Octave Tuning

Matthew Todd pianotech88@yahoo.com
Wed, 22 Sep 2004 10:55:21 -0700 (PDT)


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Isn't the 10th (F3-A4) suppose beat maybe 1/2 a beat faster than the 3rd (F3-A3)?
 
Matthew

jason kanter <jkanter@rollingball.com> wrote:
This is the third-tenth test. For example, F3-A3 and F3-A4. The fifth partial of F3 beats at x/second with the second partial of A4. Then you make the fifth partial of F3 beat at exactly the same x/second with the fourth partial of A3. Voila, a perfect 4:2. 
-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]On Behalf Of Matthew Todd
Sent: Wednesday, September 22, 2004 9:54 AM
To: Pianotech
Subject: Re: Octave Tuning


Now, how exactly do you tune the fourth partial of the lower octave note to the second partial of the upper octave note?  I have heard that some techs just tune the octave 1/2 a beat wide, and leave it at that.
 
Now you can call me stupid
 
Matthew

Don <pianotuna@accesscomm.ca> wrote:
Hi Mathew,

Current thought is that a unison is the only "pure" item in tuning. An
Octave can only be "beat free" at one partial at a time. Do an archive
search for octaves and you will get loads of hits.

narrowest possible octave 2:1; a3 to a4 beatless at a4
wider 4:2; a3 to a4 beatless at a5
wider 6:3; a3 to a4 beatless at e6

It is common to tune a3 to a4 somewhere between 4:2 and 6:3--just to make
the task a little more difficult. I believe this is what Virgil Smith does
when he attempts to tune the "whole sound" of the octave. I.E. his 4:2
beats at a rate which may "cancel" the beat of the 6:3. How long such a
"balance" will last is dependant on nothing in the enviroment changing,
including barometric pressure.

More on unisons:

We also have to deal with the "coupled" motion of piano strings. The bridge
is a f! lexible termination. Some studies have suggested that a one hertz
difference in two strings will result in zero beating heard. One hertz at
A4 is approximately 4 cents--a huge number for a unison to be "out". There
is also some suggestion that a truely "pure" unison gives the piano a
rather "dead" sound with poor sustain.

Inharmonicity:

There is no doubt that the impedance mismatch between the strings, bridge
and soundboard produces a measureable effect on the width of octaves. In
some cases this "para inharmoncity" can be a negative number.
Translation--the narrowest octave would be smaller than a "theorectical" 2:1.

Setting Temperament:

I'd suggest you use one of the "self correcting" temperments such as the
Baldassin-Sanderson. Have a look here:

http://www.accu-tuner.com/SATIIImanual/apf.html 

At 07:42 PM 21/09/2004 -0700, you wrote:
> need some help from all of you. Is it true that the two things that
&g! t;remain pure in a piano when we tune is unisons and octaves? And if we do
>that, the octave will have a slight beat to it, right? I think I missed
>something. You guys are great! Thanks!!
>Matthew 
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Regards,
Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T.

mailto:pianotuna@accesscomm.ca http://us.geocities.com/drpt1948/

3004 Grant Rd.
REGINA, SK
S4S 5G7
306-352-3620 or 1-888-29t-uner
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