Dear Fred: The reason I mentioned in my post that I tuned each string within .1 cents was this: If the unisons are not tuned quite accurately, there is more difference between the single string and the full unison. I was trying to eliminate that as a possibility for the cause of the difference. I will continue to do additional studies on this. I agree that sometimes we see a difference in our completed unison from what we started with, merely because in the process of tuning, we have knocked the first string down a bit. I have often had to go back and retune the first two strings when I have just completed the third string. The sagging pitch of the full unison was the tipoff. I am like you, I watch for this more carefully now. In the 3rd and 4th octaves, I believe it is possible to tune unisons more accurately by ear than with the machine. We can hear the 8th, 9th, 10th or 11th partials often which helps zero in. But, in the 6th, and 7th octaves I find that it is reversed except for the "wild string" effect where the single strings actually vibrate at two different frequencies at once. By the way, the RCT cannot tune these more accurately than the SAT, because the RCT apparently does an average of the pitches it hears, whereas the SAT will actually display both pitches of a string, thereby permitting you to tune each string to the higher or lower pitch. Have you noticed the two dots wiggling back and forth on the SAT? It is showing both pitches. If this sounds confusing, let me know. I can give you an example of how this works and you can try it yourself. Jim Coleman, Sr.
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