Most accurate IOS app for turntable speed check

Sutherland Time Line. It is accurate to about 2 parts per million.

There is no way that anyones eye measuring a moving spot on the wall is accurate to 2 parts per trillion, so whilst it sounds impressive, it does not in of itself provide an accuracy check anywhere near what is claimed.

Personally I have found the KAB to be very good. ( Best value ) It is also easy to check the speed with the stylus playing on the record as well ( outer part of record ).

Shknspin2 is really good if you want to see how your TT is performing with wow flutter etc.

RPM and other apps I have tried are not accurate. Results are inconsistent. They are only good for entertainment - not calibration.

Record based speed checking systems are garbage - they only work if there is 0 eccentricity in the vinyl record, and the hole is the exact same size as your spindle ( but those 2 conditions are seldom the case.

SOTA's  RoadRunner is not only a tachometer but it continuously monitors and makes micro adjustments in real time to achieve 33.333 or 45.000 rpm.  

This table sounds amazing,  it is pitch perfect.   

SOTA's  RoadRunner is not only a tachometer but it continuously monitors and makes micro adjustments in real time to achieve 33.333 or 45.000 rpm.  

This table sounds amazing,  it is pitch perfect.   

If it is constantly making micro adjustments, then it cannot be pitch perfect.

@lewm 

The KAB strobe with battery powered strobe light is old fashioned but the best I know about. The battery power assures that the strobe light is spot-on accurate.

+1000 on this. The KAB strobe is reasonable cost, and effective. It also takes into account stylus drag on a record. I've used it for a while, and continue to trust it, even with my costly Clearaudio Master Innovation.

The sota motor package  is more stable in speed than most  any direct drive.     Several people have reviewed this table and said it was the most stable speed they have had in their set up to date.  It is about as close to ideal as you can get.   

It must be decent because VPI owners are installing it on their tables too....