Tuning machines & RPT exam

[Dean L. Reyburn, RPT]

> First, I select the scale that is closest to the piano I'm
>tuning.  For example, for a small vertical, I would select the M1
>scale.  The electronics in the PT100 have already stretched the
>octaves based on the amount of stretching that would be needed for a
>M1-type Yamaha piano.  That stretching may or may not be best for my piano.
>Next, I tune F3 with the PT100 set to 0 cents and the tuner set to
>F3.  Then I set the tuner to F4 and measure the second partial of F3.
>On some pianos, the display for the second partial will be
>stationary, indicating that the built-in stretch for a Yamaha piano
>is correct for my piano.  On other pianos, the display for F4 will be
>flat by a cent or so, indicating the built-in stretch is too
>wide.  In this case, I divide the amount of flatness by 12 to get a
>fractional-cent correction factor for each note.  Then, I
>set the tuner back to F3 and tune F3#, etc. up through E4, entering
>the correction factor for each note.

Wow! That sounds like a lot of work to me.  But I think I understand what
you are doing now, sorry I misunderstood.  I only used a PT-100 once for
testing out my PT-100 version of my Reyburn Accu-Switch 2 (tuning hammer
thumb switch for SAT (Sanderson Accu-Tuner) or PT-100, works great!).

As I remember, the PT-100 has several built in scales but only one tuning
slot for storing a custom tuning, is that right?  If so it sounds like
you are storing the standard, say Yamaha M1 to the custom page, then
modifying it to match the stretch of your piano.  That sounds like it
works ok, but I wonder if the PT-100 has the same "gotcha" as the SAT
when it comes to generic tunings.  The problem on the SAT is what I call
the "step" where the partial changes from say 6 to 4, 4 to 2, or 2 to 1.
That can change anywhere with the SAT depending on how the tuning was
recorded or calculated, but I suspect the PT-100 has locked in listening
partials, is that correct?

What are the listening partials on the PT-100?  Normal would be 6 or 4 in
the bass, 4 or 2 in the midrange and 1 in the treble.

When the SAT changes listening partials, if the change in cents doesn't
match the piano's inharmonicity between those 2 partials, the parallel
intervals will have a jump, either up or down in beat speed.  I use
parallel tenths, major thirds, fourths and fifths to detect this.

The big problem spot on the SAT's FAC system is between B2 and C3.  FAC
commonly estimates this jump poorly (from partial 6 to 4) on poorly
scaled pianos (ingore this note if you only tune 7 & 9 footers ;-)

On Tuning Manager/Chameleon tunings tranfered via MIDI to the SAT, the
partial changes are almost always smooth since Chameleon sample notes are
on A's and partial changes are all between G#'s and A's.

> The result of all this is that
>I have shrunk the built-in stretch such that 1F3 and 2F3 (is that an
>acceptable way to denote the first & second partials of F3?) are in
>tune, and they define the width of my temperament octave.  Then I tune
>2:1 octaves going from E3 down to A1, and then from F4 up to C8.
>This procedure is taken from Reblitz.
>
That's a new and unique way to indicate partials, but it works, and is
shorter that "1st partial of F3".  I think it sounds like you are not
tuning what we would normally call 2:1 octaves, but you are modifying how
the PT-100 tunes octave similar to 2:1 octave tuning.  Comments?

>I mentioned above that for some non-Yamaha pianos, the built-in
>stretch is too wide.  I've never tuned a piano in which the built-in
>stretch is too narrow.  Interesting.
>
Yes that is interesting, I would suppose it is because the stretch in the
PT-100 is very low, since yamahoppers are real low in inharmonicity
(usually).  Either that or the PT-100 designers were just more
conservative stretchers than you!

>Since I don't know the algorithm used in the PT100 to stretch the
>octave, I don't know how closely this would match typical aural
>tunings.  Even though this procedure couldn't be used in the exam on
>the two octaves you mentioned that have to be aurally tuned, I would
>be interested to know if this procedure would pass the exam if it
>were allowed, hence my original post.
>
It sounds like your system would have a good chance at passing, but I'm
not sure...

I would be happy to try to run your numbers through my test program with
a master tuning if you want, or for any PTG associate for that matter.
(This would be a pre-pre-test <g>)  All I would need is the cents offset
for notes C1 thru B7, preferably recorded at these partials:

C1-G#2: 6th partial (2 octaves + 5th up from note)
A2-G#4: 4th partial (2 octaves)
A4-G#5: 2nd partial (1 octave)
G#5-B7: 1st partial (fundamental)

Make and model of piano. (don't use a Kimball spinet please! ;-)

If you can't do this, then any reasonable partials are ok, I just have to
convert.

Or just the midrange can be checked, C3-B4 at say the 4th partial.

The PT-100 (or SAT) using any method you like *is* allowed on the exam,
its just that if you use it, you have to re-take the midrange by ear, to
show you can check the machine's tuning.

I have always made it my goal to be able to tune aurally to a higher
standard than the electronic system I use.  I can tune better aurally
than the SAT, but not if you give me a reasonable time limit like an
hour!  In that case I tune better with an SAT.  Combining the ears with
an electronic tuner is (in my humble opinion) the best tuning method of
all.  Sound like that's what you are doing with the PT-100.

Dean



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