Pierre Lurne: Audiomeca's Turntable Designer
Linn in Scotland led the way in the '70s, but additional standard-bearers in the CD era have been SOTA, VPI, Well-Tempered Lab, and now Versa Dynamics in the USA, Audiolabor in West Germany, Micro Seiki in Japan, and Goldmund in France. It is widely known that the Goldmund series of turntables, from the Studietto to the incomparably expensive Reference, are the result of the activities of one Michel Reverchon; what is less well-known is that the technopreneurial Monsieur Reverchon has made use of the skills of a number of engineers, one such being Pierre Lurne.
Pierre Lurne's company took over responsibility for the manufacture of the straight-line tracking T3 tonearm in 1981, and was responsible for the design and manufacture of the Goldmund Studietto turntable in 1983 and the straight-line Goldmund T-5 tonearm the following year. These activities ceased last year when Goldmund moved the center of their operation from France to Switzerland, and Pierre introduced a turntable of his own, the $2700 Audiomeca J1, at the 1987 Las Vegas CES.
So who is this M. Lurne? And why does he persist in designing products to maximize the retrieval of information from black disc in these days of its eclipseat least as far as the mass market is concernedby CD? As the J1 is distributed in the USA by Madrigal Laboratories, they kindly arranged for me to visit their Connecticut headquarters in the early summer in order to get some hands-on experience with the turntable and meet with its designer. After a tour of Madrigal's impressive Mark Levinson manufacturing facility, we sat down over sandwiches and soda while I asked Pierre how he had gotten started in hi-fi design.
He explained that he had designed his first tonearm in 1968 when 20 years old, and, one thing leading to another, he formed the Audiomeca Company in 1979 to design and manufacture tonearms and to design turntables. His first turntable, designed in 1979, was called the "Minimum." Very big and heavy, it was never offered for sale but was a research vehicle to develop his ideas on turntable fundamentals. (A direct descendant of the Minimum is now marketed in France by Vecteur, a company best known in the US for its cable.) An important part of Pierre's background was his study of physics; virtually every detail of his products, as described to me in our conversation, was a direct consequence of the laws of physics.
His first commercial tonearm, for example, the Lurne Model 1 of 1980, was the result of a complete examination of the role of the tonearm in the French magazine L'Audiophile in September 1978 (Issue #6), published under Editor-in-Chief Gerard Chretien's byline. An area Pierre looked at in detail was the need to keep construction simple.
"The different parts of a turntable or tonearm should always be simple and as compact as possible. By doing so, you avoid vibration problems. When you have too many pieces, there's too much decoupling. And if you have too much decoupling, at the end of the story, you cannot understand what is happening on the disc. Loosen every screw on a turntable, for example, and the resultant decoupling means that the vibrations can't follow a path.
"It's the same in tonearm design. An important point of the design is that you must have a path for the vibrations in the arm. I used a unipivot bearing in the Model 1 for that reason. You need to choose a single path for the vibrations to leave the system, in effect to be grounded to earth. If you have two points, it is possible for the vibrations to return by the other one. With just one point, you have a mechanical diode; you say to the vibrations ~'go that way.' And you can then start to control what is happening in your system.
"Similarly with the counterweight. For years there has been a big debate about whether it is better to have a rigidly mounted counterweight or one that is decoupled. For a long time I preferred the fixed counterweight; otherwise, again, you don't know what is happening in your mechanical system. A decoupled counterweight may be good at certain frequencies, but the overall sound might not be as good as you expected."
The unipivot bearing may provide this mechanical diode effect, providing a lower-impedance path for vibrations travelling away from the tonearm tube than for those travelling toward it, but the fact that the motional center of gravity of the system is above the bearing tends to make it unstable, just as it tends to be very hard to balance a stiletto on its point. The system's center of gravity will tend to be off center with respect to the pivot point and the whole tilts with nothing to provide a restoring force. For motion along the axis of the tonearm, the counterweight and arm tube can be placed below the pivot point, much as a high-wire walker uses a pole to provide the necessary restoring force to be able to balance. For lateral motion of the tonearm, however, it is considerably more unstable. Conventionally, tonearm designers who are committed to using a unipivot bearing rely on the restraining effect of fluid damping. Pierre, however, produces a photograph of his original arm, and points out the two lateral outrigger weights on either side of the pivot point. These render the unipivot system more stable when it comes to lateral motion.