|370,000 yen(March, 1991 release)
Stereo power amplifier developed as a succeeding machine of P-300 series.
Changing into the symmetry design which a series of Accuphase power
amplifier has adopted, foundations, such as a function, have followed 300
It has realized constituting a large current-capacity transistor
from a 7-parallel push pull, and taking out the current of 210A in 1ms.
40,000 micro F/80Vx2 was used for the toroidal transformer of high
large-sized 1KVA of efficiency, and the smooth condenser by the transformer of
the power-source part, and the Output voltage flat to 20Hz - 20000Hz has been
obtained to it.
The MOS FET+ cascode push pull circuit of Accuphase
original is used for the drive stage. This has improved the characteristic at
the time of a small signal.
Furthermore, the output stage forms the power
amplifier whose stability it is good and is high because a temperature
inclination serves as negative, a temperature inclination offsets each other
mutually and positive and its drive stage suit by MOS FET with a bipolar
Furthermore, the Class-A cascode push pull circuit is similarly used for
the pri driver, and the stability of MOS FET is increased.
input of amplifier has adopted the direct connection system to which a signal is
In order to also output a slight direct-current input greatly and to give
a damage to a speaker, direct-current domain has omitted a direct current,
having applied direct-current servo which make it hard to amplify.
Since this system has applied NFB so that output offset of the amplifier itself may be suppressed simultaneously, it has realized operation
stabilized also to the temperature change.
The input stage serves as a
balanced differential pure complimentary push pull, and the FET input buffer
amplifier of high input impedance and a low impedance drive is connected to +
(non invert) and - (invert) input, respectively.
At the time of a balance
input, it is directly inputted into these terminals and high magnification of
purity is performed.
At the time of bridge connection, the same signal is
inputted simultaneous to + input of one amplifier, and - input of the amplifier
of another side.
Thus, in the input of all systems, no excessive circuits,
such as a transducer, are added but enable homogeneous magnification.
40kohm balance input other than the usual 20kohmRCA pin jack input can be
prepared, it can be, and the balance output of all impedance can be connected
with the XLR type connector of an international standard.
Since the balance input circuit has the composition of pouring in a signal
as it is to plus of a difference input circuit, and a minus input, it must
insert a level control in plus and each minus input. So, in P-360, the
1dB step twin Attenuator with few interlocking errors is adopted. In addition,
the input circuit is considered so that a frequency response may not change
in the position of a level control.
In P-360, the twice as many output in the 4-ohm load at the time of a
stereo drive as this can be obtained by bridge connection.
Although a phase
inversion circuit is inserted in one amplifier at the time of the usual bridge
connection, the polarity of the difference input circuit of two amplifier is
used, it is the method of making a connection change so that a reverse signal
may be inputted mutually, and the pure electronic switch consists of P-360
without inserting a special circuit.
The resistance object of specular
surface finishing with a small distortion is adopted especially as an input
level adjustment machine.
What the distorted characteristic is good, is
excellent in antiwear quality, and spoils sound qualities, such as grease,
between brush resistance objects by specular surface-ization is not applied.
Moreover, general VR takes out a lead outside through a sticking-by-pressure
portion with a resistance object, and although the brush is a slide child
(rotor), in P-360, the resistance object is a rotor, the portion of a brush
is fixed, and it comes out to the directly exterior.
For this reason, a metal joining section
decreases to three places from five places, and the bad influence to sound
quality is reduced.
The input circuit is - (invert) and plus (non invert), and consists of
twin per channel. It is the Attenuator form of a 1dB step with few interlocking
errors, and an input level can be controlled correctly.
The amplifier only for headphone is formed aiming at the high-quality
sound reproduction by headphone.
Since the input stage has adopted the amplifier by servo control of an FET system, it has not affected a main circuit.
The volume of headphone can be controlled regardless of the magnitude of the
sound of a speaker.
The level reproduction for -50dB - +3dB understands
a power output meter at a glance by logarithm compression type peak display. The
Direct reading of the Output voltage at the time of dB and 8-ohm load can be
Moreover, the switch by which operation and lighting of meter
are turned off is also equipped.
The input is one balance and two
unbalance and can be changed with the switch in the front panel.
one unbalance is prepared in the front sub panel.
The speaker output
terminal can change two lines.
With a changeover switch, it can also drive
by parallel connection.
Except [ all ] the power switch, it is the
simple design stored inside the lower sub panel, and has become finishing of
Both sides are the boards of natural persimmon finishing.
||Stereo power amplifier
|Continuation average output
|At the time of stereo specification (both
channel simultaneous operation)
400 W/ch: 2-ohm load
300 W/ch: 4-ohm
200 W/ch: 8-ohm load
100 W/ch: 16-ohm load
At the time of
monophonic specification (bridge connection)
||At the time of stereo specification (both
channel simultaneous operation)
2ohms - 0.02% and 16-ohm load
time of monophonic specification (bridge connection)
4ohms - 0.02% and
||20Hz-20kHz+0 -0.2 dB (at the time of a
continuation average output level control MAX)
0.5Hz-16k0Hz+0 -3.0 dB (at
the time of 1W output a level control MAX --6dB)
||28.0dB (at the time of a stereo / monophonic
||At the time of stereo specification: 2ohms -
At the time of monophonic specification (bridge connection): 4ohms -
||At the time of stereo specification: 300
At the time of monophonic specification (bridge connection): 150
|Input sensitivity (8-ohm load)
||At the time of stereo specification
1.59V: At the time of a continuation average output
0.11V: At the time
of 1W output
At the time of monophonic specification (bridge connection)
2.76V: At the time of a continuation average output
0.11V: At the time
of 1W output
|S/N (A compensation)
||120dB (at the time of input short-circuit
and a continuation average output)
100dB (at the time of input 1kohm and
||Conformity impedance: 4ohms - 1000ohms
|Power output meter
||A logarithm compression type, -50dB-+3dB, and an output Direct-reading scale
|The semiconductor used
||Transistor: 63 pieces
FET: 32 pieces
IC: Ten pieces
Diode: 77 pieces
||100V, 117V, 220V, 240V, 50Hz/60Hz
||At the time of no inputting: 100W
Electrical Appliance and Material Control Law: 590W
At the time of an
8ohm Output power: 633W
||the width 475x height 180(piece -- it
includeds) x depth of 409mm