Accuphase P 800 Brochure

Page 1

I Complelely balanced. powerful oulfiutstage cob 'stlng
:r nsistor pairs '
I Outstanding low-impedance drive capability

KM M) 1M (W .\ "/

\\\\\\\ H

Page 2

Ever since the advent of pulse coding method to
record electric signals, the world of reproduced
music is about to undergo significant changes,
because the digital recording technology has
brought about substantial improvement in the
reality of the reproduced music. Moreover. mi,
nuts and subtle reverberation components,
which are essential to reproduce the atmos
phere of the original sounds. can now be re»
corded with utmost accuracy.

Needless to say, accurate transmission of sig-
nals is indispensable in the reproduced sound
fields; otherwise. we cannot even appreciate the
reproduced music and, in the worst case, we
may not be able to perceive what we listen to as
music but nothing more than collection of
noises. Equally important for reproducing
music. however. is an amplifier that can correct-
ly amplify even reverberation components to the
extent that you feel, when you listen to repro»
duced music. as if the music were being played
by an orchestra right in front of you. Without such
an amplifier. the atmosphere of beautiful and
elegant music cannot be reproduced. It is there-
fore vital for a power amplifier to be able to yield
power of high amplitude and. at the same time,
to amplify minute signals superimposed on the
electric signals it amplifies, with high fidelity.
However, the power an amplifier can produce
and its fidelity are. in many case, in a mutual
contradictory relation. and the higher power an
amplifier can produce. the lower its fidelity in
reproducing minute signals and reverberation
components. The P-BOO. which was developed
with Accuphases technology that has already
produced a superb monophonic amplifier. M-
1000. is an exceptional power amplifier in this
respect as it can yield a power of as high as 600
watts (into 4-ohm loads). but reproduce even
reverberation components with high fidelity.
which is not possible with most of the amplifiers
on the market today. It uses two power units in
bridged configuration. forming a totally bal-
anced amplifier. meticulous attention has been
paid to every detail, and original Accuphase
technology is used throughout. with the aim to
improve quality especially at low signal levels.
The impedance of loudspeakers on the market
varies considerably, ranging from about 2 ohms
to 16 ohms. With a direct-coupled amplifier.

mmmtmmmm
Fig.1 M Slat-I Yum mm

driving such awide impedance range with equal
aplomb is almost impossible. An output stage
designed for optimum performance at 2 ohms
will deliver less power into 8 to 16 ohms. Con»
versely. the performance of an amplifier op»
timized for about 4 to 8 ohms suffers at 2 ohms
and it will not be capable of driving i-ohm loads.
The Pv800 incorporates a special design to deal
with a wide range of load impedances. The
applied voltage of its output devices can be
switched to a lower value. to provide the high
current capability required by low-impedance
loads. This results in a truly amazing guaranteed
rating of 600 watts into 1 ohm and 400 watts into
2 ohms. with undiminished sound quality. To
achieve such stunning performance. the output
stage of each power unit employs two sets of
seven parallel push-pull pairs of wide-band
transistors with a maximum power dissipation
(PC) of 130 watts each. This amounts to 14 pairs
or 28 transistors per unit. totaling a maximum
power dissipation of 3.6 kilowatts. These truly
astounding figures testify to the no-holds-barred
design approach of the P-800.

To let you monitor its performance. the P-800
incorporates two symmetrically arranged
analog level meters.

The beautiful and simple elegance of this am-
plifiers external appearance belles its awesome
performance. But when turned on, it speaks
unmistakably through music.

two separate power units for ultimate
sound quality
The two basic principles shown in Fig. 1 are
available to transmit signals in an audio system:
(a) unbalanced. and (b) balanced lines. The

1 Totally balanced construction with

widely used unbalanced principle permits sim--

pler circuit design. as can be seen from the
chart, but this approach involves the possibility
of sound quality degradation. because the
ground line carries the signal current. DC com-
ponents to drive the amplifier. and often induced
noise from external interference sources. The
more elaborate balanced approach requires
two separate lines which carry the non-inverted
signal and inverted signal. An inherent advan-
tage of this principle is the cancellation not only

of noise induced during the transmission pro-
cess but even of distortion components arising
within the amplifier. This cancellation takes
place in the output circuits. and the overall effect
is a signal of pure and undiluted quality, The
Accuphase P-BOO uses two separate power am-
plifier units with push-pull drive in bridged con-
nection, for the ultimate in performance and
sound quality.

2 Accurate reproduction of sound field
with two independent power supplies
In the P-SOO, two power supply units with sepa-
rate transformers for both the left and the right
channels are provided with each transformer
yielding a capacity of i.5 WA. This design cuts
the power supply impedance as seen by the
amplifier in half. Moreover, four 82.000-pF filter
capacitors that determine the sound quality in a
low frequency region are employed. totaling a
capacitance of 328,000 pF. so that stable,
frequency sounds can be reproduced. Hf

Ultra-powerful output stages
consisting of two sets of seven
parallel push-pull transistor pairs
each
Fig. 2 shows the output stage of the P-800 Two
exactly identical amplifier units are used in
bridged configuration. The input signal is con-
nected to these units with inverted phase, result-
ing in a combined output power rating of 600 W
into 4 ohms and 400 W into 3 ohms. This impres-
sive power is achieved by an extravagant de~
sign involving two sets of seven parallel push»
pull transistor pairs in each amplifier unit. Each
transistor has a maximum power dissipation (PC)
of 130 watts. As there are atotal of 28 transistors.
the combined maximum power dissipation
amounts to an astounding 3.6 kilowatts.
Accuphase never sacrifices quality for quantity.
Topnotch design and construction throughout
ensure that this awe-inspiring power is delivered
with impeccable fidelity. Large heat sinks made
of solid aluminum permitoperation under normal
conditions without cooling fans, U

A?
it?

I

._4,£Q
_l

W
35"" 7&5
W
VW 72:3

+r
e!

4»

2

INPUT o-i
l

5

OIIOIIM

[s

I

Mi ZR?
95" 3h?

a EEE
g M...

H92 Bloekbllw-nolP-M(OnO-Cllnml)