Radial Speaker was originally inspired by the Ohm Walsh bending
wave speakers that radiate sound 360 degrees. Having listened to
these many times, as well as the German speakers using bladders,
and other 360 degree designs I observed that despite their flaws
they all did something special.
understand the Radials you have to understand some basics about
listening room acoustics.
On conventional speakers the ultimate goal is to hear only the direct
energy from the speaker itself and not the reflections of your room.
If this can be achieved, a coherent and believably holographic soundstage
order for our brain to perceive a focused image there must be both
a delay as well as a reduction in volume that distinguishes the
direct energy from the reflected energy. If these reflections are
not delayed by at least 50 milliseconds AND reduced in volume by
at least 15 dB or more, the brain can't tell the difference between
the two. This results in a poorly rendered sound stage with less
a conventional home listening space using conventional speakers
these reflections are not delayed or reduced in volume enough. The
direct energy passes you ear and hits the back wall of your room
where it refracts to the side wall and then reflects off the front
wall where it comes past your head a second time. To correct these
reflection points properly, a series of quadratic diffusers must
be installed on each of the four walls.
diffusers work by taking a beam of energy such as that emitted by
your loudspeaker and phase grating it out to a hemi-disk pattern.
This busts the beam and reduces its energy. One second of sound
will create over 500 reflections in your room so having diffusion
on all four walls compounds (actually squares) the effect.
can then see why conventional speakers including panel speakers
and bipolar designs sound so unpredictable from room to room. We
have developed serious room treatment products to correct these
problems, and unlike little pillows and tube traps, these products
add 2100 lbs of mass to a typical listening room. Believe it or
not this is what it takes to completely correct a 15 x 13 room.
will notice, or probably have already, that in untreated listening
rooms the louder you play a system the more these room reflections
screw up the imaging and focus, not to mention frequency balance
changes caused by nodes of standing waves which result directly
from these reflections.
goes against the tendency for raised listening levels to add more
weight, presence and detail to a recording. So you have two things
working in direct contrast with each other when you raise the volume.
Add to that the fact that nodes in your room are so numerous that
moving your head as little as one inch can actually change the frequency
balance. It's no wonder you system sounds different from time to
time since all of these variables combine to determine the actual
an untreated room using conventional speakers it is not uncommon
to have nodes creates peaks and dips in the frequency balance that
are as high as 12 or even 15 dB.
a speaker like the Walsh for example these problems are reduced
from about 2000 cycles on down by the simple fact that the energy
from the speaker is already diffused to a point where room reflections
are only a minor problem. However, these and other 360 degree speakers
have also been radiating the high frequencies at a 360 degree pattern.
have found that for holographic imaging you do NOT want frequencies
above 2000 cycles to be shot all over the room. Since high frequencies
are much narrower and therefore beamy to begin with, they travel
around the room with their original pattern or beam intact many
times more than lower frequencies. This creates a new problem in
untreated rooms that is actually more severe than a conventional
speaker. The result from 2000 cycles on up is a soundstage with
poor focus and a lack of consistency.
speakers or speakers with rear firing auxiliary tweeters actually
create an artificial ambience that many interpret as actual space
in the recording. These types of speakers compound reflection issues.
Radial speaker is designed with an inverted cone that has a tailored
dispersion with a natural shelf in the response at 2000 cycles.
Therefore it can be mated with a tweeter without the use of any
crossover. This alone adds tremendous coherency and dynamics to
its performance. Above 2000 cycles is a delicate blend of ambient
reflected energy and direct energy from a single point source.
dispersion pattern of the main driver is also designed to use the
ceiling to double the size of radial wave fronts in the mid band
frequencies. This projects an image centered between the top of
the Radial speaker and the ceiling resulting in the correct image
way these radial wave fronts react with the typical problem reflection
points in a room is by eliminating the points. The energy is already
diffused in wide hemi-disks when it leaves the walls in almost exactly
the same pattern created by our quadratic diffusers.
actual radial drivers used in this speaker utilize a top cone with
less than 6 grams of mass and a very tight compliance. This lightweight
cone has incredible speed and detail far exceeding conventional
audiophile woofers with the exception of perhaps a Lowther driver.
There is also a higher-mass cone working off the same motor assembly
that gives the driver a usably low frequency response.
cylindrical enclosure is diffraction-free making it completely invisible
to the ear. Its small size of 30 inches high makes it easy to move.
It uses an open bottom design that couples to the floor for enhanced
low frequency response and can be fine tuned. Usually placed on
carpeting, the weight of the enclosure against the height of the
feet create a varo-vent for wide band damping. Adjusting the space
between the carpet and the enclosure bottom will tailor the low
frequency response to your room acoustics and taste.
tweeter used is a very small Audax poly dome sputtered with titanium.
It has a balanced 3/8" drive where the mass of the diaphragm
and voice coil is evenly split. This particular tweeter has incredible
spatial qualities and is perhaps the fastest dome tweeter I've ever
heard so it mates well with the Radial driver.
tests found these to be far and away the best imaging speakers with
the most accurately rendered soundstage we've heard to date. Even
only 4 feet apart they created a soundstage that exceeded the width
of the room itself. Depth is seemingly boundless. The height is
wonderful, but unlike some speakers with good height to the sound
stage these were true to the recording. Instead of artificial height
that works on everything, these speakers accurately portray the
height of the original recording space.
these speakers sound better when you're sitting down and at a reasonable
distance back. Listening test confirmed this. Usually in smaller
rooms standing up creates a more dimensional perspective on the
soundstage adding to the depth. This is due in part to the comb
filter effect of your floor. With the Radials there is almost zero
comb filter effect. All of our other speakers including panel speakers
are less than tolerant of the sitting position, and all give the
best results when sitting nearfield on the edge of your seat...
a less than relaxing posture. These speakers gave the same thrill
of being "in the sweet spot" almost anywhere in the room
at a distance of 6 feet or more.
with our Magnepans found the Radials to have better detail, better
top end extension and more spank at lower listening levels. They
have none of the characteristic boxy sound of box speakers, so like
the panels the frequency balance is very well behaved. Comparisons
with our Acoustat Electrostatic Monitors and the RL-2's
we find the frequency balance to be the same, with no
apparent seam between woofer/tweeter. The imaging
was actually better doing a better job of making the
our Zen Triode amplifiers, the Radial speakers resolve more information
in the recordings than any other speaker we've tried to date.
handling on the motor assembly is very high, however the lightweight
delicate cone used to create the radial wave fronts limits the power
handling to sane listening levels. A stiffer cone with a more
compliant suspension would eliminate this restriction but at the
cost of linearity, speed, and intermodulated distortion. We feel
strongly that the trade-off is MORE than justified. So remember,
these speakers are delicate and dynamic but not meant for excessively
loud playback levels in excess of 100 watts.
end result seems to be a small speaker that is room-friendly and
creates a very LARGE lifelike sound stage with about 3 watts.
Radial project started in 1996 as part of our room acoustic tests
that helped developed our Room Acoustic Products. I posted the initial
prototype white papers in our "Wild D.I.Y. Projects" section
of the web site. You may find more in-depth technical information
on how these speakers work in a paper I wrote at that time called
"Direct vs. Reflected Energy"
information can be found in these original