When you think of classic microphones under the Shure umbrella, you invariably think of the SM58® or maybe the SM57. But there was a time before both, when the Unidyne 55S (that's right, the "Elvis mic") ruled the stage. And the iconic "Green Bullet"? What's the back-story there? Were these microphones engineered for the applications they're found in today?

Today, these veterans are still in active service and part of Shure's Classic Series. We jumped into the archives to learn a little more about the past, present and future of two classics: the 55 Series and the 520 "Green Bullet".















 The Unidyne Microphone

It all started in 1939 with a concept that Shure engineer Ben Bauer had for a unidirectional microphone with a single dynamic element. (Uni = unidirectional. Dyne = dynamic). Dyne also is a measurement of force used by engineers, including acoustical engineers.

Engineering & Development

• The Physics of Unidyne: a single pickup element equipped with rear acoustical passages that delay sound waves arriving from the rear of the microphone. Combining the delayed waves with the non-delayed waves produced a cardioid (unidirectional) pattern. This became Shure "Uniphase" technology.
  
• It is the first true unidirectional dynamic microphone.
  
• Created as a rugged public address microphone, it was recommended for fine quality public address, theater-stage sound systems, recording and remote broadcasting. It was also the standard for fixed-station use in police, fire, transportation, forestry and commercial services.
  
• Models 555 and 556 are introduced as broadcast mics in the 1940s.

Applications & Artists

• It is superior in capturing voice, minimizing background noise and becomes popular in recording studios, eliminating some of the more complex set-ups.
  
• Quickly adopted by politicians, speakers, entertainer, ham radio operators and the military. It is seen in countless newsreels, films and television programs from the 1940s to the present.
  
• Frank Sinatra, Doris Day, Dinah Shore, Ella Fitzgerald, Louis Armstrong, Elvis Presley and Nat King Cole are among the hundreds – maybe thousands – of vocalists using the Unidyne 55 vocal microphone.

The 55S Microphone
Shure 55S, a "baby" version of the Unidyne 55, is introduced.

Engineering

• Two-thirds the size of the world-famous Unidyne 55, it is developed by the Unidyne's original engineer, Ben Bauer.
  
• It incorporates a new cartridge for improved performance, frequency response and ambient noise reduction.
  
• It offers superior magnetic materials, diaphragm suspension and cartridge isolation.
  
• 556S is released for broadcast applications, the 55S for general uses. (S = small).
  
• It is updated over the years with multiple improvements.

Applications & Artists

• The 55S makes its stage debut in 1951 at Chicago's Chez Paree with Dean Martin & Jerry Lewis.
  
• Shure ad copy touts: "the microphone that needs no name."
  

• It becomes an icon: According to Shure Senior Applications Engineer Tim Vear: "The Unidynes have become cultural icons. They also had a dynamic mic element– which was the microphone design that won out over everything else. Carbon and crystal microphones fell by the wayside, but the dynamic microphones live on."
  
• The Elvis stamp featuring an illustration of The King holding a 55S is released by the United States Post Office in 1993.
  
• This microphone receives federal trademark status for appearance and shape in 1998.
  

Heirs apparent

55SH Series II
Its visual appeal continues to make it a star on stage, screen, music videos and television. Shure endorser Dierks Bentley used three 55SH microphones for the acoustic set of his most recent concerts and it has become a new favorite among podcasters.














Super 55 Deluxe Vocal Microphone
Now, the model once advertised as ‘The Microphone That Needs No Name' has gotten an upgrade. Shure has taken the iconic 55SH body, added a new supercardioid element, and also added vibrant blue foam. The resulting hot rod has the same retro-cool look as the original when parked on a mic stand but with a contemporary upgrade in performance.

It's the professional audio industry's answer to the '65 Ford Mustang or a pair of Levi's 501 blue jeans.









The 500 Series, introduced in 1940, paves the way to the 520 "Green Bullet" in 1949. It comes with a 15' cable and retails for $16.50.

Engineering & Development

• It is introduced as a low-cost heat and humidity resistant mic for two-way radio use.
  
• It is popular with ham radio operators, police, fire, and other commercial dispatch uses, as well as the military.
  
• It is modified over the years to include a volume control, a dynamic element and a low-impedance output for modern PA systems.

Applications & Artists

• It is eventually adopted by harmonica players the world over.
  
• It is known for its "dirty Chicago Blues sound".

Heirs apparent

520DX
Harmonica players still use the mighty Green Bullet on stage and in the studio.

But the 520DX has managed to transcend its blues harp heritage. Shure endorser Heidi Newfield has been using a modified wireless version in concert. Nickelback uses it as a vocal effect mic, right next to the lead vocal mic. And there are drummers and engineers who like to place it on the floor right by the kick snare to get a "trashy" drum loop sound.