John Atkinson wrote:

MINe 109 wrote:
In article ,
Howard Ferstler wrote:
MINe 109 wrote:
"Curvilinear"? Isn't that ML's way of trying to be more
Ferstler-approved by diddling the dispersion?

Actually, unless the diaphragm is changing size as it moves
back and forth, the curved shape will not allow for any
better dispersion than what we would get with a flat
diaphragm.

Poor deluded ML.

Note that Howard Ferstler took the other side of this argument
a few years back when he claimed that it was the _shape_ of the
Allison tweeter that led to its claimed wide dispersion.

It is. The tweeter behaves similarly to a pulsating
hemisphere of very small size.

If shaping the Allison's diaphragm improves its dispersion, then
the same mechanism works for MartinLogan.

The ML device is much larger in size than the Allison unit.
Actually, the central dome of the Allison is only 1/2 inch
across, which makes it inherently better at dispersing sound
than any large diaphragm, even one that expands and
contracts as a partial cylinder. The Allison tweeter has a
rather large surround, making the overall diameter about one
inch, and that surround moves in a somewhat radial manner,
which works with the small central diaphragm to disperse
sound nicely, while at the same time allowing the whole unit
do have power handling and power output approaching what we
normally have with conventional one-inch domes.

But if Howard is
correct about the ML, then he his earlier argument in favor of
the Allison tweeter must have been in error.

No. Two points:

1) Obviously you do not understand that there is more to it
than having the driver simply get larger and smaller in
size. The actual size is also important.

2) Because conventional, flat-panel systems also expand and
contract in size, compared to what the curved ML panel does,
they probably have horizontal dispersion nearly as good as
the curved versions. Unfortunately, this "nearly as good"
feature is not particularly good at all. Large radiating
areas do not disperse all that well in the midrange and
treble.

The ML systems are directional, period. Some people like
that sort of thing, and I can certainly understand why. They
exhibit one characteristic that most audio buffs favor:
superb direct-field clarity, even if, as Stan Lip****z noted
decades ago, they also have a choppy frequency response
above the lower midrange. It remains to be seen if a
dominant direct-field signal is conducive to live-music
realism in home-listening environments. With some recordings
it probably is. With others it probably is not.

The solution: have systems of both kinds in different rooms
of the house and listen to each as required. Admittedly, my
Dunlavy Cantatas are not flat-panel jobs, but they suffice
as good, focussed, strong first-arrival-signal systems.
Needless to say, my Allison IC-20 systems satisfy most
wide-dispersion requirements.

Howard Ferstler