Stylus Drag

IT's been awhile, but with many older belt and DD tables from the 70's, back when I dealt with many, I do not recall the strobe indicating any measured slowdown in speed with record playing versus not with units in good condition. WIth units with worn or dirty belts, measured speed fluctuations with the strobes were often apparent and resolved with a belt change or good cleaning. I recall many of these did use servo motors of various types.

"Also, as several designers have schooled me, there is no such flywheel effect from heavy platters that compensates for this. "

Its basically inertia. A heavier mass in motion will require greater force (friction in case of stylus tracking a record)to change speed than otherwise.

That's why I would expect greater mass platters in motion to be less susceptible to small changes in drag/friction as the stylus tracks than otherwise.

ALso I suppose higher tracking force would result in greater drag/friction than less tracking force, so of course as in most things it all depends. Drag/friction is a fact but how significant it is is more up to debate I suppose and could vary widely case by case. It all depends....

For me, if the speed measures as accurate an stays that way and I do not hear any ill effects, I would not worry about it.

Of course, that will not stop some who really really care from fretting......

Yes, a platter does store energy. Apparently, that alone is not enough to counter stylus drag.

My Final Audio TT has a 19kg platter and very sophisticated motor drive, basically a huge AC motor driven by oscillator preamp and power amplifier which reconstructs sine and cosine waves for the motor and provides precise adjustability for both speed and torque applied to the motor.
As Halcro alluded to above when setting speed, I have to do that with the stylus in the groove.
Once set though it is very stable. In recent tests with the Timeline and KAB there was no speed change from heavily modulated passages both inner groove and outer groove.
Arm and cartridge were Naim Aro/Koetsu Black tracking a 1.8g

Andrew,

I have checked my speed on my BN with a digital readout through my computer using a program that is free called iSpectrum. What I do is play test frequencies and checked the Waterfall plot and it is spot on. My biggest factor is the belt. They need to be replaced when they get old otherwise you get a sling effect. But this has been by ear. I have excellent speed stability which I can watch on a screen. I don't use a strobe but instead the computer to set my speed. Seems to match the strobe though. Once set it stays put. I have checked it often and my speed stays steady.