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The solution for high-end multi-channel surround sound six totally sepa-
rate power units with identical performance deliver ample power: 150 W × 6
(4 ohms), 100 W × 6 (8 ohms). Robust power supply with large 700 VA toroi-
dal transformer. Current feedback topology assures excellent high-frequency
characteristics. Bridged mode produces stunning 300 W × 3 (8 ohms).
The CX-260/PX-600 is the long-awaited
preamplifier/power amplifier combination from
Accuphase designed from the ground up for
multi-channel surround systems that aim for
absolute top quality in picture and in sound.
Accuphase's extensive experience in the realm
of pure audio is in evidence everywhere in these
components. Finally, the true audiophile can
move beyond two-channel stereo and build a
system that provides audiovisual enjoyment
without making any sacrifices when it comes to
sonic accuracy. Discover a new world where
sound and image blend to form a home theater
with true high-end performance.
The Power Amplifier PX-600 incorporates six
identical high-performance amplifiers, making
it possible to reproduce six channels with top-
notch quality. The amazingly realistic sound
stage and dynamic scale that can be created
with the PX-600 go far beyond the limitations of
conventional surround sound. The capability for
bridged mode operation allows further upgrad-
ing of the unit to sustain, for example, three high-
output channels. Various configurations rang-
ing from one to six channels can be realized,
combining flexibility with superb sonic perfor-
mance.
Six totally separate power units with
identical performance allow operation in one
to six channels
Figure 1 shows a block diagram of the PX-600.
The six high-quality power units can reproduce
for example the 5.1ch sound from a DVD player
source with unprecedented realism and
authority. It is also possible to bridge two blocks
each, and to combine normal mode and bridged
mode operation. This results in utmost flexibility,
covering a range from 1 to 6 channels. For
example, you can enjoy two-channel stereo in
pure audio fashion or realize a high-class bi-amping setup. In combination with a multi-
channel divider, 2-way or 3-way systems as well
as subwoofer enhanced systems can also be
configured.
Parallel push-pull output stages for ample power6-channel operation: 150 W × 6 (4 ohms), 100 W × 6 (8 ohms)
2-channel operation: 220 W × 2 (4 ohms), 130 W × 2 (8 ohms)
The output stage uses high-power transistors
rated for a collector dissipation of 150 watts and
collector current of 15 ampere. These devices
offer extraordinarily wide and flat frequency
response, and their forward-current transfer ratio
linearity as well as their switching characteristics
are excellent. These devices are arranged in a
parallel push-pull configuration (Figure 2) and
mounted to very large aluminum diecast heat
sinks for efficient cooling.Bridged mode generates even more output
muscle
3-channel bridged operation: 320 W × 3 (6 ohms), 300 W x 3 (8 ohms)
2-channel bridged operation: 420 W × 2 (6 ohms), 350 W x 2 (8 ohms)
For bridged mode, two amplifiers with opposite
polarity are driven with a reverse-phase input
signal, and the output of both amplifiers is
combined before being sent to the speaker. This
allows upgrading to even higher power,
providing ample reserves even with very
demanding source material.
Current feedback circuit topology prevents
high-range phase shifts
The PX-600 uses the signal current rather than
the more conventionally used voltage for feed-
back. The impedance at the current feedback
-œ» Do not stack the CX-260 and PX-600.
Principle of current feedback amplifier
Fig. 1 Block diagram of PX-600
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point is kept very
low, which means
that there is almost
no phase shift.
Phase compensa-
tion via negative
feedback can there-
fore be kept to a
minimum, resulting
in excellent tran-
sient response and
superb sonic trans-
parency. Figure 3
shows frequency
response for differ-
ent gain settings of
the current feed-
back amplifier. The
graphs demon-
strate that response
remains uniform
over a wide range.
Robust power supply with large "Super
Ring" toroidal power transformer and high
filtering capacity
In any amplifier, the power supply plays a vital
role as the source of energy for the entire unit.
The PX-600 spares no efforts in this regard
thanks to its large, highly efficient 700 VA toroi-dal power trans-
former. The trans-
former is housed in
a non-resonant
aluminum enclo-
sure filled with
damping material
that has excellent
heat transfer char-
acteristics. This
transformer type is
ideal for high-
power amplifiers,
since it is charac-
terized by very low
impedance, com-
pact size, and very
high conversion ef-
ficiency. In addition, two enormous 47,000 µF
electrolytic capacitors provide more than ample
filtering capacity for the rectified current.
Three large analog power meters can be
switched to show direct power readings
for 6 channels. A meter operation/light on/
off switch is also provided.
Large speaker terminals
Balanced connection protects against
externally induced noise.
BIAS STABILIZER
CIRCUIT
Balanced input connectors
Fig. 3 Frequency response with current feedback
(Response does not change when gain is varied)
Total of six channel
power amplifier
units (with parallel
push-pull output
stage and current
feedback)
mounted to large
aluminum diecast
heat sinks.
Fig. 2 Amplifier section circuit diagram (1 channel)
