Tuning machines & RPT exam

[allen@pengar.com]

> From:          "Dean L. Reyburn, RPT" <75601.2765@compuserve.com>
> Wow! That sounds like a lot of work to me.  But I think I understand what
> you are doing now, sorry I misunderstood.

That's the same comment Reblitz made after explaining the procedure.
Then he said it goes fast, and it does.  Keep in mind that it is only
done once on F3 to establish the width of the temperament.

> As I remember, the PT-100 has several built in scales but only one tuning
> slot for storing a custom tuning, is that right?

It has built in scales but none for storing custom tunings.  I switch
it to M1, measure the offset between 1F3 and 2F3, divide it by 12 so
I can apply the offset correction uniformly over the octave.
Suppose I measure -1 cent offset between 1F3 and 2F3.  I would assume
-1.2 cents, and dividing by 12 gives me a -0.1 cent change for each
note in the temperament.  Since the PT100 only has 0.2 cent
resolution, I do the following.  1F3 is tuned to 0 cents per the M1
scale.  I tune 1F3# also to 0 cents.  Then I put in a -0.2 correction
and tune 1G3 and 1G3# to -0.2 instead of 0 cents.  And so forth.  By
doing this, 1F4 will be aligned with 2F3.  I have reduced the
built-in M1 stretch by 1.2 cents for my temperament.


> 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.

I'm not familiar with the phrase "listening partials" so I'm not sure
I understand what you are saying.  I think you are referring to the
partials that you aurally tune, 6:4 octaves or 4:2 octaves?   Randy Potter
said the PT100 in the high treble approximates 4:2 octaves, and he
recommended just using the built in scale to get the 4:2
approximation.  On the base, he recommended a slight lowering of the
tuning from the built-in scale.  In my case, however, I've been doing
2:1 octaves across the full piano rather than following Randy's
suggestion.  I started out following Randy's suggestion but changed
because several of my customers were members of a local orchestra and
they liked 2:1 octaves.  After listening to both tunings, I decided I
liked them too.  Also, my mentor had taught me to do 2:1 octaves, as
well as Reblitz's procedure I adopted was for 2:1 octaves..

> 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?

As explained above, I use the built-in scale to tune the temperament,
going from 1F3 to 1E4.  Once I'm finished with the temperament, I no
longer use built-in scale; instead, I'm using the PT100 to measure
the pitch of each note.  I've just finished tuning 1E4, and the tuner
has -1.0 on its readout and the LED pattern is stationary, i.e. I'm
using the first partial of E4 as my reference.  I leave the tuner as is and hit 1E3.
I get a moving LED display of some kind.  I tune the first string of
E3 to give a stationary pattern.  Since the tuner is set to E4, I'm
measuring the 2nd partial of E3, and I tune the string to give a
stationary pattern.  When I finish, 2E3 and 1E4 are at the same
pitch.  Then I go ahead and finish the unison on E3. Then I switch
the PT100 to D4# and adjust the pattern to be stationary.  Then I hit
D3# and tune the string to be stationary.  And so on. After finishing
the base, I go upwards from the temperament, adjusting the PT100 for
a stationary pattern on the lower note (2nd partial) and tuning the
higher note for a stationary pattern (1st partial).   It goes pretty
fast. I'm doing
exactly the same thing one would do aurally by tuning for a zero-beat
between the two partials, only I'm using an "electronic ear" with 0.2
cent resolution instead of a physical ear with a larger resolution.

One reason I like the PT100 is that I can see the rate at which the
pitch changes as I torque the pin.  Since I'm working with old pianos
with high string friction, there is a real danger of string breakage.
 The PT100 allows me to see the rate of change of pitch as a function
of the amount of torque I apply to the hammer.  If I move the hammer
a little bit and the display doesn't change, then I know the string
isn't moving, and I reduce the tension  and then increase it.
Being able to visually see the rate of change of pitch is very
helpful in avoiding string breakage.  Of course, one can do this
aurally too, but the PT100 is more sensitive than my ears for very
small changes of pitch.  My background is as an electronics/software
engineer/radio ham, and I'm used to visual test equipment more than I
am of aural equipment.


> 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! ;-)

Thanks for your offer, Dean!  I'll tune my Samick SG-185 and send you
the numbers.  I may have problem with the 6th and 4th partials in the
bass notes; if so, I'll measure what ever partials I can and send you
the data.

> 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.

As I tune with the PT100, I listen to everything and satisfy myself
that it is ok.  Next week is my one-year aniversary as a tuner, and
my ears have really improved a lot compared to last year.  I've tuned
about 400 pianos.

/Allen