Connecting Musical Instruments to Your Computer

There are basically two types of musical instruments: electric and acoustic. An electric instrument has a built-in interface for output of its sound, but an acoustic instrument needs a microphone to record its sound.

Electric instruments include electric guitars, keyboards, and electric bass.

You can connect an electric instrument directly to the computer's audio-in port, if your computer has one. The computer audio-in port is a 1/8-inch mini input, so you will need an adapter or cable to convert the ¼-inch output from your instrument to the 1/8-inch audio-in port (mini input) on the computer.

To record an acoustic instrument or vocals, you can connect a microphone to your computer through the audio-in port. G5 computers also include optical digital audio-in/out ports for higher-end audio recording equipment.

You can also connect an audio interface to your computer and then connect your microphone or instruments to the audio interface. There is a wide range of audio interfaces and compatible formats, including USB, FireWire, PCI, and PC cards. With the addition of an audio interface, GarageBand allows you to record up to eight Real Instrument tracks and one Software Instrument track simultaneously. So you can record one instrument at a time or the whole band at once. An audio mixer or console will also record more than one instrument or microphone at once, but it will mix all the inputs into only one stereo track. You'll see an example of multitrack recording later in this lesson.

For recording one Real Instrument track at a time, I use the EDIROL PCR-A30 audio interface/MIDI keyboard controller. This interface is both a MIDI controller and an audio interface.

Make sure any audio interface is compatible with Mac OS X 10.4 or later (for GarageBand 3) and that your computer supports the format used by the interface.

Also, always follow the manufacturer's instructions, and be sure you install the correct driver on your computer.

Setting Up Sound Input Preferences

If you plan to record through the audio-in port or optical digital-in port on your computer, you will need to set the System Preferences accordingly.

Let's change the preferences to record through your audio-in port. If your computer doesn't have an audio-in port, you won't be able to make the changes, but you'll know how to do it if you ever use GarageBand on a Mac with audio-in.

1.	Click the blue apple to open the Apple menu. This menu is always available, even when you're running an application.
2.	Choose System Preferences from the Apple menu. The System Preferences window opens.
3.	Click the Sound button to show the Sound Preferences pane.
4.	In the Sound Preferences pane, click the Input button. The input options on your computer will reflect the current audio devices and hardware you are using. It is very likely your input options will be different from the ones shown in the screen shots.
5.	Select the audio interface you will be using for the recording. If you are using the audio-in port on your computer, select Line In from the sound input list. Likewise, if you are using the optical digital-in port, select that option.
6.	Play a riff on your instrument and watch the input level on the Input level meter. Drag the Input Volume slider to raise or lower your input volume levels as needed. The Input level meter shows the level of your input from left to right. Left is the lowest input level (quietest), and right is the highest (loudest). If your input levels are too high, you will "overdrive" the input, which means the recording is louder than the device can handle, and your music will be distorted. If the device you select does not have input controls in the Sound Preferences pane, you can raise the output volume on your instrument or device. For this exercise, I'm using the EDIROL PCR-A30 audio interface/MIDI keyboard controller as an input device. As you can see in the screen shot, this device does not have an Input Volume slider in the Sound Preferences pane.