February 1, 2009
RIP Analog: Prof. Keith O. Johnson Gives Digital a
Who is KOJ?
Most of us lesser mortals struggle through life, clinging
tenaciously to the base of Jim Carrolls
proverbial pyramid, hoping to fashion our few grains of silica into something that
sounds good. A few, however, simply impress their indelible soles on the sands of time and
proceed unhurriedly to the apex. Names such as Plato, Socrates, Alexander the Great, Isaac
Newton, Michelangelo, Beethoven, Marie Curie, Mother Theresa, and Albert Einstein
immediately come to mind.
Members of another elite group reach the pinnacle of
Carrolls pyramid through selfless, dedicated, invaluable lifelong contributions to
society in their chosen endeavors. However, their names and deeds almost always pale into
insignificance, conjuring up nothing in the mind of the common man. Nevertheless, some
facet of their creativity or genius inevitably embraces our daily life.
One such person is Keith de Osma Johnson (KOJ), Fellow,
Silver Lifetime Achievement, and Lifetime Member of the Audio Engineering Society. KOJ
studied computer science, biology, and music at UCLA, and did his graduate studies in
electronics at Stanford University. For most of his life, for good and sufficient reason,
his name has been prefaced by the honorific "Professor"; most in the high end
know KOJ as Prof. Keith O. Johnson.
As a professional, KOJ is first among equals, having
watermarked his trail in the pristine world of high-end audio engineering. For him,
"less is more (direct to two track) is preferred to more of less (multitrack)."
He is also a member of the KStars running club of San Francisco; he can still do 400m in
70 seconds and a mile in 6.5 minutes. He is married to Marcia Martin, vice president of
Reference Recordings. They have one son, Marcus.
KOJ, an only child born on March 29, 1938, had an
instinctive flair and passion for creativity and innovation from the start. According to
Reference Recordings, "While he was in grade school, Ampex Corporation awarded him a
scholarship and training program for his three-channel recorder and microphone project. He
developed photolithography construction of magnetic heads at Stanford University in the
sixties, consulted with Sherman Fairchild and applied his proprietary Focused Gap
technology to master recorders and later to high-speed tape duplicators when he co-founded
As Director of Engineering for Spectral Audio Inc., KOJ
created the Vertical Dimension Topology, in which the electrical audio signal "drops
down" into the amplifier circuitry along the Z axis to reduce to an absolute minimum
noise-causing electromagnetic-field interaction. He also developed the Focused Power
Geometry circuit architecture, a distributed array in which a separate power supply
is physically located next to each output device of a Spectral power amplifier.
Renowned for his more than 50 pioneering years of recording
and equipment design, Keith Johnson has always been at the forefront of high-resolution
audio. He has engineered nearly 150 classical and jazz albums, including seven that have
been nominated for and two that have won Grammys for Best Engineered Classical Recording.
Other accolades include two NAIRD Indy Best Recordings and, from The Abso!ute Sound,
two Golden Ear awards. However, it is my firm belief that his magnum opus is his work on
analog-to-digital conversion techniques heralded by HDCD, which is the focus of this
HDCD and Sanch
Doris Blaschkes press release of May 1, 1998, stated,
in part, "Developed by Pacific Microsonics in Berkeley, California, HDCD (High
Definition Compatible Digital) is a patented process for delivering on Compact Disc and
DVD-Audio the full richness and details of the original microphone feed. By correcting
distortions found in current digital recording technology, HDCD provides more dynamic
range, a focused 3D soundstage, and extremely natural musical timbre. HDCD recordings
offer improved sound quality on any CD player, and when reproduced on HDCD-equipped
players, they provide the ultimate in sonic fidelity."
In March 1979, in the Republic of Trinidad and Tobago, I
founded Sanch Electronix, with the principal objective of manufacturing loudspeaker
systems to complement the high-end equipment that we imported. Consequently, I made
frequent visits to the summer and winter Consumer Electronics Shows, then held in Chicago
and Las Vegas, respectively. On one of these occasions, I met the Reference Recordings
(RR) team: Keith O. Johnson, technical director; J. Tamblyn Henderson (JTH), president and
producer; Marcia Martin, vice president; and Janice Mancuso, international marketing
RR is well known for making consistently spectacular
recordings with huge, holographic soundstages and often adventurous titles. Over the past
32 years, based on the sonic quality of KOJs work, RR has created its own market
niche. My theory is that this is why JTH can be audacious in the choice of his eclectic
repertoire. RR and Sanch developed a sustained business relationship and, over time, close
friendships, and Sanch has been a distributor of RR titles ever since. I am a proud owner
of every CD, and most of the half-speed-mastered LPs, engineered by KOJ and released by
With the scarcity of foreign exchange due to the economic
downturn in Trinidad and Tobago in the mid-1980s, Sanch diversified into the recording of
indigenous music for commercial sale. When I invited Jack Renner of Telarc International
to Trinidad for the Carnival season of 1984, he brought along a pair of Brüel & Kjær
4004 omnidirectional microphones, a Nakamichi DMP 100 digital recording processor, and a
Sony SL2000 slimline Betamax tape deck. Renner recorded the 120-member Exodus Steel
Orchestra hammering out its Panorama rendition for the year, "Lucy in the
Renner returned to Ohio, Sanch purchased a duplicate set of
the components listed, and I began meddling with the production of real-time cassettes in
1986 with our famous Panyard Series. Many of these were subsequently released as
the Caribbean Carnival Series of CDs on the Delos International label. However, my
recordings had a major problem: they sounded like flat, anemic, sterile, one-dimensional,
homogeneous blobs of quasi-monaural sound emanating from a spot between the speakers. In
short, my digital recordings lacked a soul. They just werent good enough, and
I poured out my frustrations to Marcia Martin at RR.
It turned out that KOJ, too, was very unhappy with the
sound he was getting at that time. By adding noise-shaped dither, discrete analog
electronics, and an improved conversion clock, he had substantially modified the Sony
PCM-701 UMatic Digital Encoder he was using at the time. KOJ would send his microphone
feeds simultaneously to his one-of-a-kind Focused Gap, three-channel, analog two-track
recorder. He was thus able to directly compare the analog and digital versions of his
master recordings. The releases KOJ made this way were labeled "Recorded with the
Sony/KOJ modified digital encoder."
However, from the proliferation of additive and subtractive
artifacts manifest in the digital domain as a result of A/D conversion, KOJ was painfully
aware that something was terribly wrong. This was certainly not the "perfect sound
forever" touted by the creators of the "Red Book" CD standard. Marcia
Martin consoled me: "Keith has decided to build a converter. By the looks of it, he
also has to design a decoder chip. The entire process may take as many as ten years."
She was trying to encourage me, but all I could see was ten more years in the wilderness.
By 1996, the wait was over. KOJ had teamed up with software
guru Michael "Pflash" Pflaumer to coinvent HDCD. In the conclusion of a 20-page
paper presented in November 1996 in Los Angeles, at the 101st AES Convention, KOJ and
Pflash stated: "A flexible conjugate encode and decode system has been described
which addresses limitations of the current digital audio recording standards, such as CD,
while remaining compatible for undecoded playback. The system deals with limitations both
in the area of amplitude resolution and effective frequency response."
My mind was made up. Sanch ordered the first of two Model
One HDCD converters from Pacific Microsonics. I spent a week in Berkeley with the design
and production team in June 1998, and liaised with Pacifics director of engineering,
Andy Johnson; general manager Mike Ritter; and others from the company.
Before final delivery to its customer, KOJ would put every
HDCD processor through its paces, using his own master recordings. "I would like you
to listen to playback from your instrument through this pair of powered
loudspeakers," he said to me. "I believe you would like their sound, I often use
them as monitors during my recordings." He had me sit and organized the session. The
system sounded incredibly palpable. Moreover, the speakers gave the illusion of being
physically much larger than they actually were.
"Who makes these speakers?" I asked.
KOJ smiled. "These speakers are not made,
Our conversation ran to a recording he had made in San
Francisco in 1976, of organist Virgil Fox, which had never been released. "Someday we
may resurrect this performance and release it on CD."
"What about dropouts and other losses due to
"We have enough brainpower in our company to
interpolate and restore the information lost due to tape dropouts," he
matter-of-factly replied. The recording was eventually released in 2006 as The Bach
Gamut: Live in San Francisco 1976 (RR-107).
I was on tenterhooks as KOJ listened attentively to a
couple of my own recordings. We then discussed at length how I might improve their sonic
quality. He suggested that I add a pair of cardioid microphones to accent image
specificity and enhance spatial resolution. In less than the blink of an eyelid, he drew a
schematic of a fully balanced passive mixer. "Do not do anything fancy, just space
the omnis as before and point the array directly at the source."
Keith gave me advice about how to proportion the signals
from both sets of transducers. "Remember that the resulting output is 6dB down and
would need to be amplified before being fed to the processor." My brain absorbed all
the information like a sponge. I would subsequently order a specially calibrated, matched
pair of DPA 3512 microphones from my friend Morten Stove, of Danish Pro Audio, and a
Classé CP 60 preamplifier to supply the gain. I have been in seventh heaven ever
The first thing I did on my return to Trinidad was to
remaster some of my old steel-band recordings in HDCD. KOJs interpolative processing
restored so much information that I subsequently released ten titles in a Special
Edition Series, each release including two CDs for the price of one. These have become
a very lucrative part of the Sanch catalog.
Gourmet delights from KOJ
Keith O. Johnson in 1957
Every KOJ production is my favorite
recording. I have had the distinct privilege of interfacing with many of the names who
would be listed in any Whos Who of high-resolution audio. Sterling
contributions have come from Doug Sax, Jack Renner, Jan-Eric Persson, Stan Ricker, John
Eargle, Bob Katz, Jacob Botheus, Kenneth Wilkinson, Paul Stubblebine, Winston Ma, Pierre
Sprey, Ray Kimber, and many others. They could all be seated at a Round Table of audio,
but KOJ would have to occupy King Arthurs chair.
I have always been finicky about my treasures. I purchased
two copies each of most of the RR vinyl titles half-speed-mastered by Stan Ricker for
playback at 45rpm, on the theory of one to play and one to stay. Whenever I can
find quality time, I play Däfos (RR-12), First Takes (RR-6), Tafelmusik (RR-15),
or Church Windows (RR-15), on either my Oracle Premier or Delphi turntable, with a
choice of McIntosh, Ortofon, Monster Cable, or Koetsu moving-coil cartridges.
I first heard Däfos in the Spectral Audio suite in
the Conrad Hilton, during a summer CES in Chicago. Through the Entec subwoofers, the
visceral impact of "Psychopomp" gave me the illusion of being very seasick. It
was as if the entire room were resonating. "The Gates of Däfos" and "The
Beast" scared the living daylights out of me. I thought a volcano was about to erupt.
On the other hand, the serendipitous collaboration of jazz
pianist Andrei Kitaev and double-bassist Bill Douglass in First Takes, recorded
June 12, 1978, at UCLAs Royce Hall, has always intrigued me. I have asked Marcia
Martin to find a way to negotiate for the reissue of this album (its currently out
of print) in their new HRx format. Here are the complete technical liner notes for that
release, concisely written by KOJ:
"These recordings are made in solidly constructed,
well seasoned and proven concert spaces. Microphones are classic generic types having
omnidirectional first- and second-order Cardioid and bi-directional pick-up patterns.
These are constructed from Schoeps, AKG and RCA elements, direct mounted to phase and
frequency compensating fast slew, class-A line-driving amplifiers. Microphone pairs used
for these recordings are phase and frequency matched to a 0.25" B&K precision
"The recordings are made without transformers, peaking
equalizers or phase-destructive microphone matrices, almost always encountered in
professional equipment. Microphone placement techniques range from simple omni pairs to
complex multi-space delay mixes to achieve full roundness of instruments with front to
back placement in a real space. Articulation and body-felt transient impact of the real
performances are preserved through the use of these techniques and by avoiding
production-efficient multi-mono studio mix downs.
"Microphone signals feed a virtually one-of-a-kind
Focused Gap magnetic recorder. This machine features a 3.5 megahertz beamed RF bias record
head capable of recording intense high frequency energy levels. The entire system has very
low time-delay modulation and signal-induced noise, as well as elaborate low- and
high-frequency phase equalizers.
"Coupled with a near O-loop transport mechanism, the
recorder has tonal purity and transient power not available from conventional recorders.
The master lacquers are cut directly from this machine playing its master tape, operating
at half speed to preserve the phase, transient and amplitude characteristics of the
original microphone signals."
The above pretty much summarizes the philosophy KOJ has
adhered to in his relentless lifelong quest for excellence. Apart from the microphones
described above, his other favorites are Coles ribbons and his own heavily modified
versions of Sennheiser FM designs, originally popular for motion-picture sound.
I have a feeling that KOJ has finally found his comfort
zone, his optimal recording space. The concert hall of the Morton H. Meyerson Symphony
Centre in Dallas, Texas, designed by acoustician Russell Johnson and architect I.M. Pei,
has an 85-high ceiling. Its 4535-pipe organ, the C.B. Fisk companys Opus 100,
was installed in September 1992. Mary Preston is the resident organist.
The facility is also home of the Dallas Symphony Orchestra,
the Dallas Wind Symphony, and the Turtle Creek Chorale. Before going to bed each night, I
fervently pray that KOJ will soon record a live performance in the Meyerson, so that I may
attend. Some of my digital favorites he has recorded there are: Postcards (RR-61);
a disc of the music of Respighi (The Pines of Rome, Belkis, Queen
of Sheba Suite, Dance of the Gnomes; RR-95); and Crown Imperial: Music
for Organ, Winds, Brass and Percussion (RR-112).
KOJs tireless, single-minded approach to honing his
craft into a finely delineated combination of art, science, engineering, innovation,
professionalism, and intuition has borne fruit. Not long ago he retired his analog
recorder, completely satisfied that HDCD represents the optimization of linear PCM
technology. The obvious intrinsic advantages of operating in the digital domain --
increased dynamic range, lower noise floor, ease of editing, and security of archiving --
have finally prevailed.
In 2000, Keith Johnson and Michael Pflaumer sold their HDCD
patents to Microsoft. In the cruel world of high-end audio, Pacific Microsonics could not
compete with Sony and Philips. Of course, Microsoft CEO Bill Gates and his empire could,
but they have peripheral interest in audio. One aspect of KOJs patents covers dither
with intelligence that could be used to change processes such as digital filtering, etc.
However, there is also a hidden code that can convey identification information for
tracing products or identifying processes that change or corrupt data. Microsoft uses this
aspect of HDCD to digitally watermark its software.
Pacific Microsonics closed its doors after making a
combined total of some 270 Model One and Two HDCD processors. Used units are still highly
prized. My friend Paul Stubblebine, who swears by HDCD, has a total of 12 of them in his
new mastering facility. As recently as last November, another very good friend purchased a
Model Two for $7500 and sold it the next day for $15,000. (He told me only after the fact
-- what a pity.)
Mike Ritter, Pflaumer, and a few other former members of
the Pacific Microsonics team recently established Berkeley Audio Design, and have since
launched the Alpha DAC digital-to-analog converter. Ritter told me that they may consider
development of a Model Three processor in a year or so. For me, this news has caused a new
bout of frustration.
HRx and the toys of men
"The holy grail of consumer audio formats has always
been to deliver to the listener an exact replica of the signal heard by the recording
engineer. Thats been a pipe dream -- the LP is a big step down in quality from
analog tape, CD is limited by its fundamental specifications, and even real-time copies of
analog tapes suffer from generation loss.
"New technologies, however, have narrowed the gap
between what the recording engineer and consumer hears. Although DVD-Audio and SACD at
their best can deliver high-resolution digital audio to consumers, its really the
advent of computer-based audio and Internet downloads that will usher in the new era of
Thus did prolific reviewer and author Robert Harley begin
"The Promise of High-Resolution Digital Audio Fulfilled -- Reference Recordings
HRx Format," an article recently published in The Abso!ute Sound.
Having read this far, you dont have to guess at the name of HRxs creator.
I am in the midst of a systematic upgrade. Based on
Harleys review of the Classé DAC 1 in the December 1995 issue of Stereophile,
I had acquired that D/A converter and a matching set of other Classé components: the
CDT 1 transport, CP 60 preamplifier, and CA 400 power amplifier. As fate
would have it, the transport recently failed, and Classé no longer provides technical
support for it. Meanwhile, I have an NAD M5 SACD/CD player, which includes HDCD decoding,
so I am in no great hurry. Sooner rather than later, super-high-resolution transports will
My retirement sound will most probably be delivered
by a Classé (theoretically) high-resolution transport, a Berkeley Audio Design Alpha DAC,
a Simaudio Moon Evolution P-8 preamplifier and Moon Evolution W-7M monoblock power
amplifiers, and speaker cables, interconnects, and power-conditioning components from
Audience, LLC. These will all feed my Rockport Technologies Altair loudspeakers.
Then and only then will I insist that Prof. Keith O.
Johnson and Marcia Martin accept my invitation to pay me that long-overdue visit, so that
I can entertain them in my own inimitable way. It is the least I can do to repay KOJ for
the kindness he showed me in serving as technical auditor for my work. Genius, in the face
of adversity, has been manifest in the flesh.
. . . Simeon Louis Sandiford