The Realistic STA-850 receiver debuted in 1982 at a retail price of $379.95 and was their mid-range offering at the time. It produces 50 watts per channel and has clean, sleek styling. The STA-850 was a transitional receiver, bridging between the older analog, all silver face, large knob stereos and the future push button, LED, digital stereos. For a vintage enthusiast it has a great look and, as you can see, is sharp when it’s cleaned up.
Realistic was a Radio Shack brand and the STA-850 was manufactured in Korea and sold in Radio shack stores in the US. Radio Shack itself was a division of Tandy at the time.
Front Panel
The STA-850 has limited features so the front panel is not crowded. The dial face extends across the entire front and a row of red and green LED indicators run below it. The signal strength and power meters are both LED. Below is a row of push button controls for FM Mute, Auto-M, Hi-Filter, Mono, Tape Mon, and Loudness. Auto-M stands for Auto-Magic.
Tone controls are minimal with just bass and treble with no mid range control. A headphone jack is at the lower ight corner of the front panel.
FM Tuner
The FM front end section of the STA-850 employs Field Effect Transistor circuitry. This enhances the tuner’s ability to pick up weak signals with minimal background noise. It also provides excellent protection against signal distortion caused by electrical interference, especially at high frequencies and when dealing with very weak signals.
The AM/FM IF section is designed around a Linear Integrated Circuit (IC). This ensures that the circuit produces minimal noise and distortion while maintaining a high level of sensitivity, making it particularly effective in processing radio signals.
For FM reception, the multiplex section utilizes a Phase Lock Loop IC. This guarantees stable stereo separation, even when the device experiences temperature variations. A muting feature is also incorporated into the STA-850 to eliminate the annoying hissing sound between stations when listening to FM radio.
Amplifier
The Realistic STA-850 produces 50 watts of solid power and will drive most any speaker system. It can even handle two sets of speakers. Total harmonic distortion is rated at 0.05%.
The Amplifier is a complementary Output Capacitor-less (OCL) circuit configuration. This design provides good amplification, particularly in the lower bass frequencies.
The STA-850 is equipped with specialized noise-canceling circuitry, effectively eliminating disruptive switching noise. This feature contributes to a cleaner listening experience.
The Tone amplifier incorporates operational amplifier ICs (OP-AMP ICs). These allow for high amplification, minimal distortion, and an expansive dynamic range.
To safeguard the amplifier and speakers, there are dual overload protection circuits in place. These circuits automatically activate in response to thermal issues or problems with the speakers, such as short circuits.
Specifications
The dimensions of the Realistic STA-850 are 18-7/8 x 6-7/16 x 11-3/8 inches. Here are its specifications:
Realistic recommended their Optimus and Nova brand of speakers for the STA-850 and Minimus speaker series if you were on a budget.
Auto-Magic Tuning
One of the heavily advertised features of the STA-850 was the Auto-Magic tuning. Realistic described it like this:
The Auto-Magic circuitry in your Receiver automatically “locks on” and fine-tunes FM signals. Try it for yourself – tune an FM station so that one of the red LEDs on the FM Tuning Indicator is lit. Now let go of the Tuning Knob. In a few seconds, you’ll see the green LED on the FM Tuning Indicator light … thanks to Auto-Magic!
Auto Magic is really a Phase Lock Loop auto tune circuit. When you tune a station and let go of the tuning knob the circuit will automatically tune to the center of the nearest frequency and lock it. When you touch the tuning knob again it will release the lock and you can tune another station. The Auto-Magic feature can be turned on and off via a push button on the front panel. You may want to turn it off when trying to tune a weak station next to a stronger station and don’t mind some level of interference.
Reviews
I ran it thru a pair of Realistic Mach Two speakers. Wow what a sound. Playing any classic rock sounded too good. One really good receiver.
Incredible FM reception. Great match for the Nova speakers.
50 WPC. Sounds really good, cranks hard, looks good.
Inside the STA-850 is clean and well organized. Check out the four filter caps per channel instead of the usual one. The transformer is fairly large sized for a mid range receiver.
Back Panel
The back panel on the STA-850 has connections for a tape deck, Aux, and turntable. There are terminals for two sets of speakers as well as an extendible AM ferrite antenna. The one AC outlet is un-switched.
Realistic supplied the STA-850 with a wood grained, vinyl veneer covered wood case at no extra charge.
The Realistic’s receiver line is probably underrated by most audio enthusiasts. The STA-850 specifically is a very good, basic receiver. For anyone just wanting a basic setup with a turntable, tape deck and a pair of speakers the STA-850 will perform perfectly. It’s not overloaded with features but it also has fewer things that can go wrong with it. It has a classic vintage style and will look good in any audio setup. If you’re looking for an affordable, mid powered receiver then the Realistic STA-850 may be for you.
