to clear up some confusion
sorry, i was talking about two separate system designs...
When I refer to a vertical line array in a trapezoidial design, I am merely referring to a line array of drivers, ie: in this case 3 drivers mounted in a direct line--not a group of speakers mounted vertically.
This is quite different than the new series of vertical line array systems which do exactly that. These enclosures rely on a wide horizontal splay coupled with a tightly controlled vertical beam; the opposite of a trap. I don't know a lot about these new systems and have had no hands on experience with them. But, in comparing the two systems I like to think of a trap system as identical multiple mini boxes forming a summed image while the new line arrays are almost like a series of wide firing full range horns draped from top to bottom in a tall single row.
In a trap format the goal is to create a full image box with certain beam characteristics which enable blocks or clusters of identical enclosures to be used together to form a seamless "point source array." Meaning the sound image from multiple boxes grow in size, proportion and SPL in direct ratio to the number of units combined. Walking around the perimeter of the room will reveal a single image point source per cluster group. And yes the combined image can be made spherical and often is with a single large cluster in the front middle of the room. Think of a mirror ball cut in half so there is no ceiling coverage. This was a radical but old idea, which changed the thinking from a previous generation of P.A. systems that where folded horn loaded and used separate bins for bass, mid and highs. Since each enclosure is it's own full range source, the concept makes absolute sense as the number of units need only grow proportionately with the venue. With a folded horn system and even the new line array systems, you can't do that.
The shape of the box and alignment of the drivers ABSOULTELY CHANGES THROW CHARACTERISTICS.
I have A/B' trap and rectangular enclosures one on one and in a cluster with the identical driver setup and identical power rack processing, outdoors where it really matters:
(2) E120 (1) 2445 with 2380 Biradial.
amp rack: BSS 24db/octave Linkwitz Riley with QSC MX2000 bottom and QSC MX1500 top
The traps threw way further and the rectangular box with off set drivers sounded way better. The traps had far superior summing characteristics than the rectangular boxes, so yes design shape plays into it. While the rectangles sounded much better standing alone like a very loud studio monitor which does not gain as much from doubling side by side and increases driver interference as a result of firing in the same plane.
I only tell you this story because I built the above series of rectangular boxes while a competitor built the traps. This design mistake cost me a very large sale...but, that's how we learn, isn't it?
p.s. I will be posting pics of this and other designs on another post shortly.
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Here is a simple drawing.
First this is what we have