Vintage DD turntables. Are we living dangerously?

Halcro, thank you for taking the time to confirm that my original assertions on the disadvantage of using a test record to measure Wow and Flutter were correct.

10-23-15: Dover
3. Using a record with a fixed tone is prone to error. Any eccentricity or imprecision in the surface of the record will generate wow or flutter.

As Marcus Ribi from Feickert says..

10-26-15: Halcro
.. Marcus Ribi from Feikert Platterspeed
The approximate sine wave form of the chart is resulting from eccentricity of the record. 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. That's what the spikes are coming from: it's a superposition of eccentricity and "real" WOW and flutter. Measurement of WOW and flutter then tries to best filter away the regular changes comig from record eccentricity to provide best results.

In the final analysis the key sentence in Feickerts response is "tries to best filter away the regular changes coming from record eccentricity to provide best results". The Feickert software uses algorithms to calculate and remove errors generated by eccentricity. These are an approximation at best.

If you had a faulty turntable with a regular error with each rotation, the averaged WOW & Flutter reported could understate the true WOW and Flutter if the algorithm ascribes the resultant speed issue generated by the fault to eccentricity".

10-26-15: Richardkrebs
Fleib.
The error resulting from record eccentricity is surprising.
Take a small 0.5mm eccentricity on a 100mm radius and we get around a 1% error. (The tracking radius makes a difference)
Nakamichi were on to something way back then.

Assuming for arguments sake that this number is correct, then given that record spindle diameters can vary from 7.09 to 7.21 then we are looking at errors of 0.2% even before we take record eccentricity into account.

Richard, given that most records are eccentric to some degree, could you explain why you have increased the horizontal mass of your ET2 by 300% adding lead to the spindle and removing the decoupled counterweight, when it is clear that increasing the horizontal mass will increase the wow and flutter on playback by a significant degree on eccentric records. The testing I did on my ET2 with removing the counterweight resulted in audible degradation of the sound.

Dover.

Yes "removing the counterweight" would result in a dramatic degradation of the sound!

As to increasing the horizontal mass of my arm by 300%. One needs to specify at what horizontal frequency this measurement is taken.
At 0.55Hz (eccentric record at 33 1/3 rpm) the leaf spring on the ET2 counterweight is stiff. IOW on a standard ET2, at a horizontal excitation of 0.55Hz, the mass of the counterweight assembly must be added to the weight of the spindle, wand and cartridge. This means that when tracing an off centre record, my cartridge sees more or less the same mass as one mounted on a standard ET2. (applies to average weight cartridges and associated counterweights)
BT has confirmed this and I posted his response on the ET thread, maybe you missed this?

Resonance transmissibility theory 101

cheers.

10-24-15: Halcro
Dover,
All you and Richardkrebs do is disparage every scientific test method we have available for turntables without ever offering an alternative.

Henry (Halcro)

I used to have this boss; who upon first meeting you in his office would say...

"Don't dare bring any problems to my attention without offering solutions."

Now I have no boss. But my wife is trying her best to become one :^(

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AudioGon Analog Forum ratings highest on Audiophile Saturday night in this part of the world, when Richard and Dover post in succession on a thread.

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

Richard - thank you for reminding me. Yes I see where I have gone wrong - I listen to music at full frequency range, including those above 0.55hz.