Unison coupling

[Jim Coleman, Sr.]

Hi Richard:

It is my experience that TuneLab is very sensitive to the change of
pitch in respect to time. This seems to be more so in the 5th and 6th
octaves. Perhaps I should take some time and put some numbers to this.

The RCT shows this also.

Jim Coleman, Sr.

On Sun, 23 Jan 2000, Richard Moody wrote:

> 
> Ron wrote...  
> > >> >>The frequency of vibrating piano strings is not stable, but
> > >tends to 
> > >> >>lower as the string continues to sound.
> 
> ric wrote 
> > >I would like to see a reference to support this.   
> 
> Ron ...... 
> >Note the pitch in the first half second or so of the attack, and
> > the drop in pitch as the note continues to sound. 
> 
> ric...
> I do not have a SAT.   If the SAT shows pitch in the first half
> second  different from the pitch in the next 2 seconds and
> different again from pitch in the next four seconds, that would
> indeed be most interesting information.  
> 
> 
> 
>  Ron ...
> > * When I see articles like this, it is usually mentioned in the
> text that
> > the measurements are taken a couple of seconds into the sound
> envelope,
> > after everything has stabilized. Any mention of this in the
> article? 
> 
> ric....
> A decrease in the frequency of the partials was not mentioned. They
> did conduct experiments to study the amplitude of the partials from
> 0 time. I believe they were not able to record until a half a
> second. You would have to read the article to determine exactly
> what went on. 
> 
> Ron...
> > they would be concerned with measured partial frequencies
> relative to the
> > measured fundamental at any given point, wouldn't they. The pitch
> drop most
> > likely just wasn't mentioned so it wouldn't confuse the intent of
> the
> > article.  
> 	
> ric...
> 	From what I got out of the article if there were a pitch drop, it
> would be a major concern.  They were trying to determing the
> inharmonicity of partials.  If the freq of these partials
> diminished over time I don't see how they could have missed this. 
> The Frequency of these was measured with a chromatic stroboscope,
> what ever that is. 
>   
> ric (earlier post)...
> > >An interesting observation that goes contrary to what some say
> > >today was that the method of striking the key did not influence
> the
> > >frequencies of the partials, "as it was found that variations in
> > >the strength of the blow produced negligible effects on the
> modal
> > >frequencies, the key was struck manually." 
> 
>  
> Ron... 
> > * I don't have a clue one way or another. As an aural tuner, it
> hasn't come up.
> 
> ric...
> Same here. Nor has the decrease of frequency of a piano string over
> time ever come up. 
> 
> 
> > >  If the frequency
> > >really does lower in time, a strobe light should tell beyond all
> > >doubt. 
> > 
> > * Or a SAT, RCT, Tunelab, Peterson, Conn, etc.
> 
> ric....
> Tune lab does not show a significant decrease in frequency over
> time.  Other wise with those moving bars it would be impossible to
> accomplish a tuning.  The interesting thing about Tunelab is that
> you can see how the movement of the bars is affected by .01 cents
> or .1 cents, or .5 cents or 1 cent.    At .5 cents deviation they
> are moving pretty fast.  At .1 cent they are moving fast enough to
> make you wonder if the machine is really more sensitive than the
> ear..... : ( 
> 
> 
> Ron...	
> >, you're right that measured inharmonicity is suspect because the
> ETD
> > users report that it changes from measurement to measurement.
> 
> Which is why I would like to see it on an osciliscope.  At some
> point an assesemt of accuracy in the actual recording of
> frequencies should be made.  I assume something like this in in
> JASA (Jouranal of The Acoustical Society of America). 
> In the few articles I read, it is interesting to see what and how
> they made their measurements in the 30's 40's and 50's. 
> 	Perhaps with the observations of Ron and others about frequency
> shifts it might be time to repeat those experiments with today's
> state of the art instruments. 
> After all that is the foundation of Science, confirmation through
> experimentation. I have seen the Conn Stroboscope go first in one
> direction and then backward.  Tunelab can be seen to do that also,
> but less I think.  Each one has issues of accuracy that can be
> analyzed and tested. 
> 
> ---ric 
> 
> 
> 
> 
> 
>  
> 
>