Ears opened in Zurich
Just about the time I started looking into turntable motors, I attended the European Triode Festival (etf) in early December 2004. Christian Rintelen, one of the etf organizers had invited most of the American attendees to Zurich, Switzerland first, then drove us to the etf site in Langenargen Germany, just across Lake Constance. By the way, for a nice summary of the etf.04, see Lynn’s travelog and follow the links at the bottom of each page. On our first evening in Zurich, Christian had all of us: myself, Lynn Olson, Gary Pimm, Gary Dahl, Steve Bench, and Steve’s son over to his apartment for an evening of listening.
Christian Rintelen has a world-class system: Blue Thunder loudspeakers, home-brew tube amps, and an EMT 930 turntable with Ortofon tonearm and Ortofon spherical-stylus cartridge. He also has a fantastic record collection - mainly pop and early rock - many in early pristine pressings. We listened to many records on both his phono preamp and Steve Bench’s L-R preamp. The music was great and the sound outstanding. There was a slight lack of extreme highs that I attributed to the old-fashioned spherical stylus. However one thing that really struck me was the pace and drive of the music. Lynn and others noticed this too, and Christian attributed it to the EMT turntable. If you read Dr. Wilimzig’s article in Sound Practices (”Turn Your Table”), you will see a picture of the Platine Verdier turntable in Christian’s apartment - the archetype of the big-platter/small DC motor turntable. He, however, dumped it in favor of the EMT, mainly because of speed variations and poor pacing.
The EMT 930 is a German radio-station turntable of massive and rugged construction. The motor is a large three-phase induction AC motor coupled by a rubber wheel to the inside of the platter. It comes up to speed in less than one platter revolution. The platter is heavy, but nothing like the large machined billet metal platters of modern high-end turntables. The key aspect of this turntable is its strong AC motor directly coupled to the platter.
This was my first chance at hearing such an “old-fashioned” turntable in a world-class system, and the results were stunning. There was something special going on here.
I reported our listening session to my audiophile friends, and one of them, Rich Curtis, managed to pick up an old Garrard 301 turntable, and started comparing it to his SOTA turntable. The Garrard 301 is a well-built English turntable with a large AC motor coupled to the platter with a rubber wheel. With a modern arm and a Grado Gold cartridge, it was put up against his SOTA for comparison. During some careful listening sessions at his house, we compared the two. The Garrard had a higher noise floor than the SOTA, probably caused by bearing rumble, motor noise, or a hard rubber wheel. However, it had the same solidity of sound and precise pacing that I heard on Christian Rintelen’s EMT 930. This was apparent not just on pop music with a well-defined beat, but with classical music as well. It is really hard to explain the effect, since it doesn’t fall into the standard sonic categories I’m used to dealing with. I invite Lynn, Rich or others to comment here on this, but what I heard was a firmness and integrity to the music that was absent on other turntables I’m familiar with.
The importance of perfectly constant turntable speed probably is due to the incredible sensitivity of humans to pitch and rhythm. Music has a special place in the human mind - some regard it as an adjunct to the processing of language. Harmony and melody depend on the sensation of pitch and timbre while rhythm depends on precise pacing. Any variation in playback speed will affect both pitch and rhythm.
As I tried to understand the situation, it became clear to me that turntable rotational accuracy was affected by the variable drag of the needle in the groove. If the system supplying torque to the platter was not perfectly regulated, then as different music passes under the needle, the variable frictional loss will cause the turntable platter to change speed. This all intuitively makes sense, but how much is this variation, and how much can be heard? It was time to get quantitative and analytical about the situation.
Next posting: Getting quantitative.
here’s a (possible, but imho plausible) explanation why the EMT sounds so unstoppable: a felt pad soaked with oil is attached to the chassis. the pressure the pad applies to the underside of the platter can be adjusted with a set screw. the felt pad not only serves as a means to adjust the speed of the turntable - it also applies a quite strong and constant braking force. in other words: the motor is loaded and has to work against a resistance. this resistance is much higher than the drag that can possibly be caused by the modulation of the groove/needle interface. and because the motor has high torque and is directly coupled to the platter thru the idler wheel, the small variances in platter speed caused by variable needle drag will instantly be compensated.
i have witnessed the same improvement in PRaT when i applied a eddy current brake to my platine verdier with the help of a neodymium magnet positioned some millimeters away from the rotating magnet in the platter.
(this btw might also explain why high viscosity oil in turntable bearings is not the way to go and why garrards with grease bearings are said to have better PRaT than garrards with oil bearings… - imho it is a big big mistake to judge the quality of a turntable bearing by the time it takes the platter to come to a stand still w/o belt or similar attached…)