Introduction - Adding new Audio Unit effects and instruments
GarageBand's range of effects and software instruments can be expanded simply by adding plug-ins known as Audio Units, some of which (both freeware and shareware) are reviewed on this site. This article explains the basics of what they are and how to use them with GarageBand.
What are Audio Units?
Audio Units are an Apple-created plug-in standard for audio applications. The idea is that an Audio Unit plug-in will work with any audio application on your Mac, and although in practice some applications use different plug-in types (Cubase, for instance, uses VST plug-ins, a standard devised by Steinberg way before the days of OS X), GarageBand, being an Apple product, sticks to Apple guidelines and will accept only Audio Unit plug-ins.
As far as GarageBand is concerned, Audio Units come into two types effects and software instruments but the way you add these to two types your system is identical, and it is in fact impossible to tell, from simply looking at an Audio Unit component, which type it is. Both have the same standard icon:
(Though, note that some developers will give their Audio Units a custom icon.)
How do you install a new Audio Unit?
You can download free and shareware Audio Units from a number of sites on the web (see the Links page for suggestions). Once downloaded, the majority do not have an installer, but require you to move the component manually onto the right place on your hard drive.
So, where do Audio Unit Components go?
They should be copied to the Components folder in the Plug-Ins folder in the Audio folder of your Library folder (which is in your Home folder). In OS X shorthand, this is ~/Library/Audio/Plug-Ins/Components/. (To save yourself burrowing about in the Finder, you can copy that path, choose Go to Folder... from the Finder's Go menu, paste, then press the Go button to get there.)
Once the Component is in the Components folder, it will be available when you next start up GarageBand.
A couple of notes before we get to how to use this new Audio Unit in GarageBand, though. When you download a freeware or shareware component, it may come with a Read Me file or documentation. This might contain different installation instructions, though this is rare, but always check. There may also be a manual, which it is a good idea to read.
Also, a useful tip: as it is impossible to tell an Audio Unit Effect from an Audio Unit Software Instrument just by looking at it, you might want to use the Finder's Label feature to give the icon a colour, say, green for effects and blue for software instruments.
How do you use a new Audio Unit in GarageBand?
So you've downloaded you new Audio Unit, gone through all the foofaraw of dragging it into the right folder (why can't OS X automatically put plug-ins into the right Library folder, like OS 9 used to do when you dragged extensions onto the System folder?), and now you open up GarageBand and look around for a sign that your favourite music-making app has been transformed by its brand new plug-in.
Well, you have to hunt around a bit, thought not too much, fortunately, and in different places according to the type of plug-in you've just added.
Using a new Audio Unit Effect
Let's look at how to use a new effects plug-in first. This is just the same as using any of GarageBand's standard effects. You create a new track, or bring up the Track Info window for an existing track and click on one of the two effects popup menus. You'll find GarageBand's standard effects listed at the top of this menu, then, under the grey heading Audio Unit Effects, you'll find you new effect listed in alphabetical order.
Select it, then click the pencil-styled edit button to change the parameters for the new effect. When you play your song, you'll hear it in operation.
Using a new Audio Unit Instrument
This is slightly more complicated. New Audio Unit Instruments don't appear in GarageBand's browser-like list that you see when you create a new track not until you create a preset with them and save it. (See the Generators article for how to do this.) Instead, they appear in the Generators popup. Create a new track, open the Details... triangle at the bottom of the window, and open the Generators popup menu. As with new Audio Unit Effects, instruments are listed in a section below GarageBand's standard instruments, under the grey heading Audio Unit Modules.
Simply select your new Audio Unit Instrument by name, click the edit button to make any changes (if creating a track, you will have to click Create then bring up the Track Info window again to do this just a quirk of GarageBand), and you can start using your new Audio Instrument.
So, which Audio Units should you use?
At the Getting more out of GarageBand site, we have several reviews of freeware and low-cost shareware Audio Unit effects and instruments. Check out the Articles Index for a few ideas.