Measuring "Stylus Drag" with the RPM Speed and Wow app


I recently spent what I considered way too much for a Lenco L75S. But I was tired of waiting to score a bargain; and I figured life is too short; and a nice unit came available on my favourite audio website. Sold!

I won’t start another thread about how the idler drive system is the absolute best turntable system; instead I will just report that even before improvements (DIY plinth, upgraded arm), the stock Lenco sounds very fine indeed. Talk about speed stability! Talk about defined beginnings of musical attacks! Talk about lack of smear (Did I mention speed stability?)!

And it has got me thinking: maybe there is something to this concept of the importance of "stylus drag", and its effect on vinyl playback.

Which also got me thinking: why don’t we start measuring this phenomenon (seeing as it is one of the biggest issues a turntable has to deal with - after speed stability).

So then I thought, "why not use the RPM Speed and Wow app, and take readings with a record playing, and without?

And have done just that. I understand the app is considered "not accurate", but I would assume it is "consistently not accurate", or thereabouts (can anyone with more technical knowledge of a phone’s gyroscope corroborate or deny this?). And since it is a RELATIVE PROPORTION we are looking for, this app might just work for all of us to create a database of "Stylus Drag" relative measurements for all of our turntables.

With a chosen track, my Lenco’s readings are:

Playing a record: 33.33 (0.03% W & F)
Not playing a record: 33.40 (0.04% W & F)

The difference on a Lenco is 0.07. I call this figure the "Stylus Drag Coefficient Number".

Next I will do readings for a Mission 775S, a Thorens TD160, and a Technics SL-D2.

Oh, the fun that can be had after rehearsing Mahler’s 9th Symphony, and drinking a couple of beers while listening to vinyl on a new-to-you turntable!

Not that I care a lot, but I disagree that actual data would be worthless. I think it would be interesting. However I do not think it will ever happen because of the necessary controls that we really as a group cannot put into affect.
Clearaudio has a speed record that you play when adjusting the speed of the platter
You're kidding me, right?  Idler is the best?  You must listen to a lot of cassettes, too.

As for stylus drag, you can see it on a turntable with a strobe.

As @lewm points out, lots of variables. But at least one measurement isn't hard: Analogue Productions test record 1 KHz tone, running into a frequency counter.

Control condition: with platter up to speed, disconnect motor and measure the time required to run down from 1000 Hz to about 900 Hz with stylus engaged for 1 second out of every 10 seconds, giving a  good approximation to '90% stylus not engaged').
Experimental condition: time to same frequency drop with stylus fully engaged.

In this way differentiate bearing friction from stylus friction. Easier for me, as my air bearing is virtually frictionless.
Seriously, are you aware of this strobe control ?
Any change in speed is immediately visible!

If 33 1/3 rpm or 45 rpm rotation speed is not stable the dots on the strobe control are not stable too, very simple, and it was on Technics direct drive since the 70s. And you don’t need any special devices at all ! Just buy yourself a turntable with a proper direct drive motor (they are very powerful).