Record Your Music with the Straight-Line Rule
Most professional engineers are taught to record by using the straight-line rule. This is a good rule to follow if you’re recording at home also. This rule comes from the old days of analog recording. Following this rule is considered not only good engineering practice, but also a courtesy to any other engineer who may handle your tracks.
The straight-line rule basically involves setting up your input levels so that they roughly match the levels that you want when you mix the song. You do this by setting your channel fader at 0dB (also marked as Unity on some mixers) and adjusting your input gain (the trim knob on your mixer or preamp) until you have a clean signal (no distortion) on the recorder’s meters.
The signal’s level needs to be approximately the same as the level of the instrument in the final mix. For some instruments, such as a snare drum, the level peaks close to 0dB, but on other instruments, such as the string section, the level may be near –10dB.
If you follow the straight-line rule, when you’re ready to mix your tracks, set all your faders at 0dB — and you’ll have a rough mix.
The courtesy is that if someone then takes your recorded tracks to another system with another engineer, that engineer only has to set the faders at 0dB and everything is ready for final adjustments.