A TRIBUTE TO DEANE JENSEN: Visionary Genius behind Jensen Transformers

 

Young Deane Jensen

Back in the late 1970’s, if you called the Jensen Transformers business phone number, there was a good chance the man himself, Deane Jensen, would answer the phone. He did not identify himself, it was just a business-like “Jensen Transformers”. And I’d say, “I’m calling about a 21-xyz” and he’d launch into the features, advantages and benefits, no waiting, no looking in a catalog, instant knowledge, right there. He was brilliant for some products he developed but one aspect that is always overlooked; Deane Jensen was a genius marketing guy. If he got your ear, the things he said MADE you want Jensen Transformers.  He was always enlightening and educational in the dozen or so times I got to talk with him. So here is my tribute to the man who made the very best low-distortion, precision audio transformers. 

In the world of audio engineering, where precision and passion converge to shape the way we experience sound, few names resonate as deeply as Deane Jensen. A pioneer, innovator, and unrelenting perfectionist, Jensen’s contributions to the pro audio industry—through the founding of Jensen Transformers and the creation of the legendary 990 operational amplifier—have left an indelible mark on music, recording, and sound design. His legacy is not just in the circuits he designed or the company he built, but in the ethos of excellence and openness that he championed throughout his life.

Born in 1942 in Annapolis, Maryland, Deane Jensen grew up in an environment steeped in intellectual curiosity. His father, Dr. Arthur S. Jensen, was a physicist with 25 patents to his name, and young Deane recalled visits from luminaries like Albert Einstein to their home in Princeton, New Jersey. This early exposure to scientific rigor and innovation set the stage for Jensen’s lifelong pursuit of pushing boundaries. At the University of Pennsylvania, where he majored in physics and electrical engineering, Jensen found his calling in audio engineering while serving as chief studio engineer for WXPN-FM, the student-run radio station. It was here that his obsession with sound quality began to take root.

By the mid-1960s, Jensen had moved to Hollywood, immersing himself in the vibrant and rapidly evolving recording industry. The era was marked by groundbreaking albums like The Beatles’ Sgt. Pepper’s Lonely Hearts Club Band, which showcased the potential of studio technology to transcend live performance. Yet, Jensen saw a persistent problem: the audio transformers of the time, often adapted from industrial or communications designs, were compromising sound quality in mixing boards and audio systems. Unwilling to accept “good enough,” he set out to fix it.

Jensen input transformer, in mu metal can

In 1974, Jensen founded Jensen Transformers, Inc., initially operating out of his Hollywood apartment. His mission was clear: to create transformers that didn’t just function but elevated the audio experience. Using his custom-designed COMTRAN software—a pioneering circuit analysis program that became the first third-party software distributed by Hewlett-Packard—Jensen reengineered transformers to achieve a Bessel low-pass filter response, virtually eliminating phase distortion and delivering unparalleled clarity. His JE-series transformers, with innovations like double Faraday shields for noise rejection, quickly became the gold standard in the industry, used in everything from recording studios to seismic sensing and even the space shuttle.

990 op amp, Made by John Hardy

But Jensen’s genius wasn’t confined to transformers. In 1979, he unveiled the 990 operational amplifier, a discrete op-amp that redefined what was possible in audio amplification. Published in the AES Journal and later patented (with the patent made public domain in a remarkable act of generosity), the 990 set new benchmarks for low noise, low distortion, and high output drive. Its design was a testament to Jensen’s philosophy: perfection wasn’t just a goal; it was a necessity. The 990’s enduring relevance is evident in its continued use in high-end audio equipment, including Radial Engineering’s Jensen Twin-Servo 500, and its induction into the NAMM TECnology Hall of Fame in 2018.

Jensen’s approach was as much about sharing knowledge as it was about creating it. His famous 3-ring binder catalog, now a collector’s item, was a treasure trove of technical data sheets that empowered engineers and DIY enthusiasts alike. His lectures on high-frequency phase response and its audible effects influenced countless professionals, and his decision to publish the 990’s schematics reflected his belief that advancing the state of the art was a collective endeavor. As Bill Whitlock, Jensen’s successor at Jensen Transformers, noted, “Deane’s goal was to improve the state of the art; he wanted everyone to benefit.”

Tragically, Jensen’s life was cut short in 1989 at the age of 47, following a debilitating bicycle accident in 1983 and personal struggles that culminated in his passing. Yet, even in his absence, his vision endured. Bill Whitlock took the helm of Jensen Transformers, preserving its commitment to quality, and the company’s acquisition by Radial Engineering in 2014 ensured that Jensen’s designs would continue to shape the industry.

Deane Jensen was more than an engineer; he was a dreamer who refused to compromise. His insistence on doing things the “best way” rather than settling for “good enough” challenged those around him to strive for greatness. 

As Gary D. Davis, a friend and colleague, recalled, Jensen’s relentless pursuit of perfection and his willingness to question established norms led to breakthroughs that transformed audio engineering.

Open frame output transformer

Today, every pristine recording, every crystal-clear live performance, and every piece of equipment bearing the Jensen name carries a piece of Deane Jensen’s legacy. His transformers and the 990 op-amp are not just tools; they are monuments to a man who heard the world differently and dedicated his life to making it sound better. For those of us who chase sonic perfection, Deane Jensen remains an inspiration—a reminder that true innovation comes from passion, precision, and a refusal to accept anything less than extraordinary.

I called Jensen Transformers back in 1986 to order a couple of input transformers similar to the type used by API in the 312 mic preamp (they provide around 10dB of virtually noise free gain). Mr Jensen proceeded to give me a master class in transformer distortion, explaining in detail why Rupert Neve’s gear was high in distortion, and he ended up selling me a lot more stuff than I had planned to buy. I bought a couple of his 2:1 low distortion mic input transformers, noise sorted MA332 op amps, special non polarized capacitors, and output isolators. Even while ranting about Rupert Neve, Mr. Jensen was focused, entertaining and enlightening. Being able to call someone like that on the phone was amazing. RIP Deane Jensen, and know, you are missed. 

Thanks for reading High on Technology, Good Music To You!

©2025 by Mark King, It’s NOT ok to copy or quote without written permission

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In a digital world that seems "possessed" with the need for distortion, Deane Jensen was focused on minimizing the effects of transformer based distortion.