Accuphase P 20 Brochure

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The most important factor in evaluating a power amplifier is the quality of sound energy
that it can deliver. This normally is dependent to a great extent on high power output,
but since many of today's high-efficiency floor-type speakers can be fully driven with
moderate power, the quality of sound energy a power amplifier can deliver becomes the
major decisive factor.

The Accuphase P-ZO is a medium power amplifier which was designed and produced
after years of uncompromising research and planning. lt assures "perfection" in musical
reproduction when used with such high efficiency speakers of top quality. It has a power
output of 7OW/channel (into 8 ohms, both channels simultaneously driven, 20-20,000
Hz, distortion less than 0.1%),

The P-20 is a very versatile amplifier with built in power supplies for each left and right
channels it can eliminate inter-channel interference and with its extra heavy-duty
capability, it can deliver stabilized energy even at amplification applications which
require top grade amplifier performance. Musical reproduction of the highest quality can
be expected from such multi mpliiier installations which use the P-

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-<%CCUPLO$€ P-20 -

*Two Monophonic Amplifiers in Stereo Construction *Guaranty Specifications
The P720, each channel with its own independent power supply, can be Performance Guaranty: Products of Accuphase guarantee specifications
considered consisting of two separate monophonic amplifiers, and assures stated.
practically an ideal condition to minimize inter-channel interference, POWER OUTPUT: (both channels driven from 20Hz to
which may be caused by layouts of parts and wiring in a stereophonic 20 OOOHZ with no more than 0 1% total harmonic distor<
amplifier. . ' .
. . , , . tion): 100 watts er channel, ITIIII. RMS at 4 ohms
*Push-pull Circu1ts Throughout Assure High Stability, 70 watts trier channel min RMS at 8 oh ms
. . . . r - I
600d Linearity and W'de Dynamic Range 35 watts per channel, min. RMS, at 16 ohms

Accuphase's original innovation, the utilization of pushrpull amp circuits TOTAL HARMONIC DISTORTION' (from ZOHZ to

in every stage, is also adopted in the P-20. This minimizes phase

distortion and also ensures outstanding linearity over a wide dynamic 20,000Hz at any power output from 4 watt to rated
range, as well as good stability against temperature changes and line Power): 4 ohms; 01% max-

Voltage fluctuations. 8 ohms; 0.1% max.

*High SIN, Low Residual Noise 15 Ohms: 0.1% max.

Residual noise is that which is created within a power amplifier itself. It 'NTERMODULATION DISTORTIONi

has no connection with the strength of the external signal. If an WI not exceed 01%31 mid POWEVOMDM for any combination 0f
amplifier's residual noise characteristic is high, its S/N ratio and PFP frequencies between ZOHZ and 20.000HZ

characteristics will be poor. Flesidual noise is also a source of annoying FREQUENCY RESPONSE:

interference during no signal conditions. It becomes more pronounced 20Hz to 20,000Hz; +0, -0.2dB at rated power output

when high efficiency speakers are used. 5H2 to 90,000Hz; +0, -3.0dB at rated power output

Residual noise, however is practically non-existent in the P-20 due to the .

most discriminating choice of parts and painstaking circuit design. It is SLEWING RATE' 15V/S

almost unnoticeable even when the P-20 is connected directly to a horn DAMPING FACTOR: (8 ohms load at 40H2l changeable for 50, 5, 1K...

ir've Ia mum'ampmcamn app'wam INPUT sensrrivnv AND IMPEDANCE: 1.0 V0|t,100 kohms, for
Damping Faaor Selector Enhanoes Speaker Performance rated power output at the maximum level control

The Damping Factor (DF) of solid state amplifiers is normally very high

and is ideal for damping speakers. Increasing the damping factor, HUM AND NOISE 100dB below rated output

however, does not always improve speaker performance, especially with OUTPUT LOAD IMPEDANCE: 4, 8 and 16 ohms

large'floor-tvpe speakers operated under certain acousticenvuonments. SUBSONIC FILTER: cutoff frequency: 17Hz, 18dB/oct.

This is especrally true With speaker systems developed during the vacuum

tube era. ATTENUATOR: precision, 1dB stepping type
The P20 is built to work well with all types of speaker systems and POWER REQUIREMENT,
enhancg 9" performance i5 equppej W a Damping Facm' VoltageSeiectorfor 100v 117v 220v,240v 50/60Hz operation

Selector Switch which can control balance and richness of sounds in
reproduction to get the best sound that any speaker system is capable of
producing. Power is not lost when the damping factor is changed, as it is
done by varying Current Feedback.

*Perfect Overlod Measures

Consumption: 45 watts at zero signal output
290 watts at rated power output into 8 ohms load
530 watts at rated power output into 4 ohms load

SEMICONDUCTOR COMPLEMENT: 60 Transistors, 44 diodes, 1 IC

According to a test conducted by the US. Magazine Stereo Review DIMENSIONS: 482mml19inches)wide,150mmi6incheslhigh
concerning perceptibility of clipping distortion, it is reported that up to 353mm(l3<7/8 inchesldeep

3dB clipping could not be detected for string instruments in which Such mountable on 19" standard rack. rack mount pitch: 100mml4")
distortion is most noticeable. In the case of piano music, clipping rack inside horizontal measurement; 430mmi16-15/16")

dsmm" WV hem apparen 3 WW °f BdB I h W°'d5' WEIGHT: 23.5 kgs 151.7 lbsl net, 28.1 kgs (51.8 lbsl in shipping carton

one can not notice distortion of sound when a 150 watt string instrument
peak signal is reproduced through a 75W amplifier at its maximum power
output, or when piano music is reproduced through a 42W amplifier.
However this is subject to a condition that such amplifiers must have Fm capac'ms
adequate power supplies that assure stabiliezed energy at their rated AXZZ'OOO:
maximum power outputs.

For this reason it is important particularly for low and medium power
amplifiers to have some means to handle such peak input signal surges
without tripping the Protection Circuit and cutting off the program
source.

The P-20 is equipped with just such Protection Circuit. It can handle any
input signal, no matter how large as long as it is alternating, i.e. music
waveform, without cutting off the program source. At the same time, it
provides sure protection against short circuits and overloads in the output
and speaker circuits.

*Subsonic Filter Eliminates Noise Mal" 5"
Subsonic vibrations can cause intermodulation problems of interference Assembly (R)
and damage the speaker system. The P-ZO is equipped with a 17Hz
18dB/Oct. Subsonic Filter which completely eliminates such problems.
*1 dB Step Attenuator

An independent power amplifier should have its own Level Control so
that it can be adjusted in accordance with speaker efficiency, or the
volume level of sound reproduction. The P-20 is equipped with a detent
type attenuator with which volume level can be adjusted down to rZOdB
in 1dB steps.

Main Drive Assembly ".

Protection Circuit

Speaker Terminals

Heavy duty Power
Transformers

Input Terminals

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KENSONIC LABORATORY INC.

ll76730000 PRINTED IN JAPAN form 1851-0009-00