SONY ST-S555ESX
¥ 74,000 (released in 1986)
Commentary
FM/AM tuners incorporating the design philosophy of the Sony ES Series.
It is equipped with an SST circuit (Super Sound Tracing Circuit) that reduces distortion at the front end.
The front-end bandpass filter of a quartz-lock synthesizer tuner consists of a coil and a variable voltage element (varactor diode). In the SST, the control voltage of the varactor diode is corrected to optimize the filter characteristics for FM modulated waves.
In addition, the conventional front-end has a problem that the largest tracking error occurs near the center of the reception frequency band. This was caused by the fact that the control voltage of the varactor diode of the local oscillator of the front-end and the varactor diode of the RF tuning section were made to be the same. However, the ST-S555ES separates this and adds an appropriate value to the control voltage of the RF tuning section to divide the reception frequency band into eight and reduce the tracking error.
Note that the SST circuit does not operate unless the IF band is wide and the signal input level is sufficient, because the distortion factor becomes poor when the IF band is narrow, and there is a mode that increases noise. The indicator to the left of the central display lights during operation.
It is equipped with WOIS (Wave Optimized IF System) which optimizes IF waveform and combines high selectivity with high sound quality.
WOIS optimizes the group delay characteristics of the IF filter for monaural operation and the amplitude characteristics of the IF filter for stereo operation so that the distortion generated at the IF stage can be greatly reduced while maintaining high selectivity.
Equipped with WODD (Wave Optimized Direct Detector) to improve the performance of the detector stage.
The PLL system consists of a phase comparator, a low-pass filter, and a VCO (Voltage Controlled Oscillator). The IF signal is directly detected by operating the VCO at around 10.7 MHz. However, with the conventional PLL detector, it was difficult to obtain a linear characteristic of the controlled voltage versus oscillation frequency characteristics of the varactor diode used in the VCO.
The WODD optimizes the nonlinearity of the VCO by taking advantage of the fact that the feedback capacitance of the FET which is the oscillation element in the VCO circuit varies with the operating frequency.
The MPX section is equipped with WODSD (Wave Optimized Digital Stereo Decorder).
In the ST-S555ESX Server, the WODSD consists of high-speed ICs. The pilot signal in the composite signal is once generated at 152 kHz by PLL, and is used to output 6-phase signals of 0 ° / 45 ° / 135 ° / 180 ° / 225 ° / 315 ° at 38 kHz, thereby generating extremely low-distortion switching signals.
This WODSD completely eliminates the LC filter from the signal system and greatly improves the interference characteristics. The ST-S555ESX also uses low-noise, high-slew rate (20 v μ s typ.) audio OP amp and low-distortion switching device for high sound quality.
Using a direct comparator method, beat and noise are reduced by raising the comparison frequency to 100 kHz, which is the same as the channel plan.
Equipped with two antenna input terminals that can connect and switch two antennas for the target broadcasting station.
It also has a multi-pass indicator that helps you set the best antenna direction.
The control and signal windings of the power transformer are made independent to improve sound quality. In addition, the transformer and chassis are mechanically floated using materials with different specific acoustic impedance in order to prevent the small vibration of the power transformer from being transmitted to the chassis.
In addition, an ES filter is used to improve the frequency characteristics of the transformer winding itself.
In order to minimize the adverse effect of magnetism on sound quality, we have adopted a top plate with a hole in the vicinity of the audio stage and a unique ES substrate that prevents deterioration of sound quality due to increased electrostatic capacitance between patterns caused by resist.
Equipped with 4-station timer compatible program memory function.
It also has a 10-station random preset function.
It is equipped with memory scanning function and cartone function.
Model Rating
| Type | FM/AM Tuner |
| Practical sensitivity | 0.9 μ V/10.3 dBf |
| Harmonic distortion factor (1 kHz, wide) | mono:0.005% stereo:0.008% |
| Effective selectivity | wide:65dB(400kHz) narrow:65dB(300kHz) |
| Frequency response (1 kHz, stereo) | 15 Hz to 15 kHz + 0. 2-0. 5 dB |
| Spurious interference ratio | 120 dB or more |
| Signal-to-noise ratio | mono:99dB stereo:92dB |
| Separation (1 kHz) | wide:70dB |
| Power consumption | 21W |
| External dimensions | Width 470x Height 86x Depth 345 mm Side Wood Removal : Width 430 mm |
| Weight | 5.6kg |
| Attachment | AM loop antenna FM feeder antenna Antenna connector Connection code |