Thanks for that guys. So from what I understand throw is a product of directivity. A narrower dispersion focuses the energy into a smaller area and results in a greater distance travelled before the energy is dissipated?
If that is the case, then is there an ideal distance to have a listener from a loudspeaker? For a singer woofer and a horn, is there a point where you can be too close? I'm thinking that the directivity at certain frequencies may result in an imbalance in the frequency spectrum up close?
What explains my observations about intelligibility and stability in the drum fill? I've also noticed this when listening to program material when sitting in the drummers stool compared with listening from a couple of meters back. While the level is lower further away, the balance is dramatically better.
What facet of speaker design contributes to the long/short throw charateristics of a loudspeaker? I've always hated using powered boxes like eons and srm450 for monitors and had put that down to their "throw". I'm always amazed at how good the drum fill sounds from monitor op position, but then just falls apart on the riser.
A church I attended years ago hired a consultant to spec a system. The church was a 208' diameter concrete dome. The consultant spec'd a system that absolutely did not work. There were 20 horns total, all huge with JBL 2445 drivers. 10 of the horns were "long throw", about 4' long, intended to "develop" at 300'-400'. As noted, the back was was less than 200' from the horns. As expected, there were hot spots and cold spots with regards to sound. At the back of the room, the horns had not spread out enough to meet each other's coverage. At the front, where the shorter "throw" horns were aimed, it was equally spotty, since those horns were still too narrow in coverage for the distance they covered.
I ran into the same sort of thing a number of years ago when the consultant spec JBL PD horns for a traditional Baptist church. The reason was that the narrow pattern would not energize the room as much. OK, But you have to use enough of them to adequately cover the audience or else you end up with hot spots and dead spots-like they did.
Ivan, with 10 of the narrowest horns JBL made, and 10 somewhat wider pattern horns there was probably enough to cover the room, even if it was in the round. Ten 40º horns in a circle should cover 360º.That doesn't make the design a good one, but it seems unlikely the dead spots were completely due to horns being too narrow. It would help to know about the actual design and implementation.Mac
What kind a system fixed the problem? In an acoustic disaster area like a concrete dome I don't think those horns were a bad idea. There is no such thing as a horn intended to "develop" at 300'-400', there are only horns with different coverage angles. AFAIK the narrowest coverage horns JBL made were 40ºHx30ºV. If these were arrayed 5 wide by 2 high, with 5º of overlap, the 10 horns would have a coverage pattern of about 180ºHx55ºV, without significant gaps in coverage, at any reasonable distance. In a concrete dome, it is certainly possible, even probable that reflections off the ceiling and walls were causing those dead spots. Those big horns were used to try to reduce those reflections by keeping sound off the ceiling and walls. Maybe it was not possible to have a good sound in that room at that time, but it wasn't because the horns didn't have enough coverage.Mac
some of the horns were intentionally aimed at the walls, to counteract whatever. That didn't work at all. I took four of the shorter horns and aimed them down into the audience and turned the rest of them off. The longer horns were stadium horns, they were huge. 31" square at the end, 54" long. They had no place in that room. Shortly after that the Astrodome in Houston put in a new sound system. I recognized the horns in that setup distinctly, they were the same as the ones in the church. That system MIGHT have worked had all the horns been pointed into the seats and properly aimed and levels properly set, but that is not the way it was installed. I didn't have the wherewithal to set all of them up that way. This was 20 years ago. I was just learning about live audio. What I did improved it immensely, but had I had some horns with wider dispersion, it would have been even better. Here are the horns in question, JBL2366a.http://www.jblpro.com/pub/obsolete/23606566.pdf
More evidence that the problem wasn't the fact that long throw, narrow coverage pattern, horns were used in what may have been the right room, but that it was a bad design or installation. No sound system in the world will work in the face of bad design and installation. Mac
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