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Hi Stephen and all,
What a document this is. I have BCC'd Peter=20
Gardner from Pianos Onlide with this post also. I=20
presume he approves with the content of the said=20
article, since it is published on his website.
At 1:28 AM -0400 15/8/04, Stephen Birkett wrote:
>
>I've seen, and been troubled by, this article=20
>before. It's quite a mixed bag, with some good=20
>points, as well as quite a few howlers and a=20
>rather naive attitude to both piano design and=20
>the capabilities of modern engineering methods.=20
>The author gets the point that design stagnation=20
>needs addressing. The basic premise is sound up=20
>to a point:
I would concur with your view Stephen, and with=20
the author's also with regard to design=20
stagnation. Otherwise however, the author would=20
not appear to have made a particularly in-depth=20
study of piano design.
In the web page at;
http://www.pianosonline.co.uk/pol/org.paneris.pol.controller.Page/Home/Event=
s/Dain_Eng.htm
Richard Dain wrote;
>. . . Drawing on his knowledge and analysis of=20
>B=F6sendorfer, Steinway, Fazioli and Stuart & Sons=20
>pianos, Richard Dain discusses and displays=20
>features of piano sound and piano design to=20
>highlight areas where the potential for=20
>improvement exists. Conservatism and resistance=20
>to change in the classical music industry is=20
>criticised for failing to offer the public the=20
>best in quality and variety of piano sound. . . .
>
>
>. . . Modern instrumentation and engineering=20
>techniques open a whole new vista of=20
>possibilities for refinement and optimisation=20
>that has been little used except as a tool for=20
>facilitating mass production to a tolerable=20
>standard. . . . Yet there is so far no apparent=20
>recognition of this opportunity amongst the=20
>great piano builders, perhaps because their=20
>tradition has not been linked with engineering=20
>and they do not comprehend the power of modern=20
>technologies.
Do I detect a sweeping statement here?
>. . . conventional soundboards are made of=20
>spruce backed by belly bars which add to=20
>stiffness. . . The author has yet to see an=20
>instrument where these bars have been designed=20
>to minimise the mass required to develop the=20
>required strength . . .
Keep looking Richard. Something will turn up.
>. . . Financial pressures have driven all but=20
>B=F6sendorfer to adopt artificially cured wood for=20
>piano building despite the damage this process=20
>may have on the material acoustic properties.
This claim is unlikely to stand close scrutiny.
> This may account for some of the perceived=20
>variability in modern piano quality compared=20
>with instruments from the middle of the last=20
>century.
How can we possible know, from our vantage point=20
in time, that yesterday's sound boards were less=20
variable? While there is clearly considerable=20
variability in the sound boards of today, they=20
most likely always have been so. Furthermore, the=20
widespread practice of using compressional forces=20
in the sound board panel, perpendicular to the=20
long grain, as a source of structural strength=20
and stiffness, is perhaps the most compelling=20
reason why there remains considerable variation=20
in modern piano quality (presuming that Richard=20
is talking about tonal-quality when he uses the=20
term 'piano quality'). Since compression crowned=20
and supported sound boards are more prone to=20
premature failure, and I suspect more prone to=20
variability.
And yes, before the arrows start reigning down, I=20
have done bench testing with real size models of=20
both types to arrive at this conclusion. How many=20
of the compression-crowned school of sound board=20
manufacturers have actually tested a=20
rib-supported sound board to test its validity or=20
otherwise?
>. . . The down-bearing force of the strings on=20
>the bridge was historically determined by the=20
>need to keep the strings in contact with the=20
>bridge when they are struck from underneath and=20
>as they vibrate.
And what about the wooden diaphragm spring,=20
commonly known as the sound board, being in a=20
state of equilibrium against the down ward force=20
which results from the sum of the string=20
tensions*sin of the angle of downbearing. I=20
realise that a tiny percentage of piano=20
manufacturers do not believe in down bearing.=20
However, to my knowledge that non-bearing school=20
of piano manufacturers numbers only one.
> Contact across this interface is enhanced by=20
>making the strings zigzag across the bridge=20
>(known as side draught) between inclined bridge=20
>pins- a device which obviously introduces=20
>undesirable friction interfaces. It is well=20
>known that excess down bearing force shortens=20
>the duration of sound although a small amount is=20
>probably beneficial. The Stuart piano has=20
>re-introduced a device pioneered decades ago=20
>that locates the string to the bridge by an=20
>agraffe (clip) without the need for side draught=20
>across the bridge or for bridge pins.
Now Richard, as an engineer, tell us about the=20
effect of the vertical string offset which the=20
bridge agraffe introduces as a substitute for=20
side draft of a conventional bridge. Are you=20
suggesting that the side draft introduces=20
undesirable friction interfaces while the bridge=20
agraffe, with its equivalent string offest in a=20
vertical plane, does not? I think it was only a=20
short distance earlier in your article where I=20
read of you lamenting the lack of application of=20
'engineering principles', with regard to piano=20
design.
> The Stuart piano develops uniquely long=20
>duration sound and employs minimal down-bearing.
I measured a Stuart 220 and a Stuart 290 concert=20
grand recently with Ron Nossaman when he was here=20
in Sydney. The average setting of these two=20
pianos was sound board crown - essentially zero,=20
down bearing - essentially zero (measured with a=20
Lowell downbearing gauge and a string across the=20
underside of the belly at several points).=20
=46urthermore, I am not so sure that we should=20
describe the sustaining qualities of the Stuart=20
pianos as being 'uniquely long'. Just speaking=20
from listening experience, at the pianos, here.
>. . . Several makes of piano, notably=20
>B=F6sendorfer and Stuart now have extra strings at=20
>the bass and/or the treble end, these are not=20
>always provided with keys and action components.=20
>The extended width and thus extra flexibility=20
>and area of the soundboard undoubtedly=20
>contributes greatly to the quality and dynamic=20
>range of the piano sound and resonance in these=20
>strings also contributes positively to the=20
>general sound quality.
And your engineering basis for making these=20
claims is? What makes you believe that bigger is=20
necessarily better especially with regard to=20
sound board area? And how on earth might extra=20
strings enhance the dynamic range of an=20
instrument? Bigger where and smaller where might=20
indeed be more pertinent questions with regard to=20
sound board area.
>. . . To produce a pure sound the string must be=20
>of uniform density and cross section or it will=20
>emit a warble or range of frequencies known as a=20
>false note. False notes also arise if the length=20
>of the string is even slightly indeterminate. .=20
>. If the bridge pin is not firmly encastered in=20
>the material of the bridge then it also may flex=20
>and sound purity is lost.
Yes, that's one of several causes.
> The ingenious Stuart bridge agraffe has=20
>eliminated the requirement for bridge carving=20
>and provides a uniquely definitive termination=20
>to the string length.
Agreed in principle, but this particular design=20
would appear to remain noisy, due to the nature=20
of its execution. Sure the 'silicon implants'=20
certainly are a help, but as we all know, there's=20
no substitute for appropriate design at the=20
outset.
> In consequence the Stuart piano is virtually free of false notes.
Clearly, you would seem not to have been=20
'up-close and personal' with enough Stuart=20
instruments. I could have sworn that I've heard a=20
few falsies, but then I might have been poorly=20
located in the listening area. Yes, poor string=20
terminations are a potential cause of false=20
notes, and bridge terminations if properly=20
designed and executed can help an instrument to=20
produce a purer tone, but there are other causes=20
of falseness.
>. . . At the keyboard end of the string the=20
>sounding length is determined by the string=20
>passing under a knife-edge on the capo d'astra=20
>bar or through an agraffe located on the frame.=20
>This knife-edge is subject to wear and=20
>inaccuracy of manufacture which may be a cause=20
>of false notes.
and considerable string noise . The 'inaccuracy=20
of manufacture' can be solved with a little=20
attention to detail.
> The author has experimentally fitted hardened=20
>beryllium copper wire knife edges to one=20
>instrument and obtained significant improvement=20
>particularly in reducing sliding friction and=20
>aiding the tuner's task.
Certainly, and just as one swallow doesn't=20
necessarily indicate a summer, Richard might have=20
used any of a range of materials freshly=20
profiled, and compared to an original noisy bar,=20
an improvement will be detected. The achievement=20
of a tonal improvement in the short term is is=20
common, but the results in five years time will=20
indicate if an 'improvement' has durability. It=20
might also be worth mentioning that if the=20
instrument Richard modified was one of the brand=20
name which he sells, I happen to know that this=20
particular company does not believe in hardening=20
the Capo' bars to make them more resistant to=20
string deformation and the development of string=20
noise. I know this because our established=20
practice of hardening capo bars was criticised by=20
a company representative from the said firm. In=20
fact, the representative claimed that hardening=20
bars could only be deemed experimental. I haven't=20
answered my critics directly with regard to their=20
claim. But I would like to say in my defence that=20
the practice, for us, was experimental back in=20
1995. We found at the time that it worked very=20
well indeed, and it has been a routine practice=20
in our workshop ever since, for both rebuilt and=20
new instruments.
>. . .Two modern instruments, Estonia and Fazioli=20
>employ means of accurate tuning of these=20
>extension lengths with marked beneficial=20
>acoustic results. Steinway and [SOME] others use=20
>duplex scaling with a factory set tuned length.
We use tuned lengths for the rear duplexes also=20
(plan view available at=20
http://overspianos.com.au/OS003.html). But the=20
jury is still well and truly out, as to the=20
benefits. Our front 'duplex' lengths are=20
deliberately out of tune with the harmonics of=20
the speaking length. On this matter, to us, the=20
jury is well and truly in. Further, information=20
is in the archives for recent subscribers.
>. . . Traditionally made of grey cast iron, the=20
>frame has to withstand the tensile forces of the=20
>strings that total some twenty tons. Cast iron=20
>is far from an ideal choice
Why? Please refer to my entry below - SAMPLES !
> but has survived from the days when it was the=20
>only option. Cast iron is highly absorbing of=20
>acoustic energy and has a low Young's Modulus.
There are many grades of cast iron, with varying=20
degrees of strength and hysteresis loss (as you=20
acknowledge below). The piano maker has many=20
choices of cast iron - a range which is much=20
wider today than previously.
>Historically the metallurgical content of the=20
>cast iron used in pianos has been modified to=20
>achieve better castability and to reduce sound=20
>energy loss, each maker has his own magic=20
>ingredients.
Perhaps.
> Some makers now use cast steel frames which=20
>obviously have a more favourable Young's modulus=20
>to give better stiffness and less mass. Carbon=20
>fibre frames which might be horrendously=20
>expensive would appear to offer mass, strength=20
>and stiffness advantage. Without going to that=20
>extreme one can envisage titanium might be an=20
>interesting option
A very interesting option, especially if we are=20
hoping to produce a piano which goes immediately=20
out of tune as soon the ambient temperature=20
changes a mere couple of degrees.
SAMPLE LINEAR EXPANSION COEFFICIENTS
Metal Linear Expansion (per unit length per degree F)
Cast Iron 0.00000655 (typical iron plate material)
Carbon Steel 0.00000633 (SAE 1085 piano wire)
Titanium 0.0000049 (Richard's 'interesting' plate material)
Source: Machinery's Handbook (21st Edit. - page 2270)
>. . . The roller action pioneered by Erard, a=20
>Company name still used, has been modified and=20
>refined to a high degree of perfection. It is=20
>difficult to see how mechanical actions may be=20
>significantly improved.
Keep looking Richard.
> Individual actions are now tailored to=20
>particular maker's instruments by the lead=20
>action manufacturer, Renner. All Renner actions,=20
>if well fitted and well regulated, offer superb=20
>control.
Compared to what?
>The Steinway/Renner action has wide artist=20
>acclaim because it remains reliably playable=20
>even if grossly maladjusted.
This is surely new knowledge! It's certainly new to me.
>B=F6sendorfer have in the past year introduced a=20
>new Renner built action which in the author's=20
>opinion is supreme in consistency and touch=20
>control.
Do I detect marketing spin which is in serious=20
danger of overtaking the engineering approach?=20
Please understand that I'm not doubting that the=20
said action might indeed be a significant=20
improvement. But in the author's view, it would=20
appear that there is only one piano which=20
deserves supreme admiration. Although uncle Wayne=20
and Paolo also get a fair run. Or am I misreading=20
the script?
My apologies for the length of this post.
Sincerely,
Ron O.
--
OVERS PIANOS - SYDNEY
Grand Piano Manufacturers
_______________________
Web http://overspianos.com.au
mailto:info@overspianos.com.au
_______________________
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