What is stereo?




There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.




H.H. Scott '59





Marantz Esotec PM-4 (1980)

The Integrated Amplifier which can switch a pure Class-A and AB class.

In addition to pure Class-A 15 W/ch, the change of AB class 60 W/ch is attained. And in order to raise the quality of AB class even to the level of a pure Class-A, the high speed high fT transistor which took high high region cut-off frequency with 90MHz is adopted as the power stage. Switching distortion which is a fault of AB class is banished to a limit.

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 90 MHz is adopted as a power element, and switching distortion is suppressed to the relative minimum.

Marantz PM-4 Esotec Series, Integrated Amplifier

Class: A-B Sine Power:

Class A: 15 W + 15 W (8Ω),

Class A-B: 60 W + 60 W (8Ω)

THD: 0,015% (20Hz - 20kHz at the time of an 8Ω load intensity and an Output power)

Cross modulation distortion (60Hz:7kHz=4:1): 0.015% (at the time of an 8Ω load intensity and an Output power)

Dumping factor (an 8Ω load intensity, 1kHz): 70

Transmission range: 5 - 100,000 Hz +0 -2 dB

Frequency response: 20 - 20,000 Hz -0, 3 dB

Distortion: 0.015%

Tone control:

Bass: ±10dB (100Hz)

Treble: ±10dB (10kHz)

Input sensitivity/impedance:

Phono 1, 2 MM: 2.5 mV/47 kΩ

Phono 2 MC: 2 00 mV/100Ω

AUX, tuners, tape 1, 2: 150 mV 25 kΩ

RIAA phono: 20 - 20,000 Hz, ±0.25 dB

Signal-to-Noise ratio:

Phono MM: 84 dB

Phono MC: 64 dB

AUX, tuners, tape: 104 dB

Phono max. Input: 330mV (MM); 25 mV (MC) at 1kHz

Inputs: 2 x phono, switchable phono 1: MM + MC, Phono 2: MM, 2 x tape

Outputs: 2 x speaker, headphones

Voltage: 110/120/220 V AC, 60/60 Hz

Power consumption: 150 watts

Dimensions (W x H x D): 416 x 117 x 334 mm

Weight: 9.5 kg

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