ETD question re: unisons

[Meyer Carl]

Hello Mr. Curious:  I am curious2.

Yes, I read that  and think that he really has a handle on the reason for
prompt sound and aftersound.

I had a loose leaf notebook with a Xerox of that article along with articles
by Jim Ellis, a couple of guys from Baldwin, both from the journal, and a
comment from Ed McMurrow about horizontal vibration of strings from his book
"The educated Piano".  I must have loaned it out since I can't seem to find
it.

As I understand it, a string will vibrate vertically (grand piano) and the
impedance of the bridge will be low, hence dissipating energy at a fast
rate.  Then due to imperfections the strings vibrations will slowly change
to elliptical and then progress to horizontal.  At the horizontal mode the
impedance of the bridge will be much higher resulting in a slower rate of
dissipation.  This is easily understood by comparing a capacitor in an
electronic circuit, discharging into two different resistive loads.

In the case of the piano, the two different loads are not switched abruptly,
but gradually.

One statement I read was that good pianos don't have horizontal vibrations.
Really?
I guess that if the strings were perfectly leveled, the hammer perfectly
mated to the strings, then the horizontal vibration would be minimized or
maybe delayed.

Now my question would be.  If that were true would the shape or point of
shift in the amplitude plot be delayed?  That would be an interesting
question to test with a set up to plot the timing of the transition from
prompt sound to aftersound with different string levels etc.

Anybody care to render an opinion?

Carl Meyer


----- Original Message -----
From: "Richard Brekne" <Richard.Brekne@grieg.uib.no>
To: <pianotech@ptg.org>
Sent: Thursday, February 15, 2001 9:04 AM
Subject: Re: ETD question re: unisons


> I am curious.... just how many of you have read Gabriel Weinreichs paper
"The
> coupled motion of piano strings" ?
>
>
> --
> Richard Brekne
> RPT, N.P.T.F.
> Bergen, Norway
> mailto:Richard.Brekne@grieg.uib.no
>
>
>