Realistic STA 120B (1972–1973)
A solid-state AM/FM stereo receiver offering 30 watts per channel into 8 ohms, designed 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. With a catalog number of 31-2042, it was marketed as a high-value component delivering advanced features and strong power output at a price point reportedly $100–$200 below comparable models. Designed for both performance and reliability, it uses modular construction and a carefully engineered signal path to deliver 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 uses nine basic modules in its construction, with two main amplifier boards fixed in slots. It features a sealed FM front-end containing three FETs and one bipolar transistor, while the i.f. section reportedly includes three high-gain IC stages, a ratio-detector circuit, and four additional NPN devices. Each channel uses a two-transistor preamplifier equalizer, and tone controls are implemented with a Baxandall feedback arrangement for bass and treble, while the midrange uses a "losser" circuit. The output stages are reportedly push-pull single ended with 1000 µF coupling capacitors, and drivers are in complementary symmetry, eliminating the need for interstage transformers.
Context
The STA-120B combined high power, modern styling, and innovative design at a cost significantly below competing receivers, positioning it as a compelling option for budget-conscious audiophiles during the early 1970s.
Market
Originally priced at approximately $279.95 in 1972, the STA-120B is reportedly known to suffer from failures in the original Hitachi 2SC1061 regulating transistor and the 2SC458 transistor, which can exhibit leakage, noise, or static. Some original electrolytic capacitors on the board are reported to fail to meet the factory tolerance of ±20%, often measuring well above their rated capacitance, making recapping a common and recommended maintenance step.
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