Re: Array Deployment Question
Good question, let's take a look at this in simulation and see what the consequences would be. Here's a purely imaginary room that I just happen to have a reasonable model for at 200Hz and 4kHz, frequencies that I think represent the LF and HF behavior of the array well.
Here's what happens if we just turn off the top 5 boxes, again at 200Hz and 4kHz.
Well, that's not great at all! If you imagine FOH around the 80' mark, that's going to change things a lot, and we've still got 8 boxes out of a 13 box array left. As you can see, line arrays do not behave like the simple model you may have in your head. Even at a relatively high frequency you still need to consider the effects of the entire array on your frequency response, and without the top part of the array dragging the pattern up at low frequencies your response changes even more below 1kHz.
Turning off the HF section in the top boxes isn't the worst solution, although that top lobe that was firing into drapes is now firing into your audience. What if you can't do that, since you have powered boxes, or boxes with an all-in-one amplifier solution that makes it difficult, or you don't have enough DSP control? Here's the effects of a 500Hz 2nd order BW LPF, shown at 200Hz (I didn't show 4kHz since it's almost identical to just turning off the top boxes). You have to be careful when messing with line array phase!
Long story short, if I knew those seats weren't sold I would hang differently. Maybe less boxes, certainly different angles and processing, but once that array's in the air I'm not modifying it.