Why so few high end line arrays?

You think a signal sweep disproves what I said?

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.

Tbg,

I've been researching line arrays for the last couple of weeks, but that only assures I have way more questions than answers or experience...

But, the website which you refer seems to be only concerned with is only concerned with farfield sound reproduction(stadium, club). Not that nearfield acoustic completely diverge from farfield, but the goals are significantly different.

The "lobing" and "Nulls" which you(and your link) refer to primarily become a problem for listening at the point/frequency where c-to-c spacing of the source(drivers) exceeds the distance of one-half to one full wavelength of the highest frequency produced by that particular array(low, mid, or high).

The "trick" is in designing a widerange(mid/bass) array which crosses over to the next higher frequency array below the threshold where lobing and comb filter effects become troublesome. Within the home audio industry there are a variety of drivers small enough in diameter to achieve those goals.

These issues really seem(to my inexperienced eye) to be no more difficult than the many design limitations and compromises which plague all speaker designs(including traditional 2 or 3-way "box").

Here's a far better, and more technical, analysis(besides Dr Griffin's link above) of the design parameters and limitations of array design in this ElectroVoice paper.

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.

I too had been advised of all the combing when I started considering line sources, but physics aside, my ears tell me something else.

I had a chance to hear a used pair of Scaena 3.2's today that were for sale. I have heard the 3.2 in various versions and systems over the past 2.5 years, so I am familiar with how it performs. In this particular demo, it was not setup anywhere close to ideally, since the speakers had just come into the dealer the day before, and there was alot of other gear around. However they didn't have a problem with me tweaking the placement and crossover levels, so I was able to coax a reasonable performance from them, even though no attempt had yet been made to pair them with best match of cables and amps in the store.

That being said, it was the best demo I have ever heard in that store by a significant margin, and that has included Magico V3's, Rockport Mira's various wilsons, Martin Logan CLX, etc. Now to be fair, none of those demos were what I'd consider proper set ups either, but I believe one can tell the basic character of a speaker, even in marginal setups such as these.

I'm not saying the Scaena is the typical line array, in that its almost baffleless design is rather cutting edge, but to my ear it what no other speaker in that showroom had ever done, and made me think that this was a product I could own for a long time. The level of detail, purity, and imaging achieved a level of realism that put them over the top for me. Plus the ability to listen from mid field and far field I thought was fantastic since they drop half of what point sources do over distance. And I didn't feel that instrument size was being overblown.

As I mentioned I am getting in some line sources to audition soon, where the drivers are positioned even closer together than the Scaena. I believe that this actually helps with combing, the closer the drivers are to each other.