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Author Topic: Understanding LCR/LR+M Mixing  (Read 17895 times)

Michael 'Bink' Knowles

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Re: Breshears LCR Cross Matrix multichannel mixing
« Reply #20 on: January 12, 2007, 01:58:22 pm »

Good point about CD playback. A sound system like LCR Cross Matrix is something nobody in the record industry is thinking about so of course they aren't mixing with 3 channels in mind. I don't have a problem with taking all normal stereo playback channels and dumping them to a stereo group that feeds a Dolby (or whoever) LCR separator which then feeds the matrix with three channels. It won't be very pretty but it will get by.

Another concern at venues with LCR systems is how to route sources to make a good stereo recording. Nothing's easy when you have to do both tasks at the same time.

-Bink
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Michael 'Bink' Knowles
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Brad Weber

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Re: Understanding LCR/LR+M Mixing
« Reply #21 on: January 12, 2007, 03:29:21 pm »

Valuable discussion, but also highlights why I intentionally avoided bringing up cross matrix systems.

Setup and operation of LCR cross matrix systems is critical, it's not something for just anybody to try.  I believe that Ivan has worked with a number of these systems, maybe he'll add his comments.

I have used a hybrid approach with a traditional L/C/R mains and cross matrixed fills, simply with the idea that the fills better represent the left, center and right signal content levels and timing relative to the natural sound at the fill location from the mains.
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Brad Weber
muse Audio Video

Ivan Beaver

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Re: Understanding LCR/LR+M Mixing
« Reply #22 on: January 12, 2007, 04:37:16 pm »

Yes I have quite a few.  First the room has to be "right" in order for it to work well.  The loudspeaker system has to be properly designed for such a system (different than a regular mono or stereo system) and you have to have enough seperate amps and DSP channels for it to work properly.

I have heard it used to some amazing results that made me go WOW-That is great.  

And I have also seen people totally violate the rules of routing and make mud out of it.

Don't blame the tool, blame the operator.

It is quite a bit of work to get it setup (aligned) properly, but when done well with a good room and a good operator and good source material, the results can be quite good.  Other times a mono system would be much better.

Sometimes having great flexability just allows people to shoot themselves in the foot.
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For every complicated question-there is a simple- easy to understand WRONG answer.

Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

Ivan Beaver

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Re: Breshears LCR Cross Matrix multichannel mixing
« Reply #23 on: January 12, 2007, 04:55:12 pm »

With a proper cross matrixed LCR system, the areas that the system fails is on the sides (mostly extreme) and you have the same signal sent to both the left and right channels.  Depending on the size of the room, this can get to be quite bad.

You will notice it mostly on prerecorded material that has stuff panned to the center.  You will get a delay that can be quite bad.  

With single sources this can be greatly reduced (eliminated) by panning the particular input into ONLY one of the 3 channels.  In a properly setup system everybody will still hear it just fine.

On the extreme sides the timing of the different input signals can sometimes get odd.  This is really only noticable on impulsive instruments such as drums.  Ie two drums played at the same time and panned to opposite sides will arrive to the extreme side listeners at different times.  Part of the "art" of aligning a system such as this is to reduce this problem.

I approach the alignment purely from a "scientific" standpoint first.  Then I go for the artistic side to try and get the system to "blend" properly.  I usually end up adjusting quite a few previous settings.

The real problem is getting it as right as possible to as many seats as possible, without causing to much damage to other seats.

Every time I do one, I learn something new, mostly problems that I have overlooked before.  The more I do this, the harder it gets, because I get pickier each time about what I expect, and realizing what I can and can't do.

It is real easy to get one seat right, but trying to get all of them "right" at the same time becomes a real challenge.
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For every complicated question-there is a simple- easy to understand WRONG answer.

Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

Briand Parenteau

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Re: Breshears LCR Cross Matrix multichannel mixing
« Reply #24 on: January 15, 2007, 11:13:58 pm »

Ivan,

Sounds like you have a good amount of experience with these systems.  I am trying to keep an open mind with this approach, but my experience has not been positive.  I am adhearing to all of the rules when assigning inputs, and I understand well the principles behind the design and proper utilization of one of these rigs. But I still am not happy with the results.  I do believe that the installer's calibration and set-up is perhaps flawed and contributing to my ill perceptions.

The main thing that bugs me is if you adhere to the bussing principles you are essentially setting up 3 discrete mixes.  For the sake of keeping this simpler we can call it 2 discrete mixes, a ctr mix & a L/R mix.  As instructed in the AES papers, ( http://www.sound-technology.com/Research2/Multichannel%20Mix ing%20AES01.pdf), nothing is to be bussed to multiple mixes, everything is discretely bussed to either ctr, L or R.  With Kick, snare, percusiive instruments, lead vocals going to the ctr mix and all other instruments discretely going to L or R (everything must be double mic'd and discretley assigned to L or R), you now have 2 programs that are completely different in their respective content.  

So it is absoultely essential that all 3 speaker clusters have a perfect balance (SPL & freq response) of each of these mixes, otherwise you end up with multiple programs coming from multiple locations.  When I walked through the listening field, and placed myself in proximity to one of the L or R clusters I could distinctly hear a program content (my L or R mix) that was different than the program content that I was receiving from the Ctr cluster, and vice versa.  Yes I can hear some of the Ctr in the L or R and I can hear some of the L & R in the Ctr, but not a seamless blend in such a way that the individual mixes were indiscernable.  So now I not only have multiple sources arriving at my ear, I also have mutiple programs arriving at my ear.  This is chaotic nonsense.  

The fact that these systems are so highly susceptible to misuse since they require exact adherence to source mic'ing principles and signal routing, and furthermore take the uptmost precision in the installation & proper deployment of such systems is enough reason to dismiss them as incapable of providing consistent reproduceable results in a church environment that is going to involve multiple users who are most often not skilled enough or of the volunteer nature.  I would have a hard time sleeping at night if I was advocating the use of, selling and installing these systems in churches.  The end product when it is not dialed up with exact precision will be far worse than any mono rig, or alternating L/R rig.  That point can not be argued.  

B. Parenteau
Showmix
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Ivan Beaver

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Re: Breshears LCR Cross Matrix multichannel mixing
« Reply #25 on: January 16, 2007, 06:56:50 am »

I agree totally.  As with any precision anything, the extra flexability that can be really good in the hands of someone who knows how to use it, can be worse in the hands of a beginner.

We do not install that many crossmatrixed systems.  The church HAS to have someone who knows how to use it AND be of the right layout in order for it to work properly.

The alignment is EVERYTHING with these systems.  As a general rule it takes at lest twice and very often three times as long to setup a crossmatrixed system, as compaired to a normal mono system.  Most of this time is in the listening phase and trying to "place the image" where it belongs.

As with everything, it is a compromise.

When done good it is good, but when done wrong, you are correct, a mono system would be MUCH better.
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For every complicated question-there is a simple- easy to understand WRONG answer.

Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

Tom Young

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Re: Breshears LCR Cross Matrix multichannel mixing
« Reply #26 on: January 16, 2007, 08:00:46 am »

I have zero experience with mixing on this type of system. I have heard 1-2 of them demonstrated.

I frankly think we have enough hurdles to overcome when designing and (even more so) commissioning/optimizing traditionally set up loudspeaker systems. I also do not consider churches to be a suitable arena for (what I consider to be) almost "maverick" designs and operating restrictions. If you happen to have a very technically capable sound person, will he/she be there in 3, 5 or 10 years ? Because they rely so heavily on volunteers from within the church body, churches often do not get high caliber sound mixing staff ..... period. In a secular environment, the likelihood that you can hire folks (and replacements) with excellent technical chops is much greater. And yet it appears that cross-matrixed ldspkr systems have very little, if any, presence in that (secular) market.

FWIW
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Tom Young
Electroacoustic Design Services
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Mike {AB} Butler

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Re: Breshears LCR Cross Matrix multichannel mixing
« Reply #27 on: January 16, 2007, 09:22:54 am »

Briand Parenteau wrote on Mon, 15 January 2007 23:13


The fact that these systems are so highly susceptible to misuse since they require exact adherence to source mic'ing principles and signal routing, and furthermore take the uptmost precision in the installation & proper deployment of such systems is enough reason to dismiss them as incapable of providing consistent reproduceable results in a church environment that is going to involve multiple users who are most often not skilled enough or of the volunteer nature.  I would have a hard time sleeping at night if I was advocating the use of, selling and installing these systems in churches.  The end product when it is not dialed up with exact precision will be far worse than any mono rig, or alternating L/R rig.  That point can not be argued.  


Briand,
Actually, it doesn't matter whether the system is stereo, mono, OR LCR, volunteers can quickly undo a properly set up system.  Rolling Eyes

Strangely enough, I have had fewer problems with a LCR approach.. than with a stereo system. Generally, the volunteers running the system realize that vocals always come from the middle, and instruments from the sides. Sure, the EQ, balance, and miking can be terrible.. but as I said above, that can happen with even a mono system.
After 35 years of having to go into churches and fix their various issues, the number one issue contiunues to be the fact that a "wrong" approach gets untilized on a "right" (properly optimized) system. And the fun part is, each party believes they are doing the right thing to fix a problem that was already fixed by the optimized system! So, either A.) The Contractor didn't understand (or assumed) they understood what the customer wanted; B.) Didn't fully train the customer (common problem.. a 4 hour seminar isn't enough!); C.) The customer's "volunteer" thinks they can do it better than the Contractor; D.) The needs of the customer changed.. and a contractor wasn't called to upgrade.
I'm not saying you don't have a valid point. I am saying you have to remember that a customer can mess up a properly working system.. regardless of how simple it is. And LCR, in my experience, fares no worse...
Regards,
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Mike Butler,
Principal, Technology and Operations,
Dascott Technologies, LLC

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