Siegfried Linkwitz was born in Germany in 1935. He received his electrical engineering degree from Darmstadt Technical University prior to moving to California in 1961 to work for Hewlett-Packard.
During his early years in the USA, he did postgraduate work at Stanford University. For over 30 years Mr. Linkwitz has developed electronic test equipment ranging from signal generators, to network and spectrum analyzers, to microwave sweepers and instrumentation for evaluating electromagnetic compatibility.
He has also had a long and distinguished second career as an audio engineering visionary.
Along with Russ Riley he developed the famed, and widely used, Linkwitz - Riley crossover filter in the mid-1970s.
Since then, he has contributed several important technical papers covering a variety of measurement and speaker issues to such publications as the Journal of the Audio Engineering Society, Electronics (Wireless) World, and Speaker Builder.
On the left Russ Riley, on the right Siegfried Linkwitz
Bob Katz is a self described audio mastering engineer who is known for his book on audio mastering. Katz has mastered three Grammy award-winning albums and one nominated album. He has received acclaim from audiophiles and his book on mastering has received acclaim, and some reviewers consider it the "definitive work on mastering". He has also came up with a proprietary system called K-Stereo and K-Surround. These processes supposedly "recover lost or amplify hidden ambience, space and imaging, and generate stereo from mono signals without adding artificial reverberation."
Katz taught at the Institute of Audio Research from 1978 to 1979. In 1988, Katz joined Chesky Records and began recording jazz and classical artists there, as well as producing oversampled commercial recordings. In 1990, he founded an audio mastering company called Digital Domain Mastering, where he continues to work.
Harvey Fletcher (September 11, 1884) was an American physicist. Known as the "father of stereophonic sound" he is credited with the invention of the audiometer and hearing aid. He is remembered as a trail-blazing investigator into the nature of speech and hearing, and for his numerous contributions in acoustics, electrical engineering, speech, medicine, music, atomic physics, sound pictures, and education.
Among the work that he is best known for are Fletcher's contributions to the theory of speech perception. He showed that speech features are usually spread over a wide frequency range, and developed the articulation index to approximately quantify the quality of a speech channel. He also developed the concepts of, equal-loudness contours, loudness scaling and summation, and the critical band. As Director of Research at Bell Labs, he oversaw research in electrical sound recording, including more than 100 stereo recordings with conductor Leopold Stokowski in 1931.
Much of his research is considered to be authoritative, and his books, Speech and Hearing and Speech and Hearing in Communication, are landmark treatises on the subject.
Dr. Fletcher was elected an honorary fellow of Acoustical Society of America in 1949, the second person to receive this honor after Thomas Edison. He was president of the American Society for Hard of Hearing, an honorary member of the American Otological Society and an honorary member of the Audio Engineering Society. In 1924 he was awarded the Louis E. Levy Medal for physical measurements of audition by the Franklin Institute. He was President of the American Physical Society which is the leading Physics society in America. In 1937 he was elected vice-president of the American Association for the Advancement of Science. He was a member of the National Academy of Sciences. He was also a member of the National Hearing Division Committee of Medical Sciences. He was given the Progress Medal Award by the American Academy of Motion Pictures, in Hollywood. For eight years he acted as National Councilor for the Ohio State University Research Foundation.
Fletcher was the Founding Dean of the BYU College of Engineering (now the Ira A. Fulton College of Engineering and Technology).
He died on July 23, 1981
"Big" Mick Hughes
"Big" Mick Hughes is the live audio engineer for Metallica, a position he has held since 1984. He is also currently sitting in the FOH seat for Led Zepplin!
He was born in 1960 and grew up in Birmingham, Warwickshire, England. While an apprentice at British Steel, he studied electronics at a local technical college and also gained experience on the thriving Midlands music scene. In the early 1980s, he engineered for bands including UB40, Dennis Brown, Yellow Man, and Jungle Man before becoming the touring sound engineer for The Armoury Show, who featured ex-The Skids singer Richard Jobson (television presenter) and ex Siouxsie & The Banshees guitarist John McGeogh.
The Armoury Show's management company QPrime then asked Mick to engineer a band they had just signed called Metallica (prompting Mick to ask "What's heavy metal?" when told the genre of music they played) starting a relationship that has lasted over 20 years.
Big Mick has mixed Metallica at every one of the more than 1500 shows they have performed since then, gets a dedicated mixing console, and is to be called by his moniker according to his contract.
The live mixing technique he is often credited with is adding a high mid "click" to bass drums, which evolved early on with Metallica as a means of lifting Lars Ulrich's bass drums out of the bottom heavy sound. A more recent crusade is to encourage engineers to start soundchecks with ambient mikes (such as vocal mikes) working through to close miked or gated instruments (such as drums). This is in direct opposition to the usual soundcheck which starts with the kick drum and ends with the vocals, but actually makes a lot of sense.
When not busy with Metallica, he has also worked with Halford, Ozzy Osbourne, Def Leppard, Queens Of The Stone Age and Steve Vai. He produced the album 'World Service' for rock band Radio Moscow in 1991. He managed The Wildhearts in the 1990s and has worked with them live and in the studio since their reunion in 2002. After Metallica, the band he is most strongly associated with is Slipknot who he has worked with between Metallica tours since 2001. He has even done sound for a Slipknot tribute act, Slip-not.
In 2007, he was asked to mix the FOH sound for the Led Zeppelin reunion concert at London's O2 Arena in conjunction with Robert Plant's personal vocal mixer Roy Williams. They used the facilities of the Midas XL8 digital mixing console to allow them to do this on a single desk. He consciously did not use the clicky Metallica bass drum sound, preferring instead to update John Bonham's ambient and reverberant drum sound by using a mix of close and ambient drum microphones on Jason Bonham's kit, brought into phase using a 3 or 4ms delay, and finished with a small amount of digital reverb.
Hafler had an enormous influence on several generations of audiophiles and music lovers. A graduate in mathematics from the University of Pennsylvania, Hafler served as a communications specialist in the Coast Guard during the Second World War. In 1950, he founded Acrosound, a transformer manufacturer. In 1954, he founded Dynaco, a name that became synonymous with good sound and good value. Hafler's entire career was built on the concept of providing great performance at an affordable price.
His first company's "Dynakits"—preamps and power amplifiers in kit form - were assembled by hundreds of thousands of enthusiasts in the 1950s and '60s, a period when audio was primarily an engineering hobby and most good-sounding gear was built by its owners. Several Dynaco products from the period are still regarded as among the best ever made, including the ST-70, a 35Wpc stereo tube amplifier with a highly efficient push-pull output circuit. The ST-70 was the prototype for most similar designs that followed from other companies. The Dynaco Mk.II, a 50W amplifier, was featured in a media display in the Smithsonian's Museum of American History in Washington in the 1990s. (A detailed history of Dynaco can be seen here.) Hafler sold Dynaco to Tyco in 1968, but stayed on in an advisory capacity until 1971.
In 1972, he founded the David Hafler Co., continuing the tradition of inexpensive kits, but also offering pre-assembled products. The company produced many near-legendary preamps, among them the DH-101 and DH-110, and a line of MOSFET power amps, including the DH-200, DH-220, DH-500, and XL-280.
The DH-500 and XL-280 were among the earliest high-power amps available at accessible prices. Relatively easy to assemble and elegantly designed, Hafler products spawned a secondary industry in audiophile modifications, including the well-regarded work by Musical Concepts. Always pushing the boundaries of audio reproduction, Hafler did some of the earliest experiments in surround sound and ambience retrieval, including popularizing an ingenious method that extracts the difference signal from a stereo pair by wiring a third speaker across the hot leads.
Hafler sold his namesake company in 1987 to the Rockford Corporation of Tempe, Arizona, where it is still based. The Hafler Company makes audio products primarily for the professional market, where the brand is valued for its excellent sound and reliability.
Hafler's name is permanently etched into the history of audio - along with those of Saul Marantz, Avery Fisher, and a handful of other pioneers who built the industry in the mid-20th century. David Hafler was inducted into the Audio Hall of Fame in 1984.
Manfred Schroeder studied mathematics and physics at the University of Göttingen in Germany. In his thesis he investigated the distribution of resonances in concert halls using microwave cavities as models. The chaotic distribution he found is now recognized as characteristic for complex (non-integrable) dynamical systems.
In 1954 Schroeder joined the research department of AT&T Bell Laboratories in Murray Hill, New Jersey. From 1958 to 1969 he directed research at Bell on speech compression, synthesis, and recognition. Since 1969 he has also served as a Professor of Physics at Göttingen, commuting between the University and Bell. Since 1991 he has been University Professor Emeritus.
Schroeder is also a founding member of the Institut de Recherche et Coordination Acoustique/Musique of the Centre Pompidou in Paris. In the late 1950s he helped to formulate the U.S. standards for stereophonic broadcasting, now used worldwide. Schroeder holds 45 U.S. Patents in speech and signal processing and other fields.
Schroeder has written three books: Number Theory in Science and Communication; Fractals Chaos, Power Laws: Minutes from an Infinite Paradise; and Computer Speech: Recognition, Compression, Synthesis.
In 1991 Schroeder was awarded the Gold Medal of the Acoustical Society of America for "theoretical and practical contributions to human communication through innovative application of mathematics." He also received the Rayleigh Medal of the British Institute of Acoustics, the Helmholtz Medal of the German Acoustical Society, and the Gold Medal of the Audio Engineering Society.
Schroeder is a Fellow of the American Academy of Arts and Sciences and the New York Academy of Sciences. He is also a member of the National Academy of Engineering in Washington and the Göttingen Academy of Sciences.
Paul W. Klipsch
Courtesy of: Klipsch Audio Technologies
Paul W. Klipsch is one of America's most celebrated audio pioneers because he revolutionized the way the world listens to recorded music. Unsatisfied with the sound quality of phonographs and early speaker systems, Mr. Klipsch used scientific principles to develop a corner horn speaker that sounded more lifelike than its predecessors.
The Klipschorn, which today is still manufactured and sold worldwide, proved that it was possible to reproduce the sound of a live orchestra inside a home. The resulting acoustics career of Mr. Klipsch spanned from 1946, when he founded one of the first U.S. loudspeaker companies, to 2000 when the Journal of the Audio Engineering Society published one of his papers. He died on May 5, 2002 at the age of 98.
Fred Klipsch, a cousin to PWK and current Klipsch owner and chairman, said, "Paul was a verifiable genius who could have chosen any number of vocations, but the world sounds a lot better because he chose audio. He was a great man who always tried to do the right thing in the right way."
In 1978, Paul W. Klipsch was awarded the Audio Engineering Society's highest honor, the prestigious Silver Medal, for his contributions to speaker design and distortion measurement. Mr. Klipsch was inducted into the Audio Hall of Fame in 1984. In 1997, he was inducted into the Engineering and Science Hall of Fame, an honor shared by Thomas Edison, George Washington Carver and the Wright brothers. The Engineering and Science Hall of Fame recognizes those who have improved the quality of the human condition through an individual contribution using engineering and scientific principles. Then at the 2004 International Consumer Electronics Show (CES), he was inducted into the Consumer Electronics Hall of Fame. The Consumer Electronics Association (CEA) established this Hall of Fame in 2000 to honor the leaders whose creativity, persistence and determination helped shape the consumer electronics industry into what it is today.
Mr. Klipsch received a Bachelor of Science in electrical engineering from New Mexico State University in 1926, a Masters of Science in electrical engineering from Stanford University in 1934, and a Doctor of Laws from New Mexico State University (NMSU) in 1981. The NSMU engineering department was renamed the Klipsch School of Electrical and Computer Engineering in 1995, in honor of Paul W. Klipsch.
Mr. Klipsch's interest in engineering was influenced by his father, an instructor of mechanical engineering at Purdue University in Lafayette, Ind. Although he was only 12 when his father passed on, Mr. Klipsch's interest in science and engineering endured. He built his first speaker using a mailing tube and a pair of earphones at the age of 15, which was a year before the first public radio broadcast.
After graduating from El Paso High School, he enrolled at NMSU where he played cornet in the university band and was an award-winning member of the school rifle team. He credits his four years as a member of the Aggie Band for developing his love and knowledge of music and musical instruments.
Following graduation from NMSU, Mr. Klipsch went to work for General Electric designing radios that were then sold to RCA. In 1928, he responded to a notice on the GE bulletin board. This resulted in a new job maintaining electric locomotives in Chile for three years before entering graduate school at Stanford. After receiving his Masters Degree, Mr. Klipsch worked as a geophysicist for a Texas oil company. He later served in the U.S. Army during World War II, earning the rank of Lt. Colonel.
It was during his service at the Southwest Proving Grounds located in Hope, Ark. that Mr. Klipsch refined his corner horn speaker design. Visitors to his officer's quarters were amazed by the lifelike reproduction and encouraged Mr. Klipsch to start his own manufacturing business. He received a patent on his loudspeaker design in 1945, registered the name Klipsch & Associates in 1946, and began making each loudspeaker with his own two hands until he hired his first employee in 1948.
During a 1999-videotaped interview, Mr. Klipsch claimed that he did not, in fact, name the Klipschorn himself. He said that he made a sales call to a man in New York City during the first years of operating Klipsch & Associates and, surprisingly, the business prospect already knew about the revolutionary new loudspeaker. "We've heard all about your corner horn," the man said. "We call it the Klipschorn."
The eccentric touch and no-compromise spirit of Paul W. Klipsch has indeed become part of the consumer electronics industry, the practice of engineering, and acoustic research itself. For example, Mr. Klipsch related that when he was developing a smaller speaker for use between two Klipschhorns, an acquaintance declared that he couldn't possibly introduce it to the public because it was in direct violation of Mr. Klipsch's own corner horn principles, and amounted to acoustic heresy. "The hell I can't," Mr. Klipsch said. "And that's exactly what I'm going to call it!" A year later the Klipsch Heresy loudspeaker was introduced and, ironically, it became a bestseller in the church sound reinforcement market.
In addition to the Klipschorn and Heresy, the Klipsch Rebel, Shorthorn, Cornwall, La Scala, and Belle Klipsch are among the most well known loudspeakers developed by Paul W. Klipsch. Many of these models, which are regarded as some of the world's finest, are still manufactured and sold around the world today.
The Klipschorn is the only speaker in the world that has been in continuous production, relatively unchanged, for over 60 years.
Peter D'Antonio (Founder of RPG Diffusor Systems)
Peter D'Antonio was born in Brooklyn, New York, in 1941. He received his B.S. degree from St. John's University in 1963 and his Ph.D. from the Polytechnic Institute of Brooklyn, in 1967. Dr. D'Antonio has specialized in a wide variety of scientific disciplines including spectroscopy, x-ray and electron diffraction, electron microscopy, software development, and architectural acoustics.
In 1996, Dr. D'Antonio retired after 29 years of research in diffraction physics at the Naval Research Lab, Washington, DC. During his scientific career, Dr. D'Antonio published widely and was a member of the internationally renowned Laboratory for the Structure of Matter, headed by Nobel Laureate Dr. Jerome Karle. As a musician and recording engineer, Dr. D'Antonio maintained a separate concurrent career in the music industry. In 1974, he established the current standard for modern recording studio design at Underground Sound Recording Studio, Largo, Maryland, where he pioneered the development of the reflection-free zone (RFZ) concept and the reflection-phase grating (RPG) diffusor system.
Dr. D'Antonio is president of RPG Diffusor Systems, Inc., which was founded in 1983 to carry out basic research in room acoustics and to develop designs and innovative number-theoretic architectural surfaces, to enhance the acoustics of critical listening and performance environments.
Dr. D'Antonio has significantly expanded the acoustical palette of design ingredients by creating and implementing a wide range of novel number-theoretic and fractal devices, for which he holds many trademarks and patents. He has lectured extensively on architectural acoustics and his designs and diffusor systems have been used in over a thousand recording, broadcast, educational, performing and residential listening applications all over the world.
Dr. D'Antonio has published numerous scientific articles in technical journals and magazines and his research is referenced in many acoustical texts. He currently serves as Chairman of the AES Subcommittee on Acoustic's Working Group SC-04-02 for the "Characterization of Acoustical Materials"; is a member of the ISO/TC 43/SC 2/WG25 Working Group for the "Measurement of the random-incidence scattering coefficient of surfaces"; and has served as adjunct professor of acoustics at the Cleveland Institute of Music for the past ten years.
His current research interests include surface shape optimization, performance acoustics and diffusion and scattering coefficient measurement methodology. He is a Fellow of the Acoustical Society of America and the Audio Engineering Society, a member of CEDIA and Institute of Noise Control Engineering.