[pianotech] GH-1s

[Dale Erwin]

  Hi Joe
  is this discussion helping answer all those questions you asked.The How do we decide to change scalings?
 For me I often measure the existing plain wire scale and check the tension jumps.  I'll not claim to know a huge amount of the specifics about scaling but there a few things I pay importance attention too. Overall tension and breaking strength. Some one once said the higher the tension the better it sounds. ie more amplitude, sustain. Or the notes sound best just before they break. There is something to that.
I think of several pianos that have taught me that lesson. The first was a 6 ft Ivers & Pond grand I bought to rehab and sell. In the killer range it had a few strings that had broken/snapped. After tuning the piano to get a feel for the instrument a few more snapped. Upon measuring wire sizes it had about 15 unisons of no. 15 1/2 wire in that section Very unusual. This is the kind of thing is always a red flag.  After measuring string lengths,running the scale and comparing it to the original wire sizes the problems were apparent. Quite high tension and higher than normal breaking strain. However the piano had awesome sustain. Trying to scale it more rationally was not going to be allowed becasue  the bridge shape was dictating what was possible. I wasn't going to change the bridge shape. 
   So,After consulting with my bass string maker at the time the original scale was what it wanted. Our rationale at the time was this scale worked for 75 years without incident. SO it was strung with original wire sizes with a few modifications to smooth tension jumps. The top few notes on the bass bridge were tri-chord which I choose to change to Bi-chord. An improvement to my ear
 As a side note: The belly is interesting too. It was .400 thick, ...really? yes I,m sure. It had wide ribs & not very deep. It had no measurable crown when strung and a huge crown when unstrung. It was obvious to me that the unique design of everything was very intentional. They wanted the board to flatten our completely with the bearing load. It did
 The end result is a piano I like very much and more than most. I still tune it occasionally and no broken strings after 15 or more years.



Dale Erwin R.P.T.


 
  





-----Original Message-----
From: David Love <davidlovepianos at comcast.net>
To: pianotech <pianotech at ptg.org>
Sent: Mon, Dec 17, 2012 10:56 pm
Subject: Re: [pianotech] GH-1s


Jim:

You wrote:

	"My comments mostly have to do with wrapped strings, as the small
piano "problem" becomes problematic in the transitions and low tenor through
the 	bass. The square acreage of the small soundboard limits the
amplitude of that belly. Trying to drive that amplitude when it is not there
to be had it is to my thinking a problem. So, my take is that since the
board simply cannot physically comply with amplitude requirements to the
degree a large 	belly can, the strings in a small belly are asked to make up
the difference by making a more complex, noisy, and thus loud sound."  



I've had some scales done for me that pushed the lower limits of scale
tensions and I didn't like the result.  It was weak.  I can't say that's the
same as what this wire would deliver, I've never used it.  My point was that
I don't believe that the gnarliness ("complex, noisy and thus loud sound")
that you are trying to avoid comes about for the reasons you cited.  At
least I don't think it's an issue of tension.  It may likely be the core
wire/wrap relationship in the low bass: a heavy core wire will make the wire
very stiff and push the unwanted high partials into prominence at the
expense of fundamental, that can sound complex and noisy, unfocussed with
poor pitch recognitions, gnarly.  But it's not a matter of tension
necessarily.  Rather it is the lack of flexibility in the wire and possibly
the belly.  That's the low bass.

In the transition section if the amplitude of the belly is minimized too
much then the result will be something thin and weak. Usually amplitude in
the low tenor is not a problem as it's centered more in the board where the
amplitude is the greatest.  If the very bottom of the tenor terminates
nearer the rim sometimes that's a benefit as it minimizes the end of the
bridge effect which often causes the end unisons to boom, even in a small
piano.  Often I'll install an extension there in a rebuild as well as extend
the extension at the top of the bass bridge for the same reason.  I just
don't see the reason to drop tensions in either of those areas.  

Interestingly, as an aside, I tuned a Kranich and Bach 4'11" grand today.
Not a very good piano (no agraffes, simple design, C3 was the last note in
the tenor section) but sometimes we can learn things from not very good
pianos.  Trichord wrapped unisons on the last five notes in the tenor.  The
transition through those wound strings to the bottom of the tenor bridge
from the plain wire section was really pretty good, very smooth and
consistent in character.  Jumping over to the top of the bass bridge was
something else again.  A totally different piano with a nasally, weak and
unpleasant sound.  That was a scaling problem, in my opinion.  

While there has been much bashing of wrapped trichords I would conclude that
when the transition is good, you can attribute it to the scaling.  No
soundboard feature of any type will overcome bad scaling transitions.
However, when the transition is bad it might be the scaling but it might be
a soundboard impedance issue (or both) it's harder to tell.  In this case I
would judge, however, that the poor scaling transition between tenor and
bass was created by poor bichords scaling at the top of the bass, not the
trichords at the bottom of the tenor.  The very short string length at the
top of the bass bridge to me suggests that that area might have been better
served by wrapped trichords, higher bp% and higher tension.  Perhaps a
similar smooth transition could have been achieved with bichords, without
doing the work I don't know.  While I'm only speculating and didn't take
enough data to actually run numbers it's not the first time I've seen
something like that.  

Ron mentioned that as long as he had permission to redesign that he could
avoid trichords.  I'm sure he's right, as long as he has permission to
redesign he can probably set the speaking lengths to whatever is required to
accommodate all bichord wrapped strings.  But with very short pianos you
often don't have good options.  And if you don't have permission to redesign
and must work with what's there then there is, in my view, a place for
trichord wrapped strings on certain pianos under certain circumstances.  In
your particular project (and I don't really know the details of it), I would
not rule it out, though someone with more knowledge than I have in this area
would have to look at it and make that determination.  With respect to the
low bass, Ron's suggestions are all good though he and I disagree on
thinning the panel around the perimeter.  I think it's a great benefit and
something I wouldn't leave out under any circumstances that I can think of.
I think unthinned panels, especially those that employ soundboard cut off
bars, are too tonally restricted.  With a rib scale and radius that removes
the need for compression crowning or panel support of crown, thinning the
panel is only a benefit in terms of soundboard mobility, a more open sound
and pushing out the upper end of the dynamic range.  You need it to get a
good fortissimo.  At least that's how I hear it.


David Love
www.davidlovepianos.com


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Jim Ialeggio
Sent: Monday, December 17, 2012 6:41 PM
To: pianotech at ptg.org
Subject: [pianotech] GH-1s

David wrote:
<Lowering the tension in the bass artificially because the piano is smaller
will just create something that is unpleasant or out of balance, in my
opinion. Avoiding gnarliness can result is a bass that sounds like a rubber
band.

I agree, that while we start with a string scale, the design of the the
whole system determines whether the "string scale" works or not. Its not
just a string scale or a belly structure or an action setup, or a hammer
choice but a whole interdependent system.

But my question to you regarding the above quote would be, how do you know
the alternative to gnarliness is rubberband-iness.  There are no modern
pianos that I know of, save my experiments,  which have pushed the lower
limits of the low tension bass scale to see what would happen. 
Mainly I think because the tensile strength of modern wire didn't allow the
experiment.  How do you know the alternative is rubberband-iness???

Jim Ialeggio

-- 
Jim Ialeggio	
jim at grandpianosolutions.com
978 425-9026
Shirley Center, MA


 

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