Page 1
m Output stage with 3-parallel push-pull confi guration for each channel
delivers high power and handles very low impedance loads m Instrumentation
amplifi er principle used for signal paths m Further refi ned MCS+ circuit
topology m Current feedback circuit combines excellent sound quality with total
operation stability m Bridged connection mode allows upgrading to monophonic
amplifi er m Massive toroidal transformer rated for 950 VA m 4-step gain control
Page 2
Stereo power amplifier capable of delivering 500 watts into 1 ohm (music
signal) – Instrumentation amplifi er principle allows fully balanced signal paths.
Further refined MCS+ and current feedback topology assure outstanding
S/N ratio, minimum distortion, and excellent performance in all other aspects,
resulting in superb sound quality. 3-parallel push-pull arrangement of highpower transistors in each channel, sustained by power supply with massive
950 VA toroidal transformer. 4-step gain control minimizes residual noise.
The P-4100 is a stereo power amplifi er that takes
sophisticated sound to the next level. While
inheriting design technology from highly renowned
Accuphase models such as the P-7100 and M-6000,
the new model features instrumentation amplifi er
topology and a refi ned MCS+ circuit to lower the
noise fl oor even further. Only specially selected
top-grade materials and parts are used throughout
with impressive results.
In order to bring out the full potential of the
loudspeakers, an amplifi er must be able to cope
with drastically fluctuating speaker impedance
conditions. This can only be achieved by ensuring
constant drive voltage at all times. In other words,
the output impedance of the amplifi er must be kept
very low. This also makes it possible to absorb
the counterelectromotive force generated by the
voice coil, thereby eliminating a major source of
intermodulation distortion.
The P-4100 achieves these design goals with ease.
The output stage for each channel uses three pairs of
high-power transistors with a Pc rating of 220 watts,
arranged in a parallel push-pull confi guration. This
ensures low output impedance. Stable operation
is achieved by mounting the devices to massive
heat sinks on both sides of the chassis, for effi cient
dissipation of thermal energy. As demonstrated by
the power rating of 500 watts into 1 ohm (with music
signals), the P-4100 can easily drive speakers with
very low impedance, and speakers with uneven
impedance curves are handled with complete
authority. Using the P-4100 in bridged mode creates
a mono amplifi er with even more impressive power
capability. The power supply section which acts as
energy source for the amplifi er employs a massive
950 VA toroidal transformer in combination with large
fi ltering capacitors, providing ample reserves even
with drastically fl uctuating loads.
The overall confi guration of the P-4100 employs the
latest instrumentation amplifi er principle, allowing
fully balanced signal paths throughout. In addition,
the power amplifi er section features refi ned MCS+
topology in combination with current feedback,
for further enhanced electrical performance
characteristics.
n Power modules with high-power transistors in 3-parallel push-pull
arrangement deliver 500 watts per channel into 1 ohm (music signals only),
360 watts into 2 ohms, 180 watts into 4 ohms, or 90 watts into 8 ohms.
n Amply dimensioned power supply with high-effi ciency toroidal transformer
and large fi ltering capacity.
The high-effi ciency toroidal transformer is rated for approx. 950 VA, and the two
extra-large 47,000μF aluminum electrolytic capacitors were selected for best sonic
performance.
n Bridged mode allows upgrading to monophonic amplifi er with 1,000 watts
into 2 ohms (music signals only), 720 watts into 4 ohms, or 360 watts into
8 ohms.
Bridged connection increases the output by a factor of 4, creating dramatic power
reserves in a monophonic confi guration.
n Four gain control settings minimize residual noise.
The gain control alters gain in the fi rst stage of the instrumentation amplifi er. Four
settings are available (MAX, –3 dB, – 6 dB, –12 dB).
n
Large analog power meters with on/off switch.
n
Mode selector for easy switching between dual
mono/stereo/bridged operation.
Meter on/off button Input selector
n Fully balanced input stage
shuts out external noise
interference.
n Two pairs of oversize speaker
terminals accept also Y lugs
plugs.
High-power transistors used in output stage
Assembly with meter and protection circuitryLarge speaker terminals
Assembly with unbalanced and balanced input connectors
Parts selected for sound quality and reliability
Toroidal power transformer
Filtering capacitors
Gain selector
Instrumentation amplifi er
INPUT
+
NFB
NETWORK
GAIN CONTROL
CIRCUIT
NFB
NETWORK
– INPUT
Gain control
Bias stabilizer circuit
REGULATOR
Bias stabilizer
circuit
NFB
NETWORK
Bias stabilizer
circuit
Bias stabilizer circuit
MCS+ (Multiple Circuit Summing)
Bias stabilizer circuit
REGULATOR
in 3-parallel push-pull confi guration
Figure 1 Circuit diagram of amplifi er section (one channel)
High-power transistors
OUTPUT
*
1-ohm operation possible with music signals only
Output current (A)
Output voltage (V)
Figure 2 Load impedance vs. output power
(output voltage/output current)
Page 3
Instrumentation amplifi er and further refi ned MCS+ topology
Instrumentation amp confi guration allows
fully balanced signal paths
The newly adopted “instrumentation amplifier”
principle ensures that 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 is a drastic improvement in operation
stability and reliability.
Signal input stage Power amplifi er stage
INPUT
+
NFB
NETWORK
GAIN CONTROL
CIRCUIT
NFB
NETWORK
– INPUT
Instrumentation amplifi er confi guration
n Power amplifi er assembly with three parallel push-pull
high-power transistor pairs per channel mounted directly
to large heat sink, MCS+ circuitry, and current feedback
amplifi er.
OUTPUT
Further refi ned MCS+ topology for even
lower noise
Accuphase’s original MCS (Multiple Circuit
Summing) principle uses a number of identical
circuits connected in parallel to achieve superior
performance characteristics. MCS+ is a further
refined version of this approach. By extending
parallel operation to the class-A drive stage of
the current/voltage converter, the noise floor
has been lowered further.
Current feedback principle assures excellent phase characteristics in high range
As shown in the illustration, the P-4100 uses
the output signal current rather than voltage for
feedback. Since the impedance at the current
feedback point is very low, there is almost no
phase shift. A minimal amount of NFB therefore
results in maximum improvement of circuit
parameters.
INPUT
+
Buffer
– INPUT
Buffer
Current adder
I/V converter
Trans-impedance amplifi er
Current NFB
Amplifi er
network
Principle of current feedback amplifi er
Output
Page 4
■ You can use two P-4100 units in bridged mode or in a bi-amping setup, for even higher quality. ■ Use the LEFT (BALANCED or UNBALANCED) input connectors for both units.
Bridged connection example Bi-amping connection example
Left loudspeaker
In bridged mode, the P-4100 becomes a
monophonic amplifi er with even higher power
output.
For stereo operation, two P-4100 units are
required.
Right loudspeaker Left loudspeaker Right loudspeaker
In a bi-amped setup, the speaker units for the LOW
frequency range and HIGH frequency range are driven
by separate amplifi ers, for optimum sound quality.
The speakers must have a built-in crossover network and
separate inputs for LOW and HIGH range.
Two P-4100 units are required.
P-4100
for left
channel
n Front Panel
Preamplifi er
Set Mode
selector on both
P-4100 units to
BRIDGE.
P-4100
for right
channel
P-4100
for left
channel
Preamplifi er
GUARANTEED SPECIFICATIONS
✽ Guaranteed specifi cations are measured according to EIA standard RS-490.
m Continuous Average Output Power (20–20,000 Hz)
Stereo operation 500 watts per channel into 1 ohm ()
(both channels driven) 360 watts per channel into 2 ohms
180 watts per channel into 4 ohms
90 watts per channel into 8 ohms
Monophonic operation 1,000 watts into 2 ohms ()
(bridged connection) 720 watts into 4 ohms
360 watts into 8 ohms
m Total Harmonic Distortion Stereo operation (both channels driven)
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
Note: Load ratings marked () apply only to operation with music signals.
m Intermodulation Distortion 0.01%
m Frequency Response At rated output: 20 - 20,000 Hz +0, –0.2 dB
n Rear Panel
At 1 watt output: 0.5 - 160,000 Hz +0, –3.0 dB
m Gain
(in stereo and monophonic operation)
28.0 dB (with GAIN selector at MAX)
m Gain Selection MAX, –3 dB, –6 dB, –12 dB
m Output Load impedance Stereo operation: 2 to 16 ohms
Monophonic operation: 4 to 16 ohms
With music signals only, 1-ohm loads are permissible for
stereo operation and 2-ohm loads for monophonic operation.
m Damping Factor 180
m Input Sensitivity (with 8-ohm load, GAIN selector in MAX position)
Stereo operation: 1.07 V for rated output
0.11 V for 1 watt output
Monophonic operation: 2.14 V for rated output
0.11 V for 1 watt output
m Input Impedance Balanced: 40 kilohms Unbalanced: 20 kilohms
m Signal-to-Noise Ratio (A-weighted, input shorted)
120 dB (GAIN selector at MAX)
125 dB (GAIN selector at –12 dB)
At rated output
m Output Level Meters –50 dB to +3 dB (indication in dB and %)
Logarithmic scale, with defeat switch
m Power Requirements AC 120 V/230 V, 50/60 Hz
(Voltage as indicated on rear panel)
m Power Consumption 60 watts idle
550 watts in accordance with IEC 60065
m Maximum Dimensions Width 465 mm (18-5/16")
Height 190 mm (7-1/2")
Depth 427 mm (16-13/16")
m Mass 28.2 kg (62.2 lbs) net
34.0 kg (75.0 lbs) in shipping carton
A Right/left-channel output power meters (dB
and % scale)
Function indicators
B
UNBALANCED BALANCED BRIDGE
C Speaker selector A B A+B
D Meter on/off button ON OFF
E Power switch
F Input selector button
UNBALANCED BALANCED
H Unbalanced inputs
I Right/left-channel speaker output terminals
A and B (two pairs)
J Mode selector
DUAL MONO NORMAL BRIDGE
K Balanced inputs
a Ground b Inverted (–)
c Non-inverted (+)
L AC power supply connector
G 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.
Set Mode
selector on both
P-4100 units to
DUAL MONO.
P-4100
for right
channel
Supplied accessory
● AC power cord
m
Specifi cations and design subject to change without notice for improvements.
http://www.accuphase.com
E0810Y PRINTED IN JAPAN 851-0175-00 (AD1)
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