I think I understand what you are asking, and the answer is simple, but the mathematics behind the answer are not. If you use the geometry defined by Baerwald, there are actually 2 points along the arc that provide 0 tracking error. These are your null points. What I believe you propose is a single null point smack dab in the middle of the LP. This would greatly increase your tracking error. I'm posting this response from my phone...I'll try to provide more detail later.
tonearm geometry question
I've followed the linear vs pivoted thread with some interest. Itt raises a question that someone with greater technical expertise may be able to clarify for me.
At rest, both a pivoted arm tube and an LTT tube share a common position tangent to the platter ( call it the CP line) and a common anchor ( or pivot) point (call it CAP). From there, a pivoted arm tube defines an arc across the record, while the LTT tube slides on its anchor point from the CAP along a line perpendicular to the CP line and tangent to the platter until it hits the inner groove. Call this the LTT anchor journey.
My question: Why is the pivot point on a pivoted arm not located halfway along the LTT anchor journey. Wouldn't this reduce the pivoted arm's error by half? Surely loading/removing the record can't be the reason. What am I missing?
Thanks in advance.
Marty
At rest, both a pivoted arm tube and an LTT tube share a common position tangent to the platter ( call it the CP line) and a common anchor ( or pivot) point (call it CAP). From there, a pivoted arm tube defines an arc across the record, while the LTT tube slides on its anchor point from the CAP along a line perpendicular to the CP line and tangent to the platter until it hits the inner groove. Call this the LTT anchor journey.
My question: Why is the pivot point on a pivoted arm not located halfway along the LTT anchor journey. Wouldn't this reduce the pivoted arm's error by half? Surely loading/removing the record can't be the reason. What am I missing?
Thanks in advance.
Marty