Home Recording Mixer Basics: Channel Strip Signal Flow
One of the most important things to understand when recording is how the signal moves within your home recording system. This knowledge lets you make the most of your tracks and helps you tailor the sound to match the music you hear in your head as you compose, engineer, or produce your masterpiece.
Using the ubiquitous Pro Tools as an example, here’s how the signal flows through the channel strip:
Source audio or input: This is the signal that is coming from your hardware input or that is recorded to your hard drive. The signal starts here and enters the track’s channel strip.
Insert: This function lets you insert effects into your track. This function is for effects, such as equalizers or dynamics processors, where you want to change the sound of the entire signal. Some SIAB systems, such as the Roland boxes, have separate EQ sections.
Send Prefader: The Send function lets you route part of your signal out to an Aux bus, where you can then insert an effect such as reverb. With effects such as reverb, you don’t want to use the Insert function — as you would with a compressor — because you want to be able to control how much of the effect you hear. (Compressors only enable you to affect the entire signal, not some portion of it.)
Adjust this slider or knob to send as much or as little of the signal to the appropriate auxiliary component (Aux, get it?) for effects processing, applying as much or as little of that effect to your final sound. Turning the knob to the left produces less effect, and turning it to the right gives more effect.
Along with being able to set the Effect Send level at each channel (you can send more than one channel’s signal to each effect), you can also adjust the level of the affected signal that’s brought back into the mixer by using the Aux bus fader.
The Aux Send function can often be set to send the track’s signal either prefader or postfader. Having this option gives you more flexibility to control the affected sound.
For example, you can send the dry signal of a kick drum to a reverb (with the switch in the Pre position) and then boost the bass on the dry signal. Doing this gives you some reverb on the higher frequencies without adding it to the lower ones, which would create some mud in the final mix.
The downside to this technique is that you can’t control the level of the signal being sent to the effect using the fader. (You bypassed the fader in the Pre position.) In this case, if you raise and lower the channel fader, the amount of effect that you hear in relation to the dry signal changes as well.
For example, when you lower the fader, you hear more effect because less dry signal is mixed in — and when you raise the fader, you hear less effect because the dry signal is louder and the effect level is the same.
Solo and Mute: These buttons let you solo (silence all other tracks) and mute (silence) the output of the track.
Fader: This function lets you control the level (volume) of your signal leaving the track and going to the output(s) you have chosen in the Output section of the channel strip.
Send Postfader: When you have the Pre button disengaged, your Send signal is sent from your track after it passes through the track fader. Adjusting the volume of the track also adjusts the level going through your Send function.
Pan: This control lets you adjust the amount of your signal that goes to the left or right channel of your stereo output.
Output: This is where your signal goes as it leaves the track’s channel strip. This can be the master bus (connected to one of your physical outputs) or an aux or a submix bus, where it will later be sent to the master bus.