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Author Topic: LCR reinforcement ?  (Read 1376 times)

mark ahlenius

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LCR reinforcement ?
« on: February 05, 2006, 10:09:20 pm »

Hi,

for a medium to large auditorium, do many folks use and LCR approach for live reinfocement where you pan different instruments or voices to one side vs. another?   We have a center cluster of 3 Martin WT3's and a Martin W2 on the left and right side of a wide room layout.

I know that it sounds great when you spatially align instruments from one side to another  IF you are standing in the middle.  But only few people can actually be in the center.  Many folks sit to the sides and may not hear the opposite side or the spatial separation.  Perhaps this is a cardinal rule of good live sound reinforcement that you don't break.  I can't recall ever being at a live concert where I have heard this effect used.

comments?

thanks

'markl

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Handy Brent

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Re: LCR reinforcement ?
« Reply #1 on: February 06, 2006, 08:23:34 am »

When I was touring, I did this only a few times.  Unless you have a long narrow venue, you are wasting your time in my opinion.  What i did was an L, C, R, with vocals only in the center, with vocal effects and instruments on the sides.  The artist that I was mixing also got the real concept of "sidefills" as well, so he had basically the same effect on stage.

In an install, where the spoken word is the real reason you are there, you have other things to consider.

It is true that people off axis from the other two arrays/speakers will not get the whole pircture. Only you will, if you are mixing at a centered mix position.
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Tom Young

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Re: LCR reinforcement ?
« Reply #2 on: February 06, 2006, 04:03:24 pm »

An intelligently designed LCR system works very well and most of the folks can easily hear both sides. The first rule of successful LCR or LR cluster design is that each cluster must cover all of the audience. Another *very* important design factor is that the behavior of each cluster must be very good/linear and considerable time must be taken to optimize the system.

One of the operating characeristics of these systems is that very few channels get hard-panned (all the way left or right).  Typically the channels that are hard-panned are effects returns, stereo keys and perhaps the outer choir mic's in reasonably large choir.
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Ivan Beaver

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Re: LCR reinforcement ?-Crossmatrixed systems-Sins for church sound
« Reply #3 on: February 06, 2006, 08:18:23 pm »

We do a fair number of LCR systems.  These are a crossmatrixed LCR system.  It takes a bit of DSP-amps-speakers AND A LOT of time and skill to set up/align properly.

In a nutshell: imagine a system with with 2 loudspeakers in each cluster.  Different configurations are used depending on the actual room, but let's keep it simple.  Looking at the room from left to right- 1 is outside left, 2 inside left, 3 left side of center, 4 right side of center, 5 inside of Right, 6 outside of right.  When you pan left the signal comes out of speakers 1-2-4-6.  When sent to the center channel off an aux (panning DOES NOT WORK!) the sound comes out of 1-3-4-6 and panned right it comes out of 1-3-5-6.

The advantage of this system is that no matter where you sit in the room you get all of the stereo signals.  Notice I did not say STEREO-just the information.  The people in the middle get a nice wide stereo image, and as you move to either side the width of the stereo image gets smaller, but you do not loose any information.

Balcony fills take a lot of DSP for each one as the information going to each one is different.

In this type of configuration, you have to be careful how you operate the system.  You HAVE to do fairly hard pans, and do not run ANYTHING to all 3 systems.

The time/freq/level alignment issues get to be a REAL challenge, and the alignment is the fine art of compromise.  I often spend around 6-10 hours doing one of these alignments in an average 1000-3000 seat room.

I have an attached paper about the Sins of church sound and included in these are some notes on running a crossmatrixed system.
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mark ahlenius

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Re: LCR reinforcement ?-Crossmatrixed systems-Sins for church sound
« Reply #4 on: February 06, 2006, 10:44:38 pm »

Thanks all,

while our original intention was purely for doing some effects to the sides, and stereo trax - you have all pointed out some interesting issues/complications.  The center cluster was designed to cover the room adequately by itself.  

Our center cluster is rather different than our two side fills (a cluster of 3 - three-way biamped WT3's).  The sides are just two-way W2's.  While they will be time-aligned, some of the DSP'ing woudld be difficult at best.  

As for preaching the word - yes the center cluster is all that we'll be using.

thanks again!

'mark

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Stuart O'Toole

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Re: LCR reinforcement ?-Crossmatrixed systems-Sins for church sound
« Reply #5 on: February 09, 2006, 06:19:22 pm »

hi Mark


Does your desk have the capacity to mix in a LCR enviroment? ok you can get around it by using a group, matrix or even a aux feed. If you are using the LCR system i would still be using the LR when the spoken word comes as poeple in the Left and right fields will not here the word.

LCR are a great system in the right location ie really wide setups. Also have a look at how long and wide does your centre speaker throw to.

LCR will need a fair amount of alignment as you dont want comb filtering and delay issues. personally i prefer a LCR system as you can get the vocals to stand better but in some applications LCR are a nightmare (Combfiltersing, alignment and extra DSP cost arent worth it).

Cheers
Stuart
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Ivan Beaver

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Re: LCR reinforcement ?-Crossmatrixed systems-Sins for church sound
« Reply #6 on: February 10, 2006, 02:06:36 pm »

Stuart O'Toole wrote on Thu, 09 February 2006 18:19

 If you are using the LCR system i would still be using the LR when the spoken word comes as poeple in the Left and right fields will not here the word.



In a PROPERLY DESIGNED system each of the L C and R sends  (note that I did not say speakers) will cover the entire audience properly.  If you put the vocal in all 3 zones you will have combfiltering, and more importantly, time (echo/delay) and localization issues.  If you have to put it everywhere, you need to look at a different design.  The vocals should ONLY come from the center, unless you are doing drama type stuff in which you want to shift the image to another part of the stage.
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Stuart O'Toole

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Re: LCR reinforcement ?-Crossmatrixed systems-Sins for church sound
« Reply #7 on: February 12, 2006, 05:09:32 pm »

Hi Ivan


Comb Filtering is a real issue in a LCR setup. Yes there are issues with the same voice in multiple speakers. there are some people who will not hear the spoekn word if they are slightly off axis to the centre speaker

Ivan brought out a great point "PROPERLY DESIGNED" systems. I have seen some LCR systems that were not well thought about and a simple LR setup would of done much better. I have been recently to a venue here in Melb, Oz that has its own system and has been very well designed in a awkward hall same volume, some sound brilliant.


Cheers
Stuart
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Re: LCR reinforcement ?-Crossmatrixed systems-Sins for church sound
« Reply #7 on: February 12, 2006, 05:09:32 pm »


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