Why so few high end line arrays?

They work great at concerts and for sports stadiums....definitely a mistake for home audio, IMHO.

You are getting serious comb filtering from listening close up to multiple drivers with the same bandwidth.

Darkmoebius,

For the sake of brevity I did not go into as much detail. Yes it is true that a line array of woofers operating below 300 Hz is generally no problem due to the wavelengths of low frequencies. As you go up in frequency the problems start, unfortunately right in the mid range is where it can begin to be a problem.

It is much the same reason that some people argue that center channels are more trouble than they are worth....

Tbg,

This is audiogon. Laws of physics are very often suspended here. Our favorite products do everything perfectly with no drawbacks or compromises to our favored designs. ;-)

For those with line arrays, this explanation is one of the simplest I have seen:
A good graphical explanation about lobing or "comb filtering" - which are the same thing. It shows snapshots at different frequencies but if you imagine how it will sound at a particular listening position across all frequencies then you will realize that you progressively get multiple nulls as you go higher in frequency.

Darkmoebius,

You are correct. You have to design line arrays carefully to take into account lobbing and nulls. They work very well when properly designed and will ensure a higher SPL reaches further out into the audience at a sports or rock arena event.