RPM – The Turntable Accuracy Checker
Test the rpm accuracy of your turntable, whether 16, 33, 45, or 78.
RPM uses the gyroscope in your iPhone to determine the rotation speed of your turntable, automatically determines which speed setting you’re on and reports how accurate it is.
Simply place your iPhone on your turntable, close to the centre but doesn’t have to be over the centre spindle. As the iPhone rotates the display will remain stationary from your perspective for easy reading.
The best, and UNIQUE, thing about RPM is it also shows a scrolling graph of the rpm accuracy variation over time, this shows wow/flutter effects, especially those associated with the turntable not being level, belt wear, etc.
You can even detect the small drag caused by the stylus resting in the grooves of the record.
While other utilities may well show you the average rpm over many revolutions, RPM shows you how the speed is varying within a single revolution, wow/flutter can sound worse to your ears than simply being slightly fast or slow. If you can’t identify and measure it you can’t fix it.