Monitoring Pre and Post Sound Signal Levels
Most digital systems provide several options for monitoring sound signal meter levels during the home recording process. You can have prefader input levels, postfader input levels, prefader track levels, postfader track levels, and master bus levels. Even with the same signal, different kinds of levels (prefader, postfader, input, track master bus, and so on) may end up showing different readings on your meters.
The various levels:
Prefader input levels: The prefader input level shows you the level of the signal going into the mixer’s channel strip before the signal hits the EQ or fader (hence the term prefader). Your sound source and trim adjustment (either on the mixer or a separate preamp) control the level shown on this meter.
If your signal is too low or too hot and you don’t have a separate preamp, adjust the trim knob on your mixer. If you’re using a separate preamp, adjust the trim knob on your outboard preamp. You can also make adjustments to this level at the sound source. This could be either the output level of your instrument or the placement of your microphone.
Postfader input levels: The postfader input level shows your signal level after the signal has traveled through the input channel’s channel strip — that is, after the EQ and fader settings.
This level is different from the prefader input level only if your fader is somewhere other than unity gain (or 0dB) or if you’ve made some adjustments to the EQ.
To be specific, if you’ve removed any frequencies with the EQ or set your fader below 0dB, your postfader level is lower than the prefader level. Likewise, if you’ve added frequencies with the EQ or placed your fader above unity, your level is higher than it was going in.
Prefader track levels: This is the most important level of your input signal chain (that is, if a most important level exists). This meter shows you what is actually recorded to the hard drive of the recorder.
If you’re using an analog mixer and a stand-alone recorder, you see this level on the recorder, not the mixer.
This level matches the level of the postfader input channel routed to the recorder channel. If you have more than one input channel routed to a recorder track, this level is generally higher than each of the individual input postfader levels. This is because the signals combine to produce a higher overall level (called summing).
If this is the case and the prefader track level is too high, you need to adjust the levels on all the tracks that are routed to this channel to drop the level coming in (the submix fader level, if you have these tracks run through the submix bus).
Postfader track levels: The postfader track level shows you the level after you make adjustments to the track channel’s fader or EQ settings. Like the postfader input level, the postfader track level is different from the prefader track level if you’ve made adjustments to either the EQ or the channel fader settings.
Master bus levels: This level shows you the sum of all the levels being routed to the master bus. Unless you have only one channel going to the master bus, this level is different than any of the individual levels going to it because all levels from all the instruments are taken into account (summed).
This is the level that is most important when you’re mixing because this is the level that the 2-track master records.