what started out as a wild d.i.y. project in the mad science lab
at High Fidelity Engineering Co. aka DECWARE in 1996 - the Radial
Loudspeakers are now shipping to enthusiasts around the world!
Introduced at the VSAC2001 show, the Radial Loudspeakers were able
to demonstrate the holographic properties of our Zen Triode amplifiers
in even the most adverse conditions.
From 38 Hz ~ 3 kHz these
speakers disperse sound in a hemisphere
that floats above each cabinet. The
energy is evenly dispersed across 360 degrees
so wall reflections are already diffused!
This is the same effect of having
a room treated on all 4 walls with quadratic
From 3kHz on up these speakers
using a floating tweeter become a point
source with amazing coherency. We found
the main flaw in other radial speaker designs
is that they try to shoot high frequencies
all around the room. This compounds
room acoustic problems and should be avoided.
The cone of the radial driver
weighs only 4 grams. The suspension
is very stiff and driven by a high mass
cast frame and motor assembly. The
speed of this driver when compared to conventional
box speakers is MORE than apparent. It
will have you shaking your head in disbelief.
loudspeakers are easy to drive two-way speakers
with a sensitivity of around 93 dB with 1 watt.
This makes them ideal for lower powered
amps including some SET (Single Ended Triodes).
vs. REFLECTED ENERGY
paper getting into the concept of the radial
design that was
written after the very first
prototype in 1997.
paper documenting features of the production
of the original RL-1. A good overview.
Written in 2001.
paper written during the assembly of the first
radial driver. Written in
above, a mahogany RL-1 cabinet (center)
the removable steel grill with an actual
feather weight cone sitting on it (left)
and the radial driver (right).
We had a steel die machined to the inside
diameter we needed by a large US manufacturer
who wrap the die with pulp under high pressure
to effect a thickness to within 0.030 of an
inch. These high density cardboard cylinders
are then cut to length and sealed inside and
out. Rings are machined out of MDF and
installed into each end to receive the driver
and base assembly.
next step in the main cylinder is the veneering.
We use a rather expensive solid cherry
veneer as the default finish. We do make
many other woods available such as walnut, mahogany,
maple, birch, and some exotics for custom orders.
is accomplished by using combinations of different
densities of foam inside the cylinder.
Every step of the assembly process is done by
hand using jigs for accuracy and consistency.
final result is then finished with clear lacquer
and allowed to cure for between 1 and 2 weeks.
These enclosures have tremendous strength
and are considerably more inert than an equivalent
3/4 MDF cabinet.
The tweeter is crossed
with a high grade polypropylene cap and attenuated
by the user via interchangeable resistors installed
on the top set of binding posts. This
was done to allow the greatest flexibility in
dialing in the tweeter for any given room without
the fidelity robbing side effects of an L-Pad.
There is no crossover on the Radial Driver.
It is important to
understand that there are many things
that make the Radial Loudspeakers
superior to conventional
box and even planar type speakers.
Radial Loudspeaker (based on an inverted
4 gram paper cone) is a project that
has evolved through well over 100 variations.
It became obvious about half-way
through the development why no other
manufactures have built one. It
was a problematic concept. With
exhaustive R&D we were able to overcome
these obstacles and make the dream a
How many other inverted cone drivers
exist today ... NONE.
designed these speakers for serious
audiophiles who want something that
sounds obviously superior to conventional
box speakers. Spoiled by well
designed horns and panel speakers
I myself have become allergic to the
slow & muddy sound of what I used
to think were killer audiophile speakers.
problem is that both panels and horns require
significant setup hassles to get a coherent
sound stage. Even when your room acoustics
don't prevent success you still have
to listen with your head in a vise to
get the 3D effect. The radials solve
these problems and are my
new reference speakers for imaging.
HISTORY OF REVISIONS
on the left, the original RL-1 Radial Loudspeaker
the right, the RL-2 loudspeaker.
IMPROVEMENTS in the new RL-1.5
Radial Loudspeaker for 2005 is a perfect blend
of the strong points between the RL-1 and RL-2.
Like the RL-2, the new RL1.5 has an excellent
ribbon tweeter. The biggest difference between
the RL-2 and the new RL-1.5 is the cabinet design.
The RL-2 cabinet base design has been replaced with
a more streamline design similar to the RL-1 but
with more mass, heavy cone spikes and a flat passive
radiator. This has a few advantages over the
previous models. The cabinet height is now
ideal, where the RL-1 was a touch short, the RL-2
a touch tall.
bass response is now ideal, with no need for adjustment.
Like the RL-1 it can be adjusted somewhat
by the floor surface it fires against, and the height
of the floor spikes. Like the RL-2, the adjustment
range is limited so that the user can not miss-adjust
it beyond a nominal range.
main 8 inch radial driver was redesigned to match
the improved transient response of the passive radiator
in the cabinet base. The idea being that they
should match. The closer they match, the closer
together in time will be the primary transient and
reactionary echo from the passive. If you
look at the impulse response from the RL-1 seen
below, since there is only an active driver in an
open bottom cabinet there is no reactionary echo,
whereas in the RL-2 while still less then 1ms the
echo is clearly there.
and RL-1.5 impulse response
impulse response with clearly visible echo from
basic difference between the RL-1 and RL-2 impulse
response echo showed up in the speakers overall
sense of speed in the bass. RL-1's were a
touch faster then RL-2's. RL-2's had
more weight in the bass. Now the new RL-1.5's
have the speed of RL-1's and the weight of RL-2's.
the main driver had to be redesigned with even less
moving mass to match the new passive radiator a
few opportunities presented themselves. The result
was a driver that has an obvious increase in midrange
presence over all previous designs and because of
the lighter more linear voice coil it enjoys an
increase in efficiency and coherency. When
you combine all these things you have a new Radial
loudspeaker that sounds so much better then the
two previous models we had to discontinue them.
Now if you consider how incredibly good the
previous models sounded, this is an amazing accomplishment.