It is
mistake to calculate the value of a power amplifier solely in terms of $/power
or cost/power. Other more important factors should also be consideraded 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.
Music
delivered through a good power amplifier should have an extra quality of deep,
rich bass and the subtle nuances of inner musical fabric which stir and warm
the soul with emotion. A good power amplifier must also have the range to
reproduce precisely the softest to the loudest passages of music, and, at the
same time, it must be able to handle, without distorting, all the large input
amplitudes that may be involved.
The P-300
can coast through all of these requirements without strain due to its large,
heavy-duty power transformer and 2 x 40,000 µF filter capacitors, its
all-stage, push-pull circuit configuration, and well selected and thoroughly
tested parts. Prepare to enjoy exciting music with the Accuphase P-300 which
can deliver it.
Every Stage
is Push-Pull Driven
Every stage,
from input to output, is a direct-coupled, extravagant, push-pull lineup. As a
result, a big improvement in characteristics before negative feedback
application ensures low distortion and dependable operation with any impedance
and type of speaker, throughout the audio range, from low to high powers.
Triple
Push-Pull Output Stages
Six
heavy-duty power transistors are used in
the direct-coupled, Complementary-Symmetry circuit stage of each channel. A
large efficient heat sink is provided to ensure adeguate heat dissipation when
the P-300 is required to deliver full power output continuously.
Heavy Duty
Stable Power Supply
The
stable power supply of the P-300 which can meet the heavy requirements of 400
watts of power into 4 Ω without
strain, also can maintain, with ease, well required supply voltages against
varying load conditions created by rapidly changing input signals. Even for
fff, each music part is separated smoothly, and there is no awareness of
muddlness.
Closely
Selected Parts
It is a well
known fact that different parts can be responsible for differences in sound
quality, even from exactly the same amplifier circuit. This is due to the fact
that the parts themselves often possess certain electrical characteristics
which have no relation to their designated function.
All parts,
therefore, are selected carefully with "performance first" in mind,
and they are subjected to severe durability and other tests bto determine how
their characteristics might effect sound quality.
Dependable
Speaker protection Circuit
Mistakes in
speaker connections that cause short circuited outputs or similar troubles will
disconected the speakers automatically by relay action from this amplifier to
protect expensive speakers from damage. In such cases, the power meter lamp
will flash on and off successively as a warning signal. As soon as the trouble
is corrected, the lamp will again glow steadily, and normal operation will
resume automatically.
Bandpass
Filters
Undesirable
turntable rumble and subsonic tone arm resonance vibrations that enter the
input may appear as intermodulation distortion in the mid and high frequency
ranges. Ultrasonic vibrations that enter the input can also mix with high
frequency range signals to cause "beat" interference and overheating
of transistors. Bandpass filters, with a sharp cut-off characteristic of 18
dB/oct, are provided to eliminate these undesirable signals below 17 Hz, and
above 24 kHz. These filters can be switched On or Off with a control available
on the front sub-panel.
Large Size
Power Meters
Large
size power meters indicate power output in dB. Switch selection of three
ranges, 0 dB, -10 dB and -20 dB, permit both low and high power measurements. A
0 dB reading indicates power output of 150 watts into 8 Ω when the meter range switch is set to 0 dB.
Plenty of
Input/Output Terminals
Plenty of
outputs are available to which four
pairs of stereo speakers can be connected, and switch selected. Accommodation
for two pairs of input systems are also provided, and they too can be switch
selected. Jacks are available on the front sub-panel for one pair each of these
inputs and outputs, respectively.
Power
Limiter
A power
limiter switch is provided on the front panel so that power output can be
limited to protect high efficiency speakers when thay are used. This switch
permits choice of 25%, 50% and full power operation.
Specifications
Power Output
9both channel driven from 20 Hz to 20 kHz with no more than 0,1% THD):
200
watts per channel, min. RMs at 4 Ω
150
watts per channel, min. RMS at 8 Ω
75
watts per channel, min. RMS at 16 Ω
Total
Harmonic Distortion (from 20 Hz to 20 kHz at any power output from ¼ watt to rated power):
0,1%
at 4 Ω
0,1%
at 8 Ω
0,1%
at 16 Ω
Intermodulation
Distortion: will not exceed 0,1% at
rated output for any combination of frequencies between 20 Hz and 20 kHz
Frequency
Response:
20 Hz to
20,000 Hz, +0, -0,2 dB at rated power output
5 Hz to
90,000 Hz, +0, -3 dB at rated power output
Slewing
Rate: more than 20V/µS
Damping
Factor: 60, (8 Ω load at 40 Hz)
Input
Sensitivity and Impedance:
1
Volt, 100 k Ω, for rated output at
the maximum level control
Hum and
Noise: 100 dB below rated output
Power Level
Meter :
Meters
is Calibrated to read 0 dB when amplifier produces 150 watts into 8 Ω load.
Meter Range
switch is provided to increase meter sensitivity by 10 dB or 20 dB.
Output
Load Impedance: 4, 8 and 16 Ω
Audio
Bandpass Filter
Cutoff
Frequencies:
Low, 17 Hz 18 dB/oct
High, 24 kHz
18 dB/oct
Power
Limiter: Full power outout 50 % output,
and 25% output with front panel Switching
Power
Requirement: 100/117/220/240 V, 50/60 Hz
operation
Power
Consumption: 100 Watta at zero signal
output; 510 watts at rated power output
into 8 Ω load.
Semiconductor
Complement: 73 Transistors, 1 ICs, 88 Diodes, 2 Thermistors
Dimensions
W x H x D): 445 x 152 x 355 mm (17½" x 6" x 14")
Weight: 25 kg (55 lbs) net