Belt stretch

If the speed measures stable with a strobe then what pitch related anomaly can be heard?

1. Any pitch-related anomaly whose time duration from delay through recovery is shorter than the time that passes between two marks on the strobe disc. This would be a greater risk with low resolution strobes (ie, fewer marks per circumference).

2. Any pitch-related anomaly which slows the platter by precisely one (or any other whole number) strobe mark in 1/60th of a second (1/50 in some other countries). This would be a greater risk with high resolution strobes (ie, more marks per circumference).

A strobe isn't perfect. It's a an unnumbered, circular yardstick with markings giving it one very specific resolution. Changes that are completed below that resolution won't be detected. Changes that cause a whole number shift in mark position won't be detected.

You haven't responded to Mosin's or my suggestion: listen to a good quality belt drive table properly set up with a variety of belts. Hear the differences. Supply some explanation other than speed variation for the differences you'll certainly hear.

"listen to a good quality belt drive table properly set up with a variety of belts. Hear the differences."
Doug, that is exactly my point. If the tt is properly set up and all youve done is change the belt and it strobes the same as the belt you had on before mabey your not hearing speed variation mabey what your hearing has something to do with coupling, damping or? With all the enthusiasm for the idler drive lately why assume the performance is solely (or at all) due to speed regulation since it seems these small deviations have yet to be measured or quantified or much less correlated to a paricular hearing sensitivity.
Thankyou for the fun dialogue Ill sum up by saying "if you dont know what it is you dont know what it isnt" and in that spirit Ill be researching this much farther and will report back on any ground breaking discoveries

This is a shining example of what I was talking about in one of my earlier threads, "The High end and Glubglub". Lifted from a discussions in logical argument and philosophy:

"What he (the skeptic) wants it is logically impossible to supply. But doesn't the logical impossibility of the skeptic's demand defeat his cause? If he raises a logically impossible demand, can we be expected to fulfill it? He says we have no evidence, but whatever we adduce he refuses to count as evidence. At least we know what we would count as evidence, and we show him what it is. But he only shakes his head and says it isn't evidence. But then surely he is using the word "evidence" in a very peculiar way (a meaningless way?), so that nothing whatever would count as a case of it...Might he not just as well say, "There is no glubglub?"" In short, a waste of time.

"Doug, that is exactly my point. If the tt is properly set up and all youve done is change the belt and it strobes the same as the belt you had on before mabey your not hearing speed variation mabey what your hearing has something to do with coupling, damping or? With all the enthusiasm for the idler drive lately why assume the performance is solely (or at all) due to speed regulation since it seems these small deviations have yet to be measured or quantified or much less correlated to a paricular hearing sensitivity."

Actually, this isn't so hard. Take a turntable, your flavor, and try it without an outboard speed control, and then try it with a very precise one. Even you will hear the difference. But, there is a caveat; there always is, and that is the turntable itself has to be good enough that you can distinguish differences. The system needs to have halfway decent resolution, too. I assume this to be the case with the majority of AudiogoN members, but a better system will detect more than a mediocre one. You know that, however. I mention it only because I am aware of some turntables which have signatures that color a lot of the signal fed into them. Still, you will hear the difference, but maybe not so pronounced as you would with a perfectly silent running frontend.

Because we track our cartridges at anywhere from 1 gram to 3 grams or so, we tend to think that the braking action of the stylus in the groove is minimal and that a belt-drive is then able to overcome this negative force with ease. This is the first false assumption.

Stylus force drag is very serious indeed. I took the following from the website "www.Micrographia.com", (here's a link to Pressure) on the issue of the pressures involved: "Neglecting factors such as the elastic deformation of vinyl, the distribution of forces in a V-shaped groove and the accelerations at the stylus tip during tracking, simple calculation based on these figures gives a stylus pressure of 240 grams per square mm, or 340 pounds per square inch.

Johnnantais,
In a thread about belt stretch due to stylus drag you added the information above to the discussion, but either I or you are confused. You seem to think that the force seen by the belt and/or motor is something great, like 340lb/sq. inch. That is not the case.

A simple experiment (that you should not do!) is to put a 1"x1" block of wood on your TT, place a 340lb weight on top of it, hold it in place, and turn on the TT. Of course it's not going to turn at all. The pressures you noted above (if the calculations are correct) are only seen by the vinyl and stylus but never by the belt or motor. The forces needed to overcome the friction of stylus drag are minimal.

Here's an experiment that will be hard to implement but easy to think about. Imagine a cartridge attached to your finger with a string, tracking an LP that's turning on a TT. The cartridge would have to stay up somehow, of course. Use your imagination. Because there is no counterweight, also imagine that the 8 gram cartridge is not going to destroy its suspension and cantilever. How much force do you think you are going to have to use to keep your hand in one spot? You probably aren't even going to feel a pull on your finger... and that's with 8 grams of tracking force. Belts and motors don't see as much drag as you think.

FWIW, I don't disbelieve that belt stretch and rebound occur, I just think this is good discussion :) I do think that it's not as serious as some believe, though.