Vintage DD turntables. Are we living dangerously?

Fleib.
Copied here the reference to wow and flutter from the ET2 Dampening trough owners manual.

Food for thought.

"WOW AND FLUTTER
Wow and flutter, FM distortion and surface irregularities in the LP should all be grouped
together because, as we will see, they are all tied together.
When you cut a pure tone (say 1kHz) onto an LP and then play it back on a
turntable/tonearm/cartridge system, you would hopefully want 1kHz to come back. Something
close to 1kHz comes back, but rapidly being shifted up and down around 1kHz. If the frequency
is shifted up to 1001Hz and down to 999Hz within a short period of time, the amount of shift is
.1%. If the shift occurs less than 10 times a second, it is considered as flutter. The two measures
are generally lumped together and called wow and flutter.
“Weighting” is applied to the measurement to reduce the measurement’s sensitivity to very
low and very high rate of frequency shift. The actual amount of frequency shift is much greater
than the number implies. The weighting network is supposed to create a number related to a
subjective ability to hear wow and flutter.
Reviewers have incorrectly attributed wow and flutter to the turntable. Since the advent
of the belt drive turntable, wow and flutter has been purely a function of tonearm geometry, the
phono cartridge compliance with the elastomeric damping, and surface irregularities in the LP. In
our own lab we have measured many high quality turntables using a rotary function generator
directly connected to the platters of the turntables.
The measured results are usually an order of magnitude better than the results using a
tonearm and test record (conventional wow and flutter method). Further proof exists if you take
two tonearms, one straight line and one pivoted and mount them both on the same turntable. The
straight line tonearm will give a wow and flutter reading with the same cartridge/test record of
about 2/3 to ½ that of the pivoted arm (.03% < .07% to .05%). This is because the straight line
tonearm has a geometry advantage and lateral motion does not result in stylus longitudinal motion
along the groove of the record.
Another proof is to take two different cartridges, one high compliance and one low
compliance, and take measurements with both using the same turntable and tonearm. The reading
of wow and flutter will be different. All wow and flutter readings are higher than the rotational
consistency of the turntable
A damping track applied to a tonearm (straight line or pivoted), will reduce the measured
wow and flutter usually 10-30% and sometimes as much as 50%. ET-2 wow and flutter readings
with a typical cartridge and good turntable will usually measure (.02 to .04%) which is extremely
low for an LP system. With the damping track installed flutter readings with the ET drop still
lower and with one test record we measured readings as low as .007%.
Surface irregularities on the vinyl of the LP record are the primary cause of rumble or
random low frequency noise, which causes the tonearm/cartridge spring system to start
oscillating. This oscillation occurs continuously during playback. It is a primary cause of wow
and flutter and FM distortion in phono playback. Surface irregularities occur not as a part of the
record cutting process, but result from the molding process used in making the record
You can see visually small ripples on the surface of an LP as it is turning. These continuously
excite the tonearm resonance"

RK,
Just as I thought. Thigpen says, "Since the advent of the belt drive turntable, wow and flutter has been purely a function of tonearm geometry, the phono cartridge compliance with the elastomeric damping, and surface irregularities in the LP."

He's measuring tables with no load (absolute speed) and comparing to W/F measurements with cantilever oscillation thrown in. Yes, the belt drive tables are often more susceptible to external forces presented by a pivoting arm. This is not to say DD/idlers are immune, but I think we've all heard what happens with low torque tables of any type, when the needle drops.

This sales pitch is misleading because he takes TT speed stability out of the picture and replaces it with arm geometry, although benefits might be true for those with low torque tables.
I haven't considered W/F as a function of arm damping, but I don't like low torque tables. The term oscillation implies an increase in magnitude, but that's interpretive.
Regards,

Thanks for that interesting excerpt Richardkrebs.
I wish he had included the graphs, charts and figures to properly support his claims....
We of course are now able to graphically demonstrate some actual performance charts and figures for various turntables under test.
Dover still resorts to imagined 'monsters' from his antipodal 'sleep of reason' as witnessed by

4.The timeline only measures the arrival of a single point on the platter at the same place at each time. It does not measure what happens in between.

He strangely ignores the Feikert Frequency Response Charts posted which demonstrate a 'real-time' ANALOGUE print-out over a 30 second time interval....an interval comprising 16 revolutions of the platter....which disproves his (and your) theory of malevolent speed behaviour BETWEEN the Timeline recording interval.
It is indeed revealing that Dover has never had the intestinal fortitude to post his Final Parthenon turntable performances under both the Timeline and the Feikert Speed App yet continues to boast of its abilities. I am dubious in the extreme.....😎

As for your idea of testing the various arm/cartridge combinations on my TT-101...I don't believe the Feikert Speed App is accurate enough for this contest. In fact....if you conduct three 30 second test measurements with the identical table/arm/cartridge (without touching the set-up)...you will receive three sightly different results.
But as far as we can visually disprove Thigpen's theories, here are the Frequency Charts for my three arms and cartridges.
WE8000/ST
FR-64S
507/II
And just to show that not all DD turntables are the same here is the
Onkyo CP-1050
I have seen some good performance charts for some belt-drive decks....but just to show you what some are capable of....
Wilson Benesch
George Warren

Halcro.

Thanks for the tests. Do you have the companion numbers for each arm?
I was interested in any consistent differences between the arms/carts, which could go some way to validating BT's ideas. There was nothing else in my request.

As for Dover's and my comments about what is happening "between" each pulse of the time line. I was hoping that this topic was in the 'agree to differ basket', but since it has been raised....you only need look at the traces you have just posted. Sharp spikes on the raw trace... this is a servo in action! Rapid acceleration/deceleration of the platter. Yet the platters average speed is 33 1/3. The smoothed ( green) trace filters these spikes, so it tells only part of the story.

cheers.

Sharp spikes on the raw trace...this is the servo in action.

Hmm....both belt-drive turntables must also have servos....if that's what sharp spikes indicate......🙈