Re: Endfire sub array under a stage
If the stage is as you say-then what is the point of using directional arrays?
You would get more energy out front if you DON'T use directional arrays.
Not sure on the thinking here? Are you getting confused with cardioid arrays? A cardioid array "wastes" some energy in order to get the pattern control, an endfire array does not sacrifice any output. On symmetrical waveforms ie sinewaves etc. the cardioid is ok (though still not perfect) however on complex non symmetrical waveforms such as music it is less effective. The endfire is a much more elegant solution as it uses the same point on the same cycle for the cancellation. This means there is always perfect summation at the front.
AND you have to have enough room for the waves for each of the speakers to reach the other in order to work properly.
The whole idea is to have cancellation BEHIND the array-a DISTANCE behind. Right on top of the array there is not going to be much cancellation going on-first because it is in the wrong direction (up and not behind) and second because the distance to the stage is not far enough away from the subs to really do anything.
The cancellation reduces as the vertical tangent increases. On a large stage this angle is quite low for most of the stage area. On the gig where we utilised this method there were 3 stages, the size of the middle(main) stage was bigger than some clubs I have been in!
There are lots of variables and often try to do things just because they can and it makes them "seem cool", NOT because it actually works or has any real benefit.
Ivan, "it depends"
As I said before, this was a 12,000 seat arena, large stage, no close boundaries etc. In a club sized gig I would be looking at other options.
There certainly isn't a one size fits all solution to sub arrays. The design we used was a modified endfire and gave a hypercardioid response. The null on the main stage was good and on the side stages it was very deep. As you can see from the photos and polars there was some lateral displacement also used as part of allowing for and counteracting the partial understage positioning. A LOT of time went into getting a solution for this gig and I think Peter has a few more grey hairs now because of it, lol.
I find the biggest offenders who want to "do things just because they can and it makes them "seem cool", are BE's! Not all, but most BE's have a lack of technical knowledge that never fails to astound me! And this is a all levels of the industry!
I regularly get them telling me they want external clocks or mega dollar valve comps to make digital consoles sound good, and other assorted audio foolery! But hey, if they think it makes a difference, even if it frustrates me, as a system provider I will happily add it to the invoice.
Darren
