Audio Database


Pioneer M-77
180,000yen(around the 1980 time)

Stereo power amplifier which obtained the dynamic range excellent in generous power.

Aiming at the high power amplifier reproducing the outstanding musicality, sufficient study is performed for the determine of circuitry from double-sideds of an audition and a measurement.

The first rank cascade connection differential amplification, the final-stage triple push pull, and the pure complimentary OCL circuitry are used for a circuitry.
While raising direct-current stability by making the first rank into the differential amplifier by which the cascade was carried out, the modification of the property of a high region is aimed at.
It is the push-pull circuit which adopted the current mirror circuitry, a direct-current balance is raised by the current mirror circuitry, and the pre-driver stage (Class-A driver stage) is a push-pull circuit in alternating current,A role, such as stopping high gain and the eventh higher-harmonic distorted component, is played.
The driver stage and an output stage are two-step darlington circuits, and the power transistor has triple push pull composition by which three-piece parallel connection was carried out. The electric current which flows into each transistor by making an output stage into a triple push pull dropped to 1/3, and since it can choose the operating point with a sufficient linearity, it has taken out the Oide power by the low distortion.

By constituting from an element selected carefully, it dresses up at the time of a minute output, and consideration is carried out also to warmth.

In the power-source part, internal resistance has adopted as a transformer the stream composition which uses 15,000 micro Fx4 for the low good large-sized toroidal transformer of a regulation, and a capacitor.

The peek power meter is carried.


Rating of a mode
Form Stereo power amplifier
Circuit system First rank cascade connection differential-amplification triple push pull
Pure complimentary OCL circuitry
Effective output
(Both channel drive, 20Hz - 20kHz)
250W+250W (4ohm)
250W+250W (8ohm)
THD (20Hz - 20kHz) At the time of an effective output: 0.1%
At the time of 125W output (8ohm): 0.05%
At the time of 1W output (8ohm): 0.05%
Cross modulation distortion
(50Hz : 7kHz = 4:1 or 8ohm)
At the time of an effective output: 0.1%
At the time of 125W output: 0.05%
At the time of 1W output: 0.05%
Output bandwidth (IHF, both channel drive) 5Hz - 30kHz (0.1% of distortion)
Frequency characteristic 5Hz-80kHz+0 -1 dB
Input terminal Input: 2V/50kohm
Output-terminal Speaker: 4 ohm, 8ohm
Dumping factor 50 (20Hz - 20kHz, 8ohm)
SN ratio 110dB (IHF, A network, a short circuit)
The semiconductor used Transistor: 55 pieces
Diode, other:81 piece
Supply voltage 100V, 50Hz/60Hz
Power consumption
(Electrical Appliance and Material Control Law)
Maximum electric power consumption 1200W
Dimensions Width 480x height 186.5x depth of 445mm
Weight 24.3kg
EIA specification rack mounting unit 4U