not this again...
as damon said, if it's a line array, and the sound engineer knows what they are doing, head height is the best since thats how/where it is supposed to sound best!
all in all venue/sound system dependent.
Hmm, didn't know this was covered. I actually wanted to start such a thread a few weeks back, but was too lazy to figure out how to do a poll. I would have prefered odd numbered choices (7-9, 9-11) since I think this would show some greater differentiation. I chose 8-10, but would've chosen 9-11 given the choice, and I suspect with a 7-9 and 9-11 choice, most others would choose 7-9.
Unfortunately for me, in real life I rarely get a choice, since I'm almost always clamping and am thus at the mercy of whoever I clamp from. We'll see how the poll goes, but I suspect I prefer higher than most.
I know all about the theory of line array systems, but frankly I don't buy it. Line arrays are designed so that the various frequencies come into phase/coherence at head height. Line arrays are undoubtedly more directional than traditional systems, but I'm not believing that they are nearly that directional and that they come into coherence in such a tight band of exactly 5-7 feet high. Running your stand at 17' may present problems with a line array, but I don't think you'll hear any significant difference in coherence between running at 8' and running at 10-11'.
At the same time, I think there are significant difference between running at 7-8' and 10-11' for other reasons, with 9-11 sounding much better to me. As noted, there is the issue of the chattiness of the crowd, and running higher will help here. One thing I very rarely hear mentioned (except by Doug Oade who is ignored on this front
) is the impact of the dispersion of the soundwave due to the heads of those in the audience. By being closer to head height, the sound wave gets defracted and deflected by all the people in the audience. The result of all these reflections is a smearing of all the timing information--both of the difference between the left and right channels, and between various frequencies. The result is that the soundstage and soundstage-depth information gets all distorted due to the interaction of the soundwave with the crowd, screwing up your imaging. By going a couple feet higher, you greatly reduce this crowd-related distortion of the soundwave and get much better soundstaging and imaging from your tapes.
Given the tradeoff between the potential lack of coherency by running higher with a line-array (which I find to be very, very minimal) and the distortion of the tape's imaging due to crowd interactions, I'd choose to run a bit higher and get better imaging on my tape.
Of course, like I said, as a clamp-whore, I don't generally get the choice.