Duplex scale

[Delwin D Fandrich]

Stephen Birkett wrote:

> Del responded:
> > Any mechanism or system that allows energy to be transferred from the
> > speaking portion of the string to any part of the piano other than the
> > bridge and soundboard detracts from the energy available to drive the
> > bridge. Tuned duplex systems always detract from the available sustain of
> > each string afflicted with them.
> >
> I've heard (actually read) you say this before (or should I say "heard
> you write"), Del, but I don't agree on two counts. 1) The acoustic
> performance of a bridge/soundboard is too complex than a simple total
> energy analysis to be useful...much depends on how the energy is
> distributed between the partials, and psycho-acoustic effects, to givejust a couple of ideas; and, most important,...

The above wasn't intended to be an exhaustive dissertation on the function of the bridge/soundboard/rib assembly. It was just
a simple observation of a fact of life.

You are right, of course. The function of the soundboard assembly is indeed complex. But a variety of mono-chord experiments
have convinced me that -- all else being as equal as possible -- the tuned duplex string termination system does cost energy
and does reduce sustain time.



> 2) I think you have missed
> the principle behind the tuned duplex, which is to enhance high partials
> through sympathetic vibration, rather than via bleeding energy from the
> main string. The same energy will be lost by transmission through the
> bridge, whether it goes into a listing-damped tail portion, or a
> non-damped tuned duplex. The aural effect is quite different.

No, I don't think I have missed the point of the tuned duplex. At least I sincerely hope not. I've studied them and worked
with them and struggled with them in hundreds of pianos over a period of several decades. I've tried to solve pianists and
owners complaints about them. I've tried to reduce the objectionable sounds that are generated by them to less objectionable
levels. I've listened to other technicians complain about them and struggle with them -- just think back over just the
postings to this list and consider how many problems are related to, or can be traced to, them. I've studied them and tried
to understand the theory behind them. I've listened to, and worked with, "experts" on the subject. I've read everything I
could find about them. (OK, I have to confess -- Dan Franklin has an ad in the current Journal offering a new tool for
adjusting the rear duplex bars that I've not yet investigated and will one day soon. But I think I've investigated everything
else.) I've experimented with them and I've designed and built pianos with them and, finally, without them.

In the end, I simply gave up on them and started designing them out of the system and I've never been happier. Well, that
might be a bit of a stretch. But I've certainly been able to solve a lot of string noise and sustain problems. And not once
have I had a complaint about any loss of tone quality. Quite the opposite, in fact. Pianists have appreciated the change and
the improvement in sound.

Now, I realize that the appreciation of tone quality is a very subtle and subjective thing. And I would not presume to
attempt to enforce my standard of "good" tone quality on you or anyone else. But... the people who's pianos end up in our
shop have generally had it with the down side of the tuned duplex string termination designs and are ready for what -- in
their minds and to their ears -- will be an improvement.


> With clever sleight of hand I now unite two disparate threads...I'm fully
> convinced that the tuned duplex on my little 1937 Steinway 'S' is one of the
> major contributors to the overall success of the sound...creating the
> impression of a much bigger piano.

That's great! If you're happy with the sound and the design of your piano, I'd be foolish to try to convince you that there
was something wrong with it. But, over the years, I've encountered far more piano owners who are disgusted with the problems
created by the front tuned duplex design than those who felt it contributed to their enjoyment of the piano. For me, the most
convincing argument has been that once design has been altered to give the string a more positive termination, nothing seems
to have been lost except the string noise problems. Sustain improves (although in my own simplistic way, I'm now addressing
the bridge, soundboard and rib design, as well), tone quality improves (admittedly, by my own definition), tunability
improves, etc. Except for violating some sacred laws of tradition, I've yet to find the down side.

> Early pianos often left (untuned) tail portions undamped in large parts of
> the compass, to enhance the colour of the tone...an effect that probably
> is interpreted by the ear in an non-intuitive way. And correct me if I'm
> wrong please, but I believe the tail prtions on harpsichords are
> generally undamped too.
>
> Stephen



Nearly everything negative that I have to say about tuned duplex systems applies to the tuned front duplex string segment --
the V-bar/counterbearing bar segment. The back scale can be tuned or not. It doesn't seem to matter all that much as long as
the lengths are long enough to not overly restrict the motion of the soundboard and bridge assembly.

We also leave the back scale undamped whenever possible -- which is most of the time. Most "modern" pianos have threaded back
scales through the bass and tenor out of habit and tradition, not need. The only pianos I have come across that have been
deliberately "threaded," or damped, through the upper tenor and/or treble sections are those with tuned back scales that have
been causing problems by generating unwanted extraneous tones and noises.

But I repeat myself...I wrote two Journal articles saying all of this stuff about two years ago. Not much has changed except
that we've gotten better at removing the offending front plate duplex bars and designing around them.

Del