Electro-Voice EVX-4
Fifty-nine dollars and change bought you a way into four-channel sound before anyone agreed on what four-channel sound was.
Overview
The EVX-4 is a small box - roughly 5¼ by 2½ by 6 inches, according to High Fidelity (September 1971, p.40). It did one job. It decoded Electro-Voice's own Stereo-4 matrix from two-channel records and FM broadcasts, and it synthesized a four-channel effect out of ordinary stereo for everything else. Electro-Voice's own advertising billed it at $59.95 suggested resale, a figure that held steady across the model's print run. A 1972 Audio ad lists the same $59.95. For that money you got the entry point into the company's matrix system, and the pitch was blunt about what matrixed four-channel could and couldn't do.
Electro-Voice never pretended matrix was discrete, and that's what makes the EVX-4 interesting to collectors now. Company literature conceded that Stereo-4 "is not quite the equal of 4 discrete signals," and acknowledged some loss of stereo separation. It argued there was no reduction in frequency response or overall fidelity, and that the reduced separation actually seemed to help the psychoacoustic effect for many listeners in normal rooms. That's a manufacturer making a virtue of a limitation, and owners have argued about it ever since. The bonus feature isn't in dispute. Plain two-channel stereo fed through the decoder was said to release "hidden" four-channel information captured by multi-microphone recording techniques, which enhanced the existing library rather than demanding a new one.
High Fidelity (September 1971, p.40) framed the EVX-4 exactly this way — as a means of recovering quadraphonic signals from matrixed sources or synthesizing four-channel effects from stereo, "an interim road to quadriphony" until discrete four-channel became commonplace. The same review noted that bench tests confirmed the circuit to be well designed, which is about as warm as period engineering coverage got for a budget decoder. That "interim" framing turned out to be the whole story of the format.
The EVX-4 was the original decoder for the E-V matrix system. It was soon to be surpassed by a model that would also decode the CBS SQ system, which is worth remembering when dating a used unit or reading old copy. Electro-Voice pushed the decoder into as many hands as possible. It was sold through hi-fi shops at $59.95 and, under the Realistic label, through Radio Shack at the same price. Heathkit marketed a kit version, and broadcasters could buy direct at distributor pricing that varied with quantity. A separate add-on, the E-V 1244X decoder/stereo amplifier, bundled the decoding with amplification at $149.95 suggested resale. The company's own ads invited skeptics to play Columbia SQ, Sansui, and Dyna demonstration records through the EVX-4 and judge for themselves. They claimed that in most cases listeners would hear little or no difference, and that some records might even sound better through the E-V decoder than through the competing system's own hardware.
Whether that claim holds up is a matter of taste. The EVX-4 was a compatibility play. Electro-Voice's literature was candid that discrete four-channel on records and FM would have to wait on knotty design problems and a host of new FCC regulations, and that there was "serious question" whether those problems could be solved at all. In the meantime, Stereo-4 decoders were getting four-channel recordings into the marketplace in a form people could actually enjoy. The EVX-4 was on the market in quantity, with decoder circuits being designed into mass-produced phonos and receivers and even into jukeboxes.
The EVX-4 is a low-cost, well-built matrix decoder from the moment before the four-channel market sorted itself out. It shows up in the classifieds of the era's audio magazines at used prices well under its original cost. A 1972 Audio classified offered one "like new" at $35.00. It is not a discrete quad decoder and was never sold as one. Anyone expecting it to pull four separate channels out of an SQ or CD-4 disc is going to be disappointed, and that mismatch between expectation and capability is the most common source of grumbling about the model. It works as a Stereo-4 decoder and a stereo enhancer, and Electro-Voice's own copy was upfront that the enhancement of ordinary stereo was the real everyday payoff.
The physical package is modest, and the engineering reputation rests on the circuit rather than the case. High Fidelity's bench confirmation is the strongest independent word on the design, and it's worth weighing against the marketing claims. The unit survives in collections of four-channel-era hardware rather than on anyone's main listening shelf.
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