Audio Database

The

Accuphase P-500
510,000 yen(May, 1985 release)

Description

Stereo power amplifier which supplied the technology of Accuphase tradition and was developed towards an audio new time.

Rapid changes in the music signal and occasionally, an instantaneous signal to the pulse of the response to the significant power to try and collectors loss Pc150W the output stage transistors in parallel to the push-pull 6, a total of 12 units / ch, Breakdown them.
If power efficiency of an output stage is made into 70%, a theoretical marginal output will be set to 4,200W. Therefore, it has sufficient margin, even if it takes out the rated maximum except take-off, and the safety of an output stage is raised.

In order to suppress 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 with an incoming signal.
And the preceding paragraph which drives a final stage adopts MOS FET equivalent to a non switching Class-A drive, and constitutes it from a cascode push pull. Moreover, the preceding paragraph which sends a signal to this MOS FET is also made into the Class-A cascode push pull.
The output stage stabilized also to little distorted load from the Koide power of a noise domain to the Oide power of an Output power by this is constituted.

The input circuit constitutes the cascode bootstrap push pull circuit.
A cascode bootstrap circuit is excellent in the high frequency characteristic with high gain, and has the feature that no aggravation of a distortion is also to change of input impedance.
constituting this circuit from a push pull -- a broadband drive stage -- conjointly -- the base in NF loop -- the characteristic is improved.

The direct connection system is adopted as the input unit.
moreover -- if a direct current is omitted with direct-current servo system which is the original of an Accuphase in order to prevent amplifying it and damaging a speaker, when the large preamplifier of direct-current drift etc. is connected -- bothdirect-current drift of the amplifier by a temperature change itself is also stabilized.

The 40kohm balanced input full-scale besides the usual 20kohm phono jack input is carried.

The Subsonic Filter which cuts 10Hz or less is carried.
Sound quality degradation is lost by a good element, and it is set as the frequency which does not affect an audio frequency band.

The guide type meter which can carry out the Direct reading of dB and the output watt is carried. By a logarithm compression type, the Direct reading of the large power range of -60dB-+3dB can be carried out.
Moreover, the switch by which an operation and lighting of meter are turned off is also built in.

By a bridge connection changeover switch, the use as monophonic power amplifier is possible.

Rear Internal
An

Rating of a mode
Form Stereo power amplifier
Continuation average output
(20Hz - 20kHz, 0.02% of distortion)
At the time of stereo specification :
(Both ch(es) operation)
500 W/ch (2ohms)
420 W/ch (4ohms)
250 W/ch (8ohms)
125 W/ch (16ohms)
At the time of monophonic specification :
(Bridge connection)
1000W (4ohms)
840W (8ohms)
500W (16ohms)
THD
At the time of stereo specification :
(Both ch(es) operation)
0.02% (2ohms)
0.01% (4ohm-16ohm)
At the time of monophonic specification :
(Bridge connection)
0.02% (4ohms)
0.01% (8ohm-16ohm)
IM distortion (SMPTE-IF) 0.003%
Frequency response
At the time of a continuation average output : 20Hz-20kHz+0 -0.2dB (level-control maximum)
At the time of 1W output : 0.5Hz-300kHz+0 -3.0dB (level-control maximum)
0.5Hz-100kHz+0 -3.0dB (level-control 6dB)
Gain (profit) 28.0dB (stereo monophonic recording)
Load impedance At the time of stereo specification: 2ohms - 16ohms
At the time of monophonic specification (bridge connection): 4ohms - 16ohms
Dumping factor (50Hz) At the time of stereo specification: 500
At the time of monophonic specification (bridge connection): 250
Input sensitivity (8ohms)
At the time of stereo specification : 1.78V (at the time of a continuation average output)
0.12V (at the time of 1W output)
At the time of monophonic specification :
(Bridge connection)
3.26V (at the time of a continuation average output)
0.12V (at the time of 1W output)
Input impedance 20kohm disequilibrium
40kohm balance
S/N
(A compensation and stereo monophonic recording)
120dB (at the time of input short-circuit and a continuation average output)
100dB (at the time of input 1kohm and 1W output)
Subsonic Filter 10Hz, -18 dB/oct
Power output meter Logarithm compression type
- 60dB - +3dB, and an output Direct-reading scale
The semiconductor used Transistor: 82 pieces
FET: Ten pieces
IC: Eight pieces
Diode: 79 pieces
Power source AC100V/117V/220V/240V, 50Hz/60Hz
Power consumption 115W (at the time of no inputting)
840W (Electrical Appliance and Material Control Law)
850W (at the time of an 8-ohm load Output power)
Dimensions the width 481x height 218(piece -- it includeds) x depth of 445mm
Weight 33.5kg