New Teres Direct Drive Motor Available as Option

It's generally accepted that a constant, steady platter speed will produce the most accurate reproduction. Above, Chris stated that a high mass platter will produce speed variances of low magnitude and long duration, and that light platters will produce speed variances of high magnitude and short duration.

A main goal of TT design is steady platter rotation, but could TT designers be barking up the wrong tree? Shouldn't we consider the speed variances of the cutting lathe and try to produce a TT whose platter mass, motor power, and stylus drag combine to approximate the speed variances of the cutting lathe? If the cutting lathe's platter slows down and recovers due to a heavy modulation, it might not sound right when replayed in your living room if your TT's platter also doesn't slow down and recover at the same rate. Is it possible that rock solid speed stability in TTs is actually a bad thing?

Ketchup - Your post is most intriguing, and brings up an interesting point.

Are most lathes direct drive?

Ketchup, One would need to know a lot more about how a cutting lathe works. Perhaps someone among us can enlighten the rest. But if your idea has any validity, then in effect "stylus drag" is a good thing. There seems to be a body of empirical evidence that this is not the case. I would guess that cutting lathes use powerful high torque motors that are securely connected to the lathe, so that heavily modulated passages are treated no differently from those that are less so. But I'm just guessing.

Lewm, empirical research (i.e. observation) for something as subjective as audio presents a very weak argument. I think Ketchup brought up a very valid point.

If we are to assume that physics tells us a platter will decelerate due to stylus drag, we would be mistaken if we were ignore the fact that the same force acting on the cutting lathe will have the very same effect.

From my own experience I have a few LPs that when listening to I have always thought that the transients were a little bit too quick and sharp to be real. (I am sure everybody on the BB has a few LPs that). I always put that down to the sound engineering ‘tweaking’ the recording a little, but Ketchup’s postulation does go some ways to explain the phenomenon. Simply put, it is not inconceivable that the cutting lathes used to create those LP’s slowed down more on transients than what my current TT slows down.

Sadly, we do not have any numbers or hard data pertaining to the amount of stylus drag and the effect said stylus drag has on a platter.

Regards
Paul

Just curious. Isn't the common warp in albums causing more variation in pitch than the differences between direct drive and belt drive?

I have a Cardas sweep record with what appears to be an average warp and the pitch variations are very clear as the stylus travels faster over the warp.

Am I wrong that flattening the record should come before worrying about belt versus direct drive in terms of pitch control and prat?