This short tutorial will walk you through the steps to allow you to use two USB microphones on one Mac to create a recording.
* Macintosh with 2 USB ports
* Two USB microphones (they can be XLR mics with USB interfaces)
* Soundflower (free) from http://cycling74.com/products/soundflower/
* Audio HiJack Pro ($32) http://www.rogueamoeba.com/audiohijackpro/
* Two humans who want to talk on the air
Advantages of this method are that it’s very inexpensive using mostly tools you already have on your Mac, and it allows you to stop and start during the recording process to edit as you go.
Disadvantages of this method is that your two speakers will be combined into a single channel in GarageBand so you will not be able to independently adjust their voices and it’s a little bit complicated to set up initially.
Install Soundflower & Audio Hijack Pro
From the Cycling74 Website:
Soundflower is a Mac OS X (10.2 and later) system extension that allows applications to pass audio to other applications. Soundflower is easy to use, it simply presents itself as an audio device, allowing any audio application to send and receive audio with no other support needed. Soundflower is free, open-source, and runs on Mac Intel and PPC computers.
Download and install Soundflower. It will now show up in your Sound control panel and in other applications as an audio device.
Download and install Audio Hijack Pro. We will be piping the audio from the two microphones into Soundflower using Audio Hijack Pro, and then Soundflower will be the input to Garageband.
Configure Audio Hijack Pro
Plug in both your microphones first. Launch Audio Hijack Pro and click the plus sign in the bottom left to add an audio device.
Set Source Type
Audio Hijack Pro is capable of hijacking many types of devices. in this case we want to use the pull down for Source Type and choose Audio Device.
Set Audio Input Device
Use the pulldown next to the Input Device to choose your first microphone. In this example our first microphone is an XLR microphone using a Blue Icicle USB interface, so the microphone’s name is Blue Icicle.
Set Audio Output Device
Use the Output Device pulldown to choose Soundflower (2ch) as the output device. Ignore the 16 channel option.
Verify your Settings
You should now see that you have an audio device with the input as your first microphone and the output as Soundflower (2ch). Repeat this process for your second microphone, also setting the output device to Soundflower (2ch).
Select the first microphone, then click the Hijack button. It should appear depressed and then verify that on the right it shows that you’re hijacking and how long you’ve been hijacking. Repeat for your second microphone. Now you have successfully created one audio source out of two USB microphones.
Open GarageBand Preferences
In the preferences, click on the Audio/MIDI tab, and set the Audio Input to Soundflower (2ch).
All that’s left is to start recording in GarageBand and you’ll hear both of the speakers on the two separate microphones. Note that the two voices will be combined into a single channel and you will not be able to independently edit the voices. You can, however, stop and start during the process and edit as you go rather than having to do it in post (which most people do not enjoy).