Audio Database


Pioneer M-73
75,000yen(around the 1980 time)

Stereo power amplifier which adopted 2 power transformers.

The 2 steps of ±2 powering and differentials amplification current mirror circuitry and the final-stage parallel push pull pure complementary circuit are adopted as a circuit system.

A power-source part is adoption of 2 power transformers which improve a dynamic behavior, and has eliminated the cross interferencee between channels.
Moreover, with a stream composition with the capacitor of 12,000 micro Fx4, even if there is a low-pass continuous sound of a large swing, it reproduces with a margin.

The large-sized peek power meter with a logarithmic comression circuitry which can carry out the Direct reading of the output is equipped.

The protection network constituted from a quick electronic circuitry of a reliable power relay and a response is adopted, and a speaker and a transistor are protected from an emergency outage.

Two speaker output-terminals are carried and a play of A+B is also possible.

It is the panel design which can be mounted on EIA specification rack.

Rating of a mode
Form Stereo power amplifier
Circuit system 2 steps of differentials whole page hardwired-connection parallel PP pure complimentary
OCL circuitry
Effective output (both channel drive, 20Hz - 20kHz) 85W+85W (8ohm)
(at the time of 20Hz - 20kHz, and an effective output)
Cross modulation distortion (50Hz:7kHz=4:1) 0.05%
Output bandwidth (IHF, both channel drive, 8ohm) 5Hz - 45kHz (distortion 0.05%)
Frequency characteristic (at the time of 1W output) 5Hz-100kHz+0 -1 dB
Input terminal Input: 1V/50kohm
Output-terminal A-B: 4ohm-16ohm
A+B: 8ohm-16ohm
Headphone: 4ohm - 16ohm
Dumping factor (20Hz - 20kHz, 8ohm) 30
SN ratio (IHF, A network, a short circuit) 115dB
Supply voltage AC100V, 50Hz/60Hz
Power consumption
(Electrical Appliance and Material Control Law)
Maximum electric power consumption 650W
Dimensions Width 480x height 142x depth of 390mm
Weight 15.2kg
EIA specification rack mounting unit 3U