Duplex

[Ron Nossaman]

Hi Ollie, er, Mr Cromwell - AKA Ron O.

>They tend to go out of tune to about the same degree as the speaking 
>lengths in the extreme treble,

Where the hitch to rear bridge pin lengths are most nearly the same as the
front bridge pin to tuning pin lengths. About half, actually, or a little less.

> to a bit more towards the lower end of 
>the second top section.

Where the hitch to bridge pin lengths are more like 30% the length of the
front bridge pin to the tuning pin. So a string length change would change
the back scale tensions more, proportional to the front scale, here, than
it would higher up scale where the proportions are closer to equal. 


>The initial positioning will always have errors of measurement, and 
>will require adjustment. The act of tuning will, in the initial 
>months, require a combination of moving the block and adjusting the 
>duplex tension. As the block positioning improves (by being adjusted 
>and refined at the time of tuning) the duplex tuning will come to be 
>accomplished more by tension adjustment and less by block 
>repositioning.

I understand. As you said, it takes a while to find the ideal position.



>>We have different factions using the term interchangeably.
>>They are entirely different concerns, and I'm trying to separate them here.
>
>I'm not sure I follow you. If I didn't explain this adequately, I can 
>rephrase. I have found that duplex tuned pianos tend to stay in tune 
>better with heavy handed pianists during the course of a performance. 
>I attribute this to the string rubbing and therefore tension 
>equalising across the bridge, and not to the fact that the duplexes 
>are tuned.

Yes, that is what I was trying to clarify. My understanding is that to most
of the folks moving aliquots to tune duplexes, tuning the duplex consists
of merely moving the aliquot to a "better" position than it was in before
they moved it. The test being to pluck segment lengths and listen to get
them close. After the aliquots are positioned, by this single procedure,
the duplex isn't touched again. Ever, as far as I know, because it is now a
"tuned" duplex. That's the way I understood the idea that Mr Franklin
supports, and unless my memory has holes in it (which is quite likely),
that's the procedure demonstrated in his classes. Dan, If I've screwed this
up and have it wrong, please straighten me out here. As far as I know, Ron,
you are the only one actually specifically tuning the duplex tensions with
each and every tuning.



>>How can this possibly be? Haven't we already determined that strings will
>>render across bridges?
>
>No. The wire only renders across the bridge when the speaking length 
>or duplex length is 'rubbed' down, or when the differential becomes 
>large enough for the string to pull through the friction created by 
>the bridge pin offset angle.

And isn't that strings rendering across bridges? And why do individual
strings sometimes creep high after you are through with them when lowering
to pitch, if it's not from strings rendering across bridges? I doubt that
everyone's hammer technique is that specifically erratic, and it has to be
coming from somewhere. So the tendency of your tuned duplex system
(technique) to be more stable is the result of taking the time and effort
to individually test and adjust the tension in every duplex section in the
instrument, using the pitch of the tuned system as a guide. As you said, it
isn't the tuned duplex at all that accounts for this, but the specific
effort to adjust segment tensions that makes the difference. Terry Farrell
brought this up a while back too, without tying it to tuned duplexes. Yes,
it would almost certainly produce more stable tunings. So how do you
equalize segment tensions in the tenor and bass where the duplexes aren't
"tuned" and are braided off?

This is the point I was trying to make. Positioning the aliquots to produce
a "tuned" duplex won't produce a duplex that will stay in tune with it's
corresponding speaking length. 



>Before this thread gets totally out of hand, if it hasn't already, I 
>must qualify my posts by mentioning that I'm not saying that the 
>views I've been posting are correct - they just appear to be at 
>present. One never quite knows about the validity of conclusions 
>drawn. We may recall Cromwell's famous words. Off the top of my head 
>I think they are, "I beseech you in the bowels of Christ, think it 
>possible that you may be mistaken". I now step down from the witness 
>box.
>
>Ron O.

I was just trying to get us all talking about the same thing at this point.
We can sort out the fine points, or not, over a beer some other day.
Ron N