TT speed

@lewm I agree it is somewhat meaningless in term of the platter speed and W&F levels…

But ignore the protractor and just draw a radial spoke on the paper. And there too… as the stylus moves inwards walk in “platter rotation space”… (well all except a linear tracker)

We do not need to do an experiment, as we can do it all solely with trigonometry.
(I might write a program to show it.)

However for an experiment we could do it with a two arm table if one of the arms was a LT. Then we would time align at the start… or we would just do a cross correlation every so often to show the offset as a function of time, which is the time delay as a function of platter position.

This method (being a relative measurement) would remove all the W&F and platter speed, but still probably includes some effect from the offset holes.

@cleeds 

Your belief is easily disproved with a test record - it’s easy to measure the frequency of a test tone on an LP.

We've already shown that measurements reveal it doesn't exist. It's easy to measure a 1 kHz tone on a test record.

Unfortunately you can't see the wood for the trees.

If you draw a line across the 2 null points of a pivoted arm, and are using Baerwald for example, then at the beginning of the record the stylus is behind the line, as it crosses the first null point it will move ahead of the line, and then as you cross the second null point it will fall behind the line.

Assuming the record is travelling at constant speed, then the motion of the stylus forward and back relative to the line must alter the apparent speed, as seen from the record groove, albeit minuscule.

Your fervour for FFT analysis appears to be an impediment to understanding basic maths and physics.

Your fervour for FFT analysis appears to be an impediment to understanding basic maths and physics.

• The FFT is pretty much sub-optimal for anything but gross frequency related analysis.
• There is the cross correlation (time domain) - which requires some known signal to compare the measurement to.
• Or there is direct phase, which is superior to FFT analysis.
  • Phase is the derivative/integral of the frequency 
  • So the rate of change of the phase give us the frequency much more accurately than super long FFTs to achieve small FFT bin width.

dover

Assuming the record is travelling at constant speed, then the motion of the stylus forward and back relative to the line must alter the apparent speed, as seen from the record groove, albeit minuscule.

You are really confused.

Your fervour for FFT analysis appears to be an impediment to understanding basic maths and physics.

You are really confused. I’ve never, ever mention FFT analysis. You’re apparently confusing FFT analysis with the Fourier Transform, an indicator that you’re having issues with your "basic maths."

The Fourier Transform is the theorem which explains how digital and analog audio work. It also disproves your fantasy that phono cartridge tangency affects frequency. As I’ve mentioned, I can also disprove your fantasy by measuring the frequency of a test tone as it’s played from a test record. It’s not difficult to do.

Of course, you’re free to imagine and fantasize that you’ve found some flaw in the Fourier Transform. A Nobel Prize awaits you if you can show you calculations. Good luck with that!