Startup Resonado Reinvents the Speaker With Its Flat Core Technology

Notre Dame alumni are developing speakers that can conform to small spaces

4 min read

A man holding two different speakers: a cone-shaped one and a flat one.
IEEE Member Christian Femrite, vice president of engineering at Resonado, compares the flat core speaker (right) the company has developed to the traditional cone-shaped version.
Photo: Resonado

THE INSTITUTEJust about every consumer electronics device that has gotten smaller also has changed shape. Think computers, telephones, and cameras. One product that has lagged behind is the speaker, whose conical form has been around for more than a century. But that’s about to change.

Resonado, a startup in South Bend, Ind., has developed flat core speaker (FCS) technology that allows speakers to be thinner and lighter than traditional ones. They can be shaped to fit into corners, nooks, and crannies such as vehicle headrests and steering wheels.

The technology originated in South Korea. Leeg Hyun Cho, an engineer who goes by LH, and son Brian Youngil Cho came up with the idea while tinkering on other projects. LH, once an executive at LG, is now a serial entrepreneur in South Korea with several successful “exits.”

Resonado was founded two years ago in Indiana at the University of Notre Dame to commercialize the technology, with Brian as CEO and LH as CTO. Brian recruited three fellow Notre Dame undergraduates as cofounders, including IEEE Member Christian Femrite, who is the company’s vice president of engineering.

“Flat core speaker technology is a complete redesign of the internal structure of conventional speakers,” Femrite says. “The biggest advantage is the technology offers design flexibility that has not been possible before. We’re talking about making speakers that conform to whatever shape you want, while still maintaining high-quality sound.”

The eight-person company recently signed several partnership agreements. In August, Resonado was designated the official sound partner of Notre Dame athletics. If you’ve watched the school’s Fighting Irish football team this season, you might have noticed the startup’s logo adorning coaches’ headsets. The headset logos are purely an advertising vehicle now, but in the future the technology could be implemented within those headphones or even the stadium’s entire sound system.

In July the startup partnered with Menlo Scientific, an audio consultancy firm in Richmond, Calif. The company provides prototyping resources, connections to manufacturing facilities, and engineering insights into materials technology.

Resonado also received more than US $1 million in early funding from venture capital groups including the Notre Dame Idea Center Pit Road Fund, Catapult Ventures, 500 Startups, and Queen City Angels.

The company is about to start mass-producing its first commercial speaker model at a factory in Dongguan, China. Femrite is working alongside LH Cho, who manages mass production. The goal is to finalize the product by the end of the year.


FCS technology means a fundamentally different internal structure from conventional speakers’ workings, Femrite says. Instead of a cylindrical, magnet-and-voice-coil assembly, Resonado’s speakers use a planar voice coil with bar magnets. The voice coil can be coupled to the diaphragm in different configurations including those that offer a new style of modular driver design. Different voice coil windings and material implementations are made possible by FCS structure, and the damper of a flat core speaker is now located under the speaker to offer better overall control.

“Understanding the fundamentals of a speaker and Maxwell’s equations was the key to rethinking how to use and rearrange those principles to make a better speaker,” Femrite says.

The speakers can take on virtually any shape, so they can be used in creative ways.

There is demand for a personalized audio experience in automobiles, for example, but space and weight restrictions are tight. “With purposefully placed speakers, each passenger could have a unique experience,” Femrite says. “This philosophy will gradually become the norm in self-driving cars, as these vehicles no longer will simply be a means of transportation but an entertainment center.”

Femrite says the startup’s two dozen prospective clients include vehicle manufacturers, headphone makers, and a five-star hotel chain.


The two Chos have been working on the technology since Brian was a child. The idea came about when Brian wanted to give his mother a gift of a picture frame outfitted with an embedded speaker. He couldn’t figure out how to make a speaker fit within the thin structure. He asked his father for help. LH said it wasn’t possible with the current speaker technology. The two have been trying to figure out solutions ever since.

Brian studied finance and applied mathematics in computational science at Notre Dame. As a junior, he recruited three cofounders, including Femrite, who was pursuing a bachelor’s degree in electrical engineering, minoring in engineering corporate practice and actuarial science. Cho told them about the speaker technology he was working on, and together they started Resonado to commercialize it in the United States.

The group has since participated in multiple startup competitions, winning prizes and recognition at the national level.

With the traction received from those competitions and networking events in Silicon Valley, plus the $1 million the company received from its first fundraising round, the team was able to get the company off the ground.


The startup has benefited from links with IEEE. Femrite was a member of Notre Dame’s IEEE student branch and also served as president of the Delta Sigma chapter of the IEEE–Eta Kappa Nu (IEEE-HKN) honor society.

Brian Cho spent time in California, pitching to investors, and along the way met IEEE Senior Member Joseph Wei, a partner at SkyChee Ventures and cofounder of the recently acquired hardware incubator Lab360. Wei also is a member of IEEE-HKN, a member of the IEEE Consumer Electronics Society’s board, and past chair of the IEEE Santa Clara Valley (California) Section.

Taking note of Wei's success with his Lab360 portfolio startups, Cho asked Wei for advice and later invited him to join Resonado as an advisor. In addition to counseling Cho on startup strategy, Wei introduced him to several investors.

“Joseph has been a great advisor to our team,” Cho says. “His background in manufacturing, venture capital, and startup ecosystem and his cross-border network helped us develop our company and technology to the next level.”

Femrite shared his own piece of advice for entrepreneurs: Don’t give up, regardless of the obstacles.

“Be ready to endure the barrage of no’s,” he says. “Any startup will go through that, and the successful ones are those that endure it long enough to get the one that says yes.

“I can’t tell you the number of times we got knocked down and were told, ‘You'll never be able to do this’ or ‘You’re too young,’” he says. “And every time, we’ve proven them wrong by continuing with our upward trajectory.”

A version of this post appears in the December 2019 print issue as “Resonado’s Flattened and Flexible Speakers Can Fit Anywhere.”

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