Vintage DD turntables. Are we living dangerously?

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.

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...🎧