Shure MX185 (dates not documented)
A cardioid condenser lavalier with a deliberate dip at 730 Hz — the fix for the chesty rumble that plagues every clip-on mic.
Overview
The MX185 is the cardioid member of Shure's Microflex lavalier line, and the thing collectors and working engineers tend to remember about it is the frequency response: a deliberate dip at 730 Hz, which Shure's own documentation says minimizes the "chest resonance" effect. Contemporary coverage of directional clip-on mics in the trade press reflected the same practical concern — EQ Magazine (December 2001, p.82) reported on touring engineers favoring small clip-on condensers for string players precisely because of the consistency a well-positioned directional lav could deliver.
That is not a marketing flourish — it's the entire design rationale for the family. A lavalier sits on the chest, and a chest is a resonant cavity. Shure built the correction into the capsule rather than asking the operator to EQ it out at the console. Distributor literature of the period describes the cardioid MX185 as providing "an intermediate pattern for directional use" — sitting between the omnidirectional MX183 and the supercardioid MX184 in the Microflex lineup, and the natural pick for a presenter who needs some rejection without the tight, feedback-prone supercardioid pattern.The published specs are specific and worth reading carefully, because they separate the phantom-powered version from the battery-powered variant. The MX185 is rated at 50 Hz to 17,000 Hz, with output impedance rated at 150Ω. Open-circuit sensitivity at 1 kHz referenced to 1 V/Pascal is listed at −33.5 dB for the standard MX185 and −52.5 dB for the MX185BP battery version — the large gap reflecting the different preamp topology, not a different capsule. Maximum SPL at 1 kHz at 1% THD into a 1 kΩ load is 123.0 dB for the MX185 and 139.5 dB for the BP. Equivalent output noise (A-weighted) is 29.0 dB and 33.0 dB respectively. Dynamic range is given as 94.0 dB.
Power is where the two versions genuinely diverge. The standard MX185 takes 11 to 52 Vdc phantom power and draws 2 mA. The BP version runs on a 9V alkaline battery — Shure rated battery life at 600 hours, with current drain of 0.8 mA — and, per the Microflex documentation, adds a silent mute switch. That battery life figure is the kind of number that matters to anyone who has ever had a lav die mid-presentation.
The physical package is compact: the microphone itself measures 0.46 in. (12 mm) by 0.85 in. (22 mm), and the lavalier cable is a shielded 4 ft. (1.2 m) run terminated with a miniature Switchcraft TA4F 4-pin connector. The MX1BP cable, used with the battery-powered bodypack arrangement, is a shielded 12 ft. (3.6 m) run terminated in a 3-pin male XLR. Shipping weight is listed at 0.87 lbs. (394.6 g). Each Microflex lavalier shipped with an in-line phantom-powered preamp (the MX18P) or a battery-powered preamp in the BP case, plus a tie clip and cable.
The Microflex family as a whole used Shure's interchangeable condenser cartridges, available in cardioid, supercardioid, or omnidirectional patterns — a system approach that let a house standardize on one preamp and swap capsules as the room demanded. The MX185's cardioid capsule is the middle of that road. Shure's own literature pitches the family as bringing "a new level of sophistication to personal voice reproduction," and notes full compatibility with all Shure wireless transmitters — which is the practical reason these mics turn up in so many installs and rental racks. The high sensitivity and wide response were the selling points, and the 730 Hz dip was the engineering that made a lav sound like a person rather than a chest.
Pricing in the distributor channel varied by listing and date. One dealer sheet put the MX185 cardioid at an MFR list of $280.00, the supercardioid MX184 at $290.00, and the omnidirectional MX183 at $260.00. A separate sheet lists the MX185BP at $318.00, MX184BP at $328.00, and MX183BP at $297.00 — the battery versions commanding a premium for the added flexibility. Collectors should treat these as list prices from specific dealer documents rather than a settled street price; the numbers moved between catalogs.
The honest caveat on this page: the archive has no confirmed production years, no independent period lab review, and no documented street-price history for the MX185. The specs above come from Shure's own Microflex documentation and distributor listings, which are authoritative on the design but silent on when the line ran or how it was received in the press. What is clear is the intent — a directional lav built to solve a specific acoustic problem, with the specs to back it up. The MX185 is the sensible middle child of the Microflex lavaliers, and the 730 Hz dip is the detail that tells you Shure was thinking about how a microphone actually behaves on a human being.
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