The Unidyne III and Ernie Seeler

Most Shure users have likely never heard the name Ernie Seeler, even though a fair share of their livelihood exists because of this microphone engineer.

Ernie Seeler

Born in Cuba of German parents, Ernie joined Shure in 1953 and retired in 1997. During the late 1950s, Ernie developed a new microphone element that would revolutionize the pro audio world, and find its way to every major city, country, and continent…and even to outer space (the SM58 is aboard the International Space Station).  That mic element is the Unidyne III – the engine of the SM58, SM57, 545, and 565.

Before the Unidyne III, all Shure unidirectional microphones were utilized by speaking into the side.  The 545 Unidyne III was the first Shure unidirectional model where the user spoke into the end of the microphone.  An important benefit of an end-fire, cylindrical mic is the uniformity of the polar pattern. This uniformity provides better gain-before-feedback in sound reinforcement systems.  Because sound systems could be louder using the Unidyne III, concert venues could be larger.  This led to concerts in stadiums, as well as large outdoor events like Woodstock in 1969 – where nearly all the microphones were Shure Unidyne III models.  Ironically, Ernie Seeler disliked rock music.

From the Shure 1960 catalog: New! Model 545 “Unidyne III”

The smallest unidirectional dynamic microphone.  Features truly uniform cardioid pickup pattern.    List Price: $85.00    Cable connector: Equivalent to Amphenol MC4M plug   Impedance: Dual. Choice of 50 ohms, 250 ohms, or high.  The Shure Model 545 “Unidyne III” is a new addition to the famed family of Unidyne microphones. This striking-looking, compact, slender , uni-directional, moving-coil microphones features wide-range  reproduction of voice and music and flexibility of uses as hand or stand microphone.  Recommended for dependable use in fine quality P.A. systems, tape recording, fixed-station communications, etc.  Provides highly satisfactory operation under adverse acoustic conditions – reduces or eliminates problems due to feedback and background noise pickup.  Permits placement at a distance from the performer 75% greater than possible with omni-directional microphones.  The 545 is ideal for installations where it is desired to the keep the microphone size and weight to a minimum and still retain maximum operating efficiency.  The 545 “Unidyne III” is rugged – will operate for years without deviation from its original standards.   

Ernie Seeler wanted the frequency response of the Unidyne III to be flat and was disappointed with the rising “presence peak”; he felt it was a flaw.  Yet, the “presence peak” that bothered Ernie became the signature sound of the Unidyne III family of microphones; without it, who knows if the SM58 and SM57 would have become the best-selling mics in the history of pro audio and touring sound.


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Davida Rochman

Davida Rochman

A Shure associate since 1979, Davida Rochman graduated with a degree in Speech Communications and never imagined that her first post-college job would result in a lifelong career that had her marketing microphones rather than speaking into them. Today, Davida is a Corporate Public Relations Manager, responsible for public relations activities, sponsorships, and donation programs that intersect with Shure at the corporate and industry level.

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  • victor fulton says:

    i have my UNIDYNE 111 for about 20 years still as godd as ever

  • Oliver Seeler says:

    Just a tiny correction regarding my uncle, Ernest “Ernie” Seeler: His parents (my paternal grandparents) were not both German. His mother, Francis Seeler nee Smith was very much American, a Floridian with roots going way back in America and eventually to England. His father, my grandfather, was indeed German, who had an import/export business in Havana, saw the 1929 crash coming, sold out and packed the family, including young Ernie, off to Germany in the late 1920s. Out of the frying pan and into the fire, as it turned out. But the accident of Ernie’s (and his older brother, Otto, my father’s) Cuban birth turned out to be a strange and wonderful thing, because the boys were never drafted or molested by the Nazis. Cuba, an ally of the US at that time, declared war on Germany but apparently it was beneath the Nazis to acknowledge such a thing from a tiny island, and it was simply ignored. Ernie was arrested at least once for distributing ant-Nazi pamphlets, but released because of this vague statelessness. Both brothers continued their studies at universities during the war, under the radar. After the war, both were regarded by the US as allied citizens and granted immigration into the US. Probably more than you wanted to hear about an old blog, but since you are a Shure person and I know Ernie is still revered there, I thought I’d pass this along.

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