Direct Drive turntables

I too have fallen for the "sound" of DD turntables.

I have for the past 10 years had VPI and now TW Raven AC-3 and before that the LP12 since 1985.

My recently bought vintage Exclusive P10 & P3 DD tables have a vitality and control in the bass and lower mids that I can't seem to get out of my Raven AC-3 as effectively. the Raven is spot on as far as speed goes, so it is not just speed control.
It seems more the ability to start and stop musical notes like a F1 car and at the same time be sound continous.

My route to DD heaven is a little different to some of the others as I was looking for am integrated table and the Exclusive tables fit the criteria perfectly. Both have very nice wood plinths, have effective suspension (P3 has better plinth isolation), have tonearms that offfer a great degree of resonance tuning, have fixed headshell & removable hdeadshell tonearms and sound fantastic as well.

early days for me, however the P3 is monopolizing the playing time at the moment :-)

The term speed accuracy is often misused and misunderstood. It usually is meant as average speed. The speed accuracy numbers quoted are always average speed and are mostly meaningless. Our ears are quite insensitive to average speed and most of us do not have sufficient pitch sensitivity to detect a 1% error and nobody is capable of hearing 0.1% errors.

Speed stability on the other hand is very important and our ears are remarkably sensitive to extraordinarily small deviations. Tiny, short term (less than 1ms) deviations cause a host of problems like smearing, loss of detail and loss of pace. Every turntable has some amount of variation and in my opinion no turntable in existence has been able to reduce speed variations totally below the threshold of audibility.

As Mike mentioned the same principle is in play with digital jitter. It has been well established that jitter in digital audio is clearly audible even though the amount is infinitesimally small (billionths of a second). Great strides have been made to reduce jitter but like analog I doubt that anyone has been able to completely push it below audibility.

I think that there are a number of sound, theoretical reason for the superiority of DD. For example DD in theory is much better able to deal with the effects of stylus drag. This is a controversial subject because it would appear that stylus drag is too small to be audible. That may be the case but there is good evidence that techniques that attempt to reduce stylus drag effect result in better sound.

Mike, Raul,
Actually, the 0.001% Raul quoted is equal to 10 parts per million (it already has the percent sign there). Lots of Japanese DD tables had a 10-20 parts per million speed accuracy spec (at least using the most advantageous measuring method), but those tables which also had a quote for speed drift limitations generally allowed a lot more speed drift than that. I expect that the Rockport, along with the P3 Shane has, and some of the other expensive motor tables, limited allowable drift to about that level as well, and then used a variety of methods to reduce the speed/violence at which deviations were brought back to normal (i.e. platter mass, a drag function, torque attenuation (P3 has a torque attenuator circuit), etc).

" most of us do not have sufficient pitch sensitivity to detect a 1% error..."
This would refer to 'Perfect Pitch' detection

"our ears are remarkably sensitive to extraordinarily small deviations..."
And this would be 'Relative Pitch', which many more people have.

Inherent speed stability is one of the indisputable side-benefits of high inertia (i.e. high platter mass - raw mass....).
Stylus drag - while still kind of a nebulous issue - is best addressed by securely clamping, pressing (by means of clamp (sic..), peripherical ring, vacuum - whatever suits you best) the record onto the platter thus that there is no relative movement of the record to the spin of the platter while the stylus moves its way through the groove.
In any case speed accuracy as well as stability should only measured "in action". By following this routine stylus drag won't be any issue any more.
Here again the old principle to avoid the error in the first will always give superior results to correcting the error after it occurred.
In any case - on any turntable: as long as the record has any chance for a relative movement to the spin of the platter, there is no way to discuss speed stability, stylus drag or dd vs. belt/thread, idler wheel drive.
As long as the record isn't clamped down it is all an "orchestra manoeuvre's in the dark".