Delivering amazingly flat response - which means
"No Shout!" and more realistic sound!
Imagine your speakers having
such extreme speed
and top-end detail that
instruments, drums and virtually ALL music SOUNDED REAL! Instead
of sounding real peaky like
full range drivers, the
real thanks to the super
extended ultra smooth response made
it's electromotive coupling
technology and powerful
click here 1024px high
Single Point-Source Driver for Open Baffle
37Hz ~ 22kHz response 8
Inch driver / 94 dB 1 watt/meter
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We hand make these
beauties in the USA and sell direct to the customer
as the parts required to build them
remain available. These
are constructed with donor drivers that we have no control over.
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.
taken at the time of ordering. The balance
when your speakers ship. They are guaranteed
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
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. There is no other single driver in the world
with this technology.
personally hand build these drivers to order. Build time on a pair of
these fine drivers is around eight weeks.
UPDATE FROM THE BENCH - DEC 2011
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.
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.
FULL RANGE POINT SOURCE
DRIVER FOR OPEN BAFFLE LOUDSPEAKERS
I N T R O D U C T I O N
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.
distortion—an ideal match for
lower powered amplifiers
and stabilizes response
neodymium magnet provides
- Solid bass performance,
thanks to usefully high excursion capability (>4 mm Xmax)
guide to enhance
on and off-axis response
frequency response and speed
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
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
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
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.
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).
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.)
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 reponse. Below is the same
plot as above, but showing the minimum phase response of these
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 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
driver in a Zen Open Baffle:
15-DEGREE OFF AXIS FREQUENCY RESPONSE
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
here is the averaged response of all three which gives you a general
sense of what the FRX2 will sound like overall from different
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:
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
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
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
Yourselfers who have top notch amplification and source
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
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
These things are GOOD."
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
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
Sealed Box volume
cubic feet -3dB = 60Hz
-10dB = 32Hz
Ported Box volume
cubic feet -3dB = 38Hz - 10dB = 27Hz
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.