@lewm So, to summarize my position, move pivot point down in the vertical direction and the set VTF goes down. Move pivot point up in the vertical, and the set VTF goes up.
Not so - it depends where you start. If the arm is level, then moving the pivot point up or down moves the counterweight closer to the pivot and increases vtf in BOTH instances. In your example you would have to start with the arm up at the back for your statement to be true.
@hdm Effects of tonearm geometry and mass distribution on the measurement of VTF :
http://www.tnt-audio.com/sorgenti/in_balance_e.html
There you go. Settled once and for all :)
If you calculate the change in overhang from moving the arm up or down 5mm then there is more distortion caused by this than the increased tracking force.
Not a big deal with many tone arms. But a very big deal with arms unipivots with under slung counterweights.
Only if you play lots of warped records.
The reason the counterweight is often placed lower on the unipivot is to stabilise the unipivot bearing by lowering the centre of gravity below the bearing point. This lowering of the centre of gravity also has a mechanical benefit of damping stylus motion.
Lowering of the centre of gravity has little, if any, benefit on a conventional arm with captured bearings. In fact if you read up on Pierre Lurnes design of the Romeo unipivot he presents an argument for having the centre of gravity slightly forward and only slightly below the pivot point to reduce the pendulum effect of a lowered counterweight which is not desirable on warped records.
At the end of the day the designer has to balance the pros and cons of each design facet and choice.
