The term buss refers to a part of the console that re-routes and sums incoming signals. Busses then allow you to route that signal to other parts of the console such as another existing channel strip, aux return tracks, outboard effects or, a common used one, the master buss.
By default, channel strips are bussed to the master channel. This is how the master fader controls all the sounds collectively. If I wish to introduce a method of processing, I must buss that signal elsewhere before it is routed to the master buss. Busses can sum and process multiple signals at a time. Hence, the master buss producing the sound of all individual channels together.
Summing and routing multiple signals into other channel strips allow you to control those sounds collectively with the parameters available on the channel itself, such as the input section, EQ, dynamics control and most importantly the mixer functions. Volume fader, pan pot, mute and solo.
Large format consoles have intricate buss matrices to allow for complex patching and routing of electrical signals, especially for consoles with up to 64 or even 32 channels. Each channel must have its own means of being bussed externally.
To buss a signal, means you are re-routing the signal output (typically from the master buss by default) elsewhere. If you are bussing a signal to an outboard processor, that signal must be returned to the console for it to be present in a mix.
Therefore, you must either route the processor in-line so the processed signal appears back onto the original channel strip upon returning from the processor or you must route the output of the processor onto a secondary channel strip, once a signal has been processed.
The capability of returning a signal to its original channel after being processed depends solely on the console itself. You have in-line vs. split consoles. In-line consoles allow you to return the signal back to its original channel strip whereas split requires two channels to introduce specific processors.
Using two channel strips for the introduction of a singular process sounds like an extremely ineffective method of conservative usage of channels for smaller format consoles BUT when a signal appears on more than one channel strip, you are presented with an additional set of channel functions such as EQ, dynamics control and volume fader when needed. Not to mention the fact that you may buss multiple channels to a singular channel strip and process them as a group! So, no need think you are ever limited in terms of signal flow and processing if you have a split console.
Consoles and mixers have hard wired functions as well as “soft-wired” functions where you may re-route electrical signals at the press of a button…hence a buss matrix. Even for the so called hard-wired functions, it’s nothing an electrician can’t rewire!
As large format consoles are considered modular, they may be customized to an extensive degree. Often, consoles are hard-wired to benefit the needs of specific engineers, workflow or even ergonomic advantages due to physical setup within a control room.
Within the console itself, the buss matrix can route a signal from one channel strip to another. Buss matrices are often hard-wired to devices called patch bays which becomes the hub for all incoming and outgoing signals from external processors. The patch bay is an extension of the consoles functionality as it offers customizable methods of signal routing. Patch bays can be as intricate or simplistic as needed by wiring a combination of bays together.