Direct Drive turntables

We have been here before. It is hard to say exactly why the best DD and the best idler-drive turntables seem to have more drive/pace/rhythm, because any differences in "speed accuracy" among all good turntables, including good belt-drive tables, are miniscule at most. One can invoke the factor of "stylus drag" and the ability of DD and idler-drives to maintain absolute stability in the face of this force. Yet one has to be skeptical that stylus drag could be of such magnitude as to play into this equation, especially as regards the massive platters of some BD tables that would seem to be able to overcome stylus drag by virtue of inertia. In any case, the measurements of speed accuracy that we read about are likely to have been derived by averaging the speed over a relatively long-ish time interval (even seconds constitute a long time in terms of musical transients). What I think we are hearing in DD and idler-drive tables that may distinguish them is speed stability over micro- or millisecond time intervals. Yet intuitively one wonders whether the servo mechanisms of dd tables can operate effectively in such a small time window. So, I don't know what's going on, but I like it.

Dear Lewm: +++++ " So, I don't know what's going on, but I like it. " +++++

this is all about.

I like to have very precise answers on the why's of what I'm hearing in some kind of quality performance but many times I can't have those precise answers ( IMHO no one have it. ) and what I have to do is just enjoying it.

Regards and enjoy the music,
Raul.

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).