Ask any person on the planet to think of a vintage microphone, and the Shure Model 55 is what probably comes to mind.

This iconic mic was introduced in 1939, and two models that sport the distinctive box shape are still in the Shure catalog. Pretty good for a design celebrating more than 75 years!

Not only is the Model 55 one of the best looking mics ever made, it also introduced a breakthrough technology in using just a single dynamic element and achieving pattern control.

Up to that time, attaining anything other than an omnidirectional pattern meant using more than one diaphragm and combining their outputs. This resulted in a large mic head that usually didn’t sound all that good because the elements were spaced apart and usually had different frequency responses.

Shure developed the mic element in the 1930s, using small ports that allowed sound waves to reach both sides of a diaphragm at different times, resulting in a more linear frequency response.

The design is called UNIDYNE (short for Unidirectional Dynamic), and it’s a basis of many designs today, including another icon, the SM58.

The element of the Model 55 was also suspended on springs dampened with foam to isolate the diaphragm from handling noise.

The combination of great sound, compact size, cardioid pattern and classic styling made the Model 55 an instant hit. By the 1950s, it was so recognizable that a company advertisement simply featured a picture of the mic and copy reading “Used the World Over More Than Any Other Microphone” and “The Microphone That Needs No Name.”

The King & Mic

The Model 55 has changed over the years. When introduced it came in three types: the 55A, optimized for 35-50 ohm low impedance; the 55B, built for 200-250 ohm systems; and the 55C, designed for use with high impedance equipment. The next year, a new broadcast version offered an isolation mount called the model 555.

The broadcast version became the 556 in 1947, and the three types were replaced with a single model that featured a multi-impedance selector switch at the rear of the mic head.

In 1951, a smaller 55 hit the market, offering improved isolation of the cartridge and a wider frequency response. It was available as the 55S standard and the 556 shock mount broadcast version. The larger 55 was discontinued the following year.

By the way, the larger model is commonly referred to as the “Fatboy” while the smaller model picked up the moniker of the “Elvis” microphone, memorialized on a commemorative postage stamp (with “The King”) that was issued by the U.S. Postal Service in 1993.

The head shape of the smaller 55 has remained the same, but the base eventually changed to a more modern design with a built-in XLR connector. (Earlier models had used the three pin Amphenol-type connector.) By the late 1970s, the multi-impedance switch was gone, with only a low-impedance version available.

While the inner workings were periodically upgraded to improve sound quality, the most visible change was to the material lining the housing behind the grill.

The silk lining material started as reddish-brown, then was changed to blue silk, and then to black silk, with later models switching from silk to black or blue foam.

The standard finish was satin chrome, but the mics were also available for a time with a gold finish.

Currently, two models are available as new. The 55SH Series II has a cardioid pattern, an on/off switch, and black foam behind the grill, while the Super 55 offers a supercardioid pattern, no switch, and blue foam. Both offer the latest iteration of UNIDYNE technology.

I had wanted a Model 55 ever since I started playing music, and found my first one at a swap meet several years ago. This early 1940s Fatboy 55C had been used with a ham radio rig and was considered too dated and bulky by the previous owner.

It usually sits on my desk, one of only three mics on display at my house.

My most recent model is a modern Super 55 that is part of my working inventory, providing a cool vintage look with modern sound pickup.

Shure Model 55B “Fatboy” Specs

Transducer Type: Non-metallic diaphragm dynamic
Polar Pattern: Cardioid
Frequency Response: 40 Hz – 10 kHz +/- 10 dB
Sensitivity: -74 dB at 600 ohms
Nominal Impedance: Switchable, 200-250 ohms
Size: 7.7 x 3.2 x 3.5 inches
Net Weight: 2.7 lbs
Retail price for a new one in 1940: $26.46

Read more of Craig’s Microfiles articles here.