Sony ST-3950 tuner

Sony FM Stereo / FM-AM Tuner

The ST-3950 is Sony's answer to the audiophile's need for ultra-high tuner performance, without a correspondingly high price tag. The new tuner, which includes a Dolby noise reduction system, is built to satisfy demanding listening standards, while also providing the convenience of top-notch tuning and control facilities.

 

Features:

MOS FET RF amplifier

RF front-end electronics untilized into 4-gang tuning capacitor assembly

Buffered local oscillator for high spurious and AM suppression

Two 4-element uni-phase IF filters, plus 5 stages of limiting IF differential amplifier and quadrature detector

Phase-Locked-Loop IC stereo MPX stage

Direct coupled audio output amplifier with separate power supply

Dolby noise reduction system for decoding Dolbyized FM broadcasts, and Dolby indicator light.

Center station and signal strength/multipath meters

Dial pointer with LED station indicator, plus smooth flywheel tuning action

Frequency linear calibration for both FM and AM dial scales

FM interstation muting with FET circuit

FM discriminator output for future 4-channel FM

High Blend Switch

Variable output level control to match tuner with other program sources, and 2 pairs of audio output terminals

Automatic mono/stereo switching, and stereo indicator light

Wooden side panels included

 

FM Section

FM circuitry incorporates the same type of advanced electronics which are used in Sony's most expensive tuner. To start, the front-end is unitized into the 4-gang tuning capacitor assembly - a Sony construction that assures ultra-high stability, almost permanent alignment and an extra-high degree of accuracy in dial calibration. Nextt, the MOS FET RF amplifier assures high sensitivity and interference rejection. The local oscillator is equipped with a buffer amp, for good spurious response rejection and AM noise suppression, plus high stability with strong input signals. IF design features two 4-element uni-phase IF filters. These new devices provide for good selectivity while at the same time maintain a wide band-pass characteristic, with high phase linearity. This means there's no trade-off between excellent selectivity and low audio distortion.

Additionally, the IF section includes a stage of differential amplification, 5 stages of limiting and a quadrature detector - for excellent caapture and Signal-to-Noise ratios and high AM suppression.

For FM stereo decoding, there's a Phase -Locked-Loop IC, a circuit element which accounts for the unit's superior stereo performance - wide separation across a wide range, and low distortion. A direct coupled audio amplifier stage, with an independent, stabilized power supply circuit, completes the final stage design, assuring low distortion and wide dynamic range.

For listening to the growing number of fine music programs broadcast with Dolby encoding, the ST-3950 features a built-in system that simplifies the decoding process to one step, one touch. This eliminates the need for an outboard noise reduction unit, along with the complication of altered FM de-emphasis.

 

AM Section

Because Sony designed the AM section with only-top-quality elements - like a balanced AM mixer circuit - the ST-3950's AM performance is exceptionally good. Listening to AM only broadcasts over the ST-3950 will not offend sound connoisseurs, since the AM ssound approaches hi-fi level.

 

Tuning

Precision and luxury combine to make tuning the ST-3950 a smooth, comfortable process. The unit's highly readable tuning meters provide for pinpoint accuracy - even in crowded urban dial areas where the multipath reading can provide additional aid.

The wide, frequency linear dial scale and LED equipped dial pointer also provide for high readability. And the large flywheel-coupled knob provides an added touch ofluxury with ultra-smooth action

 

Specifications

FM Tuner Section

Antenna Terminals:  300 Ω (balanced), 75 Ω (unbalanced) F-coaxial connector

Usable Sensitivity (IHF '58):  1,7 µV

50 dB Quieting Sensitivity: 

Mono :  3,0 µV

Stereo :  40 µV

Signal-to-Noise Ratio: 

Mono :  75 dB

Stereo :  70 dB

Capture Ratio:  1,0 dB

Selectivity:  50 dB

Image Rejection:  80 dB

IF Rejection:  100 dB

Spurious rejection:  90 dB

AM Suppression:  56 dB

Total Harmonic Distortion:

At 100 Hz

Mono :  0,15%

Stereo :  0,25%

At 1 kHz

Mono :  0,15%

Stereo :  0,25%

At 10 kHz

Mono :  0,2%

Stereo:  0,6%

IMDistortion: 

Mono :  0,15%

Stereo : 0,3%

Frequency Response:  30 Hz - 15,000 Hz  +0,3 -1,5 dB

Stereo Separation

At 100 Hz -  35 dB

At 1 kHz - 40 dB

At 10 kHz - 35 dB

RF Intermodulation:  65 dB

Subcarrier product Ratio:   60 dB

SCA Suppression:  60 dB

AM Tuner Section

Antenna:  Built-in ferrite bar antenna w/terminal for ext.wire

Sensitivity: 

250 µV/m (w/built-in antenna)

100 µV (w/ext. Antenna)

Selectity:  35 dB at 50 mV/m

Signal-to-Noise Ratio:  50 dB at 50 mV/m

Image Rejection:  40 dB at 1,000 Hz

Total Harmonic Distortion: 0,5% at 50 mV/m, 400 Hz

General Section

Output Level/Impedance 9at 100% modulation)

Fixed : 750 mV / 10 k Ω

Variable : 1,5 V / 1,5 k Ω at max

Discriminator :  150 mV/2,5 k Ω

Semiconductors:  4 ICs , 5 FET, 34 Transistors, 15 Diodes, 1 LED

Power Requirements:  AC 120 V, 220 -240 V, 50/60 Hz

Dimensions (W x H x D):  460 x 170 x 335 mm

Weight:  8 kg (17 lb 10 oz)