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Sweetwater Forums [Archived]

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What's in your array ???

SpiderswebFOH

I was just curious; what type of mix is being sent to a typical line array?
If you have a set on each side, are they an odd number or even number?
Are the vocals on top and music on the bottom or mixed in?
Inquiring minds want to know.
December 19, 2008 @04:13pm
DAS

The number depends largely on the coverage and SPL needed. Normally the mix is just left to the left side and right to the right side. I don't know people doing clever things like sending different signals to different cabs. Actually, it stops being a line array if you do that.
December 19, 2008 @04:52pm
cmchamp

I believe RAT (RATT?) Audio has been doing something different with arrays, but not what you're asking.
He uses an array stack for the instruments on each side of the stage, then he adds a duplicate stack next to the instrument stack just for vocals. I have read about it in MIX, FOH, etc. but haven't heard his rig.
Prior to reading those articles, I had done something similar with traditional boxes.
In order for a vertical array ("J" or Progressive) to work efficiently and effectively as a line array, each box should have identical acoustical characteristics AND be fed the identical program material and voltage. Any deviation changes the characteristics of the array.
C.
December 19, 2008 @05:25pm
michaelhoddy

A short line array treatise...
The big buzz with line arrays is their ability, when properly implemented, to have even coverage and gain over long throws and to control the dispersion of midrange and lower frequencies without the use of gigantic horns.
The low/mid-frequency directivity (ability to control the coverage pattern into the lower octaves) in a line array is dependent on the length of the line. Line array characteristics and coupling are a phenomena of what are otherwise non-pattern-controlled LF cone drivers which become more directional when they are stacked vertically. The longer the line, the more stable and (generally) lower the pattern control goes in frequency.
HF in any typical modern line array (Vertec, V-DOSC, MILO, etc) is direct and controlled by horns with very narrow vertical dispersion. The reason for this is because at any given point in the vertical listening plane, you are hearing the sum of all the LF drivers in the line, but only one HF device- the one whose vertical coverage hits that particular spot.
Most individual line array HF devices cover only about 5 degrees of the vertical plane each, and there may be 2 or three of them in each box, with the sum of each box equalling perhaps 10 or 15 degrees of coverage. The narrow energy dispersion of each HF horn helps it keep up with all those LF cones coupling.
Any "line array" under about 5 boxes (and therefore 5 cone mid drivers and/or woofers) long is not going to exhibit line array characteristics very far down in the midrange, and therefore, is not really doing what a line array is supposed to do. This would include systems like the JBL VRX. It's a great-sounding system, but while advertised as a line array, it physically does not do what a line array is supposed to do very well at lower frequencies, especially in the usual two-box-per-side configuration, even at the max 3-box-per-side configuration. (but it's great in wide, relatively short rooms for other reasons).
Additionally, a long line will have low-mid frequency buildup at or below the frequency where the ability of the line to control dispersion from the cones falls off. This necessitates some reductive EQ at those frequencies.
All that to say that a stack of line array boxes should get fed the same signal, as the theory falls apart when they are not. On longer lines, sometimes the level of that signal will be varied plus or minus a couple decibels on the boxes at the very top and bottom of the array to manipulate the coverage pattern, and also to control the high frequency output of the boxes which much throw further in relation to those which are throwing a shorter distance.
Rat Sound does often do separate arrays left and right for both instruments and vocals. Since you're a church guy, Willow Creek Church in Chicago also does this- they have a Meyer MILO system for music, and an M2D system for speech and/or vocals.
Line arrays are not a panacea- they work great for wide rooms with varying throws, not so well in rooms with low ceilings or narrow rooms. There are still many situations where a conventional trap box array works just fine if not better.
December 19, 2008 @07:02pm