Experiment: string termination / duplex

[Cy Shuster]

Calin,

This is a great experiment!  May I suggest another test case?  I would be
interested to know the results of modifying Situation 1 so that both
duplexes are not perfectly in tune with the speaking length, but yet still
within a millimeter or two of the same length.  Is there any difference in
sustain in these two cases?

--Cy Shuster--
Rochester, MN

----- Original Message ----- 
From: "Calin Tantareanu" <dnu@fx.ro>
To: <pianotech@ptg.org>
Sent: Monday, September 15, 2003 1:32 PM
Subject: Experiment: string termination / duplex


> Hello!
>
> I made quite an interesting experiment with a sort of monochord. What I
> wanted to see was the influence of the string termination is on the sound.
> To that end I constructed a very simple monochord: a spruce board, 2 grand
> piano agraffes, 2 hitch pins, 2 tuning pins and a brass string (see the
> attached photo).
> The agraffes form the main terminations of the speaking length.
> I used two mobile wooden, each with an iron nail (with the head cut)
placed
> on it's top for providing the secondary termination point after the
> agraffes. This point is set higher, so the string segment between it and
> agraffe is at an angle to the speaking length.
>
> I have used the following set-ups:
>
> - Situation 1 = secondary terminations (wooden pieces) set such as to form
2
> duplexes in tune with the speaking length (2 octaves above it's frequency)
>
> - Situation 2 = secondary terminations set such as to form very short free
> string segments, at no more than 1 cm from the agraffes.
>
> - Situation 3 = string segments between agraffes and secondary
terminations
> (duplexes) muted with some paper strips (as shown in the picture).
>
> - Situation 4 = no secondary terminations and waste lengths muted.
>
>
> A few conclusions:
>
> - The worst sustain and tone quality has been achieved when the secondary
> terminations (wooden pieces) were missing and waste lengths were muted,
> because the string segments after the agraffes formed a very shallow angle
> to the speking length (Situation 4). Hence the conclusion that an angle is
> needed to achieve a better termination.
>
> - The second worst was with the secondary terminations in place and
duplexes
> muted (Situation 3).
>
> - The best sustain and tone quality was achieved when the string segments
> between agraffes and secondary terminations were not muted => Situations 1
> and 2.
>
> I couldn't determine better sustain for either set-up, but there were
> different tone qualities:
> Situation 1 had a definite harmonic ring from the duplexes, sounding 2
> octaves higher.
> Situation 2 had a very good and open sound, but without the extra
harmonics.
>
> I can't really say which set-up I prefer, among these two. they both sound
> good, but different - further experimenting is needed.
>
> - The main conclusion that I drew is that the secondary termination is
> crucial for the sustain of the string, because a lot of energy bleeds
> through the agraffe. Touching the duplex segment (both when tuned and when
> kept very short - Situations 1 & 2) with a finger and plucking the
speaking
> length produced much less sustain than without touching it plucking.
>
> - Of course I realise that this experiment doesn't exactly reproduce the
way
> a string is fixed in a piano, because I used 2 agraffes instead of 1
agraffe
> and 2 bridge pins.
>
> Any opinions?
>
> Regards,
>
>
>  Calin Tantareanu
> ----------------------------------------------------
>  e-mail: dnu@fx.ro
>  http://calintantareanu.tripod.com
> ----------------------------------------------------
>
>


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