Good points Den. So, before I post my additional measurements, I want to reiterate that positive benefits of the double pulley were audible, in my system. Based on my previous PlatterSpeed posts, measurements using the double pulley seem to support an increased speed precision obtained by the mod - or at least by using two belts with the mod. As you will see in a future post, this observation appears to be borne out in additional measurements.
And, being a scientist (not an engineer), I want to make clear that my postings are simply a few data points. There need to be more measurements in order to come to any agreement about how to interpret the data. In other words, my measurements are not enough to draw conclusions with - if that is your goal. Like I have said in other posts, I've known all along that my TT ran fast, but it doesn't bother me. If however, I can bring it closer to the desired speed, I will experiment and post my findings for others to contemplate and build on, in keeping with the scientific method.
However, if your goal is to set and forget as much as possible, leave well enough alone and trust your ears. My rig sounds muy bueno regardless of any measured deficiencies or deviations from a standard.
More later, and take my future post with all the above in mind.
WT Simplex, Shelter 501 II, DV20xl, Benz ACE SL > Aleph Ono, Bel Canto PL1/DAC3 > Pass X1 > XA30.5 > DeVore Nines
: Beyond measurements and theory, there's intuition and feeling: