Sony TC K50 (c. 1978)
A feature-rich cassette deck from Sony’s late-1970s lineup, emphasizing recording precision and automation.
Overview
The Sony TC K50 is a cassette deck introduced around 1978, designed for high-fidelity recording and playback. It features a range of professional-grade functions, including an automatic music sensor (AMS) for track detection, memory stop/play for repeating sections, and a real-time LED peak program meter with fast 1 msec response. The unit supports Dolby NRIC noise reduction, integrating the circuit with other amplifier stages to reduce part count and improve reliability. It uses a 3-stage switching tape selector with independent bias and equalizer settings, allowing optimized performance across tape types.
Specifications
| Heads | Erase: 1, Recording/Playback: 1 (special 3-stage S&F head) |
| Motor | BSL Green Motor |
| Signal-to-noise ratio | 59 dB (Dolby off, Peak Level, Dual Cassette) |
| Frequency response | 30 Hz ~ 18 kHz ± 3 dB (Dual Cassette) |
| Wow and flutter | 0.045% wrms |
| Total harmonic distortion | 1.0% (Dual Cassette) |
| Power consumption | 15W |
| Power | AC 100V 50/60Hz |
| External dimensions | Width 430 x Height 155 x Depth 290 mm |
| Weight | 6.5kg |
| Original price | ¥67,800 (c. 1978) |
Design
The TC K50 uses a special 3-stage solid core structure S&F head that combines Sendust alloy for excellent magnetic saturation linearity with ferrite for superior high-frequency response and low core loss. The BSL Green Motor features a slotless design to eliminate torque unevenness, enhancing speed stability. An integrated IC with built-in electronic switches reduces component count, improving reliability and sound quality. The deck includes a 20-segment dual-color (red/yellow) LED peak program meter with 1 msec attack time and real-time peak hold. It also features a Rec Mute function, MPX filter, separate volume controls for line-out and headphone, and support for an optional timer for unattended recording and alarm playback.
Market
The Sony TC K50 commonly requires maintenance involving belt replacement, with specific kits including three belts and a roller listed for servicing. Units advertised as serviced typically include belt replacement, indicating this as a standard restoration step.
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