Turn table speed variation question

Thinking about the original post and other instruments possibly used for evaluation, electronic music or electronically generated signals, comes to mind. The pitch doesn't waver on these tones unless it's done deliberately.
Depending on your musical fare, I've heard records with out of tune pianos.

Standard wow and flutter test signal is a 3150Hz tone evaluated on a wow and flutter meter. This might not be a great test for subjective evaluation unless the table needs a new belt, but electronically generated harmonics with dynamic content, might. Offhand, I can't think of a good candidate though.

BTW, my previous referral to KOB being a 1/4 tone off was off the cuff and apparently wrong. The original record is a little bit sharp.
Regards,

Thanks for the Link Peterayer.....
Not a bad performance from the SME....
This is what any 'good' belt-drive table should be able to achieve?
There is a slight drift backwards of the Timeline mark from the beginning to the end.....but you will notice that he doesn't show the result when the arm is 'lifted' from the record or when it is 'dropped' on the record?
Nor are there multiple arms lifted on and off?
In my experience.....a belt-drive needs to be adjusted for correct speed with the cartridge 'tracking'.
I have yet to see one which doesn't suffer from 'stylus drag'?

Thank you Halcro. You are indeed correct about the SME needing to be
adjusted while the stylus is tracking the LP. There is no option for a second or
third arm on my table. So my result is basically the "real world" for
my situation. There is no doubt the a well designed DD table like the Victor can
deal with a changing load like playing three tonearms together on one LP better
than the SME. But I would hardly describe the SME, or an owner, as
"suffer(ing) from 'stylus drag'." I simply adjust the speed while
playing an LP.

In this link, you will find a discussion about the accuracy of the SME in my
video:

http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1320876538&&&/Turntable-
speed-accuracy-

Speed is slightly slow by .003% or 6/1000th of one rotation out of 73 rotations
over the course of the 5 minute video. The calculations were done by Tonywinsc
on 12/27/13.

A close examination of your Victor video also shows a slight drift to the left of
the blue tack mark over the course of the 4 minute video. You can notice this by
watching the right trailing edge of the laser dash as it moves to the left. At the
beginning of the video, the blue tack is basically in the center of the laser dash,
but after four minutes, the dash is to the left of the blue tack and just barely
touching it.

This looks to be just slightly less than the 1/2" drift that the SME does,
but it is hard to tell precisely.

I have started a thread over on WhatsBestForum which asks for submissions of
similar videos to ours in an effort to create a database of turntable speed results.
So far, your Victor and my SME videos are the only two videos that I have located
on YouTube to include in the database. Perhaps others will add videos to the
thread and database. Here is a link:

http://www.whatsbestforum.com/showthread.php?13137-Turntable-
SpeedWhat-matters

I'm hoping that the thread prompts a discussion of the differences between
various drive types and the distinction between speed accuracy and speed
stability. Clearly, your Victor excels at both. Perhaps you would like to make a
video of your TW Akustics and add it to the database.

Small correction: 5.2 minutes of playing time is 173 revolutions. You dropped the "1". :)

Keep in mind that closed loop speed control systems like used in DD turntables will compensate for changes in load (such as dropping a needle on a record or raising it) and depending on the amount of torque that the motor has- the platter may hold speed even with light pressure of your finger applied to the edge. But closed loop speed control has its own design challenges.
I suspect belt drive became popular because open loop motors w/o controllers is much cheaper to execute and high mass platters do a lot to smooth out the speed variations; not to mention easier to apply isolation and dampening from vibrations. In other words- belt drive offered more bang for the buck. In the end, given the resources and proper design execution, the type of drive system becomes a moot point. I think Peter's website, if successfully populated with data from various types of turntables will reach that conclusion.

Fleib, electronically generated tones can indeed be a very good way to
judge pitch stability. This brings up an interesting issue related to the
previous discussion about the tuning of acoustic instruments, and the
"improvements" in intonation of some modern instruments, and
why these "improvements" are not always a slam-dunk and
often have a clear downside. Some modern instrument manufacturers
attempt to bend the laws of physics and acoustics in an attempt to correct
some of the traditional and naturally occurring pitch issues in acoustic
instruments. A very simple example would be this: the clarinet, being a
cylindrical vs conical (saxophone) woodwind instrument overblows the
twelfth as opposed to the octave. IOW, the first naturally occurring
overtone is an octave and a fifth. For argument's sake, lets assume that
the first (lowest) note on the instrument is a "C". The easy part
is getting the first twelfth ("G") to be fairly well in tune, then you
have to start finding the absolutely correct placement of the tone holes as
you ascend the scale. You may be able to determine a good placement of
the tonehole for the first note after "C" ("D"); but
then, because of the mathematical imperfections of the harmonic series
(and other issues) what might be a good placement of the "D"
tonehole in relation to "C" below it, that D's twelfth
("A") may be too sharp. So, what to do? Leave it that way, or
do you "force" the instrument to sound that "A" lower
in pitch by manipulating other aspects of the design by, perhaps, making
that tonehole's tube slightly taller? Some modern instrument makers strive
to "correct" all these naturally occurring problems and do so
with quite a bit of success. So what is the problem? Most players will tell
you that the more an instrument's natural tendencies have been
manipulated, the more difficult it is to play in tune within an ensemble
comprised of some of these "improved" instruments. These
intruments have less "core" in their sound because the naturally
occurring harmonics are not allowed to manifest themselves and then there
is a less-well defined pitch center. You can't fool Mother Nature! While, on
the surface, all this may seem to have little to do with the issue of pitch
(speed) stability in turntables, it should at the very least highlight how
crucial issues of pitch and intonation are in just one aspect of music
making. So, why should they be any less important in its playback?

****I'm hoping that the thread prompts a discussion of the differences
between various drive types and the distinction between speed accuracy
and speed stability. **** - Peterayer

IMO, we audiophiles don't pay enough attention to pitch issues. No one is
suggesting that we can't enjoy our music if our turntables are not spinning
at the absolutely correct speed with perfect consistency. But, considering
how we agonize over tiny differences in the tonal quality of some of our
gear, it makes no sense to not give as much consideration to pitch. Just to
give an idea of just how sensitive the human ear is to pitch variation:

We are all familiar with the routine of the oboist "giving the A" at
an orchestral concert. More times than not the oboist gives that A by
playing to an electronic tuner that is supposed to be extremely accurate. It
is not uncommon for players tuning to that oboist's A to, pretty
unanimously, feel that the A is slightly high or low; this in spite of the fact
that the electronic tuner is saying that it is dead accurate. The human ear
can tell when the pitch is leaning one way or the other before our
measuring equipment can.

I have never used any technical method for judging my turntables' speed
stability other than an occasional strobe disc, choosing instead to set my
motor controller's frequency by ear and the use of recorded reference
pitches that I then check the tuning of. To the naysayers that feel that
absolutely correct speed accuracy AND stability are not important, I would
say that they are missing out on a significant amount of what the
performances on their LP's have to offer on MUSICAL grounds because of
the very profound effects that inaccurate speed accuracy has on the
musical intent of a recorded performance and the equally profound effect of
poor speed stability on the rhythm and timing of a performance. The same
way that the tuning "A" can be distorted to a degree that the ear
can detect while an electronic tuner can't, the effects of poor speed stability
on the rhythmic feeling of the music can be distorted in ways that are
subtle, and while not obvious in the usual sense, can make the difference
in our emotional reaction to the music.