Accuphase P 600 Brochure

Page 2

7-parallel push-pull power stages guarantee stereo = 300 W/ch (8 oh
By using the low impedance setting, even an extreme low impedance

The advent of new audio program sources
such as the Compact Disc (CD) and Digital
Recordings (PCM) has ushered in an era where
the true capabilities of power amplifiers are
being more closely examined and increasingly
appreciated. This is because an amplifier's
capability to reproduce musical range, details
and depth cannot be judged merely from its
rated specifications. Higheragrade power am-
plifiers must be endowed not only with superior
bastc characteristics, but with the capability
and power to drive speakers correctly with
ample energy so that they can respond accu-
rately to instantly changing. widerranging sig-
nal variations

This necessitates a power supply with am-
ple reserve margin to prowde the full energy
required by a powerful output circuit that is
driven by a large current capacity driver stage,
In other words. the impedance of the loop
circuitry formed by the power supply and the
power output circuit which supplies energy to
the speakers must be very low. in fact. as close
to 0" as possible Moreover. low impedance
should be one of the most desired basic
characteristics of this loop circuit before Nega-
tive Feedback (NFB) or Constant Voltage Reg-
ulation or both are applied to lower the impe-
dance still further,

Other fundamental requisites of a good
power amplifier must include wide dynamic
range. low distortion against both static and
dynamic input signals. and sturdy construction
that assures highest stability and complete
absence of electrical and mechanical reso-
nances.

The Accuphase P-GOO Stereo Power Am-
plifier is a product that was developed to meet
the needs of the new audio era with a deSign
approach that incorporated all the above basic
fundamentals It produces a pure and powerful
output of 300 W/ch at 8 ohms with its Push-Pull
Circuitry in every stage" that culminates in a
"Seven-Parallel push-pull" output stage com-
prising a total of 14 bipolar transistors that is
driven by a driver stage centered on powerful
MOS FETS (Metal Oxide Semiconductor Field
Effect Transistors), It boasts an extra heavy-
duty power supply which, together with its
powerful output stage. is completely capable of
driving a low 2-ohm impedance load with 700
watts of power to each channel. Furthermore, it
is also equipped with a butlt-in "Low Load
Impedance Drive" capability that permits it to
work into a one«ohm load with a power output of
450 W/oh. It is the first power amplifier in the
world that can directly drive a onerohm imped-
.ance load, This means that it has an ample
reserve margin of power when used to drive
normal speaker impedances, It thus assures
ideal constant voltage regulation regardless of
actual speaker impedance fluctuations under
actual operating conditions,

The P-600 also has a built-in Bridge Circuit
that permits it to be used as a pure monophonic
power amplifier that can deliver a high 1,000
watts of power into 8 ohms.

The P7600 is also equipped with an input for
a GOOeohm balanced cable network with which
a matched connection can be made to the
Accuphase 0-280 preamplifier, or to any com-
mercial amplifier with an output connector for a
GOO-ohm balanced type connecting cable. The
P600 also enables accurate. direct reading of

power output peak values with a digital display
system initially developed for the Accuphase
M100 Monophonic Power Amplifier.

We invite you to enjoy the stirring excitement
of good music reproduction to your hearts
content with the P-GOO which has power to
spare and is fully capable of providing this
thrilling experience.

7-PARALLEL PUSH-PULL OUTPUT
STAGE GUARANTEES 700 W/ch AT
2 OHMS, 300 W/ch AT B OHMS

The P-600 has a rated power output of 300
W/ch at 8 ohms. 500 W/ch at 4 ohms and 700
W/ch at 2 ohms. (20-200.000 HZ: distortion
ratio less than 0.02 percent)

To guarantee such high power outputs. it
has a total of 24 bipolar power transistors, each
of which has a superior wideband characteris-
tic and maximum power dissipation (Pc) of 200
watts, that form a 7-parallel push-pull output
circuitry which has a total electrical capacity of
2.8 kW. Figure 1 shows the circuit diagram in
which 019-032 constitute the 14 output tran-
ststors. They are attached to giant heat sinks
that adequately dissipate the heat generated at
the high power levels,

1-OHM SPEAKER NETWORK

LOAD CAN BE DRIVEN AT

450 W/ch

Although the P-GOO can be used to drive a

2-ohm load under normal operation. it is further
equipped with a "Low Load Impedance Opera»
lion Switch which permits it to drive even lower
impedance loads for special commercial ap-
plications, This enables the P-600 to be con-
nected to a one»ohm impedance speaker
network and deliver 450 W/ch while safely
protecting the output transistors and supplying
the large current flows required, Speakers with
impedances ranging from 1-16 ohms can thus
be connected to the P600 which makes this

Stereo Power Amplifier most useful when a
number of speakers are connected in parallel.

DARLINGTON CASCODE PUSH-
PULL PRE-DRIVER AND MOS FET
DRIVER STAGES IMPROVE
LINEARITY AND ELIMINATE
SWITCHING DISTORTION

Unlike listening in large auditoriums, the
distance between the listener and speakers is
very small in the home and the most subtle
sounds are audible. Therefore. sound quality at
low listening levels below several watts is a very
important factor We adopted a sure way to
obtain highest quality reproduction at such
levels by using MOS FETs for voltage amplifica-
tion in the driver stage. This application is an
Accuphase original with a proven recor .
ensuring the required low output imped
and large current capacity to drive the final
output stage properly, Use of MOS FETs also
greatly improves high frequency characteris-
tics.

Furthermore, the low thermal characteristics
of MOS FETs helps to stabilize bipolar transistor
operation. which in turn, stabilizes bias current
flow of the power output stage. This has
enabled us to reduce the value of emitter
resistance. Moreover. the 7-parallel output tran-
sistor connection has made it possible to
reduce the value of the seven emitter resistors
to one-seventh. resulting in the practical eli-
mination of switching distortion which is cre-
ated when the bias current of the output
transxstor is Cut off.

011-016 constitute the cascode push-pull
Pre-driver Stage which assures both excellent
linearity and large amplitude handling capabil»
ity with complete absence of Miller effects. This
stage drives the MOS FET Driver Stage, It has a
high input impedance. thanks to the Darlington
circuit formed by 011 Q13 and 012 014. This
assures high quality amplification since it does
not affect the operation of the differeu
amplifier input circuit.

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Fly. 1 PM Circuit Diagram