Measuring turntable speed

All the strobe things is what they are. 

But it lacks the resolution 3150 Hz (number/second) of  and the industry standard of DIN IEC 386 (formerly DIN 45507).
Like the "Feickert Platter speed" app.

I it is not in android app store (or Apple store). I just downloaded the app from here and side loaded it on android. 
(It side steps security so there is a risk. But you all have a old android phone laying around that can be used for this highly important task! ;) It will cost you $0.)
https://apkpure.com/platterspeed-vinyl-tool/ch.progtec.PlatterSpeed

Not just it has better resolution and graphs it also do the measurements exactly as when you are playing a record.
With the mass from it and you can use the clamp you usually use. And with the stylus in the groove with its tiny drag. 👍
In comparison I have never played a record with a phone on the platter. I see those low resolution apps more like a party trick and nothing when I want accuracy and the speed fluktration. (But that is maybe just me)

Just a discarded android phone and a record with a 3150 Hz track and you are done.

@optimize, how does one know if the 3150 hz tone was cut by the lathe at exactly 33.3333 rpm? 

I didn't read all the posts carefully.
Has anyone mentioned to measure the speed, whichever method you want, with the diamond in a groove?

Speed is different when playing music.

I guess one question is how accurate you are looking to get as yes an Android phone app is not going to be the last word in accuracy.
But if all you are looking for is to get very close and check stability they are free and fairly decent.

How many here are going to claim they can hear the difference between 33.30 and 33.40 say as long as speed is constant?

I know I cannot......

PS. That does NOT mean I am not going to strive for 33.33 but just saying.....

Cousinbilly, you are absolutely right. You have to be able to measure the speed with the record playing which big_greg's device will do. I have the Road Runner on my SOTA so I can compare big_greg's device to that and use it to check the SME. Hard to go wrong for $15.00.
As an aside, is turntable speed all that important. I think not as important as speed variations like wow and flutter. The absolute speed could be off 1 or 2% and most of us myself included would not know. The only time I ever noticed it was when I was synchronizing the turntable with the computer to compare digital vs analog versions of the same record.