Speed variance study with a Phoenix Roadrunner

I picked up a Roadrunner the other day so I could better measure the speed of my tables. Using a strobe was not good with my eyes and my app only went to .0. Here is what I noticed. If I set my speed at the beginning of a record to around 33.310, by the end the speed will increase by .07. So, depending on where the arm is on the record will depend on what the speed reads. Outer groove slower, inner groove faster. Not by much mind you, but arm placement has an impact.

I’m not using an Eagle because I run an Origin Live motor system. I'm thinking that I may increase the tension of the belt slightly to see if that reduces the variance. I modded out a Thoren TD 850. The motor is fabricated in a manner that allows me to customize the tension and use different size belts. However, .07 drift is really not bad but if I can improve upon that it would be a bonus.

I have 2 other tables that I’m going to check out. Both are modded and use a Music Hall CC2. They are a VPI HW19mkiii and a totally tweaked out Thorens TD 150, that is not yet complete.

This proven to be an interesting tool so far. What have others experienced when only using the Roadrunner as a tach?