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The search for new ribbon microphone angle

28 Mar 2016  | Tim McCune

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One of the more elegant feats in engineering is when someone takes an old idea, reconsiders it and brings it back in a new and innovative way. Among people who have done so are David Royer, Rick Perrotta and their colleagues at Royer Labs. I ran into David and Rick recently and had a chance to talk with them about their ribbon microphones, and how they are using new metals, new designs and JFETs.

Ribbon microphones date back to the early 20th century, with the first ones patented by electronics legend Walter Schottky and co-inventor Erwin Gerlach in 1924. RCA and the BBC patented their own versions in the 1930s. Ribbon microphones had vastly better frequency response than previous designs, and for decades they ruled recording studios and the airwaves. But in the 1970s, ribbon microphones generally fell out of favour as condenser microphones caught up with most of the sound advantages of ribbons, while being smaller, less cumbersome, and easier to maintain. Only the more devoted fans and engineers kept ribbons in service.

Fast-forward to 1998., Webvan, and eToys are among a slew of slick, high-tech start-ups promising investors billion-dollar valuations quicker than you could say MySpace. And while Internet companies competed to see who could sell the most convincing smoke and mirrors, Royer Labs opened shop in 1998 to design and build new versions of a quintessential old-school technology they believed still had life left in it.

Soon after opening Royer Labs, David and Rick filed a patent simply titled, "Ribbon Microphone." This patent involved a new approach, offsetting the ribbon towards the front of the microphone to accommodate higher sound pressure. Instead of magnets that tapered towards a ribbon, the Royer Labs design uses magnets that are square. And the patent, awarded in 2002 as U.S. 6,434,252, includes a new method of corrugating the aluminium used as the microphone's ribbon.

Rick Perrotta and Dave Royer.

These design changes, along with improved magnets that became available in the 1990s, are big parts of Royer Lab's success. Royer said metallurgy has made massive leaps beneficial to ribbon microphone development. "It just so happened that somebody brought neodymium magnets to my attention in about 1997 or so," Royer said. "I was thinking, `Hmm, little lightweight magnets that have horrifically powerful magnetic fields? This sounds interesting.' I got my hands on a few, started experimenting with them, and I was really, really amazed at what I was able to come up with."

Neodymium magnets increased the microphone's output, as did changing the ribbon's position. "We actually moved the ribbon forward in the transducer so that as the ribbon is being driven harder and harder by a sound wave, instead of going from the centre of magnetic flux it goes into the centre," Perrotta said. "It makes the microphone actually more efficient as it's driven harder."

The patent also covered the way Royer Labs makes its ribbons. "Up until the time we came out with them, the means of processing the ultra-thin aluminium ribbon was to place that ribbon between two pieces of glassine paper," Perrotta said. "It's kind of like a very thin wax paper, and you would run that sandwich between some very tough gears. It would corrugate the ribbon."

"The problem we found with that method was that the corrugations were very weak, and you could stretch the ribbon out quite easily," Perrotta said. "What we created was called the `direct corrugation method' which is part of our patent, where we don't use a sandwich."

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