Home Recording Sound Mixer Routing - dummies

By Jeff Strong

After you have an instrument plugged into the mixer channel strip, you want to send that signal somewhere. This is referred to as routing or busing. (The place where the signal ends up is, conveniently enough, referred to as a bus.) Most mixers offer numerous busing possibilities, as follows:

  • Master bus: This is where your signal goes before it leaves your system and where you mix all your tracks.

  • Submix bus: This is where you can mix several tracks before they go to the master bus.

  • Auxiliary bus: This is where you can add an effect to your signal and then move it along to the master bus.

Here are some of the most-used busing options and some ways to make this process easier.

Master bus

The master bus is where your music gets mixed and where you choose which of the physical outputs this stereo mix goes to. The Pan knob setting for each channel strip (how far to the left or right) dictates how much signal is sent to the left or right channels of the master bus.

The master bus has a channel strip of its own where you can insert effects such as a compressor or EQ. The master bus channel strip looks like a, ahem, stripped-down version of a regular channel strip — it doesn’t have some routing options such as an input selector, sends, or solo and mute buttons.

This is because it’s the final stage of your signal flow, so these functions aren’t necessary.

Faders for each channel control how much level is sent to the master bus and how the volume of each channel relates to the other. The master fader only determines the amount of overall volume of all channels that are routed to it (for sending out to your speakers or to the stereo mix level).

Sub (submix) bus

Sometimes you have a group of instruments (such as drums) that you want to control as a group independently of the master fader. Sending these tracks to another track and submixing them there enables you to adjust the overall volume of the drums without affecting the volume of any other instruments that aren’t assigned to this channel.

This is called a submix, and signals sent this way are sent (wait for it . . .) through the submix bus. When your signal exits this bus, it goes to the master bus, where your signal is blended with the rest of your tracks.

Software mixers, such as the one in Pro Tools, often don’t have submix buses per se. Instead, you can simply route your signal to any of the internal buses, where you can adjust the level of all the signals coming to that bus by using the channel strip fader associated with the bus.

Auxiliary (aux) bus

The aux bus is where you send your signal when you use one of the Send functions in your channel strip. This bus often has a channel strip of its own, where you can insert the effect you want to use. From this bus, your signal goes to the master bus, where the signal is mixed with the rest of your tracks.