RPM Speed & Wow

Andrea Martignano

About this app

RPM Speed & Wow lets you either look at the speed of your turntable, or measure the average speed, min/max variations and wow value.
Put your phone on the turntable the nearer to the center as possible, and you can:
- start the turntable and look at the rotational speed of it;
- click "start" on the app and start the turntable: the app waits 10 seconds in order to have a steady speed, then acquires data for other 10 seconds and displays average, max-min RPM values and wow estimation.
While still spinning, the app becomes red where the turntable runs faster than the average, and blue where the turntable runs slower. The feature is active until the phone is lifted up from the platter.

Offset correction: if you do a measure with the phone flat and steady, the mean rpm value will be automatically set as an offset for the next measurements. Offset correction remains active until the app is closed and reloaded. Active Offset-correction is indicated by a text message.

Click "reset" to reset the app to do another measurement (this does not reset the offset of the current session).
Click on the speed number to re-align it.


RPM S & W requires that your phone has a gyroscope.
Uses jjoe64 Graphview library.
Enjoy vinyl listening!

Update history:
1.6.8
- Wrong message when the speed is "perfect": corrected.

1.6.7
- The offset correction now applies also to the text rotation.
- Big bug in offset-correction corrected.

1.6.5
- Correction for gyroscope sensor offset added: if you do a measure with the phone flat and steady, the mean rpm value will be automatically set as an offset for the next measurements. Offset correction remains active until the app is closed and reloaded. Active Offset-correction is indicated by a text message.

1.6.0
- Colorfest! Now the app becomes red where the turntable runs faster than the average, and blue where the turntable runs slower. You can see where the speed changes happen. Achtung: don't worry, variations are totally normal in every turntable!
- Sensor noise filtering algorithm was rewritten.
- Clearer (and greener) average line in the graph.

1.5.2
- Average line in the graph view added.
- Solved a graphic problem with certain text size general settings.

1.5.0
- Major update! Graph visualization of the acquired data.
- Better management of the sensor noise.
- Increased resolution of the acquired data.

1.1.2
- Wow algorithm's resolution improved.
- Minor graphic modifications.

1.1.1
- Wow calculation error message corrected.
- Calculation of the deviation from the correct speed corrected.

1.1
- Added Wow estimation!
- Added 16 2/3 rpm to the recognized speeds.
- Now the average RPM shows with 2 decimals.

1.0.1
- Minor update: controls if your smartphone has a gyroscope.

1.0
- First release.

Ratings and reviews

Works fine. You don't really need a turntable weight like somebody else suggested. I always have a couple of terrycloth rags close to the turntable. Just rolled each one up and used it to support each end of the phone and then set the rolled towels on the platter on either side of the spindle. Makes it easy to center the phone over the spindle and fabric of the cloth will keep the phone from slipping or flying off.

Easy to use and very accurate. I think it probably works best if you can put your phone dead center over the spindle on a record clamp/weight, which is what I do. Also: ideally you should have a record actually playing because the needle does create some drag. Nice to be able to run it multiple times and get an aggregate set of numbers. Also reassuring to see how my deviation was 33.4 vs 33.3 and .1% wow and flutter!

I have a 40 year Japanese direct drive turntable. I had been noticing that it was having speed stability issues. Because I love this turntable, I picked up a backup a few years ago. The old one tested at 0.31-0.41% by the app. The "newer" backup tested at 0.03-0.04%. Bam, old one has a problem. Duh, to the guy dumb enough to put his phone on the mat and it spun off, use a record weight over the spindle, then put the phone on the record weight, dead center of the platter. Phone won't move.

What's new

Update to last Android API request and hopefully solved crashing problems