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Shure Webinar Replay: History of the Unidyne 55 Microphone

Stage Directions • Industry NewsTools of the Trade • May 11, 2020

One of the most recognizable images of a microphone is that of the Shure Model 55 Unidyne® microphone. Often referred to as “the Elvis mic”, it has a classic look that has become a cultural icon; so much so that Shure still produces them today. Shure celebrated the Unidyne with a webinar, focusing on the history of this classic microphone that took place on Wednesday, May 6. You can replay the webinar video here in case you missed the original livestream:

Here’s some history on the Shure Unidyne 55 microphone from the Editor-in-Chief of FOH magazine, George Petersen.

1939 — Unidyne Model 55
Seeking to create a low-cost cardioid dynamic microphone, Shure engineer Benjamin Baumzweiger (he later changed his name to Bauer), began developing the Unidyne in early 1937. Prior to this, most unidirectional patterns were achieved by multi-element mics that combined the outputs of omni and figure-8 capsules via a switch or panpot. The concept worked but resulted in bulky mics with uneven frequency response and unpredictable directional patterns.

Bauer felt a single-capsule approach was the only workable solution. Partially blocking the capsule’s rear openings created a short phase delay that effectively cancelled the sounds from the rear. Varying the rear port resistance created various directional patterns — cardioid, hypercardioid, and supercardioid — and the Unidyne was born. Debuting in 1939 as the Model 55A/B/C (three versions with different output impedances), the Unidyne was an immediate hit.

More than seven decades later, the Unidyne remains in production as the vintage-looking dynamic models 55SH II, Super 55 and — the most recent entry in the series — the 5575LE Unidyne Limited Edition. Released in 2014 in commemoration of the original Unidyne’s 75th anniversary, the 5575LE was produced in a limited run of 5,575 units that replicates the original design used by Elvis and Sinatra, but with appropriate improvements in durability and sound quality, including a modern Unidyne III capsule, yet with that classic large outer grill of the original. As a footnote, the 1993 stamp with Elvis singing into a Unidyne 55 is the most popular commemorative stamp ever issued by the Postal Service.

This 1993 stamp honored Elvis singing into a Unidyne 55.

The legendary and iconic-looking Shure Unidyne 55 microphone




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