Sony ST-A5 (1977)
A high-performance FM stereo tuner released in Japan in September 1977, designed to pair with the TA-F5 amplifier.
Overview
The Sony ST-A5 is an FM stereo tuner made in September 1977 for the Japanese market. It was meant to feed the TA-F5 amplifier in Japan and the TA-F5A elsewhere. It sits below the ST-A6B in Sony’s lineup and has nearly identical FM performance at a lower price. It has a 7-gang variable capacitor, a 270mm long dial scale and a large two-meter system for precise tuning. It has no variable audio outputs, no multipath indicator and no 400 Hz test tone generator, which is what separates it from the higher-end models.
Specifications
| FM Practical Sensitivity (IHF) | 1.7 μV |
| Signal-to-noise ratio mono | 79dB |
| Signal-to-noise ratio stereo | 74dB |
| Capture ratio Normal | 1.0dB |
| Capture ratio Narrow | 1.2dB |
| Selectivity (IHF) Normal | 35dB |
| Selectivity (IHF) Narrow | 80dB |
| Image interference ratio | 120dB |
| IF interference ratio | 120dB |
| Spurious interference ratio | 120dB |
| Distortion Factor (400 Hz, stereo) Normal | 0.1% |
| Distortion Factor (400 Hz, stereo) Narrow | 0.3% |
| Stereo separation (1kHz) Normal | 50dB |
| Stereo separation (1kHz) Narrow | 40dB |
| Power consumption | 18W |
| External dimensions | Width 410 x Height 145 x Depth 305 mm |
| Weight | 5.9kg |
Design
The tuning circuit is double-tune and quad-tune, with a 7-series varicon and a CG varicon in the FM front-end for high indication accuracy. The mixer uses a dual-gate MOS FET with remote cutoff characteristics to reduce intermodulation and improve interference rejection. A uniphase filter in the IF section gives high selectivity and a high distortion factor, and Normal/Narrow bandwidth switching is available. Multiplex stereo demodulation is done by a PLL IC (HA1196). The FM IF system uses the LA1230 IC. A reed relay handles muting to eliminate pop noise. A high-blend circuit reduces noise on weak stereo signals without sacrificing stereo imaging. Antenna input is an F-type connector for 75 Ω coaxial cable.
Context
The ST-A5 sat below the ST-A6B, which cost ¥10,000 more at ¥49,800. The flagship ST-A7B reached ¥158,000. The AM/FM ST-A4 was the model directly below the ST-A5 in Sony’s tuner lineup. The optional rack handle AH-4A cost ¥2,500. Internally, the ST-A5 shares a lot of circuitry and many components with other models, differing mainly in the HF and audio output stages.
eBay Listings
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)