Rochester man explores the science of banjos

Jim Rae uses physics to leave his mark on bluegrass banjos.

Strumming on the ol' banjo, Jim Rae, of Rochester, studied the acoustics and physics of bluegrass banjo music.
Contributed / John Sievers

Deep dives into physics topic such as driving point impedance, a part of electrical engineering, aren't the first things that come to mind when most think about the bluegrass banjo. But that's exactly where James L. Rae, Ph.D., went in his banjo odyssey.

On his 83rd birthday, just a few weeks ago, James, referred to as Jim by his wife Joan, was sitting in his banjo room playing banjo in his pajamas. His wife says she’ll treasure the moment.

Not everyone has an entire room dedicated to banjos, but Jim’s long history developing the instrument’s sound makes the room a necessity. A popular banjo tone ring, the Huber HR-30 was named in part after him. The “R” in the HR-30 stands for Jim’s last name — Rae.

Jim and his wife Joan have lived in Rochester since 1987 but moved to the Charter House senior living community near the end of 2021. Both retired from the Mayo Clinic around 2006. Jim, who earned a Ph.D. in physiology, served as a professor of physiology and bioengineering at the Mayo School of Medicine and conducted research linked to measuring very small currents that flow through protein molecules in human organs, while Joan worked as a computer programmer.

A few years ago, Jim began noticing an inability to remember names. “The resulting progressive aphasia meant he would lose his ability to effectively communicate with words,” Joan says. “That is very evident now.”


Before his memory loss, Jim set up a home laboratory to apply some of the techniques he’d learned to measure currents in the human body to study the acoustics in bluegrass banjos, an instrument he’d loved and played since 1962.

“He took over the largest room we had for his computers and measuring devices," Joan says. "We were fortunate enough to also have a large unfinished room underneath our double garage. The larger woodworking equipment that he needed went there, so he was often doing his work surrounded by stored Christmas decorations and painting tools.”

Joan says that Jim’s banjo work spilled out to their entire home. “It seemed there were banjo rims everywhere. And bags of banjo bridges. And various banjo parts, both metal and wood,” she says.

Though Joan is very fond of Jim’s banjo playing, she says that she lost several pieces of kitchen equipment to his experiments including a pizza stone that held baking banjo rims, an old pressure cooker, and even a Fry Daddy.

“I drew the line at the microwave,” she says. “He bought his own.”

Test and publish

As early as 2004, Jim was publishing his studies about banjo acoustics in “The Banjo Newsletter.” Eventually, Jim’s path crossed that of Steve Huber, a banjo player and enthusiast who was on a quest to replicate the sound of the 1930s- and 1940s-era pre-World War II Gibson banjos, the gold standard of the bluegrass banjo sound for many aficionados.

After making a trip to Rochester to see the results of Jim’s precise acoustic measurements in 2009, Huber invited Jim to come to Nashville to measure and study dozens of banjo tone rings and rims including the sought after vintage rings, modern tone rings, and the new tone rings Huber had developed in his attempt to emulate the pre-war banjo sound. Huber asked Jim to do similar measurements on vintage banjo rims as well. The studies revealed important information about the vibrational qualities that Huber needed to reproduce in order to achieve the sound he sought.

In March 2011, Jim explained some of the acoustic studies he conducted concerning something he called transfer efficiency between banjo rims and tone rings in an article for “Bluegrass Unlimited”: “For these measurements, a ring was placed on a rim and the pair, rim down, was placed on my vibrating isolators. I then vibrated the ring with driving point impedance apparatus and measured the steady state vibration levels in both the ring and rim at each of 8,000 frequencies between 0 and 8000 Hz. Then I took the vibration levels in the rim at each frequency and divided them by the sum of the ring and ring vibrations at each frequency.”


His study revealed that in the best banjos, the rim and ring vibrated equally well at almost all frequencies. Jim’s tests and collaboration with Steve Huber helped contribute to the development of Huber Banjos and the Huber Truetone system. The banjos can be found at Huber Banjos .

Lifelong love

Jim’s love of the banjo and bluegrass music goes back to his time studying at Michigan State University where he listened to live bluegrass jams at LuLu’s Café in Ann Arbor. He traded a golf lesson for a banjo lesson after purchasing his first inexpensive banjo. Golf is another of Jim’s great loves.

“It is not unusual for Jim to become enthusiastic about an interest,” says Joan. “When I first met him in 1960, he had just discovered golf. He became a pretty good golfer. The storage area under the garage once held equipment for making golf clubs to provide for analysis of different shafts, grips, heads.”

Jim Rae plucks at one of his many banjos in his Rochester home in November 2019.
Contributed / John Sievers

In Rochester, Jim was a longtime picker at the weekly jam held at Charlie’s Eatery. Jim still plays banjo but is beginning to lose some of his repertoire. Joan says that Jim’s aphasia carries with it “the gradual loss of memories.”

“His career, his banjo research, many friends and acquaintances are just vague shadows to him now,” says Joan. She cherishes the sound recordings she has of Jim playing banjo with their son Scott.

While Jim’s memories might be fading, his impact on modern bluegrass banjos will continue to live on in the music they help create.

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