Audio Database

The

Accuphase P-360
370,000 yen(March, 1991 release)

Description

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 series.

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 transistor.
Furthermore, the Class-A cascode push pull circuit is similarly used for the
pri driver, and the stability of MOS FET is increased.

The input of amplifier has adopted the direct connection system to which a signal is impressed direct.
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.

A 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 carried out.
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.
Among this, 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 champagne gold.
Both sides are the boards of natural persimmon finishing.


Internal The
Amplifying
Toroidal Filter MOS FET Resistance

Rating of a mode
Form Stereo power amplifier
Continuation average output
(20Hz - 20kHz)
At the time of stereo specification (both channel simultaneous operation)
400 W/ch: 2-ohm load
300 W/ch: 4-ohm load
200 W/ch: 8-ohm load
100 W/ch: 16-ohm load
At the time of monophonic specification (bridge connection)
800W:4-ohm load
600W:8-ohm load
400W:16-ohm load
THD At the time of stereo specification (both channel simultaneous operation)
2ohms - 0.02% and 16-ohm load
At the time of monophonic specification (bridge connection)
4ohms - 0.02% and 16-ohm load
IM distortion 0.003%
Frequency response 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)
Gain (profit) 28.0dB (at the time of a stereo / monophonic specification)
Load impedance At the time of stereo specification: 2ohms - 16ohms
At the time of monophonic specification (bridge connection): 4ohms - 16ohms
Dumping factor 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
Input impedance Balance: 40kohm
Unbalance: 20kohm
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 1W output)
Stereo headphone 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
Power source 100V, 117V, 220V, 240V, 50Hz/60Hz
Power consumption At the time of no inputting: 100W
Electrical Appliance and Material Control Law: 590W
At the time of an 8ohm Output power: 633W
Dimensions the width 475x height 180(piece -- it includeds) x depth of 409mm
Weight 27.4kg