3 New UBER Decks - Is this Turntable's SwanSong? 🦢

I'm waiting for the TECHDAS AIRFORCE ZERO MK II to come out. Then I'll buy!

Re speed stability.
As has been noted, the numbers produced by the platter speed app vary from test to test. This depends upon how the tester placed the record on the spindle, there is a small amount of clearance, so the record can appear to have different amounts of eccentricity each time it is placed on the platter. Also it depends upon when the test is started relative to the point at which the arm is swinging in and out due to the eccentricity. There will be a different reading if the test started when the arm was at mid swing compared to if it was at the inner or outer extreme. You can see the impact of this on the green trace at the start of the plots. Some show an uptick or downtick at the zero second mark due to the arm being at or near full excursion, (AF0, XD1, AC-2, 1000R, K3), where one is neutral with the arm’s swing more or less at its mid point (TT-101).This biases the low pass numbers in favour of the TT-101. The length of time the test runs also impacts on the final outcome. Then there is the low pass filter that is applied to the raw data, this designed to remove the impact of the records eccentricity. It is somewhat a blunt instrument in that it also removes key data about the platters micro speed stability within each revolution.
It is possible to do multiple tests and pick the best or worst numbers to highlight whatever point you are trying to make.  A reasonable conclusion is that beyond a certain point, the numbers produced are of interest but are not particularly robust data.

But what is pretty consistent and robust from test to test is the yellow trace. (amplitude aside as mentioned above due to record/spindle positioning) The platter speed app is interesting in that it first plots the CARTRIDGE OUTPUT as a function of frequency with respect to time.
In a perfect world where the signal generator sent a constant 3150hz to a perfect cutting lathe, we stamped a perfectly concentric record and played it back on a perfectly speed stable TT, we would see the yellow trace as a straight line at 3150hz
But of course, this is impossible and one of the major deviations from perfection is that the record spindle hole is not in the centre. So if all other parameters were still perfect and we considered a non concentric record, we would see the cartridge output a clean sine wave, symmetrically centred about 3150hz with a constant amplitude per cycle.  IOW, a TT producing a yellow trace that is a badly distorted sine wave is NOT speed stable, although its speed could average 33.333.  I hope that this is self evident.
The program then puts this raw trace thru a low pass filter to remove the effect of eccentricity, we now have the green trace. But what the low pass filter does is filter distortion as well. This distortion is a graphical representation of rapid speed changes. It is no longer visible and what we are left with is a smoothed average which is used to compute the low pass filtered numbers.

A far more accurate and useful metric of the speed accuracy of a TT is to simply look at the raw yellow trace, ignoring the numbers. How close is it to the ideal symmetrical, clean, constant amplitude, sine wave?  Some of the TTs mentioned in this thread, plot significant deviation from this ideal with quite rapid and frequent speed changes.
Remember that the yellow trace is the cartridge output plotted as frequency with respect to time, any distortion of the sine wave is a change in frequency, thus a change in speed. These speed changes would be superimposed on any music that was being played. With this in mind, I invite you to look again at all of the speed plots

.
On top of this conundrum, the platter speed app does not load the system dynamically since the 3150hz tone is of constant amplitude.  This is a whole different set of  equally important measurements. We do not listen to constant amplitude, single frequency tones.

BTW two of the TT plots posted have a low frequency oscillation with a period of approximately 9 seconds. A low frequency oscillation with a multi second period like this is not uncommon and is very difficult to eliminate.

Cheers,

Thanks, Richard.
Mijo, people like you put Tower Records out of business. That was a joke, but my point is that one cannot act as you suggest these days in the USA due to the dearth of brick and mortar LP stores. The ones we do have are primarily selling used LPs, each of which is unique. I don’t think one could get away with such buyer behavior doing business by mail order. Good story, though.

Technics SL-1200 MK7

   Will last 40 years with minimal maintenance,....yes please. 
   The asking prices for those TTs’ is just astronomical, and overpriced.  Search most expensive audio gear, some of this stuff is mind blowing. 
 

Dear @mijostyn : Then probably have to return all your  LPs:

""  One thing to note is that there is nothing to prevent the eccentricity to be different on the two sides of the record. For example, the record may be perfectly centered on one side but off on the other, or it may be off on both sides but in different directions. ""

What do you think on that?. I found it somewhere.

Btw,:

https://blog.fluance.com/off-center-pressings-on-vinyl-lps-what-is-it-and-how-can-you-correct-it/

Now, in the past I bougth an item to " fix " manually the LP off-center and it works fine. I still have it somewhere and I remember that fix it but you need time/patience to do it and in those times I was more or less ignorant of the developed distortions by the off-center LP hole and a little lazy to fix it. The seller disappeared in short time.

R.