2008 RMAF – – – all things analog.

There is no question that stylus drag does cause speed variations. The only question is if the variations are large enough to be audible. Our ears are remarkably sensitive to extraordinarily small errors in the time domain. With digital audio it has been well documented that tens of pico-seconds of jitter is easily heard. That seems vastly too small to be heard, but yet it is. With analog it is no different. Very subtle changes anywhere in the drive system are easily heard. Different belts, pulleys and even component quality in the electronics all make a notable difference in the sound. If capacitor quality can be heard in a motor regulator circuit (and it can) then it's not much of a stretch to imagine that stylus drag would also be audible.

Regardless of the theory, what is indisputable is the fact that many techniques targeted to reduce the effects of stylus drag produce audible, positive results. Stylus drag may or may not be the culprit for audible degradations that we all hear but to me it seems like the most logical explanation. It is imprudent to categorically dismiss stylus drag without evidence.

Platter mass cannot reduce the effects of stylus drag. A massive platter makes speed variation shallower but also spreads it out over a longer period of time. So the speed variation is really of the same magnitude but has a different distribution.

Raul, Stylus drag does affect platter speed. I am sure the the effect is small enough that it would be extremely difficult to measure. There is plenty of evidence that suggests that it is audible, but nothing that I would consider proof. A scientific measurement would be interesting but would tell us nothing about audibility. Only our ears can tell us that. The problem is that there is no practical way to remove the affects of stylus drag without changing other system parameters. So it is unlikely that we will see a definitive answer to the question anytime soon.

I see the issue of stylus drag as a well grounded theory because there is plenty of empirical evidence that supports it.

CD = Perfection... except for jitter. Timing errors seem to be an achillies heel for both analog an digital.

Jj2468, I should have mentioned this before. There are various types of speed anomalies that that are not manifested as pitch fluctuations. Very short term speed variations show up as smearing, lack of detail and often harshness. Longer term, shallow variations tend to make the sound sluggish and dull. Only a small subset of problems in a drive system sound like pitch variations.

It's interesting that the benefits from jitter reduction with digital playback sounds much like what I hear with improved analog drive technology.

Chris

Robdoorack, Thanks for the interesting data. The measurable deviation cited was more than I would have expected. As Doug points out the measurement time period is very significant. Most people are not able to detect relatively large errors in average speed. For the majority of us the threshold is more than 0.1% and nobody can detect a 0.0007% error. However short term deviations are a different matter. It is well documented that digital jitter of 10 picoseconds is audible. That's a short term deviation of 0.000000001%, one billionth of a percent! So it should not surprise us that a short term analog speed deviation 10,000 times greater would be audible.