Mac users should make sure that the appropriate audio input and outputs are selected. In Mac OS X, for example, the Sound system preference may give you a choice between a built-in audio controller and iMic USB audio system (assuming you have an iMic plugged in!) Similarly, in Classic Mac OS versions, go to the Sound control panel, and go to the Input tab, and make sure the proper input device (such as the iMic) is selected-- for the iMic, choose Line In... USB Audio , or External Mic: USB Audio. Activate the Check Signal Level box, and send a signal in from your audio device, testing that the signal level is showing up. Adjust the levels as required to get a signal of reasonable strength, that is close to the top of the green, flickering into the red. This makes sure that the levels of the sound coming into the computer are neither too low nor too loud, but just right.


Mac OSX Sound system preference



Mac (Classic) Sound control panel

About signal levels

The trick with recording (not just in the case, but in all sorts of recordings) is to get as hot a signal as possible that isn't too powerful. If your signal is too low, the quiet portions of the music can get lost in the ever-present background hiss and noise. So you want to boost your music signal as much as possible, relative to the background sound. However, if the signal is too high, the loud portions will over-drive the recording circuitry, causing audible distortion and clipping. Most recording software (and hardware) will include meters, (known in the trade as VU Meters). Typically, the top portion will be coloured red. While playing or recording, you're best off if the signal is high, going into the red momentarily. If it is in the red for extended periods, you're probably getting a distorted signal. If it's never in the red, you're probably too quiet.

You may be able to adjust the level with a Gain or Level control (as in the Mac Sound control panel or the Windows speaker controls), or with a volume control on your stereo. (Depending how you're hooked up, your stereo's volume controls may or may not affect the strength of the signal being sent from your audio equipment to your computer). If you can't control the levels at this stage, you're better off with a lower-strength signal; you can boost a quiet sound later, but if you've recorded a distorted signal, there's nothing you can do later to get rid of the distortion. However, if your signal is too low, you'll get a lot of background noise, and boosting the signal will also boost this noise, sometimes making the music unlistenable.

(Note: the Mac sound Control Panel has both a level control and a meter so you can see the effect of changing the level. This is a very good thing). 

On to Part 3: Ready to Record on the Mac

Last updated: July 7, 2003

The complete Burning CDs from LPs and Tapes series:

• Part 1: Getting Connected
• Part 2: Getting Set on your Mac or Windows
  
• Part 3: Ready to Record on your Mac or Windows
  
• Part 4: Making the Recording
  

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