Sony ST-S555ESX (1986)
A high-end FM/AM tuner from Sony's ES series, released in 1986 with advanced RF and audio circuitry for its time.
Overview
The Sony ST-S555ESX is an FM/AM tuner released in 1986 as part of Sony's ES (Elevated Standard) series, a line aimed at high-fidelity audio performance. It was priced at ¥74,000 at launch. Sony designed it with several proprietary technologies to cut distortion and improve signal clarity. It has a 4-station timer-compatible program memory, a 10-station random preset function, memory scanning, and a "cartone" function for grouping stations.
Specifications
| Practical sensitivity | 0.9 μV/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 470 x Height 86 x Depth 345 mm |
| Side Wood Removal | Width 430 mm |
| Weight | 5.6kg |
Design
The ST-S555ESX follows the design philosophy of the Sony ES series. It uses an SST circuit (Super Sound Tracing Circuit) to reduce front-end distortion. The control voltage of the varactor diode is separated in the local oscillator and the RF tuning section, which keeps tracking error down. WOIS (Wave Optimized IF System) handles selectivity and sound quality. WODD (Wave Optimized Direct Detector) improves the detector, and WODSD (Wave Optimized Digital Stereo Decoder) sits in the MPX section. It uses a direct comparator method with a 100 kHz comparison frequency, low-noise, high-slew-rate (20 V/μs typ.) audio op-amps, and low-distortion switching devices. In the power transformer, the control and signal windings are independent. The transformer is mechanically floated, using materials with different acoustic impedance. An ES filter improves the transformer's frequency characteristics. The ES substrate is unique to this line, with a hole in the top plate near the audio stage so electrostatic capacitance doesn't degrade the signal. There are two antenna input terminals.
Context
The ST-S555ESX is part of Sony's ES (Elevated Standard) series and is one of the first models in Sony's ES tuner lineup.
Similar items on eBay
No exact Sony ST S555ESX listings are live right now — these searches show current Sony and similar vintage audio gear on eBay:
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.
Related Models
- Sony STR 7055 (1972–1976)
- Sony SAT-333ESG
- Sony ST 1950
- Sony st-3950 (1978-1980)
- Sony st-4950
- Kenwood KR 3200 (1973-1975)
- Kenwood KR 3400 (1977-1979)
- Kenwood KR 4070 (1977-1979)
- Kenwood KR 4200 (1975-1977)
- Marantz 1515 (1976-1978)