I have the Wally tractor for the VPI 12.5/6 arm
- effective length is 315mm
- pivot to spindle 302.1mm
- overhang (B) 12.9mm, (L) 13.3.
I have used the Wally many times, but ended up preferring the sound of Harry's plain old one point jig, which Harry indicated he chooses as it ensures better sound over the last 3rd of the LP, which is where most trackling issues occur.
Yip told me he is not confident that his baer algorithim will give you any better distortion figures based on VPI's effectibge klength and pivot to spindle dustance - at least for me on the 12.7 specs
I will quote Harry's last email to me regarding the 12.7 effective length details and other alignment methods.
" If you go by science, bumble bees can't fly, tell them that when a hive is chasing you. Seriously, I don't use either of those curves, I did it by ear on my system, not by math on a computer. If you go by distortion you would never use tubes, only solid state. I began using the Mitch Cotter system and tweaked it from there.
This is not a condemnation of either system, it's just that I know what they sound like (doing this since 1958) and like my system better. That does not say you shouldn't make the guage, it may sound better for you so I would do it.
They said the same thing on Vinyl Asylum and the German guy ran the number and said the distortion is higher, then he listened to the arm and said I understand why he uses it.
Just my take on audio, yours may be different and there is absolutley nothing wrong with getting the lowest distortion possible. "