Shure Model 420 "Commando"
A modestly priced general-purpose microphone that Shure pitched as equally at home in the studio or out in the field.
Overview
The Model 420 carried the name "Commando." In the company's early-1960s catalogue advertising, the 420 was the rugged all-rounder of the lineup: a microphone that "can be used indoors or outdoors, for all general-purpose applications," positioned as "quality performance at moderate cost." That phrasing ran across multiple 1961 and 1962 issues of Studio Sound, and it is the clearest picture the surviving documentation gives of the model's intended role. It was not the flagship. It was the one you bought when you needed a competent Shure and didn't want to pay flagship money.
Shure's own advertising from the period grouped the 420 alongside the 545 "Unidyne III" (aimed at public address, tape recording, and communications work where compactness mattered), the 540S "Sonodyne II" (which offered variable frequency response so the user could tailor the mic to the job), and the 55SW "Unidyne," as seen in Studio Sound (February 1962, p.5). Next to those, the Commando is the generalist. It had no specialised party trick and was sold on versatility and price, not on a signature response curve or a famous model number.
The surviving catalogue copy makes the 420 a deliberate compromise. "Quality performance at moderate cost" sounds like filler until you read it next to the 540S's tunable response and the 545's compactness pitch. Shure was not claiming the Commando would out-resolve its siblings. It was claiming it would do a bit of everything, indoors or out, and that it would cost less than the specialised models. For a working musician, a school, a church, or a small tape-recording setup, that was often the right trade.
The "indoors or outdoors" claim is the one piece of functional character the period sources attach to this model. A microphone sold for outdoor duty is being sold on ruggedness and on not being fussy about where it sits, which fits the Commando name and the general-purpose framing. In the ads that survive, Shure leaned on that versatility and published no response figure.
The record is thin, and it helps to say so. The period advertising that names the 420 is catalogue-style promotion, not independent measurement. No review chunk here reports a frequency response, an impedance, a sensitivity figure, or a price in pounds or dollars for this specific model. The Studio Sound placements (December 1961, p.10; February 1962, p.5; April 1962, p.10; June 1962, p.9) are Shure's own "the truest sound" spreads, so everything stated about the Commando's performance is the manufacturer's claim, not a reviewer's verdict. Shure billed the 420 as a versatile, cost-conscious general-purpose mic. That is a positioning statement, not a measured result.
The catalogue describes an honest mid-range general-purpose microphone from Shure's early-1960s range, bought for utility rather than a cult following. The documentation does not support finer claims about its sound, its construction, or its production run. What can be said is narrow: the 420 "Commando" existed in Shure's British-market catalogue by late 1961, was sold through Shure Electronics Limited at 84 Blackfriars Road, London, and was marketed as the outdoors-capable, moderate-cost all-rounder of a lineup that otherwise specialised.
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