String coupling.

[Derek Gibson]

Hi Don,

Actually it was just an observation passed on from many tunings over several
years. No test procedures were thought up by me.   You are right in saying we
should set up a scheme where we can verify this in a scientific way.   When you
have a short time in which to do the tuning, and you have to service a gazillion
pianos that day, the mind only thinks, "that's interesting, but let's get back to
work".   I'm not losing any sleep over it, the end result is that the piano still
has good octaves and unisons.  To try it, and see if it works for you also just
take a stable piano without false beats where you can get a full blush on the
RCT.  Tune each note of a unison to full blush, then play the unison and see what
happens to the spinner.  In my experiences, it always moves slightly flat.  There
are several people who have greater capabilities than me, that have experienced
it and can't explain it.

Good luck

Don wrote:

> Hi Derek,
>
> I assume you were using the mic in your mac or? Please give many many more
> details. Yamaha? Baldway? No one could possible duplicate your efforts with
> the paucity of info that you and Roger are giving. How many times was each
> note measured? How was the note played? By device or by hand?
>
> At 12:54 PM 06/20/2000 -0600, you wrote:
> >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
> >
> >
> >
> Regards,
> Don Rose, B.Mus., A.M.U.S., A.MUS., R.M.T., R.P.T.
>
> Tuner for the Saskatchewan Centre of the Arts
>
> drose@dlcwest.com
> http://donrose.htmlplanet.com/
>
> 3004 Grant Rd.
> REGINA, SK
> S4S 5G7
> 306-352-3620 or 1-888-29t-uner