Vintage DD turntables. Are we living dangerously?

Dover,
As you've already pointed out.......since the availability of the Feikert Speed App I have regularly stated that the Data downloaded on its 'Chart Info' was imprecise and non-scientific as it was not possible to duplicate the results from test to test.
On this point you and I are in agreement.
The Frequency Chart on the other hand, is a more reliable visual snapshot of the absolute speed and actual speed variations over a 30 second timespan if you observe the Low-Pass Filtered Frequency.
The Raw Frequency plot should be ignored as it is subject to the Feikert-designed software algorithms to enable the Low-Pass Filtered Frequency plot to be produced.
The jagged lines are part of their software programming to compensate for record eccentricity and do not indicate, as Richardkrebs erroneously proclaimed....."significant speed changes caused by the servo control".
IMO the low-pass filtered frequency plot is a viable tool for turntable performance comparisons as indicated by those I showed of the Wilson Benesch and George Warren.
The real shock was the realisation that both these turntables were able to be listened to without much concern....😱
Analogue is so forgiving...🎧

Chris,

There is this, how do I say it, intangible, hard to describe .........chemistry between them.

😎
Perhaps it's a Kiwi thing...❓
They may both settle down a bit next week when we beat them in the Rugby World Cup.....😜

Halcro.

The explanation from Marcus confirms my comments re the 14 speed changes in the first revolution.

Here is the relevant sentence...

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

The raw data tells us much about the nature of the platters rotation. We see the "real" WOW and flutter as distortion of the sine wave.

In other words, perfect speed would show just a sine wave symmetrically centred about the 3150hz line on the raw data graph. This then being filtered by their program to produce a straight line at 3150hz for the low pass graph.

cheers.

Richardkrebs...

In other words, perfect speed would show just a sine wave symmetrically centred about the 3150hz line on the raw data graph.

Markus Ribi...

A normal measurement of WOW and flutter with a perfectly centered record will NOT show such a wave form, but a more random spiky form instead.

Richardkrebs...

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

Halcro.

Perhaps you misinterpreted my last post.
When I said "perfect speed" I did not mean "perfectly centered".

A real world test record, which is off centre, produces the sine wave. Speed errors are superimposed on this sine wave, as Markus says.

So with a real world test record running at perfect speed, we would get the results I described.

cheers.

Go the ABs!