Arny:

Please note the interpolations. Google does not conveniently insert the
carats.

They have followed more-or-less down the same path ever since...
projecting sound at maximum perceived volume over the maximum
_DISTANCE_ for at the least amount of power. All sorts of improvements
have been made over the years, but the basic concept and inherent
limitations cannot be overcome. Put very simply, they a
-horns are very axial... that is they have a very narrow sound stage.


In fact, waveguides can be built with a wide variety of dispersion
patterns.
If one could pick an ideal dispersion pattern, one would probably pick
a
narrower one in most cases.

Why? The sound as projected by a Piano is not narrow. From a clarinet,
perhaps. Speakers should be capable of projecting both with reasonable
accuracy, and not one at the expense of the other.

-That narrowness is both horizontal and vertical.

In fact waveguides can and are construced with dispersion patterns that
vary
strongly between horizontal and vertical. The transitions can be made
sharp
or gentle.

Sure. A lot can be done with physics and wave-guides. But the point is
to dissipate energy to reflect the original sound. Horns, by their
nature (and the use of waveguides) have a narrow 'sweet spot', as you
allude to above. This makes them more efficient, but less capable of
reproducing natural sound as it was originally made. One can walk
nearly 270 degrees around a piano without substantially changing the
sound as heard. Try that with a horn. Even the best dome tweeters don't
quite make 180 degrees, so don't get me wrong on this. But horns are
much more severely compromised than domes in this way.

-They rely on reflected sound to produce music.

Letsee, just about every direct radiator is mounted on a baffle that is
a
pretty good reflector of sound.

Sure, again. But at the same time a direct radiator also provides
DIRECT sound. Not nearly-only reflected sound.

that is, the path from
the transducer to the ear is neither primary nor direct.

Which is a meaningless criteria.

To whom?

Then, there is physics involved. If sound is all about moving air, bass
notes require moving lots of air relatively slowly, and treble notes
require moving much less air but much more quickly.

Nonsense - the speed of sound is about the same at all audible
frequencies.
In fact radiating sound generally involves no discernable motion of
air.
Otherwise, you'd feel a breeze!

Yeah. I can blow out a candle at about a foot with my woofers using a
20hz tone. And the 3/4" dome tweeter will sure flutter a flame at a
couple of inches. Keep in mind that a well-designed, truly full-range
speaker *system* is capable of causing discernable physical vibrations
if called upon to do so. Visceral reactions, so to speak. So a 15 pound
(or so) speaker with about a 10 pound magnet pushing only a few ounces
of voice-coil and cone material had better be able to move a LOT of air
to create that sort of effect.

The physical
limitations on a horn greatly exaggerate the limitations of the actual
transducer to do both... a full-range horn is an oxymoron in any
meaningful way.


Full-range direct radiators that actually perform are very rare, as
well. In
fact its easier to build an highly effective 2-way system that
incorporates
a horn than with direct radiators. However both are easily and
frequently
accomplished quite sucessfuly.

Define "effective". Sure, full-range single direct radiators are quite
rare. I would state that they likely do not exist if a really
challenging source is used... I use the Saint-Saens Organ Symphony as
my test-piece, as noted above. And if efficiency is your measure of
'effective', sure a horn will get down to that lower range needing less
power than a direct radiator. And as based on human perception much
below 500hz is non-directional anyway, that may be moot. But unless
that mass of air is moved, most horns are incapable of the required
visceral effect.

Just yesterday, I experienced a set of OEM Altec PA speakers with a
three-section horn woofer and two 8" standard cone-type tweeters. If
the idea is to project band sound to the 40th row, upper balcony, these
are your beasts.... these and the power to drive them. Not
high-fidelity in your living room.


SR and Hifi are different beasts, which is not to say that a SR system
can't
provide a satisfying sound with good fidelity.

Here's Altec Lansing's web site.


http://www.alteclansing.com/


From it you can readily discern that Altec Lansing does not have any
current
production of speakers for SR. Therefore this comment must relate to
some
out-of-date product that should never be mentioned in a contemporary
discussion of the capabilities of speakers that incorporate waveguide
or
so-called horn speakers.

Yikes.... has physics changed that much in 20 years? Have the equations
altered?

You will note that I do not call horns "BAD". I do call them pretty
severe compromises to achieve a very specific set of goals. To me,
those goals have dubious value, for several reasons. First and
foremost, I have -always- had enough power to drive conventional
speakers at substantial, realistic levels and without clipping. Both
tube and SS. Second, I have never been fascinated with
quality-by-measurement, preferring to let my ears drive my choices. It
may just be that I have hamburger taste in audio, but others seem to
think that my various systems are pretty stunning as a whole. But that
I like them is enough.

So, ask YOURSELF the question: If cost is no object, and your goal is
to reproduce all music at realistic levels in the typical residential
setting... not some tweaked-to-a-fare-thee-well listening room focused
on one single chair... what would be your choice of speakers? How would
you drive them, and what would be your test sources?

Since I asked the question, I will state what I have for my primary
system (the one that gets used every day by me and by my wife):

AR3a speakers, cleaned and tweaked crossovers/pots bypassed.
Dynaco 416 power-amp,
Dynaco PAT-5biFet pre-amp
Revox CD player
Revox TT
Any-of-several tuners.
Standard livingroom, about 14 x 16 x 9 feet.

Family Room System:
Also AR3a speakers, but 100% OEM (the pots are good)
Scott LK-150 amp
Dynaco PAS-pre-amp, WIMA caps, Sylvania mil.spec. 5751 tubes (blows
smooth-plate Teles (which I have) out of the water).
Dynaco FM-3
Yamaha CD Changer

The speakers will alternate with a pair of ARM5s or M6s, the tuner &
pre-amp will alternate with a Revox A720 tuner/preamp, or a Scott tuner
and Scott pre-amp.

Lots-O-Other stuff floating around too.... depending on what's passing
through.

No horns involved.

Lots of power, lots of headroom.

My test sources are the Saint-Saens as noted, Kiri Te Kanawa singing
Mozart's Exulatate Jubilata, Vivaldi's Gloria, and a solo harpsichord,
usually Bach. After that group, Bluegrass, Folk, solo guitar (Leo Kotke
or John Fahey) and standard R&R are no challenge.

Peter Wieck
Wyncote, PA