Audio Database


Accuphase P-20
\190,000 (May, 1976 release)


Developed stereo power amplifier to which searched for "completeness" as an object for high efficiency floor type speaker systems aiming at very high quality music playback, and the long time was applied without reaching a compromise.

It has composition which combined two sets of the monophonic power amplifier by an independent power source, and it is taking care so that the mutual intervention which is on a layout or wiring and is produced may also serve as the minimum.

Circuit composition has adopted the whole page push pull circuit, and over the large zone, there is little disorder of a phase and it is maintaining the linearity which was excellent to the large dynamic range.
Moreover, in order to suppress remains noise low, even if the part selected especially carefully and detailed circuit examination are performed and it links directly with high efficiency honed Leiber as a multichannel amplifier system, remains noise lessens to the grade which can hardly be heard.

In order to correspond also to a model with effective low dumping factors, such as a speaker developed in the tube amplifier heyday, the dumping factor changeover switch which changes a dumping factor and controls [ of reproduction sound / the sound quality balance and massive ] is carried.
Since the value of the dumping factor is changed by current feedback, there is no loss of the power by change.

Even if a however big input enters, as long as the exchange signal (music ripple) is inputted, the protection circuit of the new method was developed and adopted and the cure against an overload is taken so that protection may carry out differential and a sound piece may not be raised.

The Subsonic Filter is carried in order to cut a super-low-pass unnecessary noise.

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


Rating of a mode
Form Stereo power amplifier
Output power
(Both channel operation, 20Hz - 20kHz, 0.1% of distortion)
100 W/ch (4ohms)
70 W/ch (8ohms)
35 W/ch (16ohms)
THD (20Hz - 20kHz) At the time of an Output power: 0.1%
- At the time of a 3dB output : 0.05%
At the time of a 50mW output: 0.1%
IM distortion (arbitrary frequency of 20Hz - 20kHz) At the time of an Output power: 0.1%
Frequency response (at the time of an Output power) 20Hz-20000Hz+0 -0.2 dB
Dumping factor (8-ohm load, 40Hz) 50, 5, 1 (change type)
A rated input / input impedance 1.0V/100kohm
S/N ratio (at the time of an Output power) 100dB
Stereo headphone Conformity impedance: 4-32ohms
Subsonic Filter 17Hz or less, 18 dB/oct
The semiconductor used Transistor: 60 pieces
IC: One piece
Diode: 44 pieces
Power supply voltage AC100V/117V/220V/240V, 50Hz/60Hz
Power consumption At the time of no inputting: 45W
At the time of the 8ohm load maximum except take-off: 290W
At the time of the 4ohm load maximum except take-off: 530W
Dimensions Width 482x height 150x depth of 353mm
Weight 23.5kg
Remarks 19-inch standard rack attachment is possible.
Rack-mounted pitch: 100mm (4")
Rack bore (horizontal): More than 430mm (16 15/16")