SONY ST-S333ESX
¥ 49,800 (around 1986)
Commentary
An FM/AM tuner incorporating Wave Optimaizer Technology (waveform optimizing technology) into each stage of the circuit.
An SST circuit (Super Sound Tracing Circuit) is used for the front end.
First, the band pass filter is synchronized with the FM broadcast signal, and when the frequency changes, the control voltage is changed so that the center of the band pass filter also has the same frequency.
This flattens the filter characteristics in the band and completely eliminates the front-end distortion.
In order to reduce the tracking error, the varactor diode of the local oscillator and the varactor diode of the RF tuning section are separated. By adding a correction voltage to the control voltage of the RF tuning section, the receiving frequency is divided into four and the tracking error is reduced to 1/4 of the conventional one.
The SST circuit operates only when the IF band is wide and the signal input is 35 dBf or higher because the distortion factor becomes worse when the IF band is narrow band is narrow, and there is a mode that increases noise.
WOIS (Wave Optimized IF System) is adopted for the IF stage.
In the IF filter, WOIS optimizes the group delay characteristics for monaural and the amplitude characteristics for stereo to ideal waveforms. As a result, we have succeeded in greatly reducing distortion while maintaining high selectivity.
In addition, an IF band switching circuit is also installed to cope with severe reception conditions that cause interference even with WOIS.
WODD (Wave Optimized Direct Detector) is adopted for the detection stage.
This method utilizes the fact that the feedback capacitance of the FET, which is an oscillating element in the VCO (Voltage Controlled Oscillator) circuit, varies with the operating frequency to optimize the nonlinearity of the VCO, and an ideal straight line can be obtained depending on the characteristics of the FET.
In the MPX stage, a new PLL MPX IC (CXA-1064) with more than 500 elements has been developed and is equipped with a Wave Optimized Digital Stereo Decoder (WODSD).
In this system, L and R demodulation signals obtained by 38 kHz switching are switched by a blend switch with signals obtained by balanced multiplication of 38 kHz and 114 kHz, and finally the switching signal itself is made close to a sine wave without harmonics. Even if the composite signal has distortion components, the switching signal has few harmonics components, so that the distortion is not demodulated into the audible frequency band.
As a result, a beat-cut filter is no longer needed, and the phase and amplitude of the composite signal are transmitted as they are, further eliminating interference while maintaining high-purity sound quality.
It uses a direct converter method, and by raising the comparison frequency to 100 kHz, which is the same as the channel plan, beats and noise that pollute the sound are greatly reduced.
To prevent the small vibration of the power transformer from being transmitted to the chassis, the transformer and the chassis are mechanically floated using materials with different specific acoustic impedance.
In addition, the ES filter that improves the frequency characteristics of the transformer winding itself, and an electrolytic capacitor that is four times larger than the conventional one is used as the power supply for the signal system, thus realizing a comfortable power supply circuit with less noise.
The LC filter is completely removed from the detection stage to the outlet of the tuner, eliminating distortion and other causes of sound quality degradation.
An active filter is used for the MPX filter of the final stage, and holes are made in the top plate of the printed circuit board after the detection stage to prevent the influence of magnetism on sound quality.
The an integrated chassis, rigidity is strengthened, and together with legs which are about 6 times larger than conventional ones, vibration is protected firmly.
In addition to the frequency of the target broadcasting station, it is equipped with various functions such as an FM/AM random preset function using multi-process memory that simultaneously stores reception conditions such as muting ON/OFF, FM auto / stereo / mono, and FM IF BAND position, two tuning mechanisms of auto / manual, and a 4-station program memory with timer support that allows recording of absence across 4 stations.
It is equipped with an FM IF band switching function that can always obtain high quality even under different reception conditions when receiving FM signals.
The AM section is equipped with a 4-element ladder filter.
Equipped with F-type connector for 75 Ω coaxial antenna.
Model Rating
| Type | Quartz Lock FM/AM Digital Synthesizer Tuner |
| Practical sensitivity | 0.9 μ V (New IHF) 10.3dBf(IHF) |
| Harmonic distortion factor (1 kHz, WIDE) |
mono:0.005% stereo:0.0095% |
| Effective selectivity | 65 dB (400 kHz, WIDE) 60 dB (300 kHz, NARROW) |
| Frequency characteristic | 30 Hz to 15 kHz, + 0. 2-0. 5 dB (1 kHz, stereo) |
| Spurious interference ratio | 120 dB or more |
| Signal-to-noise ratio | mono:98dB stereo:91dB |
| Separation | 65 dB (1 kHz, WIDE) |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 16W |
| External dimensions | Width 470x Height 86x Depth 335 mm |
| Weight | 5.2kg |
| Attachment | AM loop antenna FM feeder antenna Antenna connector Connection code |