quickly become a major player in the audiophile grade, Class D
amplification market over the past five years. While the NuForce
product line is now quite extensive, ranging from amplifiers to
headphones, the company is best known for their Class D mono block
amplifiers, the latest version of which is the Reference 9 V3 Special
Edition reviewed here. The NuForce amplifiers differ from traditional
amplifiers in that they are a "switching amplifier" or "switched power
supply amplifier." Most switching amplifiers on the market today are
digital switching amplifiers that are considered by most to be a Class
D design. The NuForce amplifiers
themselves from this group of amplifiers by utilizing a closed-loop
system with analog modulation driven by the audio signal. A traditional
analog amplifier is controlled by fixed frequency, carrier based pulse
width modulation. The NuForce topology is said to greatly increase
efficiency, bandwidth, control (damping), phase problems, linearity and
signal to noise ratios.
V3 series released in October 2009 is NuForce's third generation
amplifier. Owners of V1 or V2 series amplifiers can have their
amplifiers upgraded to V3 for a relatively modest fee. In the case of
my V2 Special Edition amplifiers the cost to upgrade them to V3 Special
Edition was only $400. Of course you can buy a brand new V3 Special
Edition for $5,000. The only difference between the upgraded and new
amplifiers is the face plate; the upgraded units will have an old style
faceplate with the new "V3" moniker and the new units will have
NuForce's new three dimensional faceplate.
describes the V3 circuit as having an improved feedback path and better
control over a wider bandwidth. The V3 circuit has different power spec
than the V2: 175 watts RMS into eight-Ohms as opposed to the V2's 190
watts. However, into four-Ohms the V3 has 335 watts of RMS power as
compared to the V2's 300 watts. V3 has lower gain than V2 due to design
optimization with the new feedback control system. NuForce notes that
the lower gain allows the preamplifier's volume control to be run at
higher level which produces better sound quality with many of the
preamplifiers on the market today. The V3, like prior generations of
NuForce amplifiers is offered in both standard and Special Edition
versions; the Special Edition features an custom designed capacitor
array instead of the standard dual big capacitors design. While I have
never had both the standard and Special Edition versions of the same
amplifier for comparison, NuForce claims sweeter highs and a smoother
midrange set in a more coherent and deeper soundstage.
I first saw a NuForce Reference 9 I was surprised by their diminutive
extruded aluminum chassis' which measure eight and a half inches wide,
14 inches deep and nearly two inches tall, and weigh in at eight pounds
a piece. Most of the monoblocks I have had in my system over the years
were large, heavy units. These traditional monoblocks can be visually
impressive but they can also be difficult to move and find a place to
set up. This is where Class D amplifiers can have a large advantage; I
can easily carry both units under my arm and then set them up in the
same amount of space as a traditional source unit.
extruded aluminum chassis on the Reference 9 amplifier series is
reasonably solid and well finished but will not be confused with a
Rowland, McIntosh or similar component. There are no half inch thick
metal panels or surfaces polished to a mirror finish. The images I have
seen of the new faceplate style indicate an upgraded aesthetic for
those who need eye candy to go along with their ear candy. The
amplifiers have both single ended and true balanced XLR inputs and a
set of Eichmann Cable Pod binding posts.
used the NuForce amplifiers in my dedicated two channel system,
utilizing Logitech's Transporter and Classe CDP-202 as sources. During
the course of this review, I switched pre-amplifiers from Conrad
Johnson's excellent CT5 to another tube unit, McIntosh Laboratories'
C-500 (review pending). I spent a lot of time listening to the
Reference V3 Special Edition amplifiers with both preamplifiers but my
listening notes were done with the McIntosh preamplifier in the system.
The speakers I used in this review were Martin Logan Summit's and
Acoustic Zen Adagio's. All connections were made with Kimber Select
cables, single ended with the Conrad Johnson preamplifier and balanced
from source to amplifier with the McIntosh. Power conditioning was
courtesy of a Richard Gray Power Company 1200 and power cables were
small size of the amplifiers allowed me to easily fit the amplifiers on
a single Billy Bags amplifier stand. The Eichmann Cable Pod binding
posts may provide a good electrical connection but did not provide the
tactile reassurance of a more traditional 5-way binding post. The
layout of the amplifier itself forced me to feed my spade fitted
speaker cables from above the amplifiers, if the back of the amplifiers
extend past the shelf you may be able to access the binding posts from
the bottom, side access will be tight with most speaker cables.
Regardless, the Eichmann Cable Pod binding posts kept a firm grip on
the Kimber speaker cables throughout the course of my review.
any serious listening I let the amplifiers break in for over a couple
of weeks, including six straight days of non-stop music. These
amplifiers need a seriously long time to break in, close to 200 hours
seemed to do the trick for me. I also left them on unless it was going
to be days between listening sessions as I found that it took over an
hour for them to fully warm up to maximum performance levels.
Read more about the performance of the Reference 9 V3 on Page 2.