Onkyo TX-666 (1972–1974)
Fifty watts a side, a walnut-grained cabinet, and a phono stage with enough headroom to swallow any cartridge you own.
Overview
Onkyo's TX-666 is a solid-state AM/FM stereo receiver sold in the early 1970s. Onkyo was making a specific, testable promise to buyers at the time: its published specs were honest. The TX-666 was rated at 50 watts per channel RMS into 8 ohms, both channels driven, across 20 Hz to 20 kHz at no more than 0.2% total harmonic distortion. Onkyo's own advertising made the conservative-rating claim explicit, and the period press backed it up.
The phono section is what separates the TX-666 from a hundred other mid-power Japanese receivers of the era. Onkyo built in a 200 mV/RMS phono overload capacity at 1 kHz. That is a large number for a receiver of this class, and it means the preamp handles the dynamic peaks of a hot-cutting cartridge or a well-recorded disc without breaking up. That was real money in 1972, and the receiver was priced accordingly against Onkyo's own TX-555 at $349.95.
The amplifier is direct-coupled with differential circuitry. Onkyo leaned on this topology hard in its marketing, because it handles complex musical waveforms - transients - better than a conventional capacitor-coupled design. The protection scheme is thorough: an ASO (area of safe operation) detection circuit guarding the output transistors, a transient killer circuit, fused speaker protection, and automatic thermal shutoff. Four layers of protection on a 50-watt receiver explains why so many of these survive today.
The tuner is a six-element ceramic filter design with a four-stage differential IF amplifier, FM muting, and a linear-scale FM dial. Onkyo claimed accurate calibration and no drift, and the period reviews didn't argue. The front panel carries a tuning meter and a separate signal-strength meter, a lighted station pointer, push-button switching, and separate left/right channel tone controls. That last one is a slightly unusual arrangement that lets owners trim each channel independently. There's a front-panel mic input with mixing circuitry, plus two tape and two aux inputs and switching for two sets of speakers. The cabinet is walnut-grained wood.
On the reception side, the TX-666 earned consistent praise. Hirsch-Houck's test report called it a high-performance receiver, and High Fidelity (May 1973, p.37) described its behavior as well above average. Onkyo reprinted both verdicts in its own advertising. High Fidelity (September 1973, p.23) ran an ad quoting Hirsch-Houck's "auspicious entry from Onkyo" line alongside the magazine's own test experts, who singled out the conservative amplifier ratings and the unusually accurate dial calibration.
That's a better bet than a flashier receiver with inflated specs and no headroom.
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Related Models
- Onkyo TX-1500MKII (1975)
- Onkyo TX-4500II (1975)
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- Onkyo TX-2500II (1975)
- Onkyo TX-3500 (1971)
- Marantz 2226 (1974-1976)
- Marantz 2226B (1979-1980)
- Marantz 2235 (1974-1977)
- Marantz 2238B (1978-1980)
- Marantz 2250B (1978-1980)