plug-ins. If you don't need VST plug-ins in Audacity, you can edit/create audacity.cfg so that VST plug-ins are also disabled:
General instability after installing plug-ins
Sometimes it may be unclear what type of plug-ins have caused Audacity not to launch, or you may possibly notice Audacity has become generally less stable after installing plug-ins of various types.
In that case it may be best to reset Audacity so that it only loads the enabled effects it came with on first installation. To do this, quit Audacity, open Finder, use ~/Library/Application Support/audacity/. In that "audacity" folder, delete the pluginregistry.cfg and pluginsettings.cfg files and restart Audacity. Then you can use the Plug-in Manager dialog to selectively enable effects to find the possible culprit.then type in
|If you identify any specific AU, VST or other plug-ins that are problematic in Audacity, please contact our feedback address.|
OS X 10.10 Yosemite
Although some third-party Audio Units worked from the outset in Audacity on Yosemite, Apple Audio units failed to open due to Audacity's prior lack of Cocoa support. Support for Apple Audio Units on Yosemite was introduced with Audacity 2.1.0.
OS X 10.4 Tiger and 10.5 Leopard
Due to the changes in 2.1.0 to support Audio Units on Yosemite, Audacity 2.1.0 and later do not run on Tiger. Additionally, 2.1.0 and later do not support Audio Units on PPC Macs running Leopard.
The last version of Audacity for Tiger and the last version that can run Audio Units on PPC Macs running Leopard is Audacity 2.0.6.