Tuesday, 29 May 2018

Tech Review: CONSOLE CONFIGURATIONS : BASIC MIX OUTPUTS


So we’re looking at console config and this time the output section.
Depending on the size of your console there may be a variety of output types. Most consoles will typically have Main Left and Right, and at least 1 aux. The bigger console the more options, sub groups, matrix’s, mono / centre feed there are.


Every console has has at least one output often called L and R. The L R output is very much the basic output of any mixer. Along side the L R we may also find a mono feed which is a sum of both the L R send. On some consoles the L R and mono sends can be individually selected. But there are more and this article intends to scan over those which you might use and come across.

OUTPUT OR OUTPUT:

When thinking about outputs it tends to generally tends to revolve around those with physical connections skipping over DCA’s (Digital-Controlled Amplifier) and VCA’s (Voltage-Controlled Amplifier). Although DCA’s and VCA’s are part of the ‘output’ section they don’t physically output anything instead they control a group of channel volumes.

This then creates a dilemma in writing this article. DCA’s and VCA’s I would describe at a basic level are more a method of control. The complication and an area where a majority of mix engineers get stuck is when moving from subgroups to a console with DCA’s / VCA’s. The common mistake is that as they are located in the output section they seem a direct replacement. For the purpose of this article I decided to mention DCA’s/ VCA’s as it is a common misunderstanding but to better understand and add more clarity, I will post a separate article.

SUBS:

Subgroups on the other hand are an output. If you still use an analogue console then most likely you will have several of these on your mixer. A common way that many engineers utilise them is for control of a group of instruments.

Using subgroups is very much like sending the channels direct to the main L R output. A really handy feature of subgroups is the insert point. Especially on an analogue setup having lots of outboard can be costly and take up a lot of room. Quite often I will subgroup lapel mics and put a graphic EQ over these. Similarly on vocal mics I might put a compressor on the subgroup. Although you don’t get as much individual control with a grouped compressor etc it adds that extra bit of control without requiring lots of outboard.

Similar to the main L R output, subgroups are also configured in stereo, hence why if you have 8 groups you will generally have 5 routing buttons (1 & 2, 3 & 4, 5 & 6, 7 & 8, L & R). In reality we therefore only actually have 4 group. The way to access to full 8 groups is via using the pan control. If you select group 1&2 and pan a channel to the left it will then only feed group 1. Within the master section each subgroup will have some aspect of routing, this maybe on push buttons or a rotary control. If control is via a rotary pan control, centering the pan on subgroup 1 will create a mono subgroup. This sub group can then be routed to the main L R output.
Depending on your console, audio manufactures tend to ship consoles with 2 (generally on small consoles), 4, or 8 subgroups. Of course the more subgroups the more control you can have. In a 4 subgroup environment I would ideally set it up in the following

1 – Drums
2&3 – Instruments
4 -Vocals
If using an 8 sub group setup I would use the following

1 – Drums
2 – Kick and Bass
3 – Electric Guitars
4 – Acoustic Guitars
5&6 – Keyboards
7 -Vocal mics
8 – FX

In the above examples I have only been using the sub groups for internal routing more and managing the level going to the master L R as well as putting outboard into the signal chain. Another role you could use sub groups for is to send a feed to another room a more popular way of doing this though is via matrix sends.

MATRIX:

Unless you have a more expensive analogue console, typically most won’t have matrix outputs unless they have a digital console, and still they can be limited in number on lower end consoles. Although less common now, matrix outputs tended to be advertised as 6×4 matrix, 12×8 matrix etc. What this means is there are 4 matrix sends which each have 6 sources that can be routed to it. Traditionally on an analogue desk the routing generally came from the subgroups and the main L R. Digital consoles though tend to be different. Some digital consoles still follow the analogue system of just routing the from subgroups and the master section, where as others allow you to mix individual channels to the matrix. Another option is similar to a traditional analogue setup for example 12×8 but, will allow you to choose what the 12 sources are.

Matrix outputs can be used for a variety of routing and control options these can include sending feeds to other rooms, external recorders, control of speakers etc. A common way I often use Matrixes in a live environment is to separate my speakers out, for example subs, front fill, Main L R, Delays. I find that this allows me to adjust much easier what is going to each speaker and to achieve more control. At the church I once attended, we use the matrix outs to feed other rooms and parts of the building as all of the speaker routing is handled by a distribution device system.

AUXES:

The most commonly used output apart from the main L R is Aux sends. There are very few consoles that do not have at least one aux send. The most common uses for aux sends are monitor mixes and outboard effects units. whether you are using a digital or analogue console aux sends have 2 main output options, pre fade and post fade.

Digital consoles will often have several pre fade options but at the core they work the same as analogue. So whats the difference. The difference is where in the signal chain the feed is taken from. A pre fade aux signal is taken before the fader but generally after the eq, post fade auxiliaries are after the fader meaning the level of the fader will affect the level going to the aux send.

Generally aux sends are a mono output but there are consoles that do have stereo aux sends and digital consoles can have multiple stereo aux sends. This is something to be aware of as if you have a digital console which is advertised as having 12 aux sends and you need 4 stereo mixes this will mean you will be left with 4 mono mixes or 2 stereo.

As I have mentioned before in analogue consoles are generally limited and have little flexibility. Having been around many churches, most church consoles tend to have around 6-8 aux sends. Large format analogue consoles tend to have auxes configured as a 4/6 post and 2/4 pre or, 6 post, switchable pre/post and 2 fixed pre, where as digital consoles allow you to individually choose whether you want pre of post.

MIX BUS:

Digital consoles have brought about a new term, mix bus. With the much more flexible architecture of digital consoles manufactures are dropping the traditional terms aux and groups and using mix bus as a more general term. Before writing this post I have used a Soundcraft Si Expression. This console is a really good example of this having 14 mix bus out. I have set the mix bus’s up in various ways. I have used one of them as a group. In essence I have set the mix bus to a post fade output with routing to the main L R. I have individually routed the channels I need to this group, in my case the headset mics, and have set them to 0db on the send. This same method can be achieved on more or less most digital consoles. Some consoles will make it much easier than the Si Expression and you can tell it how many aux/group sends you want on start up and it will configure them

IT WONT CHANGE MUCH!

Truth be told in an install situation like a church your output configuration is very unlikely to change from week to week. I would suggest that from time to time you make sure that your system is still setup in a way that works well. It can be very easy to add an extra speaker here or there and to just plug it in. If you never installed your system I would suggest making sure you know how it is setup and configured.

So thats outputs. There are areas that I have only just touched on and could cover much more, if you have any inputs kindly plug them into the comment channels below.

Thanks Guys and always remember to keep the creativity perfected.
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