Vintage DD turntables. Are we living dangerously?

A good point guys...
I recall on another Forum where someone used the Feikert Speed App to measure a CD player (a theoretically perfect 3150Hz sine wave) yet it produced a frequency response chart very much the same as the TT-101 albeit with slightly smaller ripples.

Whilst we are talking up the benefits of SOME vintage DD decks in relation to speed consistency and low wow and flutter.....it is not to say that surprisingly good results can't be obtained from certain belt-drive turntables.
Here is the Frequency Plot for my Raven AC-2 which is almost as good as that for the Victor and is better than that of even the VPI Direct...😱
Compared to other belt-drive models like the Wilson-Benesch and George Warren that I showed previously, it shows that 'smarts' and 'implementation' is everything in the world of analogue.
It also explains why I can happily listen to either of my turntables...😍
The main differences between a really good belt-drive and a really good direct drive is in the micro and macro handling-ability of 'stylus drag'.
With the Victors, the Frequency Charts (and Timeline tests) are the same whether an arm (or two or three) is tracking the record or not.
With the belt-drive however, the speed is different between tracking a record and not.
Now this may seem initially like no big deal...?
Just adjust the speed to be accurate when tracking a record....
But the 3150Hz test tone produces a steady state undemanding mid-frequency sine-wave.
The music embedded within vinyl grooves is an ever-changing torture test of low to high frequencies totally unlike the steady test tone.
If the belt-drive deck changes speed with the cartridge in the groove....it is also changing speed (at the micro level) with every change in frequency and amplitude within the groove.
The fact that most of us are not audibly aware (or bothered) by such an occurrence is highlighted by our abilities to be unperturbed by the Wilson Benesch.
But there is just something elusive to the experience of great speed-consistent analogue reproduction when you get used to it..😋

10-28-15: Halcro
Dover has comprehension problems (as well as others) with both my statements and those of Markus who designed the Feickert software.
The spikes in the generated sinewave are NOT "speed corrections generated by turntable error correction".

Halcro, read my post again - I wrote

Richardkrebs argued that the spikes were speed corrections generated by the TT error correction, but they could be caused by many things, all we know is that they are speed deviations.

The statement you ascribe to me was an argument put forward by by Richardkrebs. The second half of my sentence states clearly that my view does not agree with this notion. It is not I that has a comprehension problem.

10-28-15: Halcro
They are simply part of the software program to compensate for non-centricity of the test record and the effect it has on the steady-state 3150Hz test tone.

That statement is not correct. That is not what Markus says. Markus says quite clearly

That's what the spikes are coming from: it's a superposition of eccentricity and "real" WOW and flutter.

In engineering "superposition" is the overlapping of waves.
It is very simple - the raw data graphs are the sine wave generated by eccentricity (a) PLUS the wow and flutter ( speed deviations ) (b). The software uses a notch filter to remove the sine wave generated by eccentricity.
In a nutshell the deviations from a pure sine wave ( the spiky aberrations in the raw data graph ) are the wow and flutter as Markus says..

To verify this I went to the Adjust+ website and downloaded their manual. On page 37

Please note: most vinyl records are not perfectly centered. You will often see periodical fluctuations of speed at an interval of 1.8 seconds. This is exactly the time for one revolution at 331/3 RPM. In order to mask these effects, the recorded data is filtered using a steep 0.55Hz notch filter (results beneath "Filtered at 0.55Hz"). But please bear in mind that problems with the turntable bearing probably may also cause similar fluctuation patterns at 0.55Hz. These are also attenuated by the notch filter. Both values – filtered and unfiltered - are displayed.

This extract from the manual confirms that the unfiltered graphs are a summation of both the wow & flutter due to eccentricity and the wow and flutter to to the playback system ( TT/arm/cartridge ).

Guess what - in my previous post I stated if a TT had a fault that resulted in a regular speed deviation, like a faulty bearing, this would be assumed to be eccentricity and not reported in the filtered graph. The manual confirms this.

Lewm, I do not intend to be condescending, but where errors have been made they should be corrected.

Sorry Dover,
I did mis-read your Post.

Halcro, you're a gentleman. Thanks.