Well-Tuned Duplexes (was!Re: Songwriters, ect.)

[Bill Ballard]

>>Bill writes:
>>>Among other very interesting things was Dan Franklin's class. Apparently
>>>one class was quite dramatic.)
>>
>>Now you got me curious, what was Dan's class?
>>Ed
>
>Tuning the back duplexes.


I went to Dan's Sun 2d period class. The explanations here were a 
little sketchy. The results were less obvious than at the early class 
period on this (Sat) in which, as reported by a good friend and 
respected source, the duplex bar in the 5th octave got pushed back 
nearly 5/16th ". He witnessed a surging forth of the sound.

At the second class, Dan worked over the same 5th octave, but this 
time there was slimmer work to be done. It was a convincing 
demonstration that the duplexes could be tuned from the tuning 
hammer. I also noticed that to be able to affect the pitch of the 
duplex, the speaking length had to drop in the neighbor hood of 100 
cents (¢, for those of you with the full character set). This was a 
relief to me, finding that the tension differential across the 
bridge's friction barrier was far greater than anything I going to 
cause during a normal tuning at pitch.

I also wondered if you knock the string down a 100¢ to nudge the 
duplex tension downwards, then retune the speaking length to standard 
pitch, wouldn't the duplex tension be nudged back up to, in fact, 
land where it had been before. All the transactions of tension, from 
the tuning hammer at the beginning of the system to the duplex 
section near the end, constitute a leverage. The available leverage 
in far end doesn't seem like a good, workable handle on the tension 
at that far end. We could have had some good figures for movement of 
wire tension across the bridge by taking before an after frequency 
readings of duplex section. But we didn't.

So after seeing the tuning done in the octave where it had been fix 
yesterday afternoon, there wasn't much result to point at. I asked 
Dan if there was a note in that region which could remind us of the 
"choked" sound so pervasive in the piano yesterday. (I would find out 
30 minutes later that Dan had just paved over the section of road 
which got paved yesterday.) Dan promptly pointed out a note in the 
lower octave.

I have a few more comments, but mainly lots of questions. Like, is 
the contribution of the well-tuned duplex to the resonance of the 
board a function of the match of tension on either side of the 
bridge, or the harmoniousness of these two sections. IWO, is the 
board paying attention to the downward pull on each side of the 
bridge or do the two pitch on either side of the bridge find each 
other and reinforce each other, oblivious to the balance of tensions 
across the bridge?

(You might wonder that tension and pitch would be consistent with 
each other, that where one is there, properly, the other also is. 
Probably not in this piano. I asked Dan whether the most 
straightforward way to tune the back duplex section was laying it out 
by old fashioned linear arithmetic, say, with a ruler and dividers 
every five notes. That done, you would know that when the tension was 
right, the pitch was right. No this idea wasn't particularly 
interesting to him, and he didn't do it.)

That's it, fur starters. And I hoping that this list can shine a few 
flashlights on the subject.

BTW,
At 5:13 AM -0400 5/3/02, A440A@AOL.COM wrote:
>Now you got me curious, what was Dan's class?
>Ed

You mean you weren't in the slightest interested in the two 
suggestions I made earlier in my comments on the current thread of 
HTs. that:
	1.) The easiest way to make an HT was to tune an ET and let 
it sit'n'sag out in the summer sun.
	and 2.) ETDs probably aid in exploring and perfecting 
temperaments in pianos with noticeably bent harmonicities, because of 
the consistency of ETDs' mathematical processes.

All in good fun, I hope.

Bill Ballard RPT
NH Chapter, P.T.G.

"We mustn't underestimate our power of teamwork."
     ...........Bob Davis RPT, pianotech '97
+++++++++++++++++++++