Actusreus, on any tonearm I know of the VTA tower is designed to move straight up and down, subject only to random variations in the threads. I'm unaware of any tonearm with a VTA tower designed to move on an arc with a radius matching the arm's eff. length. That would be technically correct and I presume it could be done using computer-controlled machine tools, but it would probably be very costly.
Nice summary Peter.
That said, the sonic benefits of aligning zenith and overhang with the Mint are also very easy to hear.
I haven't checked visually with my Mint, but my suspicion is that the amount we alter arm height from one LP to another has only a trifling effect on overhang, possibly within the margin of setup error even when using a Mint. That would merely shift the null points slightly, which might actually be superior for some LP's, depending on the diameter of the innermost music groove.
Let's not forget that any chosen alignment scheme (Baerwald, Loefgren, whatever) is a compromise. Only a perfectly set up tangential tracking arm can achieve zero tracking error across the entire LP. On all pivoting arms we're simply choosing between compromises. Such is not the case with SRA. There is an absolute best for that parameter.
Nice summary Peter.
I suppose those who adjust VTA on a regular basis feel that the sonic benefits of proper SRA outweigh the penalty of a slightly off overhang.They do for us.
That said, the sonic benefits of aligning zenith and overhang with the Mint are also very easy to hear.
I haven't checked visually with my Mint, but my suspicion is that the amount we alter arm height from one LP to another has only a trifling effect on overhang, possibly within the margin of setup error even when using a Mint. That would merely shift the null points slightly, which might actually be superior for some LP's, depending on the diameter of the innermost music groove.
Let's not forget that any chosen alignment scheme (Baerwald, Loefgren, whatever) is a compromise. Only a perfectly set up tangential tracking arm can achieve zero tracking error across the entire LP. On all pivoting arms we're simply choosing between compromises. Such is not the case with SRA. There is an absolute best for that parameter.