Duplex

[Richard Brekne]

18.11.2001 01:29:09, John Delacour <JD@Pianomaker.co.uk> wrote:

>At 10:10 PM +0100 11/17/01, Richard Brekne wrote:
>
>>how are we to ascertain when the tensions
>>are really equal ?? If we were to go by sound then we would have to 
know in
>>advance just exactly what pitch these segments were supposed to 
sound at. And
>>there seemed to be a lot of reasonable argumentation made as to why 
this would
>>not be possible.
>
>
>I must have missed that reasonable argumentation.

I am not sure what you mean by this...being easily confused as I am..;) 
It seemed clear enough by the many posts by the many reasonable and 
informed opinions posted.  Perhaps you didnt get these posts...I know I 
have been having some problems with my email server this fall.

>  Of course we know 
>in advance exactly what pitch these sections are supposed to sound 
>at.  The positioning of the supports at distances from the main 
>bridges that give string lengths in simple mumerical proportions to 
>the speaking length makes it inevitable that when the whole length is 
>brought to uniform tension, the front and back sections will sound 
>the required partials.

Yes, we have been through that. This prerequisits that the factory did its 
job correctly, and quite precisely to begin with. And then there are all the 
factors sighted by our many reasonable and informed contributers about 
how climatic effects on soundboard, bridge, etc effect the exactness of 
the back duplex section (I assume you are refering to  the back duplex 
system)

>  All that is needed is skilful manipulation of 
>the tuning lever and a little encouragement from a hardwood stick or 
>something to equalize the tensions in the three lengths.  

That would seem to follow if indeed one can rely on the back duplex 
length in the first place.

>I don't do 
>outside tuning work but I do a lot of restringing and have never had 
>any problem quickly getting the partials in tune, though I admit the 
>circumstances of a restring do facilitate the task, since you are 
>working with smooth surfaces and unstretched wire.  How easy or 
>difficult people may find it is not the point though; in my view 
>tuned partials are there to be tuned and I tune them.  

Im curious then, what tolerances to you operate with in tuning the back 
duplex. Do you go so far as to count beat rates since you refer to them 
as partials ? How accurate is accurate enough for the back duplex to 
function as advertised ?

>If subsequent 
>tuners pay no heed to them (and very few do) then that's not my 
>lookout -- I just pass comments such as "Oh, you don't tune the 
>partials, I see.  Interesting!".

You do ??  I see... Interesting !  ...grin


>
>JD
>
>