was Accu-Tuner now tuning question

[Doug Hershberger]

Kent,
   Thank you for your expert opinion, verrrrrrry interesting.
Doug Hershberger
----- Original Message -----
From: Kent Swafford <kswafford@earthlink.net>
To: pianotech list <pianotech@ptg.org>
Sent: Thursday, July 15, 1999 5:20 PM
Subject: Re: was Accu-Tuner now tuning question


> Doug  Hershberger wrote:
>
> >In the
> >area of the piano we generally use 4:2 octaves such as the mid range, I
> >sometimes  will tune the octaves aurally and then check to see what the
> >accu-tuner says about it using a FAC tuning on a page of memory. I am
> >talking about a well scaled piano and a FAC that fits pretty well. What
> >seems to be the case with me is that no matter how conservatively I try
to
> >make the octave stretch the accu-tuner still says the octave is sharp
>
> This is a standard feature of FAC tunings, as calculated by the SAT I,
> SAT II, and the SAT Librarian computer program. I don't have specific
> knowledge of the SAT III.
>
> In FAC tunings the notes of octave 4 are tuned at the 4th partial.
> In FAC tunings the notes of octave 5 are tuned at the 2nd partial.
> This means that FAC tunes "direct interval" 4:2 octaves between octave 4
> and octave 5.
> Check it out. In an FAC tuning, the C4-C5 will generally be tuned as a
> pure 4:2 octave.
> This means that the C4 value at the 4th partial (C6) will be the same as
> the C5 value at the 2nd partial (also C6). However, above C4-C5 the 4:2
> octaves become narrow in almost _all_ FAC tunings. The reading for each
> note in octave 5 will be lower than the same note in octave 4, and both
> are being read at the level of the 4:2 coincident partials.  This
> explains your observations completely.
>
> Try it and compare the readings between corresponding notes in octaves 4
> and 5. Raising the A value will not help; a higher A value will _not_
> keep the 4:2 octave4-to-octave5 octaves from being contracted in FAC
> tunings.
>
> Raising the C value will widen the octave 4 to octave 5 4:2 octaves, but

> may affect the the rest of the treble too much to be of much value.
>
> Kent Swafford