According to the values in the white paper, the ARF needs to be 80% or better.

RIBBON PLANAR DRIVERS use another method.

eric j.

Here are a few things that may help.

The first concept is that if 2 waves are 180 deg out of phase they combine to 0 spl. That is how the bose silence headphones work.

The second concept is that each wave travels to the ear in a straight line from the source.

The next thing to consider is the variance of the paths each wave makes as it travels to the ear. The far sources have to travel farther than the near ones.

So now when they combine they may be 180 deg out of phase and you will hear nothing.

So the horn will cause the wave front to have different path lengths from the start.

Now if the sources are 1/4- 1/2 a wave length apart they have a tendency to combine as a plane wave. I have seen arguments for and against this description.

Some times math and sometimes geometry are the best tools for these things. A few lines in a chat forum can be difficult and frustrating. Let me know if you want some book sources. There are good sources on acoustics on the web also if one digs.

-Linc

• JBL 2370 in vertical horn arrays

Too bad. That means you still have to spend a bunch of money on drivers, especially the tweeter arrays, to build a good sounding pair of line arrays. Maybe we should all find a less expensive hobby, like restoring vintage automobiles or motorcycling:)

But the real problem as I see it is the huge difference in sensitivity between the horn array and the mid/woof cone array. Balancing this even using active crossovers, would be hard. On would need a power amp that is adjustable. And doing it with passive crossover would just destroy all the benefits of the horns, in my opinion.

eric j

I did an entire chapter on this subject in my book and from what I found, the prevailing philosophy was mostly incorrect.

There are three things that have to be considered - dimensions, numbers of units, and mouth wavefront shape, including frame gaps. They are all more and less important depending on the specific configuration.

Some say the wavefront shape is the most important and some the spacing, others the gaps between the drivers. In what I found, all of these factor interplay in a complex way for short lines of a few units. At two units the wavefront and the gap are more important then the spacing, at three and four the gap becomes unimportant and the wavefront shape and spacing are the most important. But above about four units, these factors all have almost no effect, the total height of the array being dominate.

There are also near field and far field differences, etc. In detail, the subject is very complex. A complete analysis can be found in my book where techniques are also given to analyze any specific configuration.

One well know reviewer of the book found this chapter the most interesting because it dispelled a lot of prevailing beliefs about line arrays.