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DUAL CHANNEL PCIWER AMPLIFIER
It is a mistake to calculate the value of a power amplifier solely in terms
of $lpower or cost/power. Other more important factors should also be
considered to assess its overall value such as those power qualities like
low distortion, well~regulated power supply and power bandwidth, as
well as additional functions and appearance values.
The deep reverberating sound quality and expression of music detail that
is heard through‘an extra powerful amplifier can be far more dynamic
and inspiring than sound from an ordinary amplifier. However, powerful
amplifiers that may sound good at high volume levels often fail to sound
as well at low listening levels. This is because technically, the higher the
power, the more difficult it becomes to capture clearly the very soft,
delicate passages of music. The “difference" in Accuphase sound
becomes readily apparent during reproduction of such soft passages, or
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when listening at low volume, since the P-250, like other Accuphase
amplifiers, was designed to ensure clear, clean sound quality at ALL
There has been much discussion recently concerning amplifier and
speaker connections and the harmonious relation between them. This can
be said to reflect the feeling of a growing number of audiophiles that
more could be done by amplifier manufacturers to make their products
better able to induce the maximum potential performance from any
speaker, and enhance a speaker's characteristic tonal qualities. The
Speaker Damping Control feature of the Accuphase P-250 is a perfect
answer to this question as it can change the speaker damping factor
quickly, and thus reveal a speaker's maximum sound reproducing
capabilities and characteristic tonal qualities immediately.
*High power output of 100 watts per channel into 8 ohms with
clean sound quality at ALL listening levels.
This high power capability, with distortion at less than 0.1% from 20 to
20,000 Hz is fully gUaranteed. Heavy duty power transistors in a parallel
push~pu|l drive output stage and large heat sinks back up this Accuphase
High power amplifiers need an especially reliable power supply that must
not only provide the energy to drive the speakers. but the capacity to
store and deliver adequate power to trace the sharpest fluctuating signal.
The P-250 has just such a power supply with an oversize power
transformer and two giant 20,000uF filter capacitors that can easily
supply the energy required to deliver 280 watts of continuous power into
4 ohms. A severe rise in distortion when volume is reduced to low levels
is a problem with many high power amplifiers, but not so with the P-250
in which such distortion has been eliminated to the lowest possible limit.
It permits enjoyment of clean. clear pianissimo passages at ALL volume
*Speaker Damping Control enhances characteristic tonal quali-
ties of speakers.
The damping factor of solid state amplifiers is generally very large and
ideal for damping the speakers. However, some speakers require an
amplifier with a low damping factor to reproduce rich, full-bodied sound.
The P-250 has a Speaker Damping Control which permits choice of three
damping factors and induces maximum potential performance from any
speaker. Damping factor with an B—ohm load becomes more than 50
when this control is set to NORMAL. Likewise, it is 5 at MEDIUM
position, and 1 at SOFT position. It enables choosing the speaker sound
that one prefers.
“Foolproof protection Circuit safeguards power transistors and
The P-ZSO has a built-in Protection CirCUit which guards against damage
to speakers or power transistors in case of shorts when the speakers are
connected, or when abnormally low impedance output load connections
are made. If the speakers are shorted, this circuit automatically cuts them
from the amplifier.
*Large size power meters.
Large size power meters indicate power output in decibels (dB). The
meters also provide indications to read output power level directly in
watts. Switch selection of three ranges, OdB, —10dB and —20dB, permit
both low and high power measurement. A OdB reading indicates power
output of 100 watts into 8 ohms when the meter range switch is set to
“Plenty of INPUT/OUTPUT terminals.
Plenty of outputs are available to which three pairs of stereo speakers can
be connected. and switch selected. Accommodations for two pairs of
inpUt systems are also provided, and they too can be switch selected. One
pair of input system is provided on the front sub-panel for easy
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Products of Accuphase guarantee specifications stated.
POWER OUTPUT: (both channels driven from 20Hz to
20,000Hz with no more than 0.1% total harmonicdistortion):
140 watts per channel, min. RMS, at 4 ohms
100 watts per channel, min. RMS, at 8 ohms
50 watts per channel, min. RMS, at 16 ohms
TOTAL HARMONIC DISTORTION: (from 20Hz to
20,000Hz at any power output from 1/4 watt to rated power)
4 ohms; 0.1% max.
8 ohms; 0.1% max.
16 ohms; 0.1% max.
will not exceed 0.1% at rated power output for any combination of
frequencies between 20Hz and 20,000HZ
20Hz to 20,000H2; +0, —0.2dB at rated power output
5H2 to 90,000Hz; +0, —3 dB at rated power output
SLEWING RATE: more than 15 V05
DAMPING FACTOR: (at 8 ohms load, 20Hz to 20,000H2)
with "SPEAKER DAMPING" switch set to;
“NORMAL" "MEDIUM" ”SOFT"
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INPUT SENSITIVITY AND IMPEDANCE:
1.0 Volt, 100 k ohms, for rated output at the maximum level control
HUM AND NOISE: 94dB below rated output
POWER LEVEL METER:
Meter is calibrated to read OdB when amplifier produces 100 watts
into 8 ohms load.
METER RANGE switch is provided to increase meter sensitivity by
10dB or 20dB.
OUTPUT LOAD IMPEDANCE:
AUDIO BANDPASS FILTER:
cutoff frequency; LOW, 17H: 18dB/oct
4,8 and 160hrns
For listening with low impedance I4—32 ohms) dynamic stereo
Voltage selector for 100V, 117V, 220V, 240V 50/60Hz operation
Consumption; 70 watts at zero signal output
375 watts at rated power output into 8 ohmr
195 kgr.(42.9 lbs.) net, 23.8 kgr.(52.3 lbs.) in shipping carton.
36 Transistors, 34 Diodes
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KENSONIC LABORATORY INC.
Iorm:8510003A10 PRINTED IN JAPAN