What first strikes you about Charles Sprinkle—JBL innovator, engineer and multiple patent holder—is the glint in his eyes and the palpable welling up of enthusiasm that accompanies his talking about the reference monitors, consumer loudspeakers and other audio solutions he’s found a deep passion for in a second career.

Charles joined HARMAN nearly 16 years ago, after a classic light bulb moment heralded a dramatic career switch. Previously, he had worked in retail management in Bakersfield, California, biding his time and unsure of his professional calling. ”I was always into science, but had no idea what I wanted to do with it,” says Charles. “My hobbies were literally playing with Tesla coils and other kinds of crazy hi-voltage types of stuff, but beyond that, I had no direction.”

Meeting an audiophile with the tools to build loudspeakers, and a willingness to show Charles the craft, changed everything. “That first experience of designing something, building it and having a finished product that I could use in my living room—that sense of accomplishment—really primed my going back to school and getting a degree,” he says. “It finally clicked. I knew exactly what I wanted to do. I wanted to design loudspeakers.”

Moving to Southern California, Charles enrolled at Cal State Northridge and, while pursuing his Bachelor’s degree in Mechanical Engineering, met HARMAN Acoustic Research Fellow, Dr. Sean Olive at an Audio Engineering Society (AES) gathering. Sean told him that an internship that was available at JBL and Charles jumped at the opportunity.

While working with Sean and HARMAN’s former VP of Acoustical Engineering, Floyd Toole (since retired), Charles completed his degree and was hired to develop consumer loudspeakers. As a systems engineer, he was charged with the acoustic integration of new products, working with mechanical and electrical engineers to shepherd home and office loudspeakers from R & D to marketplace. For 13 years Charles remained ensconced in JBL’s consumer division, developing a wide variety of premium loudspeakers. From floor standing and bookshelf loudspeakers to wall-mounted, in-ceiling, in-wall and multimedia loudspeakers, and even fine-tuning the voicing for television sets, Charles reveled in providing quality sound.

During this time, Charles developed a measurement template for virtual system integration. This allows the JBL R & D team to accurately predict the response of a wide variety of loudspeaker tunings using a single prototype and has resulted in better product performance for their customers.

“My goal was to make a contribution to music by delivering an accurate product,” he says. “Sean and Floyd have a remarkable body of work that analyzes the preference of listeners to define what makes a good loudspeaker ‘good’. Their research has led them to conclude that neutral—what we call flat frequency, projecting the music precisely as it was created and meant to be heard—constitutes ‘good’. That level of accuracy is at the core of everything I strive for at JBL. Floyd’s personal tagline is, ‘Science in the service of art’ and that’s exactly what we do.”

In his last two years at HARMAN’s consumer division, Charles began work on a new waveguide for high-frequency transducers. Sometimes called a horn, waveguides provide a physical structure for directing sound waves into space. Through the years, these devices had acquired a negative reputation for imparting a “horn sound” into speakers. Although Charles felt the reputation was unjustified, he was confident that there were ways to improve the waveguide’s performance. By developing the JBL Image Control Waveguide, he made it possible to get truly neutral sound from premium loudspeakers and even studio monitors.

In 2013 Charles seized the opportunity to move to JBL Pro, applying the systems and technologies he developed for consumer products to studio monitors and loudspeakers for portable PAs. “I’m not a musician, but getting to play a part by building studio monitors, and becoming part of the musical creation is amazing,” he says.

Charles’s first assignment at JBL Pro was to usher the M2, JBL’s flagship Master Reference Monitor, into production. Next, he embarked on his first full project, the extremely popular near-field studio LSR 3 Series. Charles has since been primarily occupied by the 7 Series broadcast and post production line.


“The technical elements of working on studio monitors are interesting, but the really fun part is visiting the recording studios and post production facilities to meet the people who use them. It’s so valuable and motivating to hear, firsthand, what works for them. It reinforces how what we do here really matters,” says Charles. “We’re not just making widgets or designing tail lights, this is important for our culture. You have to be able to record a unique musical performance correctly, before it goes away. Using studio monitors with a neutral frequency response through an entire room can make a major difference in the final product.”

Between studio monitor projects, Charles has also worked on portable P.A. products such as the EON615 and the EON ONE. For the EON615, Charles invented a new low-frequency aperture waveguide which matched the directivity of the woofer to that of the high-frequency driver. And, for the EON ONE, he developed a transducer configuration for better coverage. “What makes good sound for home loudspeakers and studio monitors also makes good sound for portable P.A., namely having neutral frequency response not only directly on-axis, but everywhere in the listening area,” says Charles.

With a fervor for invention that extends beyond work, Charles’ wife, son and daughter are accustomed to his spending weekends designing and building new products—such as a recent project, a fan duct for a 3D printer—and experimenting with food. Charles is currently experimenting with the nuances of the savory flavor balance the Japanese call umami. “Culturally, there are two big communicators—music and food,” says Charles. I’m really fortunate to be immersed in both!”

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