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G-928
I
t combines fi rst-
rate musicality
and exceptional
delicacy with a bottom-
end solidity and power
that was fully up to
the job of reproduc-
ing todays dynamic
soundtracks. Transient
impact was extraordi-
nary-bass extension
was outstanding.
Robert Harley, The Perfect Vision magazine Visit www.genesisloudspeakers.com
to download a complete copy of this review.
T
he Genesis G-928 Servo-Subwoofer was
created using several refi ned technolo-
gies - servo-control, metal cone drivers and
effi cient, hyper-linear switching (Class D) am-
plifi cation - which makes it able to accurate-
ly and instantaneously reproduce the subtle-
ties of a bowed double bass or the shuddering
footfalls of an angry T-Rex.
The G-928 transducers.
In contrast to the comparatively heavy or
lossy materials used in almost all other
woofer cones, the G-928s dual 12-inch driv-
ers are made of lightweight yet inherently
stiff metal. Thanks in part to massive magnet
structures and long-throw voice coil assem-
blies, these precisely contoured cones are free
of the transient-blurring artifacts imposed by
lesser materials. With greater radiating area
than even a 15-inch transducer, the dual 12-
inch cones respond instantly to input signals
to reveal details often obscured by heavier,
less responsive designs. Also, they can deliver
surprisingly substantial volume levels for
their modest size.
True Servo Control.
Inertia is the enemy of accurate low fre-
quency reproduction. The woofer must start
instantly- and stop suddenly. However, its
inertia makes it sluggish, resulting in over-
hang, bloat, lack of tautness and a blurring of
dynamic impact.Rather than simply send the woofer pulses
of power and hope for the best, the solution is
to carefully monitor the woofers movement
and make instantaneous power corrections to
get it up to speed and stop it on a dime.
Very few loudspeakers use servo drive, ei-
ther because most designers think that it is too
diffi cult to design, too expensive, or because
of the extraordinary demands a servo system
makes on the amplifi er and woofers.
However, Arnie Nudell, Genesis Chief
Scientist, is more than comfortable with servo
control: he designed the servo system in the
legendary Infi nity Servo Statik One back in
1968 - and has continued to refi ne the design
using new materials and technologies.
The G-928 is the latest iteration of his
research. A precision accelerometer on the
woofer continuously monitors motion and
sends a signal to high-speed circuitry that compares actual cone movement to the input sig-
nal. The comparison circuit instantly identifi es any
deviation from ideal response. Then, in real time,
it adds a corrective signal to compensate for any
deviation from the input signal even when they in-
clude complex, rapidly evolving musical bass lines
or cinema special effects.
With this constant-feedback servo control, the
transducers are essentially massless and anechoical-
ly fl at. While typical non-servo woofer systems have
distortion levels that exceed 10% at even moderate
levels, the G-928 servo bass system reduces distor-
tion to below one percent at almost any output level.
In short, the G-928 guarantees earth-shaking
bass coupled with stunning articulation.
The G-928 power amplifi er.
The servo system places extraordinary demands
on the amplifi er since the system uses enormous
amounts of current to precisely control the woofer.
The best amplifi er for this application is a Class-D
switching amplifi er with its dynamically increased
effi ciency, especially at extreme low frequencies.
The G-928s proprietary and ultra-effi cient Class
D, discrete MOSFET switching amplifi er is a prime
example of intelligent power application in the
service of sonic subtlety. With output capability up
to a full kilowatt of peak power, the G-928s Class
D design provides extraordinary control and excep-
tional thermal stability even when playing the most
demanding sources continuously at high volume.
It is remarkably cool running, too, thanks to the
designs inherent 90% effi ciency (versus as low as
50% for traditional Class A/B amplifi ers).
