Four high-end audio enthusiasts from diverse aspects of the audio community – Mark Dohmann, Eric Jacobs, Dr. Steven Levene and Jacob Heilbrunn – share their opinions on Negative-Stiffness vibration isolation. By Jim McMahon.
Since the early 2000s, Minus K Technology, the developer of Negative-Stiffness vibration isolation, has released several vibration isolation platforms for the high-end audio market. These products have been accepted with high acclaim by audiophiles and audio system manufacturers worldwide.
Aside from the acknowledgment of its technical performance, Minus K’s Negative-Stiffness vibration isolators have generated considerable interest because they operate as a totally passive device. No vacuum pump, and none of the extra noise that goes with a pump or the complexity that it brings to an audio system. It also does not use electricity. If audio systems can be isolated from vibrations without having to deal with compressed air or electricity, then it makes for a system that is simpler to install, easier to set-up, and more reliable to operate and maintain.
Minus K’s Negative-Stiffness platforms are known for isolating vibration down to 0.7 Hz vertical frequency, which has set the low-frequency standard for vibration isolation, not just in audio reproduction, but in ultra-sensitive nanotechnology scientific research.
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| Schematic of a Negative-Stiffness isolator. (Image courtesy Minus K Technology) |
Vibration isolation in the playback process of high-end audio systems is crucial. Any external vibration, no matter how slight, even someone walking near the turntable or vibration from floor-mounted speakers, is sensed by the turntable’s stylus and affects the sound being played back from the record. Capacitors, resistors, transistors, tube amplifiers and other electronic components are likewise sensitive to vibration.
External to the building, audio equipment can be influenced by vibrations from adjacent road traffic, nearby construction, loud noise from aircraft, and even wind and other weather conditions that can cause movement of the structure.
Vibrations in the range of 2 hertz (Hz) to 20,000 Hz will influence the sound reproduction in audio systems. But these internal and external influences primarily cause lower frequency vibrations which are transmitted through the structure, creating strong disturbances in sensitive, high-end audio systems. Depending on how far away the audio system is from these vibration sources, and where in the structure the audio system is located, whether on the third floor or in the basement, for example, will determine how strongly the sound quality will be influenced.
How critical is vibration isolation to high-end audio playback? Four audiophiles, representing various aspects of the audio community, comment on this, and their experience with Minus K’s Negative-Stiffness.
MARK DOHMANN
Director of Design & Systems Architecture, Dohmann Audio
“Analog audio is a very detailed and information-rich storage and retrieval mechanism,” said Dohmann. “Vinyl remains unsurpassed for reproducing music. Every aspect of the turntable design requires the preservation of the micro-signals found in the grooves of the LP, to be retrieved with as little modification and distortion as physically and electronically possible.”
“To convey vinyl’s rich, nuanced potential a turntable must have precise speed control and operate without producing mechanical or electronic noise,” added Dohmann. “The goal is an uncompromised signal emerging from a silent background, resulting from precisely designed construction that eliminates noise and gives precision speed control for ideal playback.”
“The enemy of retrieval information is vibration, which can modulate with the needle as it works its way through the groove,” continued Dohmann. “If you can remove exterior vibration and allow the needle to operate in an optimally quiet method or platform, then you will get more information out because your noise is much lower.”
“Analog audiophile aficionados talk about blackberry notes, where the base is too prominent and muddy,” explained Dohmann. “This is often caused by a reinjection of vibration into the playback mechanism, adding to the amplitude of the needle movement and creating more signal than what is physically in the groove. Negative-Stiffness vibration isolation cleans this up, so that the base is more natural. The timbre of the instrument used to produce the base, whether a string, piano or drum, sounds more like the real thing. It enables a sense of peace and calm to the playback.”
The Helix One® and Helix Two® turntables incorporate a number of engineering advances to deliver the lowest resonance profile for any pickup arm and LP combination,” said Dohmann. “They come fully integrated with Negative-Stiffness vibration isolation. The turntable sits directly on top of the Negative-Stiffness isolator. At this level the isolator becomes the turntable.”
“The Helix One and Helix Two turntables set new benchmarks for performance in Analog,” continued Dohmann. “Coupled with a Schroder CB arm and Negative-Stiffness vibration isolation, these tables offer unsurpassed sonic results. An immediate distinction in terms of sound accuracy is noticed by experienced listeners. This is not a direct-drive sound, rather it presents as an organic rightness with macro and micro dynamics that astonish.”
“The ability of Negative-Stiffness to deal with vibration and resonance is unsurpassed, and allows the music to be enjoyed with an outstanding level of realism,” added Dohmann.
DR. STEVEN LEVENE
Audio Enthusiast, Professor of Bioengineering, University of Texas at Dallas
“When higher-end turntables are designed, a lot of attention is paid to the quality of the bearings, and inertia from the platter, those are the components that seem to get more emphasis,” expressed Levene. “Cost and benefit analysis is done, and since every installation is different turntable manufacturers do not appear to pay as much attention to vibration isolation.”
“My first experience with Negative-Stiffness was when I purchased a unit for my 85-pound turntable many years ago,” said Levene. “I lived in a house that was built in 1927, and had a lot of trouble with vibrational feedback. Now, even though my sound equipment is set up in the basement, and is resting on a solid slab, the Earth produces lots of vibrations. The same Negative-Stiffness isolator is continuing to be effective at countering these vibrations.”
“This addition to my analog source has allowed me to hear everything that is on the LP by thoroughly isolating the playback system from ambient vibrations,” continued Levine. “It is difficult to overstate the benefits of this level of isolation to analog music reproduction. It’s now possible to appreciate the full scale and dynamic range of an LP recording. The technical specifications are impressive, and should be considered mandatory by anyone who is serious about vinyl playback.”
“My university research involves working on problems having to do with the interactions of proteins that organize DNA to tertiary structures that are biologically important,” explained Levene. “Because of my success using Negative-Stiffness vibration isolation on my home audio system, we now use it in our laboratory to isolate vibrations on our ultra-sensitive atomic force microscopes, particularly for isolating vibrations in the low-scale hertz band, which has enabled our research.”
ERIC JACOBS
President, The Audio Archive, State-of-the-Art Audio Transfer
“Most manufacturers of high-end turntables recognize that external vibration is a problem, and will go to great lengths to minimize it in their turntable designs,” said Jacobs. “Quality turntables, for example, are built with superb platter bearings to minimize rumble. Some turntables use air or magnetic bearings, and other sophisticated approaches. They often incorporate high-mass platters that are designed to increase speed stability and reduce flutter. They might use exotic materials to dampen vibrations without deadening the sound. Tone arms have their own set of vibration and resonance characteristics which manufacturers attempt to isolate from the audible frequencies through geometry, localized vibration isolation and damping. Turntable designers go through this elaborate process to try and eliminate vibration throughout the entire turntable playback structure.”
“Having thoroughly tested systems available to the audio market and generally been unsatisfied, we then looked outside of the audio world and conducted an in-depth search of industrial vibration isolation systems,” explained Jacobs. “We learned about Negative-Stiffness vibration isolation, which was being used to eliminate vibrations in ultra-sensitive atomic force microscopes, and in nanotechnology labs where objects are literally built one molecule at a time. As we learned more about Negative-Stiffness isolators, the more interesting it seemed for audio vibration isolation.”
“After extensive testing in our own audio laboratory, which is outfitted with extremely sensitive and accurate audio reproduction systems and measurement equipment, we confirmed that Negative-Stiffness isolators are unrivaled in vibration isolation for high-end audio reproduction,” continued Jacobs. “Negative-Stiffness isolators were not just a little bit better, they were significantly better. Whether with turntables, tube electronics, CD transports or other audio equipment, these isolators provided an unheard of 0.7 Hz isolation performance vertical, and 1.5 Hz horizontal, using a totally passive mechanical system – no air or electricity required. We were not really expecting to find a passive vibration isolation system that outperformed an active system – that was a big, and very pleasant surprise for us.”
“What is very advantageous about Negative-Stiffness isolators is that they achieve a high level of isolation in multiple directions,” said Jacobs. “Not just vertically, which is very important for audio systems to isolate against footfall, but also in all horizontal directions. The horizontal direction is often overlooked because horizontal building vibrations that are transmitted to the turntable are less obvious.”
“With Negative-Stiffness isolators there is a sense of harmonic rightness,” added Jacobs. “Instruments sound much more like real instruments, and voices sound like they are in a real acoustic space, with real air around them. The ability to see clearly into the entire three-dimensional soundstage is greatly enhanced. Improvements in rhythm and pace are captivating. Negative-Stiffness isolators truly represent a significant advance in sound quality for high-end audio.”
JACOB HEILBRUNN
Senior Contributing Writer for the Absolute Sound
“I’m a pretty serious audiophile,” said Heilbrunn. “My audio system is in a large, acoustically-finished room in my basement. Even though the basement has a solid slab, the Earth still produces lots of vibrations.”
“My turntable is a Continuum Caliburn, with dual Cobra tonearms,” explained Heilbrunn. “The turntable sits on a platform, and coupled directly underneath to the platform I have a Minus K isolator, which I have used for nine years. I also have a Minus K isolator situated under my preamplifier and CD player.
“I have tried various vibration isolation systems, and the technical specifications of the Minus K are impressive,” continued Heilbrunn. “It is very effective to counter these vibrations.”
“The turntable tracks the LP better,” said Heilbrunn. “The sound is audibly improved with greater clarity. The treble, the base, it’s more musical. It really improves everything.”
“The isolator adds, no that’s not correct, it removes the extraneous noise and allows you to truly experience the robustness of the performance,” added Heilbrunn.
ABOUT MINUS K TECHNOLOGY, INC.
Minus K® Technology, Inc. was founded in 1993 to develop, manufacture and market state-of-the-art vibration isolation products based on the company’s patented negative-stiffness technology. Minus K products are used in a broad spectrum of applications including microscopy, nanotechnology, biological sciences, semiconductors, materials research, zero-g simulation of spacecraft, and high-end audio. The company is an OEM supplier to leading manufacturers of scanning probe microscopes, micro-hardness testers and other vibration-sensitive instruments and equipment. Minus K customers include private companies and more than 300 leading universities and government laboratories in 52 countries.
Dr. David L. Platus is the inventor of negative-stiffness isolators, and President and Founder of Minus K Technology, Inc. (www.minusk.com). He earned a B.S. and a Ph.D. in Engineering from UCLA, and a diploma from the Oak Ridge School of (Nuclear)
Reactor Technology. Prior to founding Minus K Technology he worked in the nuclear, aerospace and defense industries conducting and directing analysis and design projects in structural-mechanical systems. He became an independent consultant in 1988. Dr. Platus holds over 20 patents related to shock and vibration isolation.
For more information on Negative-Stiffness isolators please contact Steve Varma, Minus K Technology, Inc.; 460 Hindry Ave., Unit C, Inglewood, CA 90301; Phone 310-348-9656; Fax 310-348-9638; email sales@minusk.com; www.minusk.com.