Accuphase c 290 brochure

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PRECISION STEREO PREAMPLIFIER

-290

.8uperior balanced line amplifierOAll-stage class~A
push-pull design with low-noise input moduIEOPF'O
printed circuit boardSOComplate mono consuuction
with separate amorphous-core transformers 0 Four-
gang volume control with CP resistor elements

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The most important task of a preamplifier is
to faithfully reproduce the sound of a pro-
gram source. With the sonic evolvement of
the CD and other high-quality sources, this
has become even more essential. Accu-
phase has always been a champion of
quality, as exemplified by our dedication to
the balanced transmission principle It is no
coincidence that the C-280V preamplifier
with its perfect balanced line amplifier has
been praised the world over as representing
the pinnacle of preamplifier design.

The 0-290 now takes the balanced trans-
mission technology developed for the Cv
290 to an even higher plane of perfection.
All aspects of circuit topology were reex-
amined, and only the very best parts and
materials were used to create this master-
piece. We are proud to have once again
redefined the state of the art in preamplifier
design.

in View of today's program sources, the
0-290 was developed into a line amplifier
that is the epitome of purity. But we have
not forgotten the traditional side, either,
Among other things. Accuphase is famous
for giving full play to analog disc reproduc»
tion, and the (3-290 is no exception. For
audiophiles with a valued analog disc col»
lection, the optional phono equalizer unit
provides an ideal way to enjoy the best of
two worlds. The add-on unit fits into a
dedicated compartment on the rear of the
amplifier and offers two inputs for MM or
MC cartridges.

One of the most notable features of the
0-290 is the fact that the sonic perfor-
mance of its line amplifier is equally out-
standing with balanced as well as unbal~
anced input and output connections. The
balanced output stage employs a symmetri-
cal cross-feedback design that results in a
full-floating balanced circuit of the highest
order where the signal path does not

Full-floating balanced line amplifier assures id
All-stage class-A push-pull design with low-nt
Printed circuit boards made of PPO resin witl
Complete mono construction with separate amt
Four-gang volume control with CP resistor e1
Optional Dhono equalizer unit for analog disc

depend on the ground line. The differential
complementary push»pull stage is executed
as a high-performance module which pro-
vides reliable protection against noise and
enhances temperature stability and reliabil-
ity. For the printed circuit boards, which are
highly important components affecting
electrical and sonic performance, poly-
phenylene oxide (PPO) with printed circuit
pattern of gold-plated copper is used,
resulting in a definite sound quality
improvement.

The various unit amplifiers are housed in
massive aluminum enclosures which are
mounted on a motherboard and in turn the
motherboard is firmly mounted on an 8-mm
thick chassis made of hardened aluminum.
This provides perfect protection against
electrical and mechanical interference and
vibrations. Complete mono construction
with two sets of power transformer and
filtering capacitors prevents unwanted
interaction between the stereo channels, to
assure absolutely stable operation,

The 0-290 fully reflects the fact that the
power supply of a preamplifier is of vital
importance. The power transformers
employ an amorphous core material with
non-crystalline structure, which yields
excellent frequency characteristics and
keeps magnetic distortion at a minimum.
The volume control is a four-gang type with
conductive plastic (CP) resistor elements.
This provides attenuation that is virtually
free of sonic degradation and other un-
wanted side effects. Logic~controlled relays
are arranged close to the input and output
connectors, in order to allow the shortest
possible signal paths. The hermetically
sealed relays are filled with nitrogen gas,
for outstanding reliability and long service
life.

The optional phono equalizer unit features
the same superior circuit topology as used

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in the C-280V, with dedicated input stages
for MM and MC cartridges. Of course,
high-quality PPO circuit boards are used, to
assure analog disc reproduction of the
highest order.

Whether one considers circuit design,
materials, parts, or workmanship, the 0-290
is nothing less than perfect. Its sonic excel-
lence lets the connoisseur rediscover the
true meaning and pleasure of high-end
audio.

The ultimate balanced line amplifier
Accuphase has for a long time advocr
the balanced transmission principle. T -
fore it is a matter of course that the (3-290
should offer perfectly balanced circuit
design at least on the order of the C«280V.
In balanced signal transmission, two identi»
cal signals are transmitted simultaneously
with inverted phase and combined at the
receiving end, thereby canceling out
common-mode noise, This principle
assures ideal transmission characteristics,
since any extraneous components such as
RF interference from other equipment and
other types of noise are canceled and
cannot affect the sonic purity of the signal
path. For this reason, broadcast studios and
other professional facilities where extended
signal lines are inevitable have long been
using balanced transmission. Recently, this
principle is gaining increased popularity
also in the home, since there are many
possible sources of electrical and air-borne
high-frequency noise which can enter the

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(b) Unbalanced input/output

Flg.2 Comparison of balanced and
unbalanced signal transmission

cables of audio components and cause
sound quality degradation, Balanced signal
transmission reliably guards against this
danger, making it an important requirement
for true high fidelity.

The balanced line amplifier in the 0-290
carries the balanced principle to its fullest
consequence, in order to provide perfect
balanced output. Fig. 2 shows the amplifier
during balanced operation (a) and unbal-
anced operation (b). A total of three differ-
ential amplifiers are used. During balanced