Sony MX-650
A six-into-two portable mixer with illuminated VUs, an oscillator, and a headphone socket — the little Sony that pro-audio shops kept listing year after year.
Overview
The MX-650 is a six-input, two-output portable mixer. That is the whole of what the manufacturer's own trade description says, and it is worth reading slowly: mic, line, and phono inputs, two panpots, twin illuminated VU meters, an oscillator, and a headphone socket. Six channels in, two out, in a box you could carry. Sony's trade listing lays the feature set out in a single line, and it reads like a working engineer's checklist rather than a brochure: the phono inputs mean a turntable or tape return could sit alongside microphones without a separate preamp, the two panpots give stereo placement, and the oscillator is there for lining up levels before a session rather than hunting for a tone generator.
What the documentation makes clear is that the MX-650 sat in the small-format mixer market that British pro-audio dealers were pushing hard in the late 1970s. REW, the Charing Cross Road pro-audio and disco dealer, listed the MX-650 alongside the Sony MX8 and MX510 in its mixer inventory across Studio Sound advertisements in 1977, 1978, and 1980 — the same shop that stocked Soundcraft, Allen & Heath, Hill, Canary, and the TEAC-TASCAM line. That placement is the telling detail. A Sony mixer sharing shelf space with Soundcraft Series II and Allen & Heath consoles was not a consumer toy; it was a budget entry into the same dealer network that supplied small studios and disco installs. The REW ads bracket the mixer range at "£35–£2500," so the MX-650 sat somewhere inside a spread that ran from pocket money to serious console money.
The MX-650's own trade description does not spell out its filtering or its power arrangement, so collectors should not assume the 510's feature set transfers wholesale — but the family resemblance in the naming and the six-versus-five channel split is obvious, and the 510's a.c./d.c. capability hints at how Sony positioned these small mixers for field and studio use alike.
The phono inputs are the detail that dates this mixer precisely. A six-channel portable with dedicated phono inputs was built for a world where the source material arrived on records and tape, and where a small studio or a disco rig needed to fold turntables, microphones, and line sources into a stereo pair without a rack of outboard gear. The two panpots and twin illuminated VUs put the MX-650 in the same operational idiom as the larger consoles of the day, scaled down to something a single operator could carry and set up.
High Fidelity's February 1980 home-studio feature (p.113) framed the small-mixer problem exactly as a buyer of this Sony would have faced it: with a limited budget, the mixer "has to be inexpensive, but good," and the magazine's advice was to record music and listen back for hiss, distortion, and whether the meters led to the right recording level. That is the test an MX-650 was built to pass — twin illuminated VUs that actually guide level-setting, an oscillator for calibration, and a headphone socket so the operator can monitor what the meters are claiming. Whether it passed is a matter for the bench rather than the brochure, and no independent bench test of the MX-650 itself appears in the surviving period press.
What the record does not contain is just as important as what it does. There is no confirmed production run, no original retail price for the MX-650 specifically, no published frequency response, distortion, or noise figures, and no dimensions or weight. The Archive's own documentation for this model is thin enough that the honest entry is a short one. What survives is the dealer listings — REW's repeated inclusion of the MX-650 in its stock across at least three years of Studio Sound advertising — which confirms the mixer was a catalogued, orderable product in the UK pro-audio trade from the mid-1970s into 1980, and the single-line trade description that tells a collector what the thing actually does.
For anyone hunting one today, the practical picture is this: a six-into-two portable with phono inputs, panpots, illuminated meters, an oscillator, and a headphone out is a usable small-format front end for a modest home setup, and the Sony badge carries the brand's reputation for competent small-format gear. But the absence of service documentation and published specs means buyers are working from the unit in front of them rather than a data sheet. Check the meters illuminate, confirm the oscillator produces tone, and test every input — mic, line, and phono — because the phono stage is the part most likely to have been abused and the part least documented. The MX-650 is a working tool from the tail end of the small-studio boom, and it deserves to be judged as one.
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