Audio Database

The

Accuphase P-800
750,000 yen(July, 1988 release)

Description

Stereo power amplifier which followed the development technology of M-1000 and aimed at coexistence of the high sound quality of grace, and the Oide power.

It constitutes from a balance system which connected 2 sets of whole page push pull drive unit amplifier to the bridge, and the engine performance is improved.
Although the transmission system only for a plus signal and a minus signal is needed by a balance system, distortion generated with amplifier is also canceled in an output circuit, and purer signal transmission is possible for it at the same time the noise which entered from the outside is canceled theoretically.

The power-source part has adopted the power source only for right-and-left independent in order to realize the engine performance equivalent to monophonic amplifier.
Moreover, with two power sources which only made power capacity the half, since power-source impedance goes up compared with a single transformer system and it becomes disadvantageous, in P-800, the mass transformer of 1.5kVA which can be used for a stereo by one piece was adopted, and sufficient margin has been secured.
Furthermore, a total of 82,000micro-Fx4 and 328,000-micro F large scale is carried in the filter capacitor.

The broadband transistor of collector loss (Pc)130W is adopted as the output stage of each unit amplifier with 7-parallel push pull composition, and it has become a total of 28 pieces in single-sided channel 2 unit in it. For this reason, the total collector loss amounts to 3.6kW.
Moreover, to the switching distortion at the time of the Koide power produced in an output stage, the operating point is strictly set up so that the element of PNP and each NPN may not be cut off (state current not flowing at all), with an incoming signal.
In further P-800, the low load impedance switch by the low impedance drive system using the fundamental character of the transistor is carried, and it considers so that low load can also supply large electric power by changing service voltage. Thereby, 1-ohm load and 2-ohm load are also supported, and sufficient drive of low impedance, and the monotonous speaker of a feebleminded rate and an electro static speaker is also enabled by full-load correspondence.

MOS FET equivalent to a non switching Class-A drive is adopted as the preceding paragraph which drives a final stage, and it constitutes from a cascode push pull. Moreover, the preceding paragraph which sends a signal to this MOS FET is also considered as Class-A cascode push pull composition.
This constitutes few stable output stages distorted from the Koide power of a noise domain to the Oide power of an Output power.

The Class-A cascode differential push pull system is adopted as an input stage.
A cascode circuit is a circuit used as an object for high frequency magnification, its operation is stable over a large frequency band, the linearity of an input is good, and it is possible to secure a large dynamic range.

The analog type large-sized power meter which can carry out the Direct reading of the power for -60dB - +3dB by logarithm compression is carried.
Moreover, the switch by which operation and lighting of meter are turned off is also carried.

The input terminal carries both the balance input and the imbalanced input.

The sideboard of natural persimmon finishing is carried.

When setting to the bad place of the heat dissipation effect or performing the Oide power drive over a long time, the optimal fan is an option, and setting inside a sideboard is possible.

Internal Rear
A
Output

Rating of a mode
Form Stereo power amplifier
Continuation average output
(20Hz - 20kHz)
Normal Load Imp.Operation (0.01% of distortion) : 600 W/ch (4ohms)
400 W/ch (8ohms)
200 W/ch (16ohms)
Low Load Imp.Operation (0.05% of distortion) : 600 W/ch (1ohm)
400 W/ch (2ohms)
200 W/ch (4ohms)
THD 0.05% (1ohm - 4-ohm load)
0.01% (4ohms - 16-ohm load)
IM distortion 0.003%
Frequency response 20Hz-20kHz±0dB (at the time of a continuation average output level control MAX)
0.5Hz-150kHz+0 -3.0 dB (at the time of 1W output level control MAX)
0.5Hz-80kHz+0 -3.0 dB (at the time of 1W output level-control 6dB)
Gain 28.0dB
Load impedance Normal Load Imp.Operation: 4ohms - 16ohms
Low Load Imp.Operation: 1ohm - 4ohms
Dumping factor 200 (EIA, 50Hz)
Input sensitivity
Normal Load Imp. Operation: 2.25V (at the time of 8-ohm load and a continuation average output)
0.12V (at the time of 8-ohm load and 1W output)
Low Load Imp. Operation: 1.13V (at the time of 2-ohm load and a continuation average output)
0.06V (at the time of 2-ohm load and 1W output)
Input impedance Imbalanced Input: 20kohm
Balance input: 40kohm
S/N (A compensation) 125dB (at the time of input short-circuit and a continuation average output)
95dB (at the time of input 1kohm and 1W output)
Power output meter Logarithm compression peak display type
- 60dB - +3dB, and an output Direct-reading scale
The semiconductor used Transistor: 158 pieces
FET: 20 pieces
IC: 15 pieces
Diode: 158 pieces
Power source AC100V/117V/220V/240V, 50Hz/60Hz
Power consumption 110W+110W (at the time of no inputting)
550W+550W (Electrical Appliance and Material Control Law)
740W+740W (at the time of an 8-ohm load Output power)
Dimensions the width 481x height 239(piece includeds) x depth of 489mm
Weight 47.2kg
Option Fan for heat dissipation O-83 (one set, 10,000yen)