[CAUT] Tuning the back duplex

[Richard Brekne]

Hi Cy

For the moment... I'm just insuring it has a bit more tension then the 
speaking length... and that the <<unisons>> are tuned to the same 
frequency... and that that frequency is one in which I hear nothing (or 
as little as possible) of anything resembling a single string beat when 
any of the three strings back lengths are plucked.

Interestingly... I found right from the get go that factory installed 
aliquots (or whatever you call them) are far from consistantly placed in 
just about any make. That is to say, I havent measured the actual 
distance from the back bridge pin to the contact point of the aliquot on 
pianos... but I have noticed that the highest obtainable pitch for any 
given back length varies greatly from piano to piano of same make and 
design. Easy example... take the top few notes of Steinways.  The 
speaking length and back length should be able to yield the same 
frequency with the string up to pitch.  But I've found several that no 
matter what you do... you cant get the back length up to the same pitch 
as the speaking length. Perhaps the speaking length varies from piano to 
piano and the back length remains constant... I dont know...  But 
clearly... if the idea is that these lengths should be able to have 
clearly defined consonant frequencies to harmonics of the speaking 
lengths... the placement of the back length termination is not 
consistent enough to do the job.

I dont really know that this matters much... for the moment I just get 
the feeling that as long as the back length has a higher tension then 
the front length, and that these are tuned to as close a state of 
beatlessness as possible... that the result is a cleaner sounding piano.

Cheers
RicB

    Do you tune the rear duplex by its proportional length,
    geometrically -- i.e. move the little Monopoly house so that the
    length of the rear duplex is exactly half of the speaking length --
    or do you account for inharmonicity, and tune the rear duplex to the
    exact frequency of the second partial of the speaking length?

    --Cy--

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