New Teres Direct Drive Motor Available as Option

Dgarretson,
Dougdeacon is completely right about the profile of the motor pulley being slightly bulged in the center. While my Delphi uses a belt, the convex profile of the pulley keeps the belt perfectly centered. It never touches the flanges above and below the belt during operation.

Lewm,
First, you say that stylus drag might be a good thing. It might, but there is much more to it than stylus drag. My instincts tell me that a cutting head cutting a lacquer puts much more drag on the lathe's platter than a modern stylus does playing vinyl. The trick might be to use a lighter platter than that of the cutting lathe and, along with a stylus, hope that the speed variances are about equal in magnitude and duration.

Second, I would love to hear what some people in the record making industry have to say about speed variances in cutting lathes, but I fear whar I might hear. I think a lot of people into "pro audio" seem to think that we're nuts and that we shouldn't hear any difference between A or B, whatever they might be, or that we couldn't possibly hear something so subtle, whatever it is. How often have you heard that?

Whether my point has any validity or not will take A LOT of very careful experimentation that I bet will NEVER be done, but let's for a second assume that it has no validity what-so-ever and that cutting lathes are rock solid with respect to speed stability. If we assume this, then all the rim drive (Teres), mylar or tape drive (Galibier/Teres) belt drives with massive platter (Maplenoll/Walker) turntable designers are just wasting their time trying to reinvent something that has rock solid speed stability and has been around for years.

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?

I think it's important, Jj, but we do already have vacuum platters, reflex clamps, ring clamps, and concave platters to help with warps.