Sony ECM-51
A telescopic electret wand that turns a reporter's arm into an extension of the microphone itself.
Overview
The ECM-51 is a Sony microphone, and the "ECM" prefix paired with its product category points to a condenser design — specifically the electret-condenser family Sony was pushing hard in this period. What sets it apart from a conventional handheld is its physical form: it is a telescopic microphone, a wand that extends from roughly 7¾ inches out to 17½ inches, letting a reporter reach the mic into a crowd or across a desk without shoving a fixed body into someone's face. Sony's own advertising described it as acting like an extension of the reporter's arm for field interviews and actuality news work, which is exactly the use case the telescoping shaft was built around.
According to period coverage, the ECM-51 was one of a quartet of Sony electret condensers promoted together — alongside the ECM-50 tie-tac/lapel mic, the ECM-22 condenser with its on/off switch, and the ECM-53 — under Sony's "Innovation through imagination" banner. DB-Magazine (August 1969, p.9) ran that four-mic feature and singled out the ECM-51 as the telescopic model, positioning it squarely in the broadcast and newsgathering market rather than the studio. For a working reporter, the appeal is obvious: a tie-tac mic disappears on a lapel, but an interview wand needs reach, and the ECM-51's collapsible shaft delivers it while still packing down small enough to live in a kit bag.
The spec sheet Sony/Superscope circulated in its professional microphone advertising rounds out the picture. The ECM-51 is listed as an omni (omnidirectional) telescopic condenser with a frequency response of 50 Hz to 16 kHz, a maximum SPL of 126 dB at 1% THD, sensitivity of −53.2 dB at 250Ω impedance, and a price of $195. That sensitivity figure and the 250-ohm output put it in the same family as Sony's other electret condensers of the era — the ECM-50 lapel mic shares the identical −53.2 dB sensitivity and 126 dB max SPL, which tells you these were cut from the same cloth electrically even though their physical formats diverge sharply. The 50 Hz–16 kHz window is honest broadcast bandwidth: it captures speech and most musical content cleanly without pretending to be a full-range studio condenser.
That architecture is what made these mics practical for field work in the late '60s and early '70s — no phantom power supply to lug around, just a battery in the inline package.
There's no documented service history or failure-mode data to lean on here; the honest position is that a used ECM-51 is a gamble on a 50-plus-year-old electret element and a mechanical shaft, and buyers should test both before committing. The $195 original price was serious money in its day — this was professional gear, not a consumer toy — and that heritage is exactly why the mic still turns up in the hands of people who want a period-correct interview wand rather than a modern replacement.
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