Audio Database

The

Marantz PM-4 74,800yen(around the 1980 time)

Description
 
The form of the external heat sink adopted by "#14", "#15", and "MA-5" is adopted, and it is an Integrated Amplifier in which a Class-A / AB class change is possible.

Good dual FET of the pair property was adopted as the input stage of a power amplifier part, and the property failure by an impedance variation is prevented with the source follower stream composition. Moreover, both a Class-A and AB class can be enjoyed by switching the bias current of an output stage.
A super high ft transistor with a cut-off frequency of 90MHz is adopted as a power element, and switching distortion is suppressed to the relative minimum.

By adoption of the external heat sink, it is the design which can always be kept at around 60 degrees C below one-half to the operating temperature of a transistor being usually around about 150 degrees C.

The Low-TIM design which was consistent from the power amplifier part to the control part is carried out.
A nakedness property is improved by original 2 pole phase compensator, the amount of prevention NF is low stopped for an open loop gain to 26dB with 64dB, and the reduction of the TIM in a RF area is aimed at.

The phone amplifier part serves as a low-noise high gain type which MC cartridge can direct connect by original Low-TIM design.
Moreover, the thing of a low-impedance is selected carefully especially for the element which sets up a RIAA curve, and the SN ratio on Hearing impression is raised.

The oxygen-free-high-conductivity-copper line of a tin coating is adopted as output cables, such as a power circuit and a speaker. Furthermore, the twice as many ordinary code of 10A as this is adopted as a power cord.
Moreover, shortening of the product line is attained with devising a construction.

Rear

Rating of a mode
Form Stereo Integrated Amplifier
Output power (20Hz - 20kHz, both channel drive) AB class: 60W+60W (8ohms)
Class-A: 15W+15W (8ohms)
THD (20Hz - 20kHz) 0.015% (at the time of an 8-ohm load intensity and an Output power)
Cross modulation distortion (60Hz:7kHz=4:1) 0.015% (at the time of an 8-ohm load intensity and an Output power)
Frequency characteristic 20Hz-20kHz+0 -0.3 dB
5Hz-100kHz+0 -2 dB
Dumping factor (an 8-ohm load intensity, 1kHz) 70
Input sensitivity/impedance Phono1, 2 man-month:2.5mV /, 47kohm
Phono1 MC: 200 microvolts/100 ohms
Tape, Tuner, AUX:150mV/25kohm
RIAA deflection 20Hz-20kHz±0.25dB
SN ratio (IHF-A) Phono MM:84dB
Phono MC:64dB
Tape, Tuner, AUX: 104dB
Tone control Low-pass: ±10dB (100Hz)
High region: ±10dB (10kHz)
Phono maximum permissible input (1kHz) MM:330mV
MC:25mV
Supply voltage AC100V, 50Hz/60Hz
Power dissipation (Electrical Appliance and Material Control Law) 150W
Dimensions Width 416x height 117.5x depth of 334mm
Weight 9.5kg