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Back To The Future: Looking Into Notable Recent Microphone Milestones

Newer innovations and old standards given new life...

By Gary Parks November 6, 2014

The modern Shure Super 55, descendent of the original Model 55.

Rugged Ribbons
Ribbon designs were a fairly early innovation, dating back to the early 1920s, with the RCA PB-31 introduced in 1931. They offered superior frequency response compared with the condensers of the time, yet their structure was typically too delicate to go on the road. Recent improvements in materials and technologies have made ribbon mics tough enough to tour.

Gary Boss, Audio-Technica marketing director, explains that “we wanted a ribbon that could endure the rigors of the audio world – both studio and stage, and the mics we came up with (the AT4080 and AT4081) have a lot of firsts. We developed a tool where the ribbon itself is stamped with a patterned imprint, providing a lot more rigidity than earlier ribbons that were corrugated by running the material through two gear-like cogs.

“The mics actually have two ribbons mounted back-to-back, which gives a much higher output,” he adds. “And they are active mics, so are not preamp-dependent and have more of a condenser-like output level.”

Shure’s Born notes, “We’ve really advanced technology in our ribbons with Roswellite material, creating a really low distortion, really high SPL mic that you can pretty much take an airgun to and the ribbon isn’t going to warp, tear, or change its shape. It’s not foil, but is a molecularly-bonded film.”

The Audio-Technica AT4080 and AT4081, two ribbon mics designed for the road.

Roswellite is used in the company’s KSM313/NE and KSM353/ED mics. In addition, beyerdynamic has taken ribbon mics into a handheld format with the M 160 dual-ribbon instrument and TG V90r vocal mics, and Royer has advanced these technologies with the R-101 and other models. 

Rare-Earth Magnets
Using a powerful neodymium-iron-boron magnetic structure to drive dynamic mics is widespread today, but had its beginnings in EV’s microphone lab in the mid-1980s. The N/DYM program formed around the company’s determination to create a rugged dynamic mic for live performance that integrated the key characteristics of condenser mics – including extended high-frequency response and a considerably “hotter” output. Al Watson headed the development team, with senior engineer Mike Bryson shepherding the design effort. 

The polar pattern of a Shure KSM353ED, a ribbon design enhanced by Roswellite.

The first step was to find a magnetic material with enough power to double the gap flux, compared with then state-of-the-art alnico magnets. Watson had learned of neodymium magnets, which were not yet commercially available, and “bought one square magnet for $90 and machined it down to size” to begin the design experiments.

Numerous trials with that one magnet eventually resulted in a magnetic structure that yielded about 6 dB greater output. The company also took the risk that these magnets would be available in production quantities by the time the products were ready for launch.

Electro-Voice led the neodymium revolution in mic design, and it’s still at the heart of designs like the N/D767a and N/D468.

It was only the beginning of the effort, according to Watson. To complement the more powerful magnetic structure, Bryson developed a porting system and diaphragm that extended the LF and HF response—“a very advanced capsule design for the time”—as well as advanced shock mounting and handle design.

Watson adds that though neodymium was only responsible for increased sensitivity, for simplicity of the marketing message it was credited with all of the mic’s other audio attributes. 

Innovations in the N/DYM program extended into manufacturing, including the development of a conical engraver to letter the mic collar with model and serial number, a production-line test chamber to QC plus print and record a response curve for each mic, and an automated process mated with a measurement system to adjust the mic damping for mic-to-mic consistency.


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About Gary

Gary Parks
Gary Parks

Gary is a writer who has worked in pro audio for more than 25 years, holding marketing and management positions with several leading manufacturers.

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