Sony ECM-55
An omni electret lavalier with a 7/16-inch head — the refinement of the mic that started the whole lavalier category.
Overview
The ECM-55 is an omnidirectional electret condenser lavalier, and Sony's own documentation frames it plainly: it is the successor to the ECM-50, which the company describes as the world's first electret condenser lavalier microphone. That lineage is the whole story of this mic. Everything about the ECM-55 reads as a company that got there first and then spent the following years quietly making the thing better rather than reinventing it.
The head measures 7/16 inch in diameter — large by lavalier standards, and Sony's literature makes a point of it, noting that the big capsule is what delivers the "rich sound reproduction" the model is known for. The omnidirectional pattern is the other half of that bargain. Sony positions it as the pattern for "the widest variety of applications," and that tracks — an omni lav is forgiving of placement in a way that cardioids are not, which matters when you are clipping a mic to a moving subject and cannot chase them with a boom.
The capsule is an electret condenser, and Sony's spec sheet lists a frequency response of 30 Hz to 18 kHz — a range that covers speech and most of what a lavalier is actually asked to do, with headroom at the bottom for chest resonance and body noise that a narrower mic would thin out. Those are workmanlike numbers rather than headline-grabbing ones, which is exactly what you want in a lav: predictable, easy to match to a preamp, and unlikely to surprise a mixer mid-shoot.
Powering is where the ECM-55 earns its keep on location. Sony built two-way powering into the design — a single AA-size (LR6) alkaline battery internally, or external DC from 12 to 48 V. The ECM-55B ships with an in-line battery unit and an XLR-3-12C connector, so you can run it off phantom power when the mixer provides it and fall back to the internal cell when it does not. The period advertising made a virtue of this flexibility, and it is the kind of feature that reads as boring on a spec sheet and indispensable on a shoot day.
Sony's own 1985 advertising positioned the ECM-55 as "the latest refinement of our successful ECM-50 series," introduced alongside the ECM-66 unidirectional and the tiny ECM-77. That framing is worth taking at face value: the ECM-55 was not a new concept but a mature one, and the company's marketing leaned hard on the ECM-50's track record rather than on novelty. Studio Sound (August 1985, p.41) noted the broader launch of Sony's new lavalier generation, describing the line as building on a reputation for quality, performance, serviceability and reliability established across broadcasting and entertainment — the ECM-55 sitting in that lineup as the omni workhorse rather than the headline act.
Supplied accessories were practical rather than lavish: a single horizontal-type tie clip, a urethane windscreen,. A horizontal clip on a lapel puts the capsule at an awkward angle, and the vertical clip would save a trip to the accessories drawer — but it is supplied with the ECM-66B only, not the ECM-55. The windscreen is urethane rather than foam, which holds up better over years of use but does not hide the mic quite as well.
Finish and termination options varied by catalog and by year. Sony's literature lists black or satin-nickel finishes, and output configurations spanning XLR, pigtail, and Sony wireless-compatible connectors — the pigtail and wireless variants being the ones broadcasters actually bought, since they let the mic mate directly to a bodypack transmitter without an adapter. The ECM-55B is the black XLR model with the in-line battery unit; the pigtail and SMC variants that Sony lists for the ECM-77 and ECM-88 do not appear for the ECM-55 in the available documentation, so buyers chasing a wireless-compatible ECM-55 should verify the exact suffix before assuming.
Pricing moved over the model's life. One distributor catalog lists the ECM-55 at $229.00, another at $259.00 — a spread that reflects either different years or different dealer margins, and a reminder that list prices in this era were suggestions more than facts. Either way, it was priced as a professional tool, not a consumer accessory, and it sat above the ECM-44 that Sony sold as the economical omni entry point.
For collectors and working engineers today, the ECM-55's appeal is straightforward: it is a known quantity with a documented lineage, a repairable battery unit, and a capsule that has aged well if it has been stored dry. Electret capsules of this vintage can drift in sensitivity and develop noise if the diaphragm has been contaminated, and the in-line battery units are the usual failure point — corroded AA contacts from a cell left in over a winter. None of that is unusual for the breed, and none of it is fatal. The mic rewards the buyer who checks the battery compartment first and the capsule second.
What the ECM-55 is not is a collector's trophy. It was made in quantity, sold to broadcasters and production houses, and used hard. That is fine. This is a mic that wants to be used, and the fact that so many are still in service decades on is the most honest review it will ever get.
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