Sony ST-3950 (1976–1979)
At 6.7kg, it sits in your rack with clean reception, quiet backgrounds, and a dial that glows.
Overview
The Sony ST-3950 is a vintage analog FM/AM stereo tuner, produced from 1976 to 1979. Sony marketed it as "Sony's answer to the audiophile's need for ultra-high tuner performance." It was built to give precise, stable reception with minimal distortion, which was not easy when FM stereo was still maturing. It was designed to pair with amplifiers like the TA-3650, though it stands on its own with serious RF engineering inside. The front panel is laid out for function: a large tuning dial, multi-pass indicator, muting switch, and volume control. Owners report an illuminated power switch, a small touch that fits its premium positioning.
The ST-3950 stays practical. It uses a Euro-type power input connector instead of a fixed power cord, so the cable is easy to replace or upgrade. The metal case houses MOS FET and CG varicon components, aimed at high sensitivity and resistance to strong input distortion. Two 4-element uniphase filters improve both selectivity and harmonic distortion. This tuner was built for people chasing the cleanest signal, the quietest noise floor, and the most accurate stereo separation available at the time.
Specifications
| Manufacturer | Sony Corporation |
| Type | FM/AM Tuner |
| FM Practical Sensitivity (IHF) | 1.7 μV |
| FM Signal-to-noise ratio | 75dB (Mono), 70dB (Stereo) |
| FM Capture ratio | 1.0dB |
| FM Selectivity (400 Hz) | 80dB |
| FM Image interference ratio | 85dB |
| FM IF interference ratio | 100dB |
| FM Spurious interference ratio | 100dB |
| FM Distortion (THD) | Mono: 0.15%, Stereo: 0.25% |
| FM Stereo separation | 100Hz:35dB 1kHz:40dB 10kHz:35dB |
| FM AM Suppression | 50dB |
| FM Output Level | 650mV (100% mod.) |
| FM Output Impedance | 1.2kΩ |
| AM Sensitivity (with bar antenna) | 250 μV/m |
| AM Signal-to-noise ratio | 50dB |
| Frequency Response | 20Hz–20kHz (±0.5dB) |
| Power consumption | 23W |
| External dimensions | 430 (W) x 168 (H) x 335 (D) mm |
| Weight | 6.7kg |
| Outputs | FIXED: 750 mV, 10 kΩ; VARIABLE: 0-1.5 V, 1.5 kΩ; FM DISCRI: 150 mV, 2.5 kΩ |
| Made in | Japan |
Key Features
MOS FET and CG Varicon Front-End Design
The MOS FET and CG varicon in the input stage were chosen to balance high sensitivity with resistance to overload from strong signals. That combination helped prevent intermodulation distortion, a common problem when multiple stations or nearby transmitters interfere. It makes the ST-3950 particularly stable in urban environments. The design reflects Sony's focus on real-world performance, not just lab-sheet specs.
Two 4-Element Uniphase Filters
The filters are central to the tuner's clean stereo separation and low distortion. They refine the intermediate frequency (IF) response, which improves both selectivity and stereo decoding accuracy. The result is a more defined soundstage and reduced crosstalk, especially at 1kHz where separation hits 40dB.
Front-Mounted Output Volume and Muting Panel
Many tuners put level control on the rear. The ST-3950 puts the output volume knob on the front panel, alongside the muting switch and multi-pass indicator. That makes it easy to adjust signal strength before it hits the amplifier, which helps with overmodulated stations or mismatched input sensitivities. This layout is rare in tuners of this class.
Illuminated Power Switch
A small but memorable detail: the power switch glows when engaged. Multiple owner reports confirm this feature, which adds a touch of elegance to the darkened equipment rack. It’s not just cosmetic—the illumination provides instant status feedback, a subtle cue that the tuner is live and ready.
Euro-Type Power Input Connector
Instead of a hardwired power cord, the ST-3950 uses a detachable IEC C14 (Europlug) inlet. This was not standard on all consumer gear at the time, and its inclusion suggests Sony anticipated serviceability and cable upgrades. It also simplifies international use, since only the cord needs changing for different voltages, though the internal power supply requirements are not documented.
Collectibility & Value
Current market examples show the Sony ST-3950 selling for around $200 USD when tested and working, such as at The Turntable Store. Untested units have sold for as little as $50, so condition and function heavily influence value. A repair kit listing on eBay offering "all capacitors" for the ST-3950 suggests that aging electrolytics are a known maintenance concern. Collectors also note that ceramic filters, which are critical to IF performance, can fail over time and affect selectivity and stereo decoding. No widespread reliability trends are documented, but these components are likely failure points after decades of dormancy.
Market Value
┌──────────────────────────────────────────────────────────────────────────┐ │ SONY ST-3950 Nov 2026 │ ├──────────────────────────────────────────────────────────────────────────┤ │ High $1,243 Latest $418 │ │ Median $307 Trend — │ │ Low $175 Volume ~1/mo │ ├──────────────────────────────────────────────────────────────────────────┤ │ $2,000 ┤ │ │ │ │ │ │ │ │ $1,186 ┤ . │ │ │ │ │ │ │ │ │ .│ │ $100 ┤. . │ │ ├─────────────────────────────────────────────────────────────────│ │ vol │█ █ █ █│ │ └─────────────────────────────────────────────────────────────────│ │ 2026-04 2026-06 2026-07│ └──────────────────────────────────────────────────────────────────────────┘
eBay completed sales. Excludes accessories, parts, and non-working units. Hover points for details.
eBay Listings
Recently sold on eBay: $175–$1,243 (median $307, based on 4 completed sales, past 12 months)
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