Matrix feeds and subgroups usage.

Kevin Maxwell

Junior
Feb 6, 2011
313
5
18
The subject of matrix feed and subgroups came up in the Midas Pro1 thread and rather then drift even farther I thought I would start a new thread.

I use matrix outs and sub groups. I am not trying to tell anyone how they should set up their system I am just explaining how I do it.

I use subgroups mostly so I can insert EQ on like mics. For example if doing a singing group we usually use the same model mic for all of the vocals. Since the system is EQed for linearity (what goes in is what comes out) I find that close miced instruments and playback sound the best and most accurate this way, but vocals don’t. But I don’t want to skew the whole sound system for the vocals. So I put them in a group and EQ them for gain before feedback and tonality. Leaving the channel EQs for individual vocal input EQ needs.

Taking it a bit farther when doing musical theater I have subgroups for body mics, and then for picking up the non-body miced chorus I have other subgroups for mics on the apron/ floor of the stage, and maybe hanging mics. Sometimes I have multiple rows of hanging mics. So not only do I route and EQ each of those into their appropriate sub group I also (delay) time align the area mics to the speakers which I find makes the use of those mics more transparent. I also have separate singing and separate talking subgroups for the body mics. Because I use automixers on the dialog parts.


Now for the matrix. For musical theater I usually use the matrix to feed the different speaker zones. Which include the front fill, the main speakers, the delay and some times even more. Because those zones get a different ratio of the subgroups. The front fills don’t get the apron mics because they are too close to the front fill speakers and the people that are that close that would need the front fill don’t need those mics in those speakers. The delay gets more of the area mics then the main speakers. And other things like that.

I also use a matrix to feed the conductors monitor because they usually need more of the talking sub then the singing sub and they don’t need the area mics or the sound effects.

And I also use VCAs of should I say DCAs. For example I use a DCA to be my overall master. I also try to use one DCA for the male vocals and one for the female vocals because a lot of times I need to push or pull back one or the other. I also use a DCA for all of the area mics. And other things depending on the capabilities of the console and the needs of the show.

I have been working with a church that seats about 1800 people and they have a very distributed speaker system. There are about 19 bi-amped speakers hung branching out from the front center, plus subs. This is controlled from 4 DSPs. At the moment it is feed from 2 outputs from an SC48 one for the main (bi-amped) speakers and one for the Subs. The DSPs that I recently moved to be next to the amps (when we relocater the mix position) have AES inputs that we will soon be using and I will feed them from the matrixes. I have noticed in that room that some areas would probably sound better if I was able to change that ration of vocals to instruments. So with the matrix feeds I can easily do that.


I hope this gives you an idea as to why some of us do things differently.
 
Re: Matrix feeds and subgroups usage.

I already wrote about some of this in this thread:

http://soundforums.net/varsity/4591-midas-pro-1-a.html

and also in this thread on PSW:

How come I never heard of this? Alternative mixer routing


I used yet another group/matrix setup this weekend that I found very usable:

It was a small local festival, but with a few very well know national level artists.

The main mixer was my Yamaha PM1D, but there were BEs using other mixers and we needed a conventient way to to interconnect the systems so that there would be a minumum of patching involved come time for changeover.

For those who aren't familiar with PM1D it has 48 mixes (groups/aux) and 24 matrices (12 stereo). It cannot route an input channel directly to a matrix, only to groups/auxs, which in turn can be routed to matrices.

I set the mixer up in such a way that the input mix channels on the PM1D were routed to the usual suggestions of mix buses (or directly to the LR master). This LR master was in turn routed to a stereo matrix that fed the physical PA system as well as a mono matrix that was delayed for a delay speaker feed.


The monitor mixes were routed to matrixes, one matrix for each monitor mix (8 in total).

The other mixer was connected to the PM1D in such a fashion that eight monitor auxes and the LR master output from that board were routed to 10 input channels on the PM1D which were sutably gained and otherwise left "flat". Each of these channels were fed to an audio group each, and each of those groups were in turn routed to the 8 monitor-feed matrixes and 2 PA matrixes.

The end result was that the matrix outputs were fed from both the 8 internal monitor auxes and LR master of the PM1D as well as being fed from the 8 monitor feeds and LR master of the other desk.

What I loved about this setup was that the matrix outputs could be given equipment-specific EQ for speaker protection, etc - while whoever mixed on the PM1D could EQ the monitor outputs and LR output as they wished for artistic/feedback reasons.

Whoever mixed on the other setup were free to use whatever output EQs they wanted on that system, but had no way of overriding the equipment-specific EQs set on the matrix outputs.

A guest mixing on the PM1D would of course be able to override these, but there is a fair chance most BEs wouldn't even realize the setup since the monitor auxes and LR outputs function exactly as expected.

The PM1D has the actual IO and DSP in a rack on stage, and the other setup was connected to stage via a normal analog multicore. The outputs from the other desk were extracted at the stage end and just patched with XLR shortes into the PM1D rack which in turn also fed the speakers with their signal.

The patch guys on stage patched subsnake XLRs between the mixrack and the analog sneake head during changeover, which worked relatively pain-free. At least there was no reason for them to worry about the returns, and the "next guy mixing" had all the return feeds ready for "tuning" and "talkback" as soon as the previous set was over.