Subject: Re: Partials of Forks?

[pianotune05]

I thought we're supoed to use F2 with the fork.
Marshall
----- Original Message ----- 
From: "Robert Scott" <robert.scott at tunelab-world.com>
To: <pianotech at ptg.org>
Sent: Thursday, May 04, 2006 8:57 AM
Subject: Subject: Re: Partials of Forks?


> David Ilvedson wrote:
>  > They used an A440 fork to tune A3 (temperment starting point)
>  > F3 - A3 = F3 - Fork.
>  >
>
> and Mark Schecter responded:
>
>> Well, call me old fashioned, but this tunes the fourth partial of A3 to
>> the second partial of the fork (?880), which would only yield A4=440.0by 
>> luck. They are introducing two variables; the distance betweenpartials 1 
>> and 2 of the fork, and the distance between partials 1 and 2of A4. The 
>> sum of those differences, unless by chance it is 0.0, is the_offset_ of 
>> A4 from 440.0. At least, that's the way I figure it.
>
> Forks do not have partials - at least not in the same sense that piano 
> strings have partials.  When a fork is struck and held in the hand, the 
> only sound coming from that fork is A-440.  There is no 880 at all.  So if 
> you play the note F3 along with an A-440 fork, you will not hear any beat 
> because 440 is not in the partial series for F3.  However, you can hear a 
> beat if you do this:  strike the fork and then rest the support on a 
> wooden surface, like we normally do to make the sound of the fork louder. 
> Now play F3 along with the "amplified" fork and suddenly you do hear the 
> beat at 880.  What made the difference?  It is not simply that the fork is 
> louder.  The 880 comes from the non-linear interface to the wooden surface 
> which introduces harmonic distortion products.  These distortion products 
> are true harmonics - exact multiples of the fundamental.  So if you do 
> manage to coax some 880 out of a 440 fork using harmonic distortion, you 
> can be assured it is exactly 880, not !
> 880.5.
>
> Robert Scott
> Ypsilanti, Michigan