Turntable speed accuracy


There is another thread (about the NVS table) which has a subordinate discussion about turntable speed accuracy and different methods of checking. Some suggest using the Timeline laser, others use a strobe disk.

I assume everyone agrees that speed accuracy is of utmost importance. What is the best way to verify results? What is the most speed-accurate drive method? And is speed accuracy really the most important consideration for proper turntable design or are there some compromises with certain drive types that make others still viable?
peterayer
Ct, Altho I am currently a partisan of direct- and idler-drive turntables, I would nevertheless take those data you quoted (0% speed deviation at 5 kg.cm) with a grain of salt. The Technics uses a servo to keep speed stable, but a servo is not perfect in terms of avoiding "micro" changes in speed that it then has to correct for. So "average speed" may indeed not vary, but the devil is in those corrective measures mediated by the servo to keep the speed stable. The jury is out as to whether we can hear that happening. Some claim that they can. BD turntables pose entirely different problems as regards speed stability at the micro level. Some of us can hear that, too. Pick your poison.

kg.cm (kilogram X cm) must be a unit of Work or Energy. Work is defined as Force (F) acting through a distance (s); W = F(s). Kilogram is formally a unit of mass, but by convention we also refer to it as a unit of weight. Weight is mass X acceleration due to gravity (W = m(g)). The analogy to F = ma is obvious. So "weight" is actually an expression of force. That's what they taught me in college. It's a bit confusing, but I think that kg.cm is a unit of Work. (I've just been reading a book about how Einstein interpreted Newton, so I have been thinking about this stuff.)
Adult persons watching the laser spot on the wall instead of listening to the music. This hobby really become some kind of 'decadent bourgeous inclination' as Lenin would
call it.
Dear Nandric, focussing the eye on the laser spot frees the mind to set for a kind of "zen meditation" and allows the music to flow directly into the heart and soul of man ....
See - it always depends how you use things ..;-) ..... but I admit being part of the decadent bourgeous inclination of mankind.
After all it took us (mankind) a long way to get here...
Cheers,
D.
Hmm. Something not mentioned so far with regards to speed stability is soundstage. Anyone who has heard a good tape machine knows what I mean.

When the 'table speeds up and slows down the skating forces on any radial tracking arm will change. This in turn places forces upon the stylus. In effect, the lateral tracking force of the stylus oscillates. IOW we hear the speed variation as an instability in the soundstage.

Tape is immune to this sort of thing. So are straight tracking arms.

When the machine is really good at speed stability, and if you have a concentric LP(!) then the soundstage will match that of tape.

When the total speed is off, sometimes I hear it due to the pitch, other times I hear it due to the timing. Musicians play things in certain keys and tempos for a reason. With some pieces a speed error is of no consequence and with others it means the heart and soul of the piece is not transmitted to the listener...
Dear Daniel, While Marx is your countryman I refuse to believe that my German friends are 'petty bourgeous'. On the contrary you are all the world citezens with some peculiar hobby. However 'love makes blind' is a Dutch proverb. Not easy to choose among the social rules between so many countries btw.

Regards,