Console System Control

The rise of digital consoles has seen a huge increase in features available at a much lower price point than ever before. It almost doesn’t matter what level of show you’re doing these days, the chance of seeing a digital console complete with all the toys is high, even at the lowest level. While this gives us great opportunities to dramatically improve sound quality on a tight budget, I firmly believe it’s important that the distinction still be made between mix engine and system alignment.

The Artistic/Technical Line
This is a concept that was introduced to me by Bob McCarthy and it is centred on the two main roles concerned with FOH sound in a typical audio crew.

A Band Engineer at work

The band engineer is the person who mixes the show, runs the console and makes all artistic decisions regarding a band’s particular sound. They mix all the inputs together and produce a stereo (or stereo + sub-bass) output. All EQ, dynamics, effects and volume decisions are in his/her hands. Their tools are the FOH console, outboard processing and microphones/DIs.

The system engineer is the person who presents the mix to the audience. They take the stereo (or stereo + sub-bass) feed from the band engineer and distribute it to the audience evenly and linearly, with the goal of creating an identical audio experience for every audience member of the band engineer’s mix. They take overall control of the speaker distribution and system control.

This is somewhat oversimplified as the 2 roles are often intertwined; the band engineer making decisions about how the system controllers should affect the signal after delivery, how the PA is hung or even both jobs being undertaken by a single person. However, there is a clear physical line where the mix engineer should deliver the stereo output to the system engineer, and that is the console XLR outputs.

Matrix Mixing
Matrices are hugely useful console tools for generating extra mixes or stems, but I often see them misused. The most common problem is using them as an add-on to the stereo master bus. The console is typically setup with the ‘Stereo L’ and ‘Stereo R’ physical outputs as the main feed to the left and right PA stacks with any extra outputs required, such as front-fills, VIP or record feeds, setup as matrices and fed from the stereo bus.

The problem with this method is that you may want to insert an equaliser across the PA output to tame room and/or PA frequency response problems. With this configuration, the EQ will be applied to every output, which is usually not desired. I certainly don’t want PA correction EQ on my record feed!

It also means that if you want to turn up the PA, you can’t easily do so without simultaneously affecting all the matrix feeds. Sometimes it may be necessary to operate this way however. It may also be possible depending on the console to set up the matrices so that they are pre-fader, but why not make it simple and have all of your outputs in the same place?

This is a much more versatile way of routing the console, keeping the stereo bus as a ‘clean’ mix. Musical EQ and compression may be applied here if desired, provided it is a creative tweak rather than PA/room corrective and would also be required on a board recording. This bus can be routed to any applicable matrices, which in turn feed the PA. EQ can be applied to each matrix individually to compensate for the PA/room without detrimentally affecting any other feed.

Personally, I regularly leave my stereo bus clean with no physical output and set up all my outputs on matrices as below:

Matrix Description
1 / 2 PA Left / Right
3 / 4 Sub Left / Right
5 / 6 Spare
7 / 8 Record Left / Right

Console System Control
Most digital consoles that feature matrices also feature 4-band fully parametric EQ, 31-band graphic EQ, delay and polarity switching on almost every output bus (excluding monitor/PFL etc.). These are the majority of the tools required to do a basic system alignment.

I’m not talking about spectral division here, obviously active systems require dedicated system controllers, but things that people often consider minor such as in-fills (the speakers often covering the most loyal fans) are often driven directly from a matrix on the console.

The problem with using the matrices in this way is that it blurs the line between the mix engine and the system control. If system alignment was configured on a digital console, you could not simply walk up as a band engineer and load your pre-programmed show file without removing all of the system control data. It generally requires tedious offline copying of settings, aligning the band engineer’s routing with the dictated console layout resulting in the console not being the sole domain of the mix engineer anymore and the system engineer not having access to the system controls without interrupting the mix engineer.

The most flexible way of working is that the band engineer provides a stereo (or stereo + sub) signal, and the system engineer lines up the system, including main system and all fills, within the system controllers, including EQ. The input of the system through to the reception (i.e. when the audience hears it) will be linear, and the mix engineer can apply any creative EQ he feels necessary on the console.

This means that the band engineer can walk up with his pre-programmed mix, which will (almost) definitely have 2 outputs, patch these to the system inputs and go. He can setup the console however he is comfortable with no detriment to any other band engineers who may use the same console after him. This configuration also means that any guest engineer can turn up with their own console and supply a feed to the system engineer which doesn’t have to be routed through the house console and won’t affect the current alignment.

In The End
We have fantastic tools at our disposal these days for a fraction of the previous cost, but I firmly believe there is benefit to system division, even at the price of not using every tool available to us all the time.

I imagine the reason system alignment is often partly confined to the console is due to budget; why buy another system controller for your system when the console will do everything instead? I also believe the band engineer should not be worrying about the level or timing of the front-fills, that’s the system engineers job, yet to run them off the console puts it into their remit.

There are times when these matters are not an issue, notably when you are the only person mixing on the console, the console configuration does not change and you are also the person aligning the system. However, I still believe that time spent putting every process into the right place is well spent and will result in a sleeker, simple to use and clearer system.

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