Audio Database
P-20
Commentary

This is a stereo power amplifier developed for high-efficiency floor-type speaker systems for a long period of time without compromise in pursuit of "perfection" for true high-quality music playback.

It is composed of two monaural power amplifiers with independent power supply, so that mutual interference caused by layout and wiring is minimized.

The circuit configuration employs a push-pull circuit in all stages, with less phase disturbance over a wide bandwidth and excellent linearity over a wide dynamic range.
In addition, in order to keep residual noise low, specially selected parts and careful circuit examination are carried out, and residual noise is reduced to the extent that it can hardly be heard even when it is directly connected to a high-efficiency horn driver as a multi-channel amplifier system.

Tube type amplifier In order to be compatible with models with low damping factors, such as speakers developed in the heyday of the amplifier, a damping factor selection switch is mounted to control the tone balance and volume of the reproduced sound by changing the damping factor.
Since the value of the damping factor is changed by current feedback, there is no power loss due to switching.

As long as an AC signal (music waveform) is being input, no matter how large an input is input, a new protection circuit has been developed and adopted to prevent the sound from being cut off due to the differential of the protection. This is a countermeasure against overload.

It is equipped with a subsonic filter to cut unwanted noise in the ultra-low range.

Equipped with a detent type attenuator that changes in 1 dB steps up to -20dB.

Model Rating
Type Stereo power amplifier
Rated output
(Both channel operation, 20 Hz to 20 kHz, distortion rate 0.1%)
100W/ch (4 Ω)
70W/ch (8 Ω)
35W/ch (16 Ω)
Harmonic distortion factor (20 Hz to 20 kHz) Rated power : 0.1%
0.05% at -3dB output
50 mW output : 0.1 per cent
IM Distortion Factor (any frequency from 20 Hz to 20 kHz) Rated power : 0.1%
Frequency response (at rated output) 20 Hz ~ 20000 Hz + 0 -0.2 dB
Damping factor (8 Ω load, 40 Hz) 50, 5, 1 (Switching Type)
Rated input / input impedance 1.0V/100k Ω
S/N ratio (at rated output) 100dB
Stereo headphone Applicable Impedance : 4 ~ 32 Ω
Subsonic filter 17 Hz or less, 18dB/oct.
Semiconductor used Transistor : 60 Nos.
IC : 1 pc
Diode : 44 pcs
Power supply voltage AC100V/117V/220V/240V, 50Hz/60Hz
Power consumption No input : 45W
8 Ω load maximum output : 290W
4 Ω load maximum output : 530W
External dimensions Width 482x Height 150x Depth 353 mm
Weight 23.5kg
Remarks 19 inch standard rack mountable
Rack mount pitch : 100 mm (4 ")
Rack inner diameter (horizontal) : 430 mm (16 15/16 ") or more