TT speed
When I use a protractor to align the stylus I do the alignment at the inside, and then rotate the platter maybe 20 degree when I move the arm to the outside of the LP, or protractor.
On a linear tracking “arm” it would not need to rotate at all.
At 33-1/3, then 15 minutes would be about 500 rotations. And that 20 degrees would be a delay of 18th of a rotation.
So a 1 kHz tone would be about 0.11 Hz below 1000.
It is not much, but seems kind of interesting... maybe?
Yes.
What you’re saying isn’t clear, but a properly installed pivoted pickup arm has a fixed overhang. Overhang isn’t affected by tangency - that’s fairly easy to measure. As @lewm explains above, the stylus tip is always exactly where it needs to be. |
I am sure it doesn’t matter, but unless the track is running in a circle, the pivoting arm will produce a very slight chirp in the tone. The example of a linear tracker with a moving overhang is obviously not something that one buys… but it was yet another example to convey the effect of what is happening with the arm, that makes the platter look like it is advancing or retarding as the arm moves inwards. What was an “ah ha” moment for me, was obviously not shared well or described too clearly. |
The cutter lathe is moving in a straight line. A pivoted arm is moving in an arc. They are not congruent. Does your direct drive turntable speed up and down to bridge the gap on each rotation ? |
I have never claimed that. What I have said is that the stylus on a pivoted arm, for each 1.8 seconds, deviates from the position of the cutter head at the same time interval. Frequency is a red herring because the deviation would be so small it would probably be less than that generated by normal tt issues around stability.
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