When the world’s top audio engineers are asked for their one, must-have, general purpose dynamic microphone, many always answer: Shure’s SM57. Why is this $100 mic so revered? The simple answer is it sounds good on virtually everything. But with so much great new mic technology, how has this workhorse from the mid-1960s maintained its role as one of the world’s most popular dynamic microphones?
To understand why Shure’s SM57 is so widely respected today, one has to revisit microphone history. From 1937 to 1939 Shure engineer Benjamin Bauer developed the first single-element directional dynamic microphone, the Unidyne, which had a cardioid pickup pattern. That was the early beginning of the SM57.
Ernie Seeler, the man who developed Shure's SM57
In 1959, another Shure engineer, Ernie Seeler, advanced the art of microphone design significantly with the Unidyne III. Seeler torture-tested the Unidyne III during three years of research and development. The original Unidyne III Model 545 evolved into the SM series of rugged and reliable Shure microphone capsules. The "SM" stands for Studio Microphone.
Seeler, an aficionado of classical music, “despised” rock music. It was a great irony that his development, the SM57, became a mainstay of rock music.
The SM57, now manufactured in Mexico and China, uses the same capsule as the popular SM58, which has a more robust wind and pop filter for close-up vocals. Like the SM58, the SM57 seeks to minimize electrical hum and noise pickup. The frequency response extends from 40 Hertz (Hz) to 15 kHz. An accessory windscreen for the SM57 attenuates wind noise and plosives and protects the microphone capsule.
Shure SM 57 microphone performs well on almost any audio application.
On a practical level, there is virtually no limit to the high sound pressure levels (SPL) the SM57 can handle. That’s right, no sound is too loud for it. The first frequency range to distort is around 100Hz at 150dB SPL. That is louder than a jet engine. At 20kHz, the SM57 can theoretically handle around 190dB SPL. Don’t try this or you’ll become deaf!
Every U.S. president from Lyndon B. Johnson to Donald Trump has used SM57s as the presidential podium microphone. The mic became the primary lectern microphone of the White House Communications Agency in 1966, less than one year after its introduction.
One reason for the mic’s popularity dates back to World War II, when Shure became a contractor for the U.S. military. All their products were built to military spec quality standards. When the war was over, Shure continued to build its gear to the same standards, figuring it cut down on maintenance and repair costs.
From this, Shure developed a reputation for indestructibility. The SM57, as users know, can take amazing abuse. The mics have been run over with vehicles, submerged in water and buried in the ground for long periods of time. Yet, they keep on working. Mean time between failures for this microphone is extraordinary. Because condenser mics have so many individual parts, they can’t begin to compete with a dynamic mic on this level.
Another factor contributing to the SM57’s longevity is its immunity from humidity and high temperatures. These environmental fluctuations typically happen during shipping and storage. The combination of these two conditions can cause unwanted noise (hissing, popping, crackling).
These atmospheric conditions can also change the actual sound of a microphone (frequency response shifts, changes in transient response); or even cause complete failure. Any of these are likely with humidity levels of 95 percent and temperatures above 100 degrees F.
Being a dynamic mic, the SM57 is also less susceptible to wind noise. The mass of a condenser diaphragm (the part that moves when humans speak) is much lighter than that in a dynamic diaphragm. With this lightness, condensers are much more susceptible to wind noise. Also, condensers are much more likely to pop from P-words or large exhalations of breath. Immunity from wind noise is a big reason SM57s are used on Presidents, who speak in a wide range of weather conditions.
It is also well documented that the performance characteristics of condenser mics can change substantially over time. This makes it imperative that mics about the same age are used together. New condensers can sound much brighter than older ones. Dynamic mics are very stable as they age and tend to sound the same throughout their working life.
Finally, dynamic mics need no phantom power, while condenser mics do. Though phantom power is now very reliable, it is one more point where failure can occur. More likely the problems come from noise (cracking, popping) caused by bad cables or loose/dirty connectors. This rarely happens with dynamic mics.
Finally, and perhaps most important, the SM57 costs about $100, almost nothing in the competitive world of pro microphones. The mic is a no brainer to purchase and its value and sonic quality are clearly established.
A good sounding microphone on about anything, with a low cost, rock solid reliability and stellar reputation makes for the SM57’s long term popularity.
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