TT speed

I just thought of a way one might test this idea.  You would need the shortest pivoted tonearm possible with the greatest tracking angle error, since, I am thinking, TAE correlates with this movement forward and rearward with respect to the straight line radius of an LP.  The more TAE, the more relative movement, the greater would be the frequency modulation.  Among present day tonearms, I am thinking of the Viv Float 7-inch underhung tonearm.  Underhung tonearms, which have zero headshell offset angle, inherently have much greater TAE than do conventional overhung tonearms with headshell offset.  And for an underhung tonearm, the shorter the arm the more will be the TAE.  So, if one could compare a linear tracker to a 7-inch Viv Float, on the same TT with the same test LP, one might be able to detect a difference in frequency stability.

@lewm I mentioned the scratching more as humour, but that is also the motion needed in the wrist if we put a spoke onto the record and help the stylus tip on it as the move from outside to inside.

I already gave the method for a relative test using a linear tracker and pivoted arm earlier. And an estimate of 0.11 Hz offset at 1kHz.

A relative measurement removes the platter speed and W&F from the equation.

But where does one get an LP with a tone on one side? If there a link?

@cleeds if we change the speed of the patter we would alter the tone’s frequency.
The tracking of a pivoting arm would look equivalent to linear motion of the overhang, moving slowly, in a linear tracker arm.

albeit, it is close to zero.

holmz

if we change the speed of the patter we would alter the tone’s frequency.

Yes.

The tracking of a pivoting arm would look equivalent to linear motion of the overhang, moving slowly, in a linear tracker arm.

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.