Why lower FAC partial changes?

Lowering the tenor partial change to G#2/A2 results in a full 2-octave (A2-A4) range with all notes within that range using their 4th partials for the tuning. Not having any partial changes within the A2-A4 range, makes the tuning more accurate by eliminating even the possibility of a partial change error between A2-A4. In the treble, using the 1st partial instead of the 2nd @ A5 makes determining and tweaking the treble stretch easier. 

Partials, Partial Changes, Partial Change Errors, & Partial Locations

Because we can’t use the same partials to tune A0 and C8, there must be at least one partial change in every tuning software system. All tuning software systems contain partial ‘changes’. Whenever the software switches from one partial to another during the course of the tuning, an error at that partial change is very likely. Since every partial change is a potential tuning issue, the fewer partial changes the better. The higher partials are less reliable then the lower partials.

Check/Correct All Partial Changes Using PCC

This Partial Change Correction (PCC) feature is relatively new to the SAT IV’s programming. So if your SAT doesn’t seem to be responding to the STO + MSR command it’s program may need to be updated. Being able to correct partial changes is unique to the AccuTuner.  An FAC tuning has fewer partial changes (3) than any other tuning system,  and yet it is the only device capable of  correcting them. (Contains button pressing video).