How to Use an AUv3 Effect in AUM, GarageBand and Logic for iPad

An AUv3 is an Audio Unit plugin that runs inside another app on iPhone or iPad: AUM, GarageBand, Logic for iPad, Loopy Pro, Drambo, Cubasis and others. Most effect apps on iOS ship one. Here's how to get one running, using RasterFX as the example. The steps are the same for most AUv3 effects.

This is the cause almost every time. iOS only registers an Audio Unit after its app has been opened, so a fresh install is invisible to every host until you launch it once, all the way to the main screen. Then go back to your host.

Look under effects, not instruments. In AUM, add it to a channel's insert slot. In GarageBand, it's in a track's plug-ins. Some hosts put effects that also accept MIDI in a submenu, so check there if you don't see it.

A plugin can't talk to the App Store while it runs inside a host. So buy or restore any Pro unlock in the app itself. RasterFX reads the unlock from a file the app writes; open the app once, then close and reopen the plugin's window in your host.

Your host saves the plugin's full state with the session. Presets you save inside RasterFX are stored as the host's own user presets, so they show up in the host's preset menu too. Every parameter can be automated, and dragging the XY pad records as automation just like a knob.

Send MIDI to the effect and use it as modulation. In RasterFX, MIDI shows up as sources you can wire to any control: four CCs (1, 11, 74 and 71 by default), note, velocity and gate. A controller's mod wheel can open a filter, or a drum pad can trigger a burst of repeats.

Put RasterFX on a drum loop in AUM. Load a chain of filter, drive and delay, set a different sound in each corner of the XY pad, and drag between them while the loop plays. That's the idea of the app: build a chain, then play the transformation.

The AUv3 chapter of the RasterFX manual has the details, and troubleshooting covers the rest.