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Delivering
amazingly flat response - which
means "No Shout!" and more realistic sound!
Imagine your
speakers having such extreme
speed and top-end detail
that cymbals, bells, chimes,
xylophones, horns,
stringed
instruments, drums and virtually ALL
music SOUNDED REAL! Instead of
sounding real
peaky like so many
full range drivers, the FRX2 just
sounds real thanks
to the super extended ultra smooth
response made possible by
it's electromotive coupling
technology and powerful
neodymium magnet.
click
here 1024px high res image
MODEL FRX2
E
x o t i c F u l l - R
a n g e
Single Point-Source Driver
for Open Baffle
Loudspeakers
37Hz ~ 22kHz
response 8 Inch driver / 94 dB 1 watt/meter
 a
pair
We hand make these
beauties in the USA
PURCHASING
NOTICE
These
drivers are available ONLY
as long as the parts
required to build them
remain available. These
are constructed with donor
drivers that we have no
control over. The
donors' could be changed
or discontinued at any
point so each time we
replenish our small
inventory it could be the
last. We are hand
building these
drivers. This is not
a production run.
A 50% non-refundable
deposit is
taken at the time of
ordering. The balance due will
be taken when your speakers ship. They
are guaranteed work perfectly when
you receive them and for an
additional 5 years against
mechanical defects of any
kind. There are no returns
accepted.
O V
E R V I E W
 The
FRX2 represents an obsessive
effort on my part to perfect the
full-range point-source driver
for Open Baffle speakers at a
sane cost. While the build
quality of this driver will
compete with with other brands
costing many times the price, I
don't believe any of them will
hold up sonically because of the
side effects of high flux low
mass designs. Side effects like
the occasional shouty mid-range
and forward presentation or
ringing that comes with
the tipped up response
that is characteristic of these
types of drivers. The FRX2
overcomes these side effects
with a unique motor assembly
that uses electromotive coupling
between the amplifier and the
voice coil. To my knowledge
there is no other single driver
in the world with this
technology.
I
personally hand build these
drivers in small batches of 10
pairs at a time.
UPDATE
FROM THE BENCH - DEC 2011
 In the summer
of 2011 (right after I
released the original FRX) the
donor drivers from Dayton
become unavailable as Dayton
worked to further improve the
consistency of their
product. The changes,
while subtle, left me little
choice but to start over so we
now have the second version of
the FRX driver, the
FRX2.
 By
redesigning the tuning load
I was able to eliminate the
added (foam) surround
further enhancing the
driver's uncanny speed and
gaining an even flatter
frequency response. In
addition to the improved
electromotive correction, I
added DUAL TUNING loads
selectable from a tiny
switch on the rear of the
driver. This gives
your choice of a mellower or
more present sound... very
much like having two drivers
instead of one. So in
the end, perhaps it was a
blessing... I
show comparisons in the
measurements further down
the page.
-Steve Deckert
Model
FRX2
FULL RANGE POINT
SOURCE DRIVER FOR OPEN
BAFFLE LOUDSPEAKERS
I N T R O D U C T I O N
The
FRX2 design is about ultra high
fidelity with lower powered
amplifiers at sane listening
levels. It has limited power
coupling around 15 watts or
so. That means power in
excess of that amount will be
compressed via the FRX2's novel
electromotive coupling.
Point being - this is not a party
speaker. It was designed for
critical listening using world
class gear by audiophiles with
golden ears. It's SPL
limitation is like the old QUAD 57
electrostatic speakers and in a
proper enclosure/baffle the FRX2
has a similar albeit more dynamic
sound. Unlike a panel speaker, the
FRX2's high frequency dispersion
exceeds most tweeters so off axis
listening is superior. It's
higher total Q and 4.5mm x max
makes it well suited for open
baffle use.
FEATURES
- High
sensitivity/minimal distortion—an ideal match for
lower powered amplifiers
- Electromotive
amplifier to voice coil coupling
eliminates ringing
and stabilizes response
- Machined motor
assembly with optimized
neodymium magnet provides tighter
control
- Solid bass
performance, thanks to
usefully high excursion
capability (>4 mm Xmax)
- Cast frame
with under spider venting for
excellent cooling and low mechanical
noise
- Narrow spokes
eliminate reflections behind the
cone for cleaner
response
- Motor shape
acts as a rear wave guide to enhance
dispersion
- Parasitic HF
cone and carefully engineered
phase plug extends on and
off-axis response
- Low-mass
copper clad aluminum voice coil
increases high
frequency response and speed
- Copper cap and
copper ring on pole piece reduce voice coil
inductance and distortion
- Kevlar reinforced paper
cone is lightweight yet rigid
and well controlled for cleaner bass
- Hand Built, tuned and
tested one at a time for superior
attention to detail
and overall quality
PRINCIPAL OF OPERATION
The
varying current entering the
FRX2 motor from your amplifier
creates a varying magnetic flux
in an air gaped grain-oriented
silicon steel laminated core via
a primary coil winding and thus
a magnetic field through a
secondary winding is
developed. This
varying magnetic field induces a
varying electromotive force
(EMF) in the secondary winding
called mutual induction. Once
this secondary winding is
properly tuned with a resistive
load, AC current is allowed to
flow through this air-gaped
circuit via the primary and out
to the voice coil. Since
the EMF at a given flux density
increases with frequency, the
secondary (tuning coil) absorbs
the artificial rise in response
and ringing caused by the high
strength motor assemblies used
in this type of low mass
driver. Despite
appearances, when the tuning
load is removed no current can
flow to the voice coil.
This exotic approach to
magnetically coupling current
from the amplifier to the voice
coil is what gives the FRX2 it's
uniquely smooth and highly
present sound.
This approach works by designing a
driver that is over the top in
high frequency projection and then
offsetting it with electromotive
force. The result is smooth
linear response without loosing
the hyper speed and insane detail
that comes from the overly strong
neo magnet.
The FRX2 design also brings
significant if not profound
improvements to the overall phase
angle and sense of timing and pace
when compared to normal drivers. I
believe it is part of what brings
absolutely lucid imaging to the
table when a pair of these are
used with good tube amplification.
UPDATE:
Some have suggested that using a
digital EQ in the signal path
would yield results just as good
and cost a lot less. I
mention this because this
represents a typical gross
misunderstanding of what the FRX2
really does.
This system is about storing and
releasing energy, and modifying feedback
traveling from the speaker back
into the amplifier.
It works with
the amplifier to create a better
more synergistic pairing between
that amplifier and the
loudspeaker. A digital EQ in
the signal path before the
amplifier would have no effect on
either one. Addressing frequency
balance issues or phase angle with
a digital EQ is not the same thing
and must be considered a
completely separate process.
ELECTROMOTIVE
EFFECT
This
is the the effect of the
electromotive correction.
Blue is without, Green is
with. Despite the Klippel
analysis of the original FRX
driver where it was claimed there
was no difference in frequency
response, they were wrong.
The plot below is the FRX2 taken
at 1 meter zero degrees (on axis).
To
see more clearly what corrections
the electromotive coupling is
actually making we can simply plot
the difference between the two
lines and zoom in a bit. (Grid is
1dB per div.)
See
we have about 2.5dB of correction
just before 2KHz, minor correction
until just before 5KHz and then
another nice correction at
7KHz. No capacitors were
used in the tuning load.
Of course we are not only
electromotively making corrections
to the frequency balance, but also
the phase response. Below is
the same plot as above, but
showing the minimum phase response
of these corrections.
You can see that 650Hz a nearly 20
degree phase correction, followed
by several more throughout the
bandwidth of the driver.
Remember, this is not the phase
response of the driver, this is
the phase corrections being made
to the driver relative to the
stock donar driver.
THE SWITCH
The switch on the back of the FRX2
allows you to select from two
different tuning loads inside the
motor circuit of the driver.
While easy to hear, the difference
on paper looks deceptively
small. Here is the FRX2 on
axis plot with the switch in both
positions. To the left is
green, to the right is red.
To see a little better what the
switch does we can take the plot
above and show the difference
between the two lines as was done
in the plot below where we zoomed
into 1dB per div. You can
see the additional correction
offered by the switch in the left
position is less than 1dB.
MEASUREMENTS of FRX2
Tests were performed at a one
meter distance using a B&K
calibrated microphone. Below
are the gated responses (200Hz to
22KHz) using the FRX2 driver in a
Zen
Open Baffle:
FRX2
15-DEGREE OFF AXIS FREQUENCY
RESPONSE
Listening
tests and measurements agree
that this driver sounds best
at 15 degrees off axis, the
frequency response shown above
is impressively flat.
FRX2
0-DEGREE ON AXIS FREQUENCY
RESPONSE
The point-blank measurement at
0 degrees isn't bad either and
contributes nicely to the
overall response of these
drivers.
FRX2 30-DEGREE OFF AXIS
FREQUENCY RESPONSE
The FRX2
response at 30 degrees off
axis.
FRX2
AVERAGED OVER 30 DEGREES
FREQUENCY RESPONSE
And here is
the averaged response of all
three which gives you a
general sense of what the FRX2
will sound like overall from
different locations...
SOUND CHARACTERISTICS
The FRX2 drivers
clearly push the limitations of
what is possible with a single
point source driver. By that
we mean they have extreme speed
and top end detail that makes
cymbals, bells, chimes,
xylophones, horns, stringed
instruments sound real.
These drivers set a new benchmark
for "in the room" presence.
The bass performance and timbre is
spot on and electrifyingly fast
and clean with surprising weight
and power.
The impulse response of the FRX2
shown below clearly demonstrates
how fast this driver is:
"I could care less how
they measure...I have a soft spot
for hard rock...when it sounds
live - and the attack from these
speakers combined with their ultra
controlled bass made me feel like
it was live. I felt every
guitar note and as a drummer
myself, I can tell you the drums
sound more realistic on these than
anything I've heard yet.
Very impressive."
-Dennis Hazen
Think
of the FRX2 like a super high
performance race car. The
car is designed to perform on a
good quality track and does so
better than anything else.
However, run it on a poor quality
track and the cars very strengths
become its weaknesses.
Recording quality is like the
track.
Recording quality is imperative
with speakers like these.
The differences between poor
recordings and great recordings on
most speakers are easy to hear,
but on the FRX2 that difference is
magnified in two directions...
that means the good recordings
become great and bad recordings
become horrible, thin and
distorted. I would say this
magnification effect the FRX2 has
is by a factor of at least 4
compared to normal speakers.
Literally, thin recordings will
sound like someone removed the
bass, yet warm recordings will
have low bass with impressive
weight, dynamics, and enough power
to shake your room. This is
what happens when we design
speakers that are fully honest vs.
speakers that musically interpret
the source... we hear only the
recording as it was mixed.
Coloration's in speaker designs
are what make all speakers sound
different. The FRX2 has
none, so we recommend these
drivers to the serious audiophile
and experienced Do It Yourselfers
who have top notch amplification
and source components.
"I
replaced my DFR-8S drivers simply
because I couldn't see how it
could get much better. My favorite
part of the DFR8-S was the
mid-range and while
Steve will probably probably
flinch... when I
A/B'd the FRX2 against it, the
difference was enough to make the
mid-range of the DFR-8S sound
broken. It really caught me
off guard. These things are
GOOD."
-John Waters
APPLICATIONS & FAQ
 The
FRX2 can be used by itself in an
open baffle cabinet design, or
used in an open baffle design
together with a bass driver as is
popular with so many open baffle
designs. In our Zen Open
Baffle cabinet, the FRX is a drop
in replacement for the original
DFR8 or DFR8S drivers.
Q) If I already own
speakers that use Fostex or
Lowther based 8 inch drivers
will the FRX2 fit the existing
cutout?
A) Yes, The only difference will
be the screw hole pattern on the
FRX2. It has six screw
holes vs. the Fostex and
Lowther's four screw holes.
Q) I have Zen Open
Baffles with the original
DFR-8S drivers, can I install
these myself and if I don't
like them can I put my
original drivers back in?
A) Yes, you can easily remove
the original drivers by
unhooking the two wires on the
back, and removing the 4
screws. Installing the
FRX2 is a matter of having
someone hold it in place while
you install the 6 new self
tapping screws that are
included. Just hook your
speaker cables directly into the
back of the FRX2 driver.
Q) What does FRX2 stand
for?
A) It stands for "Full"-"Range"
Project "X" Version 2.
Q) Besides open baffle
designs is there anything else
this driver will work in?
A) Of course this speaker will
also work in infinite baffle
applications. One example
is to mount it into the wall
just below your projector screen
as a center channel for
movies. The articulation
and clarity of the FRX2 makes it
unrivaled as a center channel
speaker in custom home theaters.
And as
illustrated below, it is possible
to build large conventional
cabinets with the FRX2 as well.
THIS IS A HIGH
QT DRIVER DESIGNED
FOR OPEN BAFFLE
LOUDSPEAKERS.
For
reference both sealed and ported
boxes are also modeled below:
Sealed Box volume 16 cubic
feet -3dB =
60Hz -10dB = 32Hz
Ported Box volume 16 cubic
feet -3dB = 38Hz -
10dB = 27Hz
| FRX2
SPECIFICATIONS |
T&S |
PARAMETERS |
94 dB with 1 watt
at 1 meter
Response is 38Hz ~ 25kHz
8 ohm nominal impedance
15 watts RMS/30 watts MAX
Dimensions: A: 8.7", B:
7.2", C: 4.0" D: 9.8"
1 inch voice coil
machined copper phase guide
and shorting ring
5 way machined gold plated
binding posts on rear
Shipping weight 15 lbs ea.
|
Re
Fs
Qe
Qm
Qt
Le
Vas
Xmax
Ef
Zmin
Zmax
|
7.36
ohms
70 Hz
0.83
8.45
0.76
1.88
2.04
4.22 mm
94dB 1w/1m
7.4 ohms
72 ohms
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click
here 1024px high res image
MODEL FRX2
E
x o t i c F u l l - R
a n g e
Single Point-Source Driver
for Open Baffle
Loudspeakers
37Hz ~ 22kHz
response 8 Inch driver / 94 dB 1 watt/meter
a
pair
TEMPORARILY DISCONTINUED DUE
TO SUPPLY CHAIN ISSUES
We hand make these
beauties in the USA
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