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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."

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

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

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

“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

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

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

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 theU.S.S. Missouri during ceremonies which ended the war with Japan in
  • 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