Accuphase P-300

 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