Is Direct Drive Really Better?

In my opinion first we need speed accuracy and the second most desired characteristic is speed stability.

My ears need both, equally.


Raul,
Please do extensive research on "brain masturbation" before posting about that topic again. We need clear and precise information on the subject, not speculations that cannot be corroborated. Lab-tested specifications from the manufacturer would be best. You probably have access to them!

Even a 1% static error alters the essential character of the music only very slightly, and even then usually only in direct comparison with the correct speed.

Alex,

That's the first statement you've made that I'll specifically disagree with. Given sufficiently transparent yet harmonically complex music, a 1% static speed deviation is quite audible. The music's harmonic structure will be damaged.

I'm not referring to anything esoteric. Mozart's orchestral scores are a good test. Nothing seems simpler, but his harmonic relationships are far more tightly inter-related that is usually appreciated. Change playback speed by 1% and they fall to pieces.

To be fair, this does require a very transparent sytem to be audible. Bloat or overhang from any component will readily mask the harmonic damage from a 1% static speed error. My old c-j and Bent components did. So do Aesthetix and Supratek, for that matter. Dan_Ed, Jyprez and Swampwalker could attest that our Nick Doshi stuff has the requisite transparency. When they visited recently I didn't specifically demonstrate the audibility of a 1% TT speed error. But I could have.

Having been brought to my mathematical senses, I concede the point (obvious to all but me) that harmonic relationships do not change with an absolute speed change, provided the speed is stable of course.

Makes me wonder what we're hearing though. We're doing a few experiments and (gasp!) measurements. Stay tuned.

Albert,

That pretty much settles the measurement issues. Thanks!

Dan,

Do you remember the color of the belt on the 320 and 280? That isn't as silly a question as it sounds.

While I don't believe a BD Teres will ever match a well implemented DD Teres (especially when the DD costs twice the price) it is true that torque delivery on a 320 is significantly affected by the choice of belts. I've probably tried more belts on a 320 than even CB has had time to play with. I'm curious which one he was using.

Doug

P.S. Two or three years ago I posted a thread describing belt experiments on our original Teres 265. I commented that the increased torque coupling from 1/2 mylar vs. silk thread had no real downside because the Teres motor was so quiet that motor vibration was a non-issue.
Eldartford made a wise observation: if the motor's so quiet why not make a direct drive? It looks like we're just about there, and that he was right.

That's the 2 mil mylar belt, which is a close second best of all the ones I've tried.

Dan may remember seeing a holographic silver belt on our table. It out-torques the 2 mil clear one by a small but audible margin, not because of the color (presumably) but because it's about 10% thicker. This seems to be the optimum material for this application. When I went up to 3 mil mylar the sound started going fat and soft again. That belt was too stiff to make the sharp turn around the motor capstan without slipping.

At any rate, that clear belt is quite good. This makes your report on the superiority of the DD table even more convincing.