Tunelab question?

[David M. Porritt]

Brian:

The "saw tooth" or the jumps in the "curve" occur at the places where the
program switches reading from one partial to another.  A0 - E2 is read on
the 6th partial, F2 - E3 is read on the 4th partial, F3 - G#4 on the 2nd
partial, and from A4 to C8 (the smooth part of the curve) is all read on
the fundamental.  To make the curve look smooth you'd have to read each
note on the same partial - impractical at best, impossible on most
equipment.  A4 is read on the fundamental and always at 0.0 cents
deviation.  G#4 is read on the 2nd partial so that offset is going to be
higher to compensate for the inharmonicity (IH) of the 2nd partial of G#4.
Therefore you get a break or "saw tooth" at that juncture.  

dave

*********** REPLY SEPARATOR  ***********

On 1/28/00 at 7:46 PM Brian Trout wrote:

>Hi List,
>
>Those of you who have seen Tunelab will likely know what I'm talking
about.
>I'm not sure if RCT is similar.
>
>When I measure the inharmonicity of the 5 or so notes I need to use the
>Calcul8 program, and hit "Calculate", it produces what the mathematics
>consider to be a good tuning.  (Sometimes it's better than others.)  I am
in
>the habit of going to the graphic tuning editor immediately after using
the
>calculate function just to get an idea of what it has done, and see if I
>want to do a bit of tweaking.
>
>What I noticed is that instead of a smooth sort of "S" shaped curve like
one
>might anticipate, it looks more like a modified "saw tooth wave".  I had
>noticed in an advertisement for one of the new Peterson tuners a graphic
>representation of a tuning and did notice a very smooth curve, not the
"saw
>tooth type" that the Tunelab tends to produce.
>
>I have noticed on occasion that the beat intervals are not always as even
as
>I would try to make them if I was tuning strictly aurally, and I have
>suspected that the way in which the tuning "curve" is calculated, using
>these "modified saw tooth wave patterns",  might explain the variations in
>beat rates.
>
>Does anyone have any ideas of why the tuning curves are calculated that
way?
>I'm guessing there is a very good reason.  I just don't know exactly what
it
>is.
>
>Jim C.?  Rob S.?  Dave P.?
>
>Not meaning to be critical.  Inquiring minds just want to know.  <grin>
>
>Have a nice weekend, all.
>
>Brian Trout
>Quarryville, PA
>btrout@desupernet.net




David M. Porritt
dporritt@swbell.net
Meadows School of the Arts
Southern Methodist University
Dallas, TX 75275