“Bus tracks” also named simply “buses”, are similar to summing tracks or master tracks for a lot of other tracks. It is the simplest definition you can get. The tracks that are summed doesn’t necessary have to carry audio signal. It can be effects or VCA / DCA or send tracks or return tracks. There are all bus tracks even if in fact are auxes or groups or sends, or returns and so on.
In the music production projects and process, in mixing and mastering part of things, especially, bus tracks are needed for a lot of things like sending all the drums to one group bus or through a compression or a parallel compression track or to a reverb bus or other effects tracks.
By master bus, also known as Stereo Bus we mean the right and the left summing tracks of everything including all the other buses and all the tracks in the project.
The Stereo or Master Output Bus makes up all final stereo track mix.
A mixing bus track may also be known as AUX or Auxiliary track. By a bus mixing track or by a bus we simply mean combining different signals, typically with own fader for controlling overall volume. If a mixer connects all microphones of drum to drum bus for mixing track, the bus drum fader then begins to control output from all tracks. In an analog world, a track bus would mainly have a physical connection. This, in digital world would be known as sum of all digital tracks that have been sent to bus.
Where can you apply bus routing?
Bus routing can get applied to different group of instruments: Guitars, Drums, Lead Vocals, etc. in fact you’re also able to nest bus channels into one another. For example, you can have two different types of kick drum channels (parallel and direct compression) then these can get grouped in single Kick Bus and after that you can route Kick Bus into Drum Bus. Upon using more bus, the better you’re able to control final sound.
Advanced track mixing and sidechaining
With more effects and tracks added, you get higher quality (in theory) tracks for your bus. It would be quite simple to have a lot of tracks within a mixing project after a while, and you can make this as a submix version of different element that help you in management of complex music processes. With Sidechaining, you send or use key through a bus for affecting another. A good example here is sidechaining output of drum bus to compressor on synthesizer bus.
Here it would mean that the input side chain of compressor gets linked with drum bus signals on synthesizer tracks. So while the drums get hit, the compressor for synth track would be triggered, and you can simply pull track down whenever you’re able to hit on drums. Such effect of pumping is quite common for EDM music.
Additionally to that, all bus tracks would let you use analog effects higher than a single track, or on digital realm, you can save on processing power after the use of only a single instance of one effect, instead you need to use separate plugin instance on each track. Delays and reverb, and a lot of other plugins for analog modeling like the emulation for tape machine are heavy on CPU and these can also stall your system when there are a lot of copies for one project. One instance can be easily added to bus track, or users can set auxiliary tracks to get a good effect, than the need for having an effect.
Requirement of buses headphone mix tracks
These are also commonly used for mixing tracks on your headphones. As a bus easily gets sent to your headphone amplifiers, it easily makes the pre-fader sends tracks from different channels that you wish to easily return tracks back to headphones. Mostly people use bus tracks and the additional are AUX tracks on analog mixers and these are quite common for mixing on headphones. As mixers mostly have a lot of aux tracks, you can have separate mixes for different musicians that can easily get set up through separate other level for one player.
Generally, these buses get set through pre faders for monitors and headphones and as post fader to have delays, reverbs and various other processors that are time based. This is done so that you’re able to simply bring down fader and there won’t be any signal for reverb. If bus gets set up for pre fader for headphone mixes, and you’re able to bring fader entirely down, the single still gets sent to auxiliary tracks. Likewse if you’re bringing down the fader on pre fader track bus sent for headphone mixing, it wouldn’t bring down level that is sent to headphones that remain connected with such bus.
Automation and buses to get creative effects
With bus use you get better creativity in mixes. Once you’re able to realize that you can easily send signals to bus after trying out something, you can easily add much more to that while mixing everything together for producing some cool stuff.
Rather than adding up total of 100%, it’s better to set up dry (unaffected) or wet (affected) sounds that help in turning your mixes interesting. You are easily able to apply automation for bus or can automate send to bus for differentiating among various parts in a piece through which you can easily help your mixes while exploring interesting and different special parts with interesting sound that turns your mix lively.
Having an approach to mixing buses
There are different approaches to mixing bus tracks and each of these varies:
While a few engineers would prefer placing processors on output bus (which is also known as “2-mix” prior to mixing and later on mix into such processors to get “finished” sounds. As adding up mixing processors would completely alter balance perceptions, EQ and dynamics in mix, this would help you in mixing with end outcome being clearly audible. A few producers never use mixing bus processing at all and prefer to leave all processes of post-mixing to mastering professionals. This can arguably be said as “pursuit” approach, but it would also let mixing processes to get handled through (presumably) super high quality gear for mastering mixes. Others mostly apply track mixing bus processors at late mixdown to get light touch up for the mix.
Whatever bus mixing approach you’ve selected, it’s best to have caution with how much heavily you’re applying dynamics processing and EQ. if you’re over compress or EQ, or are creating “mastered” sounds on mix, then you can likely do it all by yourself. You can use a whole lot of bus mixing and processing that is required but can leave room for mastering for letting the magic happen to your sounds.