Accuphase P-800
¥ 750,000 (released in July 1988)
Commentary
This stereo power amplifier is based on the development technology of the M-1000 and aims to achieve both high quality sound and high output.
It is composed of a balanced system in which two sets of all stage push-pull drive unit amplifiers are connected to a bridge to improve performance.
The balanced method requires a dedicated transmission system for plus and minus signals. However, in principle, external noise is canceled, and at the same time, distortion generated by the amplifier is also canceled by the output circuit, making purer signal transmission possible.
In order to achieve the same performance as a monaural amplifier, the power supply section uses an independent power supply for left and right.
In addition, two power supplies with only half the power capacity increase the impedance of the power supply compared to a single transformer system, which is disadvantageous. Therefore, the P-800 uses a 1.5 kVA high-capacity transformer that can be used for stereo by one power supply, ensuring sufficient margin.
In addition, the filter condenser is 82,000 μ Fx4 with a total capacity of 328,000 μ F.
The output stage of each unit amplifier employs a 7-parallel push-pull configuration of wide-band transistors with a collector loss (Pc) of 130W. The total number of transistors is 28 in two units of one channel, and the total collector loss reaches 3.6 kW.
In addition, the operating point is strictly set so that the PNP and NPN elements do not become cut-off (a state in which no current flows) by the input signal for switching distortion at the small output which occurs at the output stage.
The Addition, The P-800 is equipped with a low-load impedance switch based on a low-impedance drive system that takes advantage of the basic characteristics of transistors. By switching the supply voltage, it is possible to supply large power even at low loads. This switch supports 1 Ω and 2 Ω loads. Full load support enables sufficient drive of low-impedance, low-efficiency flat plate speakers and electrostatic speakers.
A MOS FET equivalent to a non-switching class A drive is used at the front stage of driving the final stage, and it is composed of cascode push-pull. The front stage of sending a signal to this MOS FET is also composed of class A cascode push-pull.
This provides a stable output stage with little distortion from the low output of the noise region to the high output of the rated output.
Class A cascode differential push-pull system is adopted for the input stage.
Cascode circuits are used for high-frequency amplification. They operate stably over a wide frequency band, have good input linearity, and can ensure a wide dynamic range.
Equipped with an analog type large power meter that can directly read power between -60dB and + 3 dB by logarithmic compression.
It also has a switch that turns off the meter and lights.
Both balanced and unbalanced equipped with both balanced and unbalanced inputs.
Equipped with a natural Persimmon finish side board.
The fan is sold separately and can be set inside the side board when it is set in a place where heat radiation effect is bad or when it is driven with high power for a long time.
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Model Rating
| Type | Stereo power amplifier | ||||
| Continuous average power (20 Hz to 20 kHz) |
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| Total harmonic distortion factor | 0.05% (1 Ω ~ 4 Ω Load) 0.01% (4 Ω ~ 16 Ω Load) |
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| IM distortion factor | 0.003% | ||||
| Frequency characteristic | 20 Hz ~ 20 kHz ± 0 dB (Continuous Average Output, Level Control MAX) 0.5 Hz ~ 150 kHz + 0 -3.0 dB (at 1W Output, Level Control MAX) 0.5 Hz ~ 80 kHz + 0 ~ 3.0 dB (Level Control -6dB at 1W Output) |
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| Gain | 28.0dB | ||||
| Load impedance | Normal Load Imp. Operation : 4 Ω ~ 16 Ω Low Load Imp. Operation : 1 Ω ~ 4 Ω |
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| Damping factor | 200 (EIA, 50 Hz) | ||||
| Input sensitivity |
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| Input impedance | Unbalanced input : 20k Ω Balance Input : 40k Ω |
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| S/N (A correction) | 125 dB (Input Short, Continuous Average Output) 95 dB (Input 1k Ω, 1W output) |
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| Output meter | Logarithmic compression peak display type -60dB to + 3 dB and output direct reading scale |
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| Semiconductor used | Transistor : 158 units FET : 20 IC : 15 Diode : 158 units |
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| Pwer | AC100V/117V/220V/240V, 50Hz/60Hz | ||||
| Power consumption | 110W + 110W (without input) 550W + 550W (Electrical Appliance and Material Control Law) 740W + 740W (at 8 Ω load rated output) |
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| External dimensions | Width 481x Height 239 (Including Legs) x Depth 489 mm (Including Rear Panel Legs) | ||||
| Weight | 47.2kg | ||||
| Sold Separately | Heat Dissipation Fan O-83 (set, ¥ 10,000) |