Audio Database


Accuphase P-300X
300,000 yen(June, 1980 release)


Stereo power amplifier which supplied state-of-the-art technology and gave the extensive improvement based on P-300 and P-300S.

MOS FET is used for a drive stage and the broadband transistor is used for an output.
By having used MOS FET for the preceding paragraph, the bias voltage of the output stage was stabilized and emitter resistance of an output stage can be removed. Generating of switching distortion is almost lost, without cutting off the bias of the output transistor at the time of the Oide power by this.
A MOS FET drive has high input impedance, and since operation of the preceding paragraph becomes easy, highly efficient-ization of it is attained.

Cascode connection of a transistor is adopted as a predrive stage, and broadband magnification is stably performed in it.

The cascode bootstrap differential push pull input was adopted as the input circuit, while obtaining the big gain, the high region characteristic has been improved, and aggravation of the distortion by the rise of input impedance is prevented.

The input coupling capacitor is directly removed and linked with constituting an FET input.
Furthermore, while applying a direct-current return with direct-current servo amplifier and intercepting a direct current, direct-current drift generated in a circuit is suppressed.

In the power-source part, a power transformer is used as the winding wire only for right and left, and interference of right and left by the exclusive commutator and a filter circuit is suppressed.

The bridge circuit which can use stereo power amplifier as monophonic power amplifier is built in, and it becomes high power monophonic power amplifier by the change of a switch.
Bridge connection also improves the characteristic in order for amplifier to work to each of the direction of direction [ of + ] -, to reinforce power when the voltage impressed to a speaker doubles, and also to also negate distortion mutually.

- Carry the step type Attenuator which changes at a 1dB step to 20dB.

Logarithm compression type peak level meter is carried, and the Direct reading of the output electric power of 8-ohm load can be carried out with dB scale.
Moreover, with a meter function changeover switch, a peak hold can be possible, a peak value in the meantime can be held every 3 seconds, and it can display.

The input-and-output terminal is carried in the front panel.

There is a wood cabinet as an option.


Rating of a mode
Form Stereo power amplifier
Continuation average output
(20Hz - 20kHz, 0.01% or less of distortion)
At the time of stereo use : 200W+200W (4ohms)
150W+150W (8ohms)
75W+75W (16ohms)
At the time of bridge connection : 400W (8ohms)
200W (16ohms)
(0.25W - an Output power, 20Hz - 20kHz)
At the time of stereo use : 0.01% (4ohms)
0.005% (8ohms)
0.005% (16ohms)
At the time of bridge connection : 0.01% (8ohms)
0.01% (16ohms)
IM distortion (new IHF) 0.003%
Frequency response 20Hz-20kHz+0 -0.2dB (an Output power, level-control maximum)
0.4Hz-500kHz+0 -3.0 dB (Output 1W, level-control maximum)
0.4Hz-150kHz+0 -3.0 dB (Output 1W and level-control 6dB)
Gain At the time of stereo use: 27.8dB
At the time of bridge connection: 33.8dB
Load impedance At the time of stereo use: 4ohms - 16ohms
At the time of bridge connection: 8ohms - 16ohms
Dumping factor (new IHF, 50Hz) At the time of stereo use: 150
At the time of bridge connection: 75
Input sensitivity/impedance
At the time of stereo use : 1.4V/50kohm (Output power)
0.11V/50kohm (new IHF and 1W output)
At the time of bridge connection : 1.17V/50kohm (Output power)
0.06V/50kohm (new IHF and 1W output)
S/N (A compensation)
At the time of stereo use : 120dB (an Output power, input short-circuit)
100dB (new IHF and 1W output)
At the time of bridge connection : 110dB (an Output power, input short-circuit)
90dB (new IHF and 1W output)
Stereo headphone Low Output-load-impedance type
Subsonic Filter 17Hz, -12 dB/oct
Power output meter A logarithm compression type, with a peak hold change
- 40dB - +3dB, and an output Direct-reading scale
The semiconductor used Transistor: 42 pieces
FET: 12 pieces
IC: Seven pieces
Diode: 61 pieces
Power supply voltage AC100V/117V/220V/240V, 50Hz/60Hz
Power consumption At the time of no inputting: 80W
At the time of an 8ohm load Output power: 550W
Dimensions usually, time: -- the width 445x height 160(piece -- it includeds) x depth of 373mm
time of wood case wearing: -- the width 466x height 190(piece -- it includeds) x depth of 385mm
Weight 22.5kg
Option Wood case A-8 (16,000yen)