Realistic STA 120B (1972–1973)
A solid-state AM/FM stereo receiver with 30 watts per channel into 8 ohms, built for high performance at an accessible price.
Overview
The Realistic STA-120B is a solid-state AM/FM stereo receiver reportedly produced by Radio Shack under its Realistic brand from 1972 to 1973. Its catalog number is 31-2042. Radio Shack sold it as a high-value component with advanced features and strong power output, at a price reportedly $100-$200 below comparable models. It uses modular construction and a carefully engineered signal path. That gives clean audio even with low-efficiency speakers at moderate to medium-loud volumes.
Specifications
| Power Output | approximately 30 Watts rms per channel, 8 ohm loads |
| THD at rated output | Under 1.0% at rated output |
| Frequency Response | 20 to 25,000 Hz ±1 dB |
| Phono Sensitivity | 2 mV (low setting); 5 mV (high setting) |
| Phono Hum | -65 dB |
| Tone Control Range | Bass, ±12 dB @ 100 Hz; mid range, ±6 dB @ 1500 Hz; treble, ±12 dB @ 10 kHz |
| FM IHF Sensitivity | 2 µV |
| FM S/N | 65 dB |
| FM Image Rejection | 75 dB |
| Stereo FM Separation | 35 dB @ 1 kHz |
| AM Sensitivity | 40 µV |
| AM S/N | 50 dB |
| AM Image Rejection | 80 dB |
| Dimensions | approximately 19 3/8 in. W, 5 3/8 in. H, 15 3/8 in. D |
| Shipping Weight | 36 lbs |
Design
The front panel is an aluminum extrusion with an anodized black center and brushed top and bottom strips. The receiver is built from nine basic modules, with two main amplifier boards fixed in slots. The FM front-end is sealed and holds three FETs and one bipolar transistor. The i.f. section reportedly has three high-gain IC stages, a ratio-detector circuit, and four additional NPN devices. Each channel gets a two-transistor preamplifier equalizer. The bass and treble tone controls use a Baxandall feedback arrangement, while the midrange uses a "losser" circuit. The output stages are reportedly push-pull single ended with 1000 µF coupling capacitors, and the drivers are in complementary symmetry, so no interstage transformers are needed.
Context
The STA-120B offered high power, modern styling, and an innovative design at a cost significantly below competing receivers. That made it a good fit for budget-conscious audiophiles in the early 1970s.
Market
The STA-120B was originally priced at approximately $279.95 in 1972. It is reportedly known for failures of the original Hitachi 2SC1061 regulating transistor and the 2SC458 transistor, which can show leakage, noise, or static. Some original electrolytic capacitors on the board are reported to miss the factory tolerance of ±20%, often measuring well above their rated capacitance. Recapping is a common and recommended maintenance step.
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