Tonearms with no anti-skate adjustment

@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.

Dover:

My reference to it being "a big deal" with unipivots was really with respect to the importance of measuring VTF directly at record height with that type of arm.

Very easy to be out/light .2 to .3 grams if measuring above record height with unipivots. With other arms, not so much of an issue.

I wasn't suggesting in the least that records would be played at that level due to warps or any other reason (ie. installing an aftermarket mat without adjusting for SRA/VTA)  that would result in the overhang being off.

@hdm 
Yes I agree - I always measure and set vtf with arm dead level and more importantly do the alignment with the arm level as well first. If the vta needs significant adjustment I recheck the alignment before doing dialing in VTF by ear. Its an iterative process.

@bpoletti 
Revealed Rega apparatus calibration marks far from accurate.  Was a great aid getting the RP10 dialed in.  YMMV.  
Regards.

Dover, I disagree.