Shure's 55 Series Microphones, November 1996

Sleek in design, with a futuristic look suited for a '30s science fiction movie, Shure's 55 Series mics symbolize what many think of when someone says the word "microphone." 5/24/2004 8:00 AM Eastern

Shure 55 Series

Sleek in design, with a futuristic look suited for a '30s science fiction movie, Shure's 55 Series mics symbolize what many think of when someone says the word "microphone." In the six decades since its 1939 debut, the microphone has reached an unmatched level of recognition. Yet, the high visibility of the 55 Series—and its ubiquity—are hardly the result of chance. Nor are they the clever craftings of some slick advertising campaign. The 55 Series earned its reputation as a tireless workhorse and dependable performer.

Shortly after its introduction, the 55 Series mic became a mainstay in the world of audio professionals and came to be relied upon by celebrities, entertainers and politicians. The mics were widely used in the military and became familiar fixtures at well-known moments in history. Hundreds of photographs, films and videos show Shure 55s in the company of kings, queens, presidents and generals. They stood in front of Frank Sinatra and Doris Day during the big band era. Elvis embraced them—both in person and on a U.S., stamp issued in 1994—as have countless other rock stars over the years. Today, so many years after their first appearance, the 55 Series microphones are still popular and sought-after.

In 1939, when the original Unidyne was introduced, audio professionals chose microphones on the basis of impedance. For that reason, three Unidyne models were offered. The first, model 55A, utilized a low-impedance design for operation within 35-50 ohm systems. Model 55B was for 200 to 250-ohm systems, while the high-impedance 55C was built expressly for 100,000 ohms or more. List price for the 55A was US $42.50, models 55B and 55C could be yours for U.S. $45.

Touted in the 1939 catalog copy as the "very latest in dynamic microphone design—the first high-quality, low-cost moving-coil type dynamic [microphone] with true cardioid unidirectional characteristics"—the Unidyne was built to address problems created by feedback, background noise and reverberation. Outfitted with Shure's proprietary "uniphase" technology, it was marketed for P.A., recording, and broadcast applications. The streamlined chrome head could be tilted up to 90 degrees. A built-in cable connector was supplied, as was a special locking microphone plug attached to the cable, and 5/8-inch-27 threads for stand mounting. The abundantly-ribbed case was 4-1/4 inches high by 3-1/4 inches wide by 3-1/2 inches deep. The entire unit had a shipping weight of 4-1/4 pounds.

A dynamic, cardioid device by design, the Unidyne shared equal billing with Shure's other unidirectional offerings for that year: the long-gone Uniplex crystal mic, and the Tri-Polar crystal microphone, which could change its pickup characteristics in a chameleon-like fashion from unidirectional to bidirectional or non-directional with the aid of a three-point selector switch.

One of the driving forces behind the creation of the first Unidyne was a Shure engineer by the name of Benjamin Bawmzweiger. Bawmzweiger (who later changed his name to Bauer), began developing the Unidyne in early 1937. In undertaking the project, his primary objective was to create a unidirectional microphone which used a single dynamic element. Prior to the Unidyne's appearance, the most favored method of achieving a unidirectional response was to use both an omnidirectional element and a bidirectional cartridge (typically a ribbon element) in a single housing. Engineers employing this method reasoned correctly that if the outputs from both cartridges were mixed together electrically in equal proportions, the results would yield a cardioid pattern. In fact, with a little finesse, you could obtain supercardioid, hypercardioid, omnidirectional, or bidirectional patterns simply by controlling the relative balance of the two cartridges with a multiposition switch or pan pot.

The drawbacks of these early twin-element "unidirectional" mics were many. First and foremost, their size tended toward the monstrous end of the spectrum. On an aesthetic level, they had all the charm of an overstuffed birdcage. Performance wasn't something to boast about either. Since the omni and bidirectional elements didn't possess the same frequency responses, their resulting combined frequency response and polar pattern was unpredictable at best. Overall, the concept was far from perfect, but better than nothing if you were facing serious feedback or noise problems.

Ben Bauer realized that the best way to eliminate these ills was to use just one element. He began by examining the physics at work. He knew that if a single element was only exposed to sound on its front side, you'd obtain an omnidirectional response. Conversely, a bidirectional ribbon microphone has both sides—the front and back—exposed to sound. With that in mind, Bauer realized that if somehow he could partially block the backside of a ribbon element, in theory he would achieve a response which was somewhere between omni and bidirectional, and that would be cardioid. He set about to create this hypothetical cartridge, and wound up with what Shure would later label the Unidyne.

When Bauer's Unidyne design was implemented, the microphone was outfitted with a series of front and rear openings which allow sound waves to reach both sides of the element's diaphragm. The rear openings, however, were partially blocked with cloth, so that sound entering the case from the rear was delayed. A phase shift resulted which canceled out sound waves arriving from the rear, and reinforced those arriving from the front. By varying the amounts of resistance encountered at the rear openings, Bauer was able to achieve cardioid, supercardioid, or hypercardioid patterns using a single element, and the first true unidirectional dynamic microphone became reality.

The Unidyne was an instant success once it hit the marketplace. It was, after all, a good sounding mic with high fidelity for the times. True to Bauer's vision, the directional response was more predictable and better behaved than its predecessors, so it offered a tremendous new ability to control feedback and reduce ambient noise pickup. In addition, its size was small compared to competitive offerings, and this fact didn't go overlooked by singers, entertainers, and public speakers.

From 1939 until 1946, the Unidyne remained largely the same. Changes to the line were insignificant for the most part during these war years, with the most noticeable ones centering around new model numbers. Other variations included the 1940 introduction of a separate broadcast version (model 555), which featured an external Darth Vader-esque call letter plate and shroud.

By 1947, the broadcast version had become model 556, and the three separate models designed for use with different impedances were replaced with one single model (model 55) which was equipped with its own multi-impedance selector switch located under the case at the rear. Real changes were in the wind by the end of the decade, however, as Ben Bauer prepared to deliver yet another breakthrough.

Howie Harwood was at the beach when he read the letter telling him a job as Shure's director of advertising and public relations was his. The surf rolled in and his feet were in the sand, but for Harwood, this was a very different--and dangerous--kind of vacation. By the luck of the draw, he was on holiday with the U.S. Army's Third Infantry Division, and the exotic locale forming the backdrop for his time off was Anzio Beach in Western Italy. The year was 1944, and the only events on Harwood's social calendar that day revolved around the allied invasion which he was a part of.

The mission was a success of course, so Harwood figured that he'd try the job for a "couple of years" when he returned stateside after the war. As things turned out, he is still with Shure today serving as a communications consultant. Part of his current duties involve placing the modern-day Unidyne in movies, print ads, TV commercials, and music videos.

"In 1950 we developed a print ad which dramatically illustrated the dominance within the industry the Unidyne held around the globe," Harwood recalls today from his home near Shure world headquarters in Skokie, Ill. "It was titled 'Used the World Over More Than Any Other Microphone' at the top. The subhead read simply 'The Microphone That Needs No Name.' Underneath the headings we ran a large photo of the Unidyne. The name or model of the mic didn't appear anywhere. The ad ran in all of the trade publications. One of the reasons we created it was to demonstrate how familiar the Unidyne had become. By that time, it was a microphone which needed no name or introduction. It was recognized everywhere."

While Harwood was busy massaging the Unidyne's image, Ben Bauer finalized all of the elements required to put the next generation of Unidynes into production. First unveiled in 1951, the new "Small Unidyne" microphones (featuring the Unidyne II cartridge) improved upon all the features which made the original Unidyne such a success. As their name implies, the Small Unidynes were lighter in weight and more compact than the originals. Compared to their predecessors (which were still offered as "Standard Unidynes" in '51), the Small Unidynes were only about two-thirds the size at 3-5/16 inches high by 2 3/16 inches wide by 3 1/16 inches deep. Offered in two model configurations—Model 556S (for broadcast) and Model 55S (for general purpose)—the Small Unidynes weighed 4-1/4 and 3-3/4 pounds respectively. Internally, the new cartridge improved performance across the board. Random noise energy pickup was reduced even further, while directional response received an added shot in the arm as well. Like the Standard Unidynes, the Small Unidynes were also equipped with a multi-impedance selector switch.

The new Unidyne II cartridge fueled added success for the product line, and carried the marque until 1987, when it was replaced by the Unidyne B cartridge. Just as in the time between the introduction of the original Unidyne and the advent of the Unidyne II element, the period between '51 and '87 saw little change in product configuration. Other than a modification made to each model's base in 1962, and the elimination of the multi-impedance selector switch in the late '70s, the only other visible changes apparent were to the material lining the housing, which started out as red silk in the earliest models, went to blue, then black, and finally to the black foam which is still in use today.

Shure's current catalog shows the latest incarnation of the Unidyne, the 55SH Series II, which still houses the Unidyne B element. As reliable as all of its forebears, the microphone's cardioid/dynamic design has been upgraded to modern standards and is operable between 50 and 15,000 Hz.

A rugged survivor, the Unidyne has literally lived through wars and been beaten, kicked, and stabbed at by time and a changing marketplace. With a little help, it even resurrected itself from the darkness of a production halt in the early '80s. For anyone who has followed its history, the question logically arises: What's so special about this microphone? Why does it remain so popular?

"Part of the answer lies in the fact that it has become a cultural icon because of its recognition factor and styling," says Shure applications engineer Tim Vear. "Technically speaking, it also had the luck of falling into a design category which proved to be the one which won out over everything else. Carbon and crystal microphones gradually fell by the wayside, but dynamic mics lived on."

One of Shure's prominent—albeit unofficial—historians and keeper of corporate folklore, Vear is a living font of Unidyne facts, philosophy and trivia. "With the exception of some re-issues of old Neumann condenser mics, I don't think there are any other microphones in production today that go back as far as the Unidyne," he states. "The reality of having been around for generations has also helped make this product an icon, both internally here at Shure and to the rest of the world. If you look around our offices, you'll find Unidyne pins, engravings, posters, etched paperweights, and bookends. Its image has even served as a watermark on invoices. When people see the Unidyne, they can't help but think of Shure."

Vear also feels that the Unidyne's ubiquitous historical presence contributes to its status as cultural icon. "The Unidyne serves as a visual cue which can help transport you to a different era. That's because it appears everywhere in our nation's history books when you get to the chapters dealing with 1939 until the present. It stood in front of Doris Day and Frank Sinatra during the Big Band era. Countless kings, queens, presidents, generals, and politicians used it to make speeches. Elvis used it, and so did the rest of the early rockers. Turn on MTV today and it's still parading across the screen in scores of rock videos. As a final complement, Madonna can be seen dishing out serious abuse to one on-stage. Wherever it has gone with the world's celebrities and opinion leaders, its image was duly recorded on film. Millions of people have seen these images for generations, and as a result, the microphone sparks mental cues which create distinct impressions. These cues can transport you to anyplace in time during the last 56 years. It all depends upon your own subjective orientation."

Then there's the coolness quotient. Every cultural icon should receive high ratings in this category, and the Unidyne definitely ranks at the head of its class. Think about it: when you look at a Unidyne, it breathes coolness through all of its ribbed openings, regardless of whether they're covered with the red silk or the black foam. It's classic cool, like a '57 T-bird, James Dean, or a Stratocaster guitar.

Given its current state of popularity, expect to keep seeing the venerable Unidyne well into the next millennium. The future will most likely find 55 Series mics still serving a variety of sound reinforcement needs, and being used in films and on TV to add realism to scenes depicting events from the past.

Will they still be cool in 2002? Take a look into the polished luster of the ribbed housing. The answer is right there.

For more information, visit Shure at

By virtue of its status, the Unidyne has led an exciting life. It helped to define different eras, and enjoyed front row seating at noteworthy events of all description. Some highlights from its illustrious history include

  • When crooner Rudy Vallee scrapped his quaint, but old-world megaphone and switched to a Unidyne, he became the first prominent entertainer to adopt the technology for live performances.

  • General Douglas MacArthur used Shure Unidynes on the decks of the U.S.S. Missouri during ceremonies which ended the war with Japan in 1945.

  • You don't have to look closely to see the Unidyne in the famous photo of President Harry S. Truman holding up the erroneous newspaper headline reading "Dewey Defeats Truman."

  • JFK was frequently photographed making speeches with a stylish chrome-plated microphone stand-mounted in front of him. You get three guesses as to the make and model, and the first three don't count.

  • Photos of Eva Peron delivering speeches clearly demonstrate her microphone of choice. True to history, the Unidyne also made it into Evita, the Broadway hit musical based on her life.

  • In 1994, the U.S. Postal Service issued six stamps which prominently featured the Unidyne. One of them was the 29-cent Elvis stamp.

  • The film Good Morning Vietnam, starring Robin Williams, made the Unidyne its virtual co-star. The mic was also seen in print ads and posters for the film across the US.

  • The list of major entertainers who used or are still using Unidynes would probably fill two thick volumes. Just a smattering of name-dropping from the complete list includes Marlene Dietrich, Dean Martin, Jerry Lewis, Tony Bennett, Red Skelton, Axl Rose, and Tom Petty.

Want to read more stories like this?
Get our Free Newsletter Here!


Millennium Biltmore Hotel, Los Angeles, California, US