Turntable speed checker

Just found out that a RPM app is available for Android here and should be available in the fruit company's app store too.

it would be interesting if someone with an accurate RPM tester could check if the app is measuring correctly.

I just checked the app on my BG 4002 and it shows 33.2 to 33.4 probably because of the unbalance the phone causes, and maybe my BG not being in exact level (checking without LP)

I now use a foam block over the spindle and position the phone over the center on the foam to lower the variability from the offset of the phone on the platter. On non-suspended or heavy platter turntables I put the phone on top of a heavy record weight over the spindle.

I’ve compared to a microphone based platter speed computer program and test tone record, I’ve compared to a professional printed strobe disc and incandescent lamp as a strobe and compared to turntables with built in strobes and I have no complaints at all with the gyroscope based phone app.

Although the beolover rpm device looks awesome, I use too many other turntables for it to be a good option for me.

The phone app looks pretty nice and I'm sure will give a pretty good measurement. I just don't know what the accuracy is and if it varies much from phone to phone. Unfortunately I don't curren't have a phone that I can try the app (maybe I'll borrow one ;-) ).

For my Beogram restorations I use the Beolover RPM tool. It is designed specifically for the Beogram 400x turntables but could be used on other turntables if a matching platter marking was on the surface. The Beolover tool works similar to the Beogram 800x tachodisc speed control and the fixed arm sensor where optic sensors read pulses. Modern electronics allow Beolover to use a tiny Arduino Nano device to measure the pulses and calculate the speed. The Beolover tool is really nice for Beogram restorers because it connects to a PC via a USB cable so you can record the platter speeds over a long time period. Using it in that mode I have run my restored Beograms for twenty four hours then plotted the results. I am always impressed how accurate these 1970's, analog control system, belt drive Beogram turntables are (after the motor restoration and a new belt). 

Thanks Peter, I adjusted my BG with a strobo disc (2 years ago), when I made a fast check with the phone app it showed 33.8 RPM with the fine adjustment I turned it down to 33.3. I will find some foam to get the phone placed center and check again.