DROP THE MIC: JUST HOW TOUGH IS THE SM58?

We’ve all heard the stories: A resourceful roadie using an SM58 as a hammer, an SM58 surviving a week underwater after a hurricane, punk legend Henry Rollins “customizing” his SM58 by crushing his thumbprints into the mic’s famous ball grille.

There is no doubt that this is a microphone built to last.

But how tough is it really?

Well for starters, the SM58 can handle extremely sound pressure levels (SPLs) from 140 to 180 dB – that’s comparable to the volume of a rocket launch and far louder than the loudest human voice. So it’s practically impossible for a singer to blow out an SM58 like some more fragile vocal mics.

The SM58 is a dynamic microphone, which is a type known to be more durable than its condenser and ribbon counterparts. A lot of that comes down to the internal mechanics of how these different mics capture and transmit sound waves.

The SM58 has a dynamic cartridge based on the Unidyne III designed by legendary Shure engineer Ernie Seeler. It also features a pneumatic shock mount that essentially eliminates stage vibration and handling noise.

The mic’s iconic silver ball grille does double duty: Firstly, it helps remove plosive and hard consonant sounds like Ps and Ks. Secondly, it acts as a so-called crumple zone on a car that protects the internal cartridge from damage.

Fun fact: the grille has been designed to dent upon impact, absorbing the energy. This, of course, is how Black Flag singer Henry Rollins ended up crushing his thumbprints into his SM58 while performing. One of his mics apparently lasted more than 750 shows over 10 years before starting to finally wear out.

Rigorous testing

How is such toughness even possible? 

It all starts with extremely rigorous testing in the Shure labs. Before the SM58 was released in 1966, Seeler and his team refined the now iconic microphone by dropping, heating, freezing and submerging prototypes. To this day, Shure continues to do this sort of military-quality durability (mil spec) testing, including saturating mics in a salty fog to check for rust and a temperature shock test that cycles test devices through extreme heat and cold.

“These quality standards that were adopted in World War II are still kept today,” says Shure corporate historian Michael Pettersen. “It's why our products are so durable.”

Shure also uses the industry reliability metric of mean time between failures (MTBF) to measure just how reliable the SM58 is.  Assuming the mic is used 14 hours per week, the average SM58 is expected to keep working for over a century. Specifically, Shure calculates that your microphone will statistically last 106.5 years by collating global repair data on all in-warrant and out of warranty units.

“If you buy an SM58 and you treat it right, you never have to buy another microphone for your entire life,” says Pettersen.

It’s no wonder the SM58 has such a reputation for durability!

Built to last

But its ability to withstand harsh conditions and repeated abuse wasn’t a function of trying to build the world’s toughest mic back in 1966. Pettersen explains that it was rather simply good business practice at the time, because selling unreliable products would damage the company’s reputation.

This, in turn, was a major factor in how a mic originally designed for studio use became such an onstage stalwart: The SM58 could handle the rough and tumble demands of live performance and still sound great.

Of course, there a plenty of stories out there how an SM58 survived far more abuse than what an average overexuberant touring musician can dish out.

One of the most infamous episodes was the “torture testing” undertaking by the Swedish pro audio publication Studio. Beyond dropping and bathing a poor SM58 in beer, they used it as hammer, froze it and even briefly microwaved it. (Shure really doesn’t recommend trying any of this at home, kids!)

As if that wasn’t enough, those Swedish scamps proceeded to bury the mic in the backyard for an entire year. Underground and unprotected, it had to endure rain, snow, freezing temperatures and whatever critters were living in the dirt. Twelve months later after exhuming it and even rinsing off the soil, the SM58 still worked.