How important is low W & F performance anyway?

@faustuss There is no question concerning Bill’s credibility.  It makes no difference whether you find his information useful or not.  It certainly comports well with my experience and with what I have been learning since acquiring AnalogMagic.  Take it for what it is worth.  

https://audiokarma.org/forums/threads/checking-speed-wow-and-flutter-on-a-turntable.1000956/

"At a playback radius of 100 mm (which is roundabout at the middle of the LP playback area), a barely visible eccentricity of just 0.2 mm (which also happens to be the tolerance of most records standards) would already cause a wow of +/- 0.2 % peak or respectively ca. +/- 0.14 % effective/RMS."

-wondering how such low W&F can be measured at all! 

@westcoastaudiophile  @phoenixengr 

At a playback radius of 100 mm (which is roundabout at the middle of the LP playback area), a barely visible eccentricity of just 0.2 mm (which also happens to be the tolerance of most records standards) would already cause a wow of +/- 0.2 % peak or respectively ca. +/- 0.14 % effective/RMS."

You bring up a very good point.

Discussions I’ve had with Bruce Thigpen ( Eminent technology, Mapleknoll etc ),

are that records are useless for measuring TT performance for the reasons quoted.

He uses a rotary function generator to measure the actual platter speed to measure  wow and flutter etc.

Bruce Thigpen on 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 1⁄2that 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.

@phoenixengr 

I would tend to agree, but some of the numbers are high enough it's difficult to believe that no one could hear it.  Depending on the amount and band of the frequency deviation, I wonder if even reviewers (and certainly the average listener) don't realize that they are hearing it or perhaps it is perceived as some sort of euphonics or "voicing".

I used to distribute high end in the heyday of analogue - mid 80’s.

Most audiophiles can’t hear much - I was shocked when I started distributing high end. I’m not only talking about speed and timing, but also resolution.

Many audiophiles can’t tap their foot in time.

The other issue is that with an analogue front end, even if folk can hear differences they cannot scientifically attribute those differences to a particular design feature or flaw because most of the time they are listening in an uncontrolled environment.

If you read Bruce Thigpens comments I posted above - a wonky cartridge or poor quality tonearm can generate wow and flutter, more so than the TT itself. In fact the largest contributor to wow and flutter in a live environment is eccentric records ( most are to a degree ).

My concern with Bruce Thigpen's approach is that he ignores the obvious fact that what we really need to know is what records on our turntables sound like.  So, a measurement that isolates everything except the turntable itself, although, perhaps intellectually interesting is essentially useless if we want to correlate and measure what the arm + cartridge + turntable sounds like on music.  It is the combination that we are listening to after all.  I do agree from years of observation that a surprising number of self proclaimed audiophiles don't seem to hear very well.  It has been my recent experience using AnalogMagik, which for the record measures arm + cartridge + turntable, that just as Raul said very low numbers for wow & flutter, which I will define as approximately less than or equal to 0.2%, are essentially inaudible.  At least to me.  But when I measure 0.8% or higher, that level of W & F is audible.  Again to me.  I try to verify these tests listening to sustain on piano notes, which must not waver.  It has also been my experience, reflecting what Bill has observed, that the cost of a given TT and measured performance do not always correlate.  I have set up a couple that surprised me both better than expected and worse.