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m Triple parallel push-pull output stage in each channel delivers
plenty of linear power even into very low load impedances
m Instrumentation amplifier derived signal path design
m Advanced MCS+ circuit topology m Bridged connection mode
allows upgrading to true monophonic amplifier m Massive Super
Ring toroidal transformer rated for 700 VA m 4-step gain control
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A stereo power amplifier capable of delivering 400 watts into 1 ohm (with music
signals) Fully balanced signal paths as found in high-quality instrumentation
amplifiers. Further refined MCS+ topology and current feedback
design. Improved S/N ratio, minimal distortion, and great
performance in all other areas. Power supply with massive
700 VA toroidal transformer and triple parallel push-pull
arrangement of high-power transistors in each channel.
The P-3000 is based on the same design
technology as the renowned P-7000 and
P-5000 models. Using only carefully selected top
quality parts throughout, the P-3000 is an ideal
match for the C-2000 preamplifier.
A new feature in the P-3000 is the fact that all
signal paths from the input terminals onwards are
fully balanced, an approach otherwise found only
in instrumentation amplifiers of the highest quality.
In addition, the power amplifier section employs
an improved version of MCS called MCS+
(Multiple Circuit Summing plus), as well as the
famous Accuphase current feedback topology.
S/N ratio, distortion, and other electrical
characteristics are further improved. And of
course, these refinements manifest themselves
in even better sound quality.
In order to drive any kind of speaker with precision
and authority, a power amplifier must provide
extremely low output impedance (Note 1) and be
capable of supplying a constant drive voltage at
all times (Note 2). To realize constant-voltage
capability over the entire frequency range, a
powerful output stage supported by a capable
power supply are necessary.
In the output stage of the P-3000, three pairs of
high-power transistors are arranged in a parallel
push-pull configuration for each channel. The
devices are mounted to large heat sinks on both
sides for efficient dissipation of thermal energy.
Rated output power into an ultra-low impedance
of 1 ohm is 400 watts per channel (music signals
only). Power remains linear also when impedance
changes, as exemplified by the rating of 300 watts
into 2 ohms, 150 watts into 4 ohms and 75 watts
into 8 ohms. Even speakers with very low
impedance or with drastic impedance fluctuations
can be driven effortlessly and accurately.
By using the P-3000 in bridged mode, it is
possible to create a monophonic amplifier with
even higher power reserves. This performance is
sustained by a massive high-efficiency Super
Ring toroidal transformer and large filtering
capacitors.
MCS+
Multiple Circuit
( )
+
B
3
+
INPUT
–
INPUT
+
–
GAIN CONTROL
CIRCUIT
–
+
NFB
NETWORK
NFB
NETWORK
–
B
3
Summing
Bias stabilizer
circuit
Q
1
Q
5
Q
Q
Q
Q
7
3
Bias stabilizer
circuit
Bias stabilizer
circuit
2
Q
6
Q
8
4
Bias stabilizer
circuit
Note 1 Low amplifier output impedance
When forming the load of a power amplifier, a loudspeaker generates
a counterelectromotive force that can flow back into the amplifier via
the NF loop. This phenomenon is influenced by fluctuations in speaker
impedance and interferes with the drive performance of the amplifier.
The output impedance of a power amplifier should therefore be made
as low as possible by using output devices with high current capability.
This absorbs the counterelectromotive force generated by the voice
coil and prevents the occurrence of intermodulation distortion.
Note 2 Constant drive voltage principle
Even when the impedance of a load fluctuates drastically, the ideal
power amplifier should deliver a constant voltage signal to the load.
Figure 2 is a graph plotting the output voltage versus current
characteristics. Even when the load changes, the output voltage
remains almost constant, showing linear current progression. Actual
measurement of clipping power at the extremely low load impedance
of 1 ohm yields 400 watts. At 2 ohms, the figure is 330 watts, at 4
ohms 220 watts, and at 8 ohms 133 watts. This demonstrates the
impressive performance reserves of this amplifier.
Power amplifier with instrumentation amp
configuration
The P-3000 features a new "instrumentation
amplifier" principle whereby all signal paths from the
inputs to the power amp stage are fully balanced.
This results in excellent CMRR (common mode
rejection ratio) and minimal distortion. Another
significant advantage is that external noise and other
external influences are virtually shut out. The result
Signal input stage Power amplifier stage
+
–
NFB
GAIN CONTROL
CIRCUIT
NETWORK
NFB
NETWORK
–
+
+
–
Instrumentation amplifier configuration
REGULATOR
13
Q
15
14
16
17
Bias stabilizer
circuit
Q
18
NFB
NETWORK
REGULATOR
Fig. 1 Circuit diagram of amplifier section (one channel)
OUTPUT
+
B
1
Q
Q
19
Q
20
Q
21
Q
Q
22
–
B
1
Q
9
Q11Q
Q10Q
Q12Q
+
INPUT
–
INPUT
Q
20
10
Output current (A)
0
0 8 16 24 32 40
Output voltage (V)
★1 ohm rating is for music signals only.
Fig. 2 Load impedance vs. output power
(Output voltage/output current)
400W
1Ω
330W
2Ω
4Ω
220W
8Ω
16Ω
133W
71W
is a drastic improvement in operation stability and
reliability.
Further refined MCS+ topology
Accuphase's original MCS (Multiple Circuit Summing)
principle uses a number of identical circuits
connected in parallel to achieve superior
performance characteristics. The MCS+ is a further
refined version of this approach. Improvements in
the bias circuitry of the input-stage
buffer amplifier result in greater
stability. This in turn makes it
possible to extend the parallel
operation approach to the class-A
drive stage of the current/voltage
converter, thereby further lowering
+
B
Q
23
25
2
the noise floor.
Triple parallel push-pull power
unit delivers guaranteed linear
power output of 300 watts into
OUTPUT
2 ohms, 150 watts into 4 ohms,
and 75 watts into 8 ohms
The output stage uses high-power
transistors with a rated collector
Q
24
26
–
B
2
dissipation of 130 watts. These
devices feature excellent frequency
response, current amplification
linearity, and switching
characteristics. The transistors are
arranged in a triple parallel pushpull configuration and mounted on
a massive heat sink. This assures
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effective heat dissipation and reduces the
impedance of the output stage.
Current feedback circuit topology prevents phase
shifts in high frequency range
The P-3000 employs the renowned current feedback
principle developed by Accuphase. At the sensing
point of the feedback loop, the impedance is kept
low and current detection is performed. An
impedance-converting amplifier then turns the
current into a voltage to be used as the feedback
signal. Since the impedance at the current feedback
point (current adder in Figure 3) is very low, there is
almost no phase shift. Phase compensation can be
Current
– Input
Buffer
+ Input
Buffer
Fig. 3 Principle of current feedback amplifier
adder
I-V
converter
Trans-impedance
amplifier
Current NFB
network
Amplifier
Output
kept to a minimum, resulting
in excellent transient response
and superb sonic transparency.
Minimal
amounts of NFB
are used to
maximum
(Large)
effect, providing
natural energy
response.
Figure 4 shows
frequency
Gain
Fig. 4 Frequency response with current feedback
(Response remains uniform also when gain changes)
Frequency
(High)
response for
different gain settings of the current feedback
amplifier. The graphs demonstrate that response
remains uniform over a wide range.
Robust power supply with "Super Ring" toroidal
transformer and high filtering capacity
The P-3000 features a massive toroidal power
transformer with a maximum rating of 700 VA. The
transformer is housed in a case filled with a material
that transmits heat and absorbs vibrations. This
n Power amplifier assembly with
completely prevents any
adverse influences on other
circuit parts. A toroidal transformer
uses heavy-gauge copper wiring on a
doughnut-shaped
core, resulting in
low impedance and
high efficiency while
allowing compact
dimensions, which
is especially useful
for audio applications.
Two ultra-large
aluminum
electrolytic
capacitors rated for
47,000 µF each
serve to smooth out
the pulsating direct
current from the
rectifier, providing
more than ample
filtering capacity.
3 parallel push-pull transistor
pairs per channel mounted
directly to large heat sink,
MCS+ circuitry, and current
feedback amplifier
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Instrumentation amp type gain control
minimizes residual noise
The gain control switches gain in the first
amplification stage after
signal input. Four settings
are available (MAX, –3 dB,
–6 dB, –12 dB). With this
approach, reducing gain
also results in reduced
noise. This is especially
beneficial when using
highly efficient speaker systems where the noise
floor could be a problem.
Bridged connection allows upgrading to a true
monophonic amplifier with 800 watts into
2 ohms (music signals only), 600 watts into
4 ohms, and 300 watts into 8 ohms
Bridged connection results in a monophonic
amplifier with four times the power output than
during stereo operation. This gives effortless
dynamic power.
n n
n Front panel
n n
nn
n Easy switching to dual mono mode
nn
In the dual mono position of the
mode selector, the left-channel
signal is supplied to both speaker
terminals, which can be used for
bi-amping with dedicated lowrange and high-range drivers.
nn
n Oversize speaker terminals accept also Y lugs or
nn
banana plugs
The sturdy terminals can handle even very large gauge
speaker cable. The
connectors are made
of extruded high-purity
brass material and are
gold-plated for utmost
reliability and minimum
contact resistance.
Y lugs or banana plugs
can also be used.
nn
n Balanced connection prevents induced noise
nn
nn
n Input selector button (balanced/unbalanced) on
nn
front panel
nn
n Large analog power meters with on/off switch
nn
Unbalanced and balanced input connectors
Output assembly
High-quality, high-reliability parts
n n
n Rear panel
n n
★
A
Right/left-channel power meters
(dB and % scale)
B
Meter operation/illumination switch
ON OFF
C
Speaker A/B selector buttons
D
Input selector button
BALANCE UNBALANCE
E
Power switch
F
Gain selector
MAX –3 dB –6 dB –12 dB
Remarks
★
This product is available in versions for 120/230 V AC. Make sure that the voltage shown on
the rear panel matches the AC line voltage in your area.
★
The shape of the AC inlet and plug of the supplied power cord depends on the voltage rating
and destination country.
G
Unbalanced inputs
H
Balanced inputs
a: Ground
b: Inverted (–)
c: Non-inverted (+)
I
Mode selector
DUAL MONO NORMAL BRIDGE
J
Right/left-channel speaker output terminals for
A and B
K
AC power supply connector
★
n Supplied accessories: • AC power cord
GUARANTEED SPECIFICATIONS
[Guaranteed specifications are measured according to EIA standard RS-490.]
mm
m Continuous Average Output Power (20 - 20,000 Hz)
mm
Stereo operation 400 watts per channel into 1 ohm (✽)
(both channels driven) 300 watts per channel into 2 ohms
Monophonic operation 800 watts into 2 ohms (✽)
(bridged connection) 600 watts into 4 ohms
Note: Load ratings marked ✽ apply only to operation with music signals.
m Total Harmonic Distortion Stereo operation (both channels driven)
m Intermodulation Distortion 0.005%
m Frequency Response At rated output: 20 ~ 20,000 Hz +0, –0.2 dB
m Gain (GAIN selector in MAX position)
m Gain settings MAX, –3 dB, –6 dB, –12 dB
m Output Load Impedance Stereo operation: 2 to 16 ohms
[★ With music signals, load impedances of 1 Ω (stereo) or 2 Ω (mono) can be driven.]
m Damping Factor 150
m Input Sensitivity Stereo operation 0.98 V for rated output
(with 8-ohm load) 0.11 V for 1 watt output
m Input Impedance Balanced: 40 kilohms
m Signal-to-Noise Ratio 120 dB (GAIN selector in MAX position)
(A-weighted, input shorted)
m Output Level Meters Logarithmic scale, with off switch
m Power Requirements AC 120 V/230 V (Voltage as indicated on rear panel) 50/60 Hz
m Power Consumption 55 watts idle
m Maximum Dimensions Width 465 mm (18-5/16”)
m Mass 24.0 kg (52.9 lbs) net
150 watts per channel into 4 ohms
75 watts per channel into 8 ohms
300 watts into 8 ohms
0.05%, with 2-ohm load
0.02%, with 4 to 16-ohm load
Monophonic operation (bridged connection)
0.02%, with 4 to 16-ohm load
At 1 watt output: 0.5 ~ 160,000 Hz +0, –3.0 dB
28.0 dB (stereo and monophonic operation)
Monophonic operation: 4 to 16 ohms
Monophonic operation 1.95 V for rated output
Unbalanced: 20 kilohms
125 dB (GAIN selector in –12 dB position) At rated output
–50 dB to +3 dB (dB/% Scale)
480 watts accordance with IEC 60065
Height 180 mm (7-1/16”)
Depth 425 mm (16-3/4”)
28.0 kg (61.7 lbs) in shipping carton
0.11 V for 1 watt output
• Specifications and design subject to change without notice for improvements.
F0405Y PRINTED IN JAPAN 851-0138-00 (AD1)http://www.accuphase.com/
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