Issue 210  February 2011
Audio's Renaissance Man

 

  In the year 2076 our descendents will celebrate the 200th anniversary of recorded sound. That occasion will likely inspire audio historians to reflect on those individuals who made the greatest contribution to audio technology in the first 200 years. Those short lists will undoubtedly include Thomas Edison, Emile Berliner, Alan Blumlein, Emory Cook — and Keith Johnson.

Two weeks from this writing I'm attending the annual gala of the Los Angeles and Orange County Audio Society honoring Keith with the Founder's Award. Because most of you can't attend, I'd like to share with you my thoughts on this remarkable man. Many of you are familiar with the name, but don't know the extent of his genius. That's because to Keith, one minute spent on self-promotion is a minute that could have been better spent on improving audio.

If Keith Johnson had done nothing else in his career except engineer the Reference Recordings titles, the LA/OC Audio Society would have still held its annual event in his honor. The same could be said if all Keith had contributed were the circuit designs for the Spectral playback electronics. The event honoring Keith would have been convened if he had merely co-invented High-Definition Compatible Digital (HDCD). The Audio Society would have recognized Keith if he had only designed and built the Pacific Microsonics Model One and Model Two analog-to-digital and digital-to-analog converters—which are still the state of the art to this day. Finally, Keith would be the recipient of the LA/OC Audio Society's highest award if he had done nothing more than designed and built the custom recording electronics and three-channel "Focused Gap" analog tape machine (and later the A/D converter) used in making those Reference Recordings titles.

But Keith didn't just do one of those things, he did all of them. It's remarkable that one person could contribute in such diverse areas of audio. But it's mind-boggling to think that he didn't just contribute in those fields, he pushed the state of the art forward in every one of those fields.

Keith is the ultimate audio Renaissance man. When he was 14 years old he built a disc-cutting lathe whose recording medium was a cardboard substrate sprayed with shellac. He was designing recording electronics and making recordings as a teenager — you can hear his early work on Red Norvo's The Forward Look from 1957(!) when Keith was just 19 (released in the 1990s on the Reference Recordings label). He developed a fundamental recording-head technology in the 1970s that made high-speed cassette duplication possible. Keith's entire recording electronics, from the modified ribbon microphones, through the custom minimalist electronics, to the analog tape machine (and later the Pacific Microsonics A/D converter) are all of his own design and construction. He's also a talented loudspeaker designer; his recording monitors are world class. His custom analog tape machine is unlike any other in the world, using proprietary magnetic systems, electronics, and even a non-standard equalization curve of Keith's own creation. When you listen to, say, Nojima Plays Liszt, you're hearing (or more precisely, not hearing) Keith's recording chain and analog tape machine. Has there ever been a more realistic recording of piano? In fact, if you listen to a Reference Recordings title through an all-Spectral system, remember that Keith designed every piece of electronics in the recording and playback signal paths. Oh, and he learns the score of every composition before the recording session.

I'll give you just one example of his recording genius, which explains why those Reference Recordings titles have such spectacular soundstaging. Many recording engineers put microphones in the back of the hall and mix in some of that ambience into the main mikes. But Keith has a more sophisticated approach. He equalizes those ambience signals in a way that precisely mimics the frequency-response change imposed by the head and ears to sound arriving from behind us. It's that specific frequency-response curve, in part, that tells the brain the sound is arriving from behind us. When mixed into the two-channel recording, that equalized signal fools the brain to some degree and results in a more spacious and enveloping soundstage. His bag of tricks is filled with out-of-the-box thinking like that.

Frustrated with the compromises of 44.1kHz/16-bit digital audio, but aware that a high-resolution consumer format was a long way off, Keith conceptualized a system that would encode into a 44.1kHz/16-bit signal some of the qualities of his high-resolution masters — qualities that were not only perceptually important but also that were lost in the down-conversion to CD. Together with Michael "Pflash" Pflaumer and Michael Ritter, Keith formed Pacific Microsonics in the early 1990s to develop and bring to market HDCD. The HDCD patent provides a glimpse into Keith's remarkable insights into psychoacoustics, particularly the correlation between specific changes in signals and the corresponding specific changes in sonic perception. To give but one example of dozens in the HDCD patent, Keith had figured out that image specificity is related to a transient signal's steepness. That is, the brain uses a sound's initial transient to locate an instrumental image. Slow down the transient, as what happens when high-resolution masters are down-converted for CD release, and the soundstage becomes less sharply defined. HDCD delivers, through a format limited to 20kHz bandwidth, transient steepness that implies a bandwidth greater than 20kHz. Michael Pflaumer, writing DSP code, devised a way to encode those vital signal components into a hidden channel buried in the least significant bit of the CD's 16-bit words, and then to extract those signal components in the CD player or DAC. HDCD is brilliant in conception and in execution.

Keith's state-of-the-art A/D converter and D/A converter designs rely heavily on proprietary measurement techniques Keith had been developing since the first days of digital. He created specialized "cluster tone" test signals designed to reveal the tiniest converter artifacts. He also developed a very precise technique for measuring jitter; he once told me that he could measure, and hear, the difference between 8ps (picoseconds) and 15ps of clock jitter. Once when visiting his lab I saw him working on a converter circuit built not on a circuit board, but painstakingly assembled in three dimensions to reduce electromagnetic interaction between the components.

When talking with Keith about audio, recording, or circuits, he exudes a childlike enthusiasm that only intensifies as he gets older. As he describes, say, what happens inside a transistor as it amplifies a transient signal, I get the feeling that he has the ability to conceptually enter an alternate universe of magnetism, electrons, and vibrating air molecules to understand these phenomena at a fundamental level.

Keith is the living embodiment of the concept of synergy. His playback electronics would not be as good as they are without his ultra-transparent recording electronics. HDCD would not have existed without Keith's high-resolution master recordings. And none of these contributions would have been possible without his remarkable ears. In working with Keith on a couple of recording projects, and having him in my home to set up systems, I've never seen anyone reach accurate judgments as quickly. He doesn't listen for several minutes before deciding to make a change, and then think about what change to make — he knows after several seconds what's right and wrong, and what specifically to adjust to make it better. (A manufacturer at one setup looked at me, smiled knowingly, and said, "Fastest ears in the West.") Despite his vast gifts, Keith is a quiet, humble man with absolutely no pretense or hint of self-promotion. He's so absorbed in his work that he must sometimes be reminded to eat.

As remarkable and creative a life as Keith has led, he's showing no signs of slowing down. In fact, from the hints I've had about what he's working on now, Keith's greatest contribution lies ahead of him. I can't wait to see what's next from Audio's Renaissance Man.

 

 

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