Audio Database


Accuphase P-600
650,000 yen(April, 1983 release)


Stereo power amplifier developed in quest of the ideal of the power amplifier of a new time.

In order to compensate the Oide power with continuation operation, the output stage constitutes the broadband transistor of Pc(collector loss)200W from 14 per channel, and a 7-parallel push pull, and is giving the power capacity of 2.8kW.

Although the low load up to 2ohms can be driven also in the state of anticipated use, for the reason in the case of driving by still lower impedance by business use etc., the Low Load Impedance Operation switch is formed.
As for this switch, it is possible to enable it to supply large current and for this to obtain the output of 450 W/ch also to 1-ohm load, maintaining the insurance of an output transistor.

The drive stage which drives an output stage is constituted from MOS FET for electric power magnification, and has performed a low impedance large current drive and improved the characteristic of a high region sharply collectively.
Moreover, in order that a heat characteristic may work in the direction which stabilizes a bipolar transistor, the bias current of an output stage is stabilized. For this reason, it is possible to make emitter resistance of an output stage low, and also it is 7. - Parallel more, equivalent emitter resistance became low with one seventh, and the switching distortion of it generated in order that the bias of an output transistor may cut off is almost lost.
The predrive stage constitutes the Darlington cascode push pull, reconciles outstanding large amplitude operation with good high region characteristic and linearity without a Miller effect, and is driving MOS FET.
Moreover, since the Darlington connection which consists of predrive stages makes input impedance of this stage high, it does not affect operation of the difference input circuit where this becomes load, but enables good magnification.

The input magnification circuit has adopted the cascode bootstrap push pull circuit of an FET input.
The cascode bootstrap has improved the high region characteristic while being a high gain, and it has prevented the distorted aggravation by the rise (change of an input level control) of input impedance.

It is possible to have adopted the push pull input circuit by dual FET, and for a direct current not to occur to an input, but to remove an input capacitor.
Moreover, direct current appears in an output in the combined use with the preamplifier of direct-current leak, and in order to prevent having a bad influence on a speaker, the direct-current return is applied with direct-current servo amplifier, and while intercepting a direct current, the drift generated in a circuit is also suppressed.

It can be used also as monophonic amplifier by bridge connection.
By inputting the signal of negative phase into each amplifier by the same ripple, and connecting a speaker to the output of both amplifier, the voltage impressed to a speaker becomes twice and the principle of bridge connection can take out 4 times as many outputs theoretically.
Moreover, it also has the merit that eventh higher-harmonic-wave distortion is canceled for a negative phase drive, and the characteristic is improved. Moreover, since the energy which flows from a power source flows alternately with plus and minus and the energy of only one way does not flow into both amplifier, it means that the rate of power source variation on appearance was improved, and energy with a good linearity can be sent out to a speaker.

The 600-ohm balance input (3P canon type) full-scale besides the usual 20kohm imbalanced input (phono jack) is carried.
The phase inversion of the balance input of P-600 is not a transformer, and has adopted the differential amplification circuit of a low distorted broadband.

The digital power meter which can carry out the Direct reading of the peak value is carried.
The digital power meter is constituted combining a 12-bit A/D converter and a 4-bit microprocessor, changes an analog signal into a digital signal by an A/D converter, and is performing the exact display.
Since a display is triple figures, it is equipped with the range change, and it can carry out the Direct reading of 0.001W-999W by range change. Moreover, if the hold time can choose 3 seconds and 30 minutes and a range is used for 30 minutes, it can read the peak value of record one side and can know the maximum cutting level.
although the digital power meter of P-600 converts and shows the Output voltage to electric power, even when an Output voltage is the same, output electric power changes with speaker impedance sharply. In order to display exact output electric power, the impedance changeover switch for power meters with which operation of an indicator is united is prepared in the nominal impedance of the speaker.

25 contact rotary switch for communication machines and the full-scale Attenuator by high precision resistance are carried.
-23dB, -26dB, -30dB, and -infinity can be chosen in the accuracy of ±0.1dB for 0dB - -20dB a 1dB step and henceforth.

The Subsonic Filter is carried.
The change of the filter has prepared the relay in the circuit on a printed circuit board, is controlling this relay with the switch of a front panel side, and has prevented characteristic degradation.

There is a wood panel of persimmon finishing of 24mm thickness as an option.

There is a fan for heat dissipation as an option, and when setting to the bad place of the heat dissipation effect or performing the Oide power drive over a long period of time, a fan can attach.

Internal The

Rating of a mode
Form Stereo power amplifier
Continuation average output
(20Hz - 20kHz, 0.02% of distortion)
At the time of stereo specification
Normal Load Imp. Operation: 700 W/ch (2ohms)
500 W/ch (4ohms)
300 W/ch (8ohms)
150 W/ch (16ohms)
Low Load Imp. Operation: 450 W/ch (1ohm)
300 W/ch (2ohms)
At the time of monophonic specification
Normal Load Imp. Operation: 1400W (4ohms)
1000W (8ohms)
600W (16ohms)
Low Load Imp. Operation: 900W (2ohms)
600W (4ohms)
At the time of stereo specification : 0.02% (1ohm-2ohm)
0.01% (4ohm-16ohm)
At the time of monophonic specification : 0.02% (2ohm-4ohm)
0.01% (8ohm-16ohm)
IM distortion (EIA) 0.01%
Frequency response 20Hz-20kHz+0 -0.2 dB (at the time of a continuation average output level control MAX)
0.5Hz-250kHz+0 -3 dB (at the time of 1W output level control MAX)
0.5Hz-150kHz+0 -3 dB (at the time of 1W output level-control 6dB)
Gain 27.8dB (at the time of stereo specification)
33.8dB (at the time of monophonic specification)
Load impedance At the time of stereo specification: 1ohm - 16ohms
At the time of monophonic specification: 2ohms - 16ohms
Dumping factor
(EIA 50Hz)
At the time of stereo specification: 300
At the time of monophonic specification: 150
Input sensitivity
At the time of stereo specification : 2.0V (8ohm, 300W, Normal Load Imp.Operation)
1.0V (2ohm, 300W, Low Load Imp.Operation)
At the time of monophonic specification : 1.83V (8ohm, 1000W, Normal Load Imp.Operation)
0.91V (2ohm, 900W, Low Load Imp.Operation)
Input impedance 20kohm disequilibrium
600-ohm balance
S/N (A compensation)
At the time of
stereo specification :
(input short-circuit, 8 ohms, a continuation average output, Normal Load Imp.Operation)
100dB (at input 1kohm, the time of 1W output EIA)
At the time of
monophonic specification :
(input short-circuit, 8 ohms, a continuation average output, Normal Load Imp.Operation)
(at input 1kohm, the time of 1W output EIA)
Subsonic Filter 10Hz, -12 dB/oct
Power output meter
Form : A triple figure digital display, a peak directions Direct-reading type
Display range : It is 0.001W-999W by range change.
Load impedance change : 2ohm, 4ohm, 8ohm, 16ohm
Hold time : 3 seconds, 30 minutes
Frequency response : 20Hz-20kHz+0 -0.2 dB
Pulse reply error : + 0 -0.4 dB (by 100Hz one wave)
The semiconductor used Transistor: 90 pieces
FET: Eight pieces
IC: 36 pieces
Diode: 104 pieces
LED: Eight pieces
Power supply voltage AC100V/117V/220V/240V, 50Hz/60Hz
Power consumption
(Normal Load Imp. Operation)
165W (at the time of no inputting)
1100W (Electrical Appliance and Material Control Law)
1100W (at the time of an 8-ohm load Output power)
Dimensions the width 480x height 232(piece -- it includeds) x depth of 476mm
Weight 38.5kg
Option Persimmon wood panel A-14 (attachment lug one set, \16,000)
Fan for heat dissipation O-81 (one set, \8,000)