Marantz St-4

Commentary

FM/AM tuner equipped with servo lock mechanism.

A servo lock mechanism has been adopted in the local oscillator circuit, and the best tuning point is always detected and strongly controlled. By this mechanism, any drift of tuning point is suppressed, and stable receiving condition is maintained forever. Moreover, the servo lock mechanism is an electronic touch type. It is released while the tuning dial is touched. When the dial is released, the servo lock mechanism operates electronically.

The FM front-end uses a dual-gate MOS-FET with excellent noise removal performance. The IF stage at the heart of the tuner uses a linear phase circuit to improve the group delay characteristics, greatly improving the distortion factor and selectivity. In addition, the MPX stage contains a PLL-IC. We have designed the basic circuit taking full advantage of our experience in the United States, where FM stations are well established.

For tuning, Marantz's unique gyro-touch mechanism is adopted. Oilless metal is used for the bearing part, and the flywheel with large inertial mass is directly driven, making it possible to perform high precision and smooth tuning.

Analog display is used to visually confirm the frequency band, digital display is used to directly read the correct frequency, and 2-way display is used to enable quick and correct tuning.

Uses a unique parametric muting circuit that reliably catches weak radio waves.

Equipped with high-precision and easy-to-see large signal & tuning double continuous meter.

There was a mahogany cabinet sold separately.

Model Rating

Type	FM/AM Tuner
FM Tuner Section
Receiving frequency	76 to 90 MHz
Practical sensitivity of IHF	1.8 μ V (IHF) 10.3 dBf (new IHF)
50 dB quadrature sensitivity	Monaural : 2.5 μ V (IHF), 13.2 dBf (new IHF) Stereo : 36 μ V (IHF), 36.4 dBf (new IHF)
Signal-to-noise ratio	Monaural : 76 dB Stereo : 72 dB
Harmonic distortion factor	0.15% (Monaural, 1 kHz) 0.25% (stereo, 1 kHz)
Frequency characteristic	30 Hz to 15 kHz (+ 0.2 dB, -1.5 dB)
Capture ratio	1.0dB
Effective selectivity	70dB
Image rejection ratio	50dB
Intermediate frequency interference ratio	100dB
AM suppression ratio	55dB
Stereo separation	45dB(1kHz)
<AM Tuner Section>
Receiving frequency	531 to 1602 kHz
Sensitivity	20 μ V
Signal-to-noise ratio	50dB
Harmonic distortion factor	0.7%
<General>
Rated power consumption	10W (Electrical Appliance and Material Control Law)
Pwer	100 VAC, 50/60Hz
External dimensions	Width 416x Height 146x Depth 243 mm Width 474x Height 172x Depth 266 mm (mahogany cabinet dimensions)
Weight	5.3kg
Sold Separately	Mahogany Cabinet WC-74N (¥ 12,000)