How important is low W & F performance anyway?

@lewm 

I think the earliest version of the 301 did use a grease lubricated bearing which then became the eddy current brake that RB describes

My Garrard 301 is the grease bearing type, and has the eddy current brake.  I am pretty sure the eddy current brake was there on every Garrard 301 and 401.

If Garrard had chosen a synchronous motor, the actual speed of the platter would depend predominantly on the diameter of the pulley on the motor shaft.  Actually, this pulley is stepped with separate diameters for 33, 45 and 78. Getting all three diameters exactly right for every deck would have been impossible, back in those days, in my opinion.

Aftermarket suppliers like the Classic Turntable Company offer replacement pulleys in multiple size increments, and recommend getting a pulley which positions the braking knob on the lighter side.  Different pulleys are needed for 50-Hz and 60-Hz operation.

These units were designed to run 24 x 7 in broadcasting studios.  The BBC would have been fastidious about speed stability, back in the day when they had a dozen self-directed audio engineers, whose speaker designs are still influential today.

@phoenixengr 

The W&F numbers for both tables are typical of belt/idler drive, but speed accuracy is more problematic.  The Holbo has a DC motor which has a negative torque/speed curve

Yes.  I posted here for several reasons.

One was to provide a data point (I cannot personally detect wow and flutter with my tables).  Maybe that's two data points.

With a plethora of standards and measures within those standards, just quoting a number is pretty meaningless unless you also quote the standard and the measure.  I was impressed with the way Garrard describe exactly what their measurements involved, and that they individually test every 301.

As I mentioned, the Holbo is pretty much a black box to me - two black boxes if you count the power / air supply box.  There is a four-wire cable from the power / air supply box which powers a DC Japanese motor (about 4-Watts) and transmits switching information, at the very least to tell the power supply when to switch on, and that the turntable has been switched off.

Garrard goes to great lengths to allow speed accuracy to be observed and corrected via a big front knob which adjusts its eddy inducing magnet.  The feedback loop is via the operator and big strobe markings cast into the rim, though.  In my experience it hardly ever needs adjusting.

Another reason behind my post was to suggest that wow and flutter can be measured and reported separately.  When these measures are combined, the same number could arise from low wow and high flutter, or high wow and low flutter.  There are unlikely to be equally annoying.

The various standards have differing filter curves, presumably to prevent rumble from affecting the flutter results, and long-term instability from affecting the wow results.  The separation of wow and flutter is at 4-Hz, as far as I know, and the curves are designed to reflect human sensitivity.  Most tests last only a second - you can't get a long-term speed stability measure in that timeframe.

At first glance, a wow and flutter measure seems to tell a casual observer the % range which a turntable's speed variation won't exceed.  Unfortunately there is much more to the standards than meets the ear 

I’m curious about the impact of platter mass on wow and flutter. My VPI has a 22Lb platter, and given Newton’s Law of F=MA , or as would be more relevant here, F/M = A, increasing the platter mass M from say, 2.2lbs to 22lbs wow, which is due to eccentricities, would be unaffected, but flutter certainly would be: the increased mass reduces the potential flutter acceleration A by a factor of 10.

Also, there has been little discussion of rumble, which is primarily a function of bearing quality, mitigated to some degree by the platter mass and/or damping. Back in the day, our entry level turntable, the Pioneer PL-12D had quite a nice tonearm, and a relatively light cast zinc platter belt driven by a synchronous motor. The only noticeable issue with it was rumble. Upgrading to a Thorens TD-160 resulted in an audibly quieter background, which we attributed to bearing quality. 

What are others experience here?

Right concept, wrong formula.  The relevant formula is for rotational inertia which for a uniform flat disc is : I=m*r^2/2.  Inertia is directly proportional to the mass, but proportional to the radius squared, so where the mass is located is more important than the mass itself.

My first table was a Pioneer PL-12DII, bought it for ~$100 in 1973 IIRC.  Hard to beat for the price, it even had a built in overhang checker.  I don't recall rumble being an issue but I did not have a better table to compare it to.  The only problem I had was the belt which stretched out over time and the slippage caused the speed to be slow by almost 10%. Since it happened slowly over time I didn't really notice it until I replaced the belt.