Audio Database


Pioneer M-75
135,000yen(around the 1980 time)

Stereo power amplifier which aimed at obtaining generous high power after aiming at a distorted reduction.

The first rank differential current mirror load-intensity, three-step Darlington, parallel push pull, and pure complimentary OCl circuitry is adopted as a circuitry.
Furthermore, the flat phase response has been obtained from the NFB circuitry over the wide band by having DC amplifier stream composition which removed the capacitor.

In order to eliminate the cross interferencee between right-and-left channels, it is the design which separated the circuitry of the right-and-left channel structurally. Moreover, the power-source part by large-sized L/R independent 2 power transformer and the mass capacitor of 22,000 micro Fx4 is carried in the power-source part, and sufficient consideration also for leading about of an internal wiring is carried out.

In 20mm and thickness, width is using a 2mm pure-copper board for the grounding product line from a capacitor. Moreover, a resistance value adopts as the hot side the 14th track (2.03phi Yori line) of the very thick set to one fourth of the conventional thick lines. The Copper foil of a substrate also achieves low-impedance-ization, such as doubling with 70micro, and is raising banishment of an electrical-power loss, and the response to a steep pulse.

The power meter which can carry out the Direct reading of the musical peaking capacity in a watt is adopted.
It is displayed to 0.01W-300W (8ohm), and since it is with a logarithmic comression circuitry, the Direct reading of the output can be carried out without a change.

The input level controller of L/R independent a step of 1dB and the speaker circuit changing switch which can perform the change of Off, A, B, and A+B are carried.


Rating of a mode
Form Stereo power amplifier
Circuit system 3 steps of first rank differential current mirror load-intensities Darlington parallel push pull
Pure complimentary OCL circuitry (DC amplifier stream composition)
Effective output
(Both channel drive, 20Hz - 20kHz)
180W+180W (4ohm)
150W+150W (8ohm)
(20Hz - 20kHz, 8ohm)
At the time of an effective output: 0.01%
At the time of 75W output: 0.01%
At the time of 1W output: 0.01%
Cross modulation distortion
(50Hz : 7kHz = 4:1 or 8ohm)
At the time of an effective output: 0.01%
At the time of 75W output: 0.005%
At the time of 1W output: 0.005%
Output bandwidth (IHF, both channel drive) 5Hz - 35kHz (0.01% of distortion)
5Hz - 60kHz (0.05% of distortion)
Frequency characteristic 5Hz-100kHz+0 -1dB (at the time of 1W output)
Input terminal Input: 1V/50kohm
Output-terminal A-B: 4ohm-16ohm
A+B: 8ohm-16ohm
Dumping factor 100 (20Hz - 20kHz, 8ohm)
SN ratio 115dB (IHF, A network, a short circuit)
The semiconductor used IC: Two pieces
Transistor: 61 pieces
Diode, other:65 piece
Supply voltage 100V, 50Hz/60Hz
Power consumption
(Electrical Appliance and Material Control Law)
Maximum electric power consumption 900W
AC outlet Un-interlocking.: One line
Dimensions Width 480x height 187x depth of 445mm
Weight 24.5kg
EIA specification rack mounting unit 4U