String coupling.

[Derek Gibson]

Hello Ron,

I am that other tech that Roger was working with this past weekend.  We were
tuning and voicing a piano that was being used for the provincial music
finals.  It was touched up several times a day over a several day period, so
it was very stable.  The result that Roger described was also found in the top
octave.   There was always a small pitch drop, and at no time was there a rise
in pitch.  No results were observed below the killer octave, as most of the
touch-ups were concentrated on the top half of the piano.  Since the drop is
consistent, there is no concerns regarding octave tuning et al.  Quite curious
to what causes this,

Derek

> 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