Pianotech

Topic: No down bearing in Stuart and Phoenix?

1.  No down bearing in Stuart and Phoenix?

Posted 03-18-2017 22:50
Fred Sturm ended his last post with:
I'd be interested to know what happens with bridge agraffe systems, either Stuart with wooden board and bridge, or with combinations of carbon fiber board and wood bridge (Phoenix). In both cases, I believe the set up is zero down bearing, which adds another wrinkle.

Can anyone (Fred included) explain the absence of down bearing in the design of these pianos, or direct me to extant discussions.  I couldn't find anything on the Phoenix site that would clarify.


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2.  RE: No down bearing in Stuart and Phoenix?

Posted 03-19-2017 08:30
Suspending my question until I finish reading the "A question for Ron..." thread.  Also found considerable info on Stuart (and associated) sites. Ultimately, though, my question(s) go to the role (need?) of down bearing in the traditional instrument.

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David Skolnik
Hastings-on-Hudson NY
914-231-7565
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3.  RE: No down bearing in Stuart and Phoenix?

Posted 03-20-2017 16:17
David,
The Stuart and Phoenix system use a bridge agraffe to couple the string to the bridge. Essentially the strings go over two bars that are triangular in cross section and rest on the bridge. The strings are deflected downward between those bars by a cylinder held in place by a fixture that is screwed to the bridge (and doesn't contact the bars).

Wayne Stuart's notion apparently has to do with unimpeded vibration of the string termination, somewhat similar to the theoretical basis for the Wapin system, except more so. The strings aren't constrained at all laterally. Their vibrational mode is not changed following the hammer blow.

What does down bearing do, and why do most piano manufacturers use it? Most answers focus on coupling with the board. A side effect is a stiffening effect, as the slight crown profile is pressed into a straighter alignment. This still begs the question of whether or not it is necessary, if  the string is mechanically coupled. (The common system of angled bridge pins actually does a pretty good job of that, and strings are known to hold a soundboard up - remove the strings and you discover that the bridge top is below their level).

Carbon fiber is quite stiff, certainly doesn't need stiffening. I suppose it could be constructed so as to have a crown, but flat is far simpler and more cost effective. Whatever Wayne Stuart's own reasons may have been, and those of Richard Dain in adopting and adapting Stuart's ideas, the bottom line is that those flat carbon boards with zero bearing have power and sustain to burn, so much so that a lot of effort is taken to damp them somewhat. (It is also interesting to note Perzina's reverse crown system, which has power to burn in the examples I have under my care).

Precise zero bearing is achieved in the Stuart and Phoenix by using a vertical hitchpin with a slot for the string and fine threads for adjustment.

What does all this say about the tradition methods and their rationales? It certainly raises questions about our assumptions we take for granted.

------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
http://fredsturm.net
http://www.artoftuning.com
"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
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4.  RE: No down bearing in Stuart and Phoenix?

Posted 03-20-2017 18:50
In the class I took, they said that the two triangular shaped bars are
set at zero downbearing, and that the downbearing is self contained in
the agraffe itself, not bearing down on the board. And, I agree that the
piano with the carbon fiber soundboard and Phoenix agraffes I heard at
that class had sustain galore. I thought that it sounded different,
however, kind of reminiscent of a digital sample. A good sample, but
different than a traditional piano kind of sound. I remember standing
next to David Hughes and making that comment, and if I remember
correctly, he agreed that it did sound different. Not necessarily a bad
different, but different. I listened to the crystal soundboard video
that Ed Sutton posted the link to, and wondered the same thing. I am
wondering what others thought of that? Clark


On 3/20/2017 4:16 PM, Fred Sturm via Piano Technicians Guild wrote:
> Fred Sturm said: The Stuart and Phoenix system use a bridge agraffe
> to couple the string to the bridge. Essentially the strings go over
> two bars that are triangular in cross section and rest on the
> bridge. The strings are deflected downward between those bars by a
> cylinder held in place by a fixture that is screwed to the bridge (and
> doesn't contact the bars).

--
Clark A. Sprague, RPT www.clarkspianoservice.com




5.  RE: No down bearing in Stuart and Phoenix?

Posted 03-20-2017 19:09
Stephen Paulello uses an agraffe of his own design in his pianos. There is no down or up bearing in his system either.  His agraffe differs in that that the strings are clamped down at the ends onto a small bearing pin.  The wire then rises over an elevated bearing pin in the middle, then down to the other end.  

He also uses a vertical hitch pin, which allows him to adjust the string bearing as needed to achieve neutral loading.  There is no side bearing - in fact, the wire forms a perfectly straight line from the agraffe to the hitch 

Interestingly, Paulello pianos have no ribs either.  Presumably this is possible because there is no load on the panel.

Will Truitt

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William Truitt
Bridgewater NH
603-744-2277
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6.  RE: No down bearing in Stuart and Phoenix?

Posted 03-20-2017 21:38
It is interesting to note that at this point, Phoenix carbon fiber boards are 1.25 mm thick. 

Do they sound different? Yes, I think they do. The way people interpret the difference would probably be colored by preconception (kind of like people finding that high gloss poly pianos "sound plastic").

When I first played one (Grand Rapids, 2008), I was struck far more by the sustain, and by the "more bang for the buck," where the actual volume and power rose far more than with a traditional piano, and there was more "power" component and less "timbre" component to a crescendo or diminuendo. It didn't bother me that it "sounded different." I was drawn in and wanted to play more. There was a lot of demand to try it out, so I didn't get as much opportunity as I would have liked. 

Richard Dain has moved along to trying to make more of the body of the piano of carbon fiber, to reduce the weight. Seems like a great direction, though challenging (one problem of replacing the cast iron plate with carbon fiber is that you lose the temperature compensation. He says he has worked out some kind of compensating interface between two parts of the plate structure). Certainly very interesting, cutting edge stuff. Dain is probably in his 80s, so who knows whether there is someone else to take over and move farther.

------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
http://fredsturm.net
http://www.artoftuning.com
"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
------------------------------



7.  RE: No down bearing in Stuart and Phoenix?

Posted 03-22-2017 13:57
What I really want to hear about these pianos, ie Phoenix with wood and/or CF boards, is what there tuning stability MO looks like. Is there anybody out there who services one of these?  ...preferably a wooden board version

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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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8.  RE: No down bearing in Stuart and Phoenix?

Posted 03-22-2017 16:24
Stuart & Sons pianos do have ribs on their CF soundboards.   Actually, a rather elaborate egg crate structure.
    Here's a photo:  http://oasisbill.zenfolio.com/stuartpianos/h3272d556#h3272d556

The Phoenix bridge agraffe design that Darrell Fandrich and I looked at some 5 years ago attached each agraffe to a cylinder of brass embedded in the wooden "bridge" member - one cylinder per note.  My recollection is the brass slug was ~8 mm diameter and 10-12 mm long.  The brass provides substantial mass loading to the system.   Phoenix has what appear to be conventional ribs.
   Here's a photo:  http://hurstwoodfarmpianos.co.uk/phoenixpianosystems.php?page=phoenix&catid=6&id=3



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John Rhodes
Vancouver WA
360-721-0728
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9.  RE: No down bearing in Stuart and Phoenix?

Posted 03-22-2017 17:34
John,  Didn't Darrell buy one of these a couple of years ago when Steingraber first floated them as a trial?  If so, would he be a source to get some tuning stability info from?

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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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10.  RE: No down bearing in Stuart and Phoenix?

Posted 03-22-2017 19:19
Jim,
Yes, (a CF soundboard with bridge agraffes throughout), and yes.  

And I have suggested that Darrell monitor/participate in this thread.  He had the Steingraber in his studio for more than two years, and will certainly have an impression of its tuning stability.

That particular instrument also developed pronounced false notes throughout the tenor/treble.  They were absent when we first met the piano at convention in Southern California, but were painfully obvious when the piano arrived at Darrell's studio one year later.  Richard Dain explained the cause and prescribed a fix; the physics involved is fascinating!  

I'd like Darrell to tell the story ...


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John Rhodes
Vancouver WA
360-721-0728
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11.  RE: No down bearing in Stuart and Phoenix?

Posted 03-22-2017 21:34
John...great...I'd love to hear what he has to say!

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



12.  RE: No down bearing in Stuart and Phoenix?

Posted 03-23-2017 13:23
My question may warrant yet another 'satellite' thread (as was this one, coming off of the "question for Ron" discussion)  but it that could end up being counter-productive.    Here it is, as best I can frame it:

While we're seeing novel engineering that would seem to challenge us to better understand the role of downbearing and crown in piano construction, have we come to the point where the absence of either or both in a new or rebuilt instrument is seen as irrelevant?  Put another way, should the absence or presence of these characteristics be a measure of the success (or lack thereof) of the (re)construction effort?  Assuming that these elements remain a basic axiomatic objective of traditional construction process and procedures, can the results be challenged for their absence, even lacking any immediately perceptible tonal deficiency? 

Vague enough?

Thanks

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David Skolnik
Hastings-on-Hudson NY
914-231-7565
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13.  RE: No down bearing in Stuart and Phoenix?

Posted 03-25-2017 11:07
<can the results be challenged for their absence, even lacking any immediately perceptible tonal deficiency? 

If you are happy with the way it sounds, having a pre-conceived conceptual beef seems counter-productive to the end game...the end game being a real nice sounding instrument. If the tone survives climate cycles, despite lack of visual evidence that tone-appropriate structure is extant...one scratches one's head and accepts that we really only understand the structural requirements when we have a very select collection of variables contributing to the tone-appropriate structure. Change one or several design variables, and the structural requirements very well may be slightly or significantly different from what we are used to looking for.

There are so many variables, and they are are highly interactive. Sometimes I see stuff working that shouldn't be working, and I struggle, with very limited success, to understand why.

Since rebuilding in my neck of the woods is in the toilet right now, I have been doing projects which I refer to as "triage rebuilds". They are not rebuilds at all, but rehabs of toasted, neglected, family instruments, with multiple system failures. I try, with ridiculously low budgets, maybe a 5th to a 6th of what on of my performance rebuilds costs, to make them pass as an instrument that has at least some musical qualities...a bit more than just "plink".  

This could be disheartening work...and indeed it would be if that were all I ever did in rebuild land. However, I'm using the opportunity to see how far I can get with structural conditions I would never dream of accepting in a performance re-build: 

-#1 bang-for-the-buck, clean, structurally healthy termination conditions at the bridge, agraffe holes and capo  
-#2 bang-for-the-buck, basic tone regulation procedures...absent crown and down-bearing, at performance levels where folks play softly and don't ask for much variation in the tone, I can mostly get a sweet attack and reasonably pretty tone as long as vanilla stuff like hammer mating, string leveling, traveling...etc...basic tone regulation stuff is attended to.     
#3 bang-for-the-buck, rescale restring with low tensile strength paullelo where I can get it to work...well up into the 6th octave with type O. Appropriate bp% low tenor. Drop tensions and cores in the bass. Make sure high treble speaking lengths tension is as high as possible, and correct lengths if recapping.       
#4 bang-for-the-buck, appropriate soft pressed light hammers. 

Crown?...Downbearing?...forget about it...recapping I make sure not to overburden the board by pre-loading the board to see what it can stand. But no juicing up the old board other than re-gluing rib separations and perimeter separations, maybe G-flex panel cracks. If crown is there ok if not, oh well.

Under these conditions, interestingly, the basses survive and can sound nice, the high treble survives and can sound nice (better than some rebuilds I did earlier on with too stiff high trebles). These areas don't seem to die given bang-for-the-buck steps 1-4 above. Low tenor up to A4 given proper re-scaling and steps 1-4 also reasonable. The problem child is, and remains the problem child in a any piano...ie A4-A6-ish. Here every trick of tone regulating required to achieve reasonable tone and attack.  But this is required on a new board too.

The differences that I can see, between this work and between high end board work, are in levels of sustain, and ability of the system to function at high force input levels. The patch-ups can't be pushed, as they break up all over the place. With my high end boards, pitch differentiation in all areas of the compass is exceptional...pitch differentiation being maintained through FF and sometimes beyond if the pianist chooses. With old board patch-ups, though attacks can be sweet at mp-mf, pitch differentiation is nowhere near as clear as the high end structure boards...muddy textures might describe it, and pitches break-up between mf-f. Texture is highly un-musical at high input levels.

There are still more variables to consider here though...suppose on the old board patch-ups, I went really light and really soft on the hammers...I think there is still room for textural improvement there. But I think my biggest complaint, when tone-appropriate board structure is absent would still be lack of textural differentiation. The tone becomes, the best word I can think of being, wide and unfocused.

Biggest complaint about all boards high end or dead, including the tier -one Faziolis & Steinways I service, and slightly lower teir Schimmel, Yamaha, or my own work, is the area from A4-A6 which must be anally tone regulated to behave well. Its an issue which I do not buy as board and board structure related. I see similar evidence in this section in boards that I know to be hyper stiff, that I know to be just reasonably stiff, that are rib crowned or compression crowned, that are dead, that have bearing, that have no bearing...etc. The tonal MO is similar leading me to suspect the problem is other than structural here, to some degree.      

Don't know if this sheds any light on your question David, or just sheds more vague-ity-ish-ness.   





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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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14.  RE: No down bearing in Stuart and Phoenix?

Posted 03-25-2017 14:16
Many interesting ideas here. Especially enjoy Jim's last post.

And regarding the weak lower treble issue with pianos, sometimes I think it is because our musical ears really demand perfection in that range.  We want to hear every nuance possible in color and dynamics that we can imagine musically to be present in that range of the piano compass. Some of the perceptual issue is that tone color is largely based on vowel perception by our ears/brain, and as you get around 1K Hz, the vowel differences become E sound and then every other vowel sound is all mushed together into one vowel sound.

E vowel sound should not be present in the tone until you reach the middle and upper parts of the dynamic range of a note. But around the 1K Hz range the transition from soft vowel sound to E will occur sooner in the dynamic range. Of course, most pianos have E vowel sound present all the time and we describe them as "thin sounding".

I continue to experiment with how L-modes influence T-modes and my results confirm the significance of the relationships to our perceptions of tone and clarity, and how the pivot termination must be configured to establish good tone.  Many false beats are due to these interactions. Loose bridge pins is only part of the problem.

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Edward McMorrow
Edmonds WA
425-299-3431
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15.  RE: No down bearing in Stuart and Phoenix?

Posted 03-26-2017 10:44
At David's request, trying to refocus explicitly on his query...

< what does Phoenix and Stuart tell us about the role of downbearing and crown in traditional construction?  

Its not clear...as I mentioned in my post Saturday, change one variable and the system behavior can be redefined in unknown ways. Specifically, change out offset pins for agraffes, and the need for downbearing may go away in a trad board...but not entirely sure if this would be the case...it needs some empirical work.

I get the sense that offset pins set in maple, which are already asked to perform pretty close to the limits of their physical capabilities, especially regarding wearing the top of the bridge pin hole wearing to allowing flag-poling, require downbearing to assist in the efficiency of their termination. In my thinking, which may not be entirely correct, downbearing assists the longevity of the offset pin's peak functionality, by taking some of the necessary but destructive lateral force and imposing that force vertically onto the face of the cap.

As many have observed, and Fred has noted in this thread, there are boards which function when the zero or negative crown board is actively being suspended by the pins. Sometimes this seems to function adequately, to well, but the question has to be, what long term prognosis could the tightness of the pin fit at the cap surface be expected to exhibit under these circumstances. Or put another way, would you do this on purpose, assuming the pins had the ability to maintain a good termination over the long haul, under these very challenging conditions. I wouldn't...its hard enough for them to function well when they are simply asked to perform the offset task.

As I mentioned in my post yesterday, #1 bang-for-the-buck in rebuilding is clean terminations. Maintaining clean terminations is task #1 in belly work, for me. I think down bearing is mainly about maintaining termination efficiency, given traditional offset pins, and impose down bearing with this in mind. I am experimenting with how much down bearing but its still there, if minimized in certain areas.

In my performance rebuilds, I often employ vertical hitches in the capo sections, especially in the soprano. The purpose, starting from 0 deg composite angle, I gradually increase downbearing just to the point where improvement in tone stops getting better. Given...note the variables...13 deg offset, 10mm front back distance (@88), quartered maple bridge, tight V (not U)shape on the capo with .5mm land, board stiffness deigned with the expectation of downbearing being imposed by necessity...improvement seems to flatten out at about 1 deg composite.

Note that the board is stiffer to start with than it would be given no down bearing, because, using offest pins, I fully expected to impose a load on the board. Remove the expectation of downbearing, and one has to rethink what stiffness is required in the panel composite.  

So, beyond termination longevity and efficiency, does down bearing have a function?  I don't know. If, as in bridge agraffes, the termiation is effected senza downbearing, one can experiment with this parameter, and Paullelo, Stuart etal have done this. But they have also changed the bridge mass significantly, adding a variable which complicates the "change only one thing" aspect of the empirical exercise...making it harder to draw conclusions.

I would really like, along these lines, to hear Darrell's take on all this, because his experience with Phoenix experiments. I am really intrigued regarding the development of false strings where flagpoling is not an issue. It will not answering your query with conclusiveness though, but would offer observations of behavior  other than what we are used to seeing.

Yours in unavoidable inconclusiveness,

Jimbo 


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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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16.  RE: No down bearing in Stuart and Phoenix?

Posted 03-27-2017 10:16
Careless once more, as an evolving response to Jim's posts got eaten by the ether courtesy of my sloppiness.  Probably for the best, but Jim's efforts deserve a reply.  

As Ron would have pointed out (at least a week before I actually said anything), I am unqualified to offer conjecture about things like board stiffness or rib scaling, as I don't install boards myself.  I read and try to understand.  On the other hand, I've measured and observed crown and downbearing in assembled pianos for quite some time.  I don't make pronouncements as to what they conclusively prove about a piano, but I try to at least make sure that my observations are documented accurately, and in a consistent manner.  

My thought was to try to keep using the information that emerged in examining the carbon fiber boards and bridge agraffes to inform our understanding of how and why the traditional components work, or don't.

When we speak of  'crown', does it matter if the soundboard panel exhibits such when initially installed, but displays none when piano is strung and brought to pitch?   If I concurrently observe significant downbearing, and have reason to believe that the board is very flexible, it could be that the string load has made the crown unobservable, even if board is providing sprung resistance (instead of static stiffness).  Again,  I'm talking 'terminology', not theory.

I don't care (don't want to argue) about whether a particular (traditionally constructed) piano can sound good, even without crown or downbearing.  I want to understand what it means when one that has been manufactured or re-manufactured with these methods and objectives does not succeed in displaying these characteristics, observably. 

To explore just one of the gifts Jim has bestowed (I mean it):
-#1 bang-for-the-buck, clean, structurally healthy termination conditions at the bridge

Then, yesterday, he was more expansive in discussing termination, so I'd like to (shortly) separate out that discussion, and maybe additional ones, so that this thread doesn't become ever more unwieldy. 

And Ed Mc, you're not off the hook if you want to talk about vowels.

Vague? NO.  Inconclusive? Sure, who cares.





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David Skolnik
Hastings-on-Hudson NY
914-231-7565
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