You have a couple of USB microphones, or a mic and a USB device for your guitar. How do you record both devices into Garageband without resorting to a mixer or other expensive gear? As it turns out, your Mac can already handle multiple input devices with ease with this mostly hidden function.
When Two Devices Become One
This is both a tip and a trick. It’s a tip, because it’s likely you’ve been stymied by Garageband’s apparent limit of one audio input source at a time.
It’s a trick, because Mac OS X gives you the tools to trick Garageband into accepting multiple audio inputs at once.
So, you need to get Garageband to recognize multiple audio input sources at the same time. But Garageband only recognizes one plugged in audio device at a time.
What can you do to overcome the single input restriction when you need to mix and match audio sources for your Garageband recording?
Well, you could opt for a USB audio mixer, then drop in microphones and instruments. That would make Garageband happy.
Here’s what the problem looks like. One audio input source at a time is selectable in Garageband’s Input Source option.
How do you get multiple USB audio input sources at the same time into Garageband (for example, using two mics to create stereo audio)? As it turns out, that old standby app, Audio MIDI Setup, is on your Mac and ready to oblige.
Here’s how it works. Click the Plus sign in the lower left corner of Audio MIDI Setup and select Create Aggregate Device.
That gives you a list of all available audio input devices. It could be a USB mixer, a couple of USB microphones, or other USB devices that you want to record with Garageband.
Audio MIDI Setup lets you select multiple audio inputs and aggregate, or mix them, into one audio source.
Garageband wants a single audio source and that’s what you’re creating. Except the new source has multiple sources and Mac OS X takes care of the mixing.
Once you’ve selected your audio sources, go back to Garageband, open Preferences and click the Audio/MIDI tab, then select the Audio Input pull down button.
Your new multi-audio input source will be available for use.
You may need to check levels for each device, but this trick gives you additional audio input options without forking over money for more equipment.