Hi Ron, Checking the coupling effect in the same manner as you described, I had similar results. However, If you tune each string separately for full blush on RCT. and redo them a second or third time so that each string gives a perfectly stable reading, them measure the unison it's very consistent 0.2 to 0.4 cent pitch drop in the killer octave range. I did this test in front of another tech on the list that has observed the same consistent results. A while back I posted some observations in tuning a full octave in the 5/6 range. These test were done on newly strung pianos and well maintained concert grands. I would be interested in your observations using the same measurement technique. Regards Roger Roger Jolly Saskatoon, Canada. 306-665-0213 Fax 652-0505
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