Turntable speed accuracy

Dear Tony,
You wrote, "the laser mark should drift slowly in one direction over the 30 minutes. That is the cumulative error" Yes and no. Yes, the drift of the Timeline laser over time is the cumulative error, but no (IMO), the laser may not drift only in one direction, as I wrote above. It could conceivably drift in either or both directions over a 30-min time frame. Therefore using the cumulative error over time as a standard might be misleading. You've got to sit there and watch that laser every single revolution.... (You are getting sleepy.... Your eyelids are growing heavy... You are in my power... You will do whatever I say...)

Hi Tony,
Yes....I think speed accuracy was indeed mastered over 30 years ago but as I mentioned elsewhere......with the dominance of belt-drive over DD turntables due in large part to the Linn propaganda and the reviewers who championed it.....'speed accuracy/consistency'.......never was mentioned as a critical factor in their design philosophy?
How do we get back to it?........I think discussions such as this is certainly one of the ways and thanks to the Timeline......I hope more designers and manufacturers will be able to judge their successes or failures and hopefully make some corrections?
'Awareness'.....is our best hope?
The .5mm speed drift I am seeing on the Raven AC-2 is almost negligible.
For instance.......the Victor TT-101 allows me to speed up or slow down, the actual speed of the platter in 6Hz increments.
33.33rpm apparently gives a pitch of 440Hz which is the de-facto standard
pitch for orchestras.
However many of the world's orchestras use a pitch either 6Hz or 12Hz up or down from this?
When I adjust the speed on the TT-101 to 6Hz lower (33.25rpm).....the drift from the wallmark is 5mm every revolution and when the speed is increased to 33.40rpm (6Hz higher).....again the drift is 5mm per revolution.
So the Raven.....running at 0.5mm per revolution could really be called...'spot-on'?

And Lew is right Tony......the Timeline is not so valuable in terms of 'cumulative' drift or speed error (as even a 6Hz pitch deviation will add or subtract 5mm drift to each and every revolution which will appear quite dire over the full side of a record).....rather it is the instantaneous speed drift due to stylus drag which is valuable for us to know about our turntable's performance?
Instead of 'fear' governing our apprehension of the Timeline and what it will reveal about our turntables.......we should really welcome this information.
Knowledge is power....and ultimately the more we know about our system's objective performance.....the more equipped we are to effect improvements?

I don't like to post without actual direct experience but here goes.

Based on my TT's and what I am "hearing" and also not owning this Timeline device.

A Belt/string or idler will do one of two things on a timeline over time.

If they are slow

<----------------

If they are fast

---------------->

A direct drive because of the nature of how the motor works goes back and forth.

The DD's can not be picked up by the timeline.

The stop - go, stop - go, stop - go, nature of the DD motor keeping speed.

The DD is only at a correct 33.3 “in transition” between the time the motor kicks in to speed up and shuts off to slow down. At all other times it is not at 33.3.

Am I wrong ?

And another thing. I am going to say a really dirty word here to some people – CD

Has anyone bothered to listen to a decent CD of your favourite music compared to LP as far as "pitch" is concerned.

I think you will be surprised.

Anybody?

Finally a message to SKSOS1 - is it your intention to have another thread shutdown ?

What is Sounds of Silence that you are affiliated with. You seem to be anything but silent. Please take Lew's advice.

Cheers

Hi Chris,

The DD is only at a correct 33.3 “in transition” between the time the motor kicks in to speed up and shuts off to slow down. At all other times it is not at 33.3.

I don't believe this is a fair assessment of the DD motor technology?
There is no difference I believe, to the maintenance of the speed via the motor of a belt-drive or direct drive. Each one has to monitor its speed via a pre-programmed sine-wave algorithm related to the power supply.
The differences between the two drive types I believe, has to do more with the speed of any correction applied once a deviation is detected?
In this.....a belt or thread drive is at a severe disadvantage.
The DD motor....usually with a lot more torque than that of a belt/thread drive....and being directly connected to the platter.....can correct deviations in micro-seconds theoretically inaudible to the human ear.
With some DD turntables like the Victor TT-101......there is instantaneous 'braking' correction as well as speed-up correction...thus not relying on the time lag slowing-down procedure after an increase is applied.
To my ears......this is a more optimum audible solution than the slow speed deviations and corrections allowed by some belt/thread drive decks?

One point not properly addressed so far.....is how idlers or rim-drives perform against the Timeline?
Perhaps Lew will be able to enlighten us on this?

"One point not properly addressed so far.....is how idlers or rim-drives perform against the Timeline?
Perhaps Lew will be able to enlighten us on this?"

As a idler user I would appreciate Lews results on his Lenco. I would also appreciate how his DP80 performs, you would think it would be spot on as the TT101. Halcro have you tried the timeline with your TT81?