Re: Under stage sub-array
Hey Tony,
It can change a lot. Part of the problem is the rear of the array is now firing into a ported chamber, which can affect the frequency response of the rear driver relative to the front, and vice versa. It's probably better than a conventional array since it will put less energy into that cavity. However, be aware that it will put nearly as much energy above it as a conventional array, where the stage is, so you may still have too much energy on stage where the performers are. Also, a three wide cardioid array puts its best cancellation in the horizontal plane, not the vertical.
Long story short, probably a cardioid ''type'' array is good, but I would not assume that the way you ''usually'' put it together will ''work'' as ''well''. If you have measurement software that will help a lot. Otherwise, be prepared to change your delay... I wouldn't even want to guess how much, and you may need some EQ as well.
