Hello folks!
Here is a question about piano soundboard design. Is there any theory or idea that pianomanufacturers have to optimize the size of the soundboard or shape of it to get the best sound. I guess this should be quite well studied, but suspect it is mostly trial and error over the years.
Why do Steinway stick to 188cm, 211cm etc for example?
Usually it seems that over 180cm (5' 11") the grands are called parlour grands and that the bass section gets somehow full bodied above this length.
Is there any substantial truth in this or just "design"? Also it seems that grands tend to be larger than before; Bechstein, Grotrian Schimmel has made slightly larger parlour grands lately then earlier for example; nowadays most are above 190cm, but long before bechstein had an A model which was 185cm and was very popular.

I guess people must have studied how to design the best soundboard; this has to be crucial for the sound. But is there any deeper physical/mathematical analysis made other than trial and error?

Kind regards
Hermerik

Hi Hermerik,
I've been studying and making soundboards since 1978. First, the size of the soundboard is determined by the size of the piano. They make different size pianos for different venues, home concert, etc.

I am glad that you noticed that some pianos sound bigger than others regardless of size. Not long ago in an email, I was told that that a pianist who has a 9 ft grand that was rebuilt, and a 7 ft grand pre 1920. The 7 ft grand was the bigger piano with more "meat" as he put it.

Basically here are some design reasons why:
1. The panel is not graded, and or is too thick. The Steinway diaphramatic method goes too far as a grading method and often leaves the panel structurally too thin and weak.
2. The rib structure is too stiff. Most rib designs in modern pianos today have way too much mass. I have measured ribs that are 1-1/4" tall in some cases. Early American pianos often stayed around 3/4" to maintain strength and flexibility. Another factor is wood choice. Steinway uses sugar pine ribs, and others will use Spruce ribs. Spruce is stiffer than pine.

I have studied Steinways soundboards as a lot of them come into my shop. Not all sound as good as another, even the same model. The ones that sound the best have the most power, always have a lower rib profile ( sum of the Height to width ratio). There's more info on my website if this topic interests you.
www.chernobieffpiano.com

-chris

Hello Hermerik,

Some of your observations are related to the scale design, not specifically the soundboard design, though it is a blurred line. In larger pianos, the string length and bridge position can be more optimized. Scale design is an optimization given other factors, an art based on quite a bit of science. In the last quarter century, computer programs have assisted some of the newer scale designs, requiring fewer prototypes be built.

Regarding soundboard design, the progression was affected by other design and material changes. Plenty of instruments incorporate soundboards, and they evolve as the marketplace demands it. There seems to be more enthusiasm from a few within the industry to improve piano soundboard design. The marketplace is not clamoring for it...like it does for cellphone batteries.

[quote=Chernobieff Piano]Hi Hermerik,
I've been studying and making soundboards since 1978. First, the size of the soundboard is determined by the size of the piano. They make different size pianos for different venues, home concert, etc.

[\quote]

I think I experienced a Steinway S at Royal Music in Bowling Green, KY where you designed (redid?) the soundboard. What a FANTASTIC sounding instrument with a really satisfying low end (really quite lovely across the entire instrument).

Kudos!!

Forrest

It's the whole system, not just the board -- it matters a lot where the bridges are, how hard the hammers are, etc. -- Given the same key press, a console can be louder than a concert grand.

I find it most productive to look at the mode density a board is capable of to get some measure of the eveness of response and warmth of tone. Many piano technicians have been using a model of analysis for the soundboard structure that I find ludicrous. They treat the ribs like floor joists that support downbearing. Soundboards are made in a way that produces an arched shape to resist the downbearing The arch geometry allows the board to resist downbearing and yet be light. It also allows for humidity changes to occur in the wood with reduced forces that can lead to cracks. In essence the crown is an expansion joint.

I have also found studying and testing how the bridges, board and plate respond to Logitudinal modes. I have discovered that even L modes too high in frequency to be directly heard have a profound effect on clarity of tone and production of false beats. L modes can couple with the normal Transverse waves and distort the sound. And inaudible L-modes can produce audible beats.

I agree with Chris that when soundboards are thinned too much they are easily degraded by the stress of fluctuating humidity and the treble tones are less clear.

Nicely put Ed.

Thank you Forrest, Nice piano for nice people, hope it serves them well. Sure was a wreck when i got it. The owner hired me to rebuild it so he could sell it, then i get a call a couple months later that he decides to keep it, and just can't let it go. My favorite success story!!
-chris

As for Steinway, they had a Model O which fools people because it is bigger than a Model L and smaller than a Model B.
As I understand it, baby grands are 5'6" and smaller, usually 5'2", parlor grands come in two sizes, 5'7" or 5'8" and 6'4" to 6'6", semi-concert grands are around 7', concert grands 9'. Kawai sold lots of 5'10" pianos. The Steinway Style 4 I recently bought is 8'4" and is the largest piano they were selling back then. Starr's biggest model was 7'6" and called a concert grand.
Soundboards can be analyzed by putting a layer of sand on them, playing the instrument, and seeing where the sand bunches up. I don't know of any practical results from this test, though.

The model L and O are the same length. The model L is the O model with the bass side of the case set at an angle to the keyed/strikeline so as to increase the soundboard area beyond the lower pitched ends of the bridges. The L also has longer speaking lengths on notes 27 to around 31. These were good ideas in my experience. The L suffered from poorly layed out tuning pin, hitch pin, and bridge pin layout. In other words a great idea sloppily excecuted.

If one corrects for these deficiencies when rebuilding, the L is stunning and merkedly superior to the O. The O and the L were both designed by Henry Zeigler. Zeigler gets little credit for his design expertise in the usual telling of the Steinway Saga. The 6'4" A is a Zeigler design that I like to describe as a "stretch" B scale.

I'd think the practical result would be you'd find out how difficult it is to get sand out of a piano..... ;-)

A relative of mine who is a rebuilder in Olympia Wa., also puts a lot of emphasis on the backscale.

My understanding is that it was Paul Zeidler who designed those pianos while working for Steinway, then went on to A.B. Chase, and then started his own firm (with his Steinway bud) Strich and Zeidler. I'm not a 100% on the details though (Zeidler's father also worked for Steinway). But I have seen the Ab Chase 9' and Parlor grand and the scales and other characteristics are pretty much identical to SS. It is a little confusing tho Zeidler or Zeigler?

On design, an interesting observation i made. I have been researching into Jacob Goss the designer of the Steiff pianos. He worked for Schiedmayer, then other piano manufacturers throughout Germany before coming to the U.S. The more i study this soundboard of his that i have, the more amazed i get. Analyzing the grading pattern of the panel, it became evident that it was laid out using the golden ratio. There seems to be a lot of "handed down" knowledge built in. I'd really be curious if Schiedmayer used compression soundboards. In a recent documentary Miss E. Schiedmayer said the Schiedmeyer piano design was directly influenced by Beethoven and Stein. Schiedmeyer worked for Stein. Wouldn't be hard to imagine the feedback from Beethoven causing builders to up their game.
-chris

Chladni patterns are more useful to Luthiers, than a piano tech. Chladni patterns help with feedback info when the same model is built over and over. Then they take of very fine shaving to control the tone in certain areas of the top. But you have to know what tones for what area work best. Not clearly defined in piano soundboards. Top notch violin makers ( like Jack Fry https://www.youtube.com/watch?v=c8-rOvWeV8k ) used their ears more effectively and accurately.
-chris

Thanks for all replies!

Could you (Chernobieffpiano) explain more how the golden ratio is used. This sound really interesting. I am a mathematician and see the golden mean in all kinds of 'natural' constructions and mathematics.

So it seems there are computer experiments making predictions.

I am also curious how the interaction of longitudinal and transverse waves interact (Ed' s comment). Maybe this has to do with the golden mean...!

This mysterious number.

So how does the original Model A fit into this? It's around 6'1" so is bigger than both the L and the O but smaller, of course, than the B. I know the A-III competed too well against the B so was "retired" but I think the current A is back down around the 6'2" size.

Paul.

I have a Sauter delta which is 6' 1" (185cm). The Steinway A is 6'2" (188cm). But it seems to me (maybe I am wrong) that there are not many grands that are of size 193--200cm. There seems to be an interval 5'8" -- 6'3" which is denoted "parlour grands". So why this gap after 6'3" ? Any "deep" reason? A similar gap but larger is 235--270cm. Above 270cm the concert grands come in.

/Hermerik

If it has anything to do with the Golden Mean I would be thrilled. I like that number. :-)
Maybe it has something to do with the fact that every frequency has to come to its full colour so to say and then the soundboard cannot emphasize certain frequencies. To me it feels like quite a delicate problem. Why is the soundboard shaped like a violin for example? (I mean only roughly shaped like that -- why not rectangular for instance?) There should be some reason..

Upright soundboards are mostly rectangular in shape, IIRC, and many uprights have better overall response than a small grand.

The golden ratio is a nice number, but 17 is better. It is the only truly random number, according to my math prof in university.

I meant to say the the 6'4" Steinway A is a "cut-down" B. Zeiglers first scale design was the O which he "cut-down to make the M. Next Zeigler modified his uncle Theodores A several times to bring it up to 88 notes and improve the scale break. After that Zeigler Then Zeigler "cut-down the B to make the big A but Hamburg never switched. And after that Zeigler modified the O to create the L but Hamburg never switched. And going further he "cut-down" the M to make the S. And somehwere amongst and following this he made the 1098 and F uprights.

The golden ratio can be found in how the string lengths progress.

We should be careful to put things like that on the internet. The Chinese may pick up on it, copy it and soon build pianos like Steinway. Or better. Mind you, they may own the outfit earlier or later anyways.

Norbert

Hi Hemerick,



Here is my attempt to explain this:
Sound-board's size is proportional to the scale design of the piano. It is worth understanding that not the whole soundboard area is functional, and in certain cases a smaller soundboard than average may provide tonal improvements.
The specifications of the soundboard-system will determine the acoustic properties of the soundboard, that ultimately affects how energy flows through the board while the energy is radiated and consumed as well. [copy and paste] (I won't say from where for now ;)) magnitude of the impedance (Z), and its phase angle (φ), and the sound level (L). These three curves summarize the acoustic properties of the soundboard.
However without trial an error we can take measurements to create specifications to manufacture a soundboard.

Ribs are fundamental contributors to the performance and acoustic properties of the soundboard: [copy and paste] A stiffening of the soundboard would improve the sound radiation efficiency, as a stiff soundboard is less inclined to subdivide into small vibrating areas. One purpose of the ribs is precisely to stiffen the soundboard.
It was important to provide this explanation as it supports the fact that the performance of the sound-board is not simply connected to size/shape.
The topic of a piano soundboard can generate technically hundreds of pages, if a scientific explanation is required, yet I believe that work-experience and the human ear lead also to very satisfactory results as well.

my two cents,

Hi Kurtmen,
Actually this statement is not correct. A couple of years ago, i made what i call a variable vibrating rib ( the stiffness is adjustable). By imparting the same energy into it to make it vibrate the stiff rib will vibrate a FAST frequency but SHORT duration. Then after adjusting it to be flexible, the same energy input made the rib vibrate SLOW and LONGER. Thats why the old Axiom among instrument makers was to get a lower tone for more warmth and depth. That gets lost with too much stiffness.
-chris

Hermerik,

So I sliced a soundboard between all the ribs to be able to mic the thickness easily.
http://chernobieffpiano.com/wp-content/uploads/2018/10/stieff-soundboard-007.jpg

Then I measured the thickness at many locations and drew a map.
http://chernobieffpiano.com/wp-content/uploads/2018/10/stieff-soundboard-thickness-pattern.jpg

By chance i noticed that the pattern looked proportional somehow.
Then I remembered the Golden Ratio.
So I made a quick drawing and laid it out the normal way. Then I drew ellipses using the top edge and other key points. And lo and behold it's almost exactly the layout of the thickness pattern of the Stieff board!!
Anyways, I thought it was interesting.
http://chernobieffpiano.com/wp-content/uploads/2018/10/Golden-ratio-thickness-pattern.jpg

-chris

Hi Chernobieff,
You are too focus in demonstrating your "perspectives" or "knowledge"
You picked a part of the text but not really understood the over all post
This is something really basic, it is just a simple partial-explanation about why ribs are placed on soundboards, versus having a board without ribs.

I don't know why you decide to attack me personally by trying to infuse what you think my motives are, and not address the issue i raised. I actually understood your post, and agree that the ear is the final arbiter. My point is that you made an error on fact. Here's another one, you said stiffness increases the efficiency of sound radiation, and the ribs job is to add stiffness. Then why not make them out of maple? On that scale maple isn't that much heavier as to be unreasonable.
Thanks,
-chris

Well you are taking stiffness as a factor without variables and degrees. Stiffness is absolutely required as well as flexibility, that's is the whole point the balance between the two.
This is why I felt you had no interest in anything, except in what you have to say. I spoke of stiffness as a required element but not the only absolute function of a rib or specification of a soundboard.

How about hickory? High strength to weight, lots and lots of twang.... ? And it's specifically American -- the last ice age killed off the hickory in Europe because the mountains there go East-West instead of North -South, so the trees couldn't seed ahead of the glaciers.

John,
I like where your going with this, but i think Ash has the highest strength to weight ratio of the hardwoods if i remember correctly. Great to work with too, machines very well.

Kurtmen,

My philosophy is simple. To learn all the different prevailing ideas( past and present) in piano technology (soundboards specifically) challenge the ones that are false, agree with the ones that are true ( for confirmation) learn of the current trends, to be well rounded. So i am absorbing what is useful and discarding the rest. It's my "Jeet Kune Do".
I've been talking flexibility in soundboards for years and everyone else talks only about stiffness like its an automatic reaction. Yet they never mention about too much stiffness. If i'm lucky and press them hard enough then i get the "impedance matching" thing. That's been the jist of conversations of the past 2 years. But all that theory stuff is fine, but i never hear any practical ways to pull that off. It just sounds like hit or miss and trying to sound intelligent while guessing.
So, care to throw in what you think the variables and degrees are? So when in the shop hovering over a newly installed soundboard, how do you know if its too stiff? Or too flexible? Where is the balance point?
-chris

One would find ribs made from hardwood way too "creepy". Sugar pine and spruce are extremely resistant to warping once properly seasoned and worked.

The "purpose" of making a soundboard "properly" stiff is to make it capable of responding with a broad range of the lowest modes that are not too far separated in frequency. This makes for even frequency response. Also one doesn't want the board to respond in multiple areas to the same frequencies until one gets high enough in the frequency range. Otherwise you could get significant phase cancellations.

The soundboard may not be the only part supporting sound formation. Here is an excerpt from Bösendorfer's web site.

Contrary to all other manufactures Bösendorfer constructs instruments concentrating on the use of spruce. More than 80% of this wood, ideal for instruments, can be found in Bösendorfer pianos. Verysimilar in principle to a violin the whole body - not exclusively the soundboard - supports sound formation. The actual core of the piano rim consists of a 10 mm quarter-sawn piece that is specially grooved by our craftsmen to allow it to be bent to the silhouette around the inner rim – this is unique to Bösendorfer. When a note is played, the integrated spruce components become acoustically active, forming a complete resonating body that allows the whole instrument to project your play. For outstanding richness of tone colour and our legendary pure and brilliant sound. This complex construction is part of the Viennese tradition of piano making.

Steve

Understanding soundboard response is very complex. It is too large to act like a piston, which, by the way is how speakers ideally behave. Additionally, the very stiff connection between the soundboard and the rim also inhibit its motion. Also, of course, a soundboard is not isotropic--its stiffness is different in different directions and different positions. Motion cannot be transmitted instantaneously--it travels typically in transverse or compression waves. So, when string movement is transmitted to the bridge it radiates outward with finite velocity until it is damped out or reflects off the rim. A soundboard has a fundamental (lowest) resonance. Below this frequency its ability to radiate sound becomes increasingly reduced (by the square of the ratio between the resonance and driving frequency). Honestly, to sort this out analytically seems impossible. Finite element analysis seems the best way to model and understand soundboard parameters. This is not a problem for large companies, though smaller ones likely wouldn't want to purchase the pricey software, and wouldn't want to pay a consultant to do the analysis.

I was never sold on the Bosendorfer "story" . It's so carefully worded as to not say anything factual that could be scientifically questioned. Even the violin comparison is questionable. The top plate and back plate are tuned to non-competing frequencies. The back plate is maple not spruce. So maybe the Spruce in the vienna construction method is holding back not enhancing sound production. Perhaps a backframe made out of ash or maple would be superior, not inferior.
The complications that would arise from beam frequency being in phase with certain notes. Do they tune beams to create a mismatch?
-chris

The "newer" Bosendorfer scales such as the 6'7" and 5'8" have verticaly laminated rims. That indicates to me the designers knew that these types of rims were structurally more desirable, and that with the older scales the company didn't want to invest the money to reformulate them for a laminated rim design. The sales people then took a negative and claimed it was a positive.

Ed, Wrong! You should go to Vienna for a tour of Bosendorfer before you tell people how Bosendorfer does things. What do you suppose is under those "vertically laminated rims" you are talking about? I've been on tours there 4 times as part of the master classes I have taken and have seen them produce rims just as they describe on their web site.

Steve

Chernbieff, really? Don't buy a Bösendorfer and you can go on believing your own story as much as you like. What story do you tell people when they want to buy a piano from you're company?

Lakeviewsteve,
I can see from looking at the pianos that the rims are continuous laminations and that there are no corner joints in the case of the smaller Bose grands. The big scales have angular corners showing a pieced up rim.

Lakeviewstiff,

Maybe you could offer a counter to the points i made, instead of a personal attack?
-chris

Bösendorfer rims were kerf-bent. I do not know whether they still are. I have seen a kerf-bent rim on a Knabe.

Only the outer rim is kerf-bent, a horrendously labour intensive process the inner rim onto which the soundboard is attached is made of segments of spruce, and more recently in the VC series, reinforced with some hardwood for greater rigidity. I was informed of the last bit of information from someone at Yamaha.

What do they mean by "vertically laminated"? Do they mean that the grain runs vertically rather than horizontally? That wouldn't be nearly as strong, but then again we're not supposed to play bumper cars with grand pianos....

No, that's ok. Personal attack? You don't know what you are talking about. End of Story.

I watched a video recently that compared 3 pianos side by side.
https://www.youtube.com/watch?v=T2GYYV8JSqM

The Steinway D sounded like the bigger piano to me when the artist played the Liszt.
Bosendorfer claims:
1. " the whole body - not exclusively the soundboard - supports sound formation."
2." When a note is played, the integrated spruce components become acoustically active, forming a complete resonating body that allows the whole instrument to project your play

Not hearing it in the side by side.

Researching on the internet for facts to support their claims, and all there is, is stories like:

"Ignaz Bösendorfer combined his music education from the Academy of Fine Arts with his knowledge of carpentry to allow for a louder sound while keeping the mellow tone quality characteristic of Viennese-made pianos."
How does being a carpenter and studying music allow for a louder sound?

What i'm asking is- How and when was it proven that the spruce components are a tone enhancement? And not leakage? Did they try other species? Pine, fir, what was the results of those?
Listening to the side by side, the Steinway had more in reserve it seems to me.
My understanding in the study of musical instrument acoustics, is that the soundboard moves more air than the music wire alone. How do those big, thick, cross braced spruce beams move more air to enhance the sound?

-chris

What I mean by vertical laminations is the glue line between the wood is vertical to the horizon. The grain orientation of the wood, I don't know.

Wouldn't that be true for pretty much every laminated piano rim?

Yes, That is my point. The "newer" Bose scales have continuous laminated rims and the older ones have kerfed and joined cases. This indicates that the designers of the newer scales thought continuous rims were better but the company never got around to "modernizing" the older scales.

It amazes me how only every once in a while, a really good sounding piano comes across my path. This time its a Baldwin L. I was looking at the rib structure today and noticed (it has 12 ribs) that ribs 8 and 9 are unusually large compared to the rest. In a Steinway for example these ribs tend to be smaller than anything sequential would show (One of my pet theories as to why there is a dead octave). Thinking this has to be a mistake, I look at a Baldwin R, and it has the same large ribs at #8 and 9. So now i'm thinking it's on purpose. Clearly someone at Baldwin was thinking along the same lines as me and bolstered those two ribs (after studying a Steinway?).
Overall the 12 ribs had a low profile structure (79%) that helps board movement, again first confirmed by ear. It's not hard to hear the difference. Low profile boards have more depth and sound bigger and have more clarity. The opposite is true for high profile rib structures. Interesting that Baldwins are a 79% profile and most Steinways are an 83% profile. Must be the competitive edge.
-chris

I have been studying the "engineering" of RC & S soundboards. It has fascinated me that CC boards have a low profile rib structure and RCS boards always have a High rib structure. It cannot really be explained away by just saying stiffness in the panel makes up the difference. Plus, I have personally seen CC soundboards that are a hundred years old, and still have a crown.
So why the extra tall ribs in a RCS board? I think it's because of a misunderstanding of the Stress and Strain Chart.

https://forum.pianoworld.com/ubbthre...stress-and-strain-chart.html#Post2774588
When the belief by an RCS builder is that the ribs are beams, then overbuilding is ok. Because sturdiness is what you want, not movement. So the beam formulas are designed with a large safety margin.
What does that mean?
In the Stress and Strain chart, there are basically two sections. The elastic section and the plastic section. When designing ribs as beams, the stress is on the low end of the chart, for added strength and little movement. But traditional soundboard making always put the stress near the proportional limit. To maximize strength and movement. As long as the design is not in the plastic section, then the soundboard will last.
The problem that gets confused and therefore overcompensated for when rebuilding, is when a CC board is examined because it failed, it is assumed to be the whole method of CC making.
This is not true!!
When I have examined many CC boards that did fail (from a design perspective), they failed because of the lack of a safety factor that put them in the plastic section. Basically, the engineering was faulty. That's different than saying the CC method is bad.
CC boards that survive time well (again from a design perspective) the rib structure was correct with a narrow safety margin.
That's why i say that ribs are springs, not beams. Because unlike beam theory, it's desirable to have a soundboard that moves the air.
It's because of the the overbuilt nature of RC&S boards don't have the depth that CC boards have.
-chris

I just recently took apart a soundboard (for study purposes) of a pianomaker (Jacob Gross) whose soundboard craftsmanship and design I admire. The picture is one of a cross-section of a soundboard rib and panel. The soundboard was a 100 years old, and out of an upright. It had great tone and nice crown. I wrote on the picture the height dimensions. This was the largest rib and was 42" long and was 1.01" wide. All the ribs on the soundboard progressively got smaller.

It was in great condition a 100 years later.

This brings me to another mistake i think RC&S rebuilders are making. By treating the ribs as beams, they isolate the elements (ribs), but as can be clearly seen in the photo, the soundboard is of a composite construction. By treating the ribs as an isolated unit, the forces that the engineering is designed will be overcompensated for.
-chris
http://forum.pianoworld.com//ubbthreads.php/galleries/2775029.html#Post2775029

Chris:

I have been preaching against the "ribs as beams" model since the 1980's. Glad you have joined the club.

Thanks Ed,
BTW, you've been on fire lately. Some great comments.
-chris

Your post says that the picture is Jacob Gross, but the picture says Stieff. I'm confused. Stieff baby grands are great, BTW.

Hi Craig,
Jacob Gross was the expert behind the Stieff piano designs. Charles M. Stieff was the financier and namesake. Gross married Stieff's daughter. Later, when the Stieff and Gross children grew up, together would run the company for a few generations more.
-chris

Steve,
Thank you for reminding me. About 7 years ago, while piano shopping, I did get a chance to play a Bosendorfer. I fell in love. The owner of the store came up and explained about the rim and all the spruce components actively producing the sound. The sound was gorgeous and I could feel the piano’s voice “vibrations” in my fingers, hands, wrists, torso and feet.

It was a wonderful experience, but sadly way above my pay grade. I have never played or felt a more responsive piano than that Bosendorfer.

I'm having a very hard time believing this. Do you have any actual measurements to back this up?

I owned a console originally, then upgraded to a 5' 10" grand, and now have a 7' grand. Each step brought a huge increase in volume from the instrument. I can't imagine what a 9' grand would do in the same room, nor that any console could come close to matching it.

Marianne,
If you want scientific evidence to back up the claims that you often hear on forums, you'll be waiting a long time. Unlike me, there are very few people these days who do the required shop experiments. People often repeat the incorrect ideas simply because they read it somewhere and believe it. Many concept are not at first intuitive and defy logic until it is further investigated. For example sustain. Most Technicians believe that a soundboard with a light downbearing will sustain longer than a board with a heavy downbearing, but i have proven the opposite is true. Another technician recently came to my shop and I had to show him a demo before he saw he was incorrect.
-chris

How do you measure the profile, since the bottom surface of the rib is curved and the center height is more than the side height?

Thanks for asking.

The formula i use is Height divide by the Width multiply by 100 (H/W*100).
The originals are made in a sloppy manner by hand which means they are full of mistakes in evenness of stiffness. I don't want to copy the mistakes so i machine mine. Therefore the only measurement i need is the tallest point (which is usually under the bridge).

How it works is and i'll use the Baldwin R i'm working on. It has 11 ribs. I add up all of the heights, the Baldwin adds up to 9.03". Then I measure all the widths, and they add up to 10.37". 9.03/10.37 *100 = 87%.

Its just one of many parameters i use to get a good idea of the original designers intent.

-chris

Hello Ed,

This is not the case (I realize this old thread was renewed, but I lacked the photos then to contradict your assertions). I toured Bösendorfer's factory last July. While there are some areas of the factory I could not photograph, I have a few relevant photos that should put this discussion to rest and let it go back to discussion of the soundboard, etc. I hope the concepts are well-enough explained with the captions to be enjoyed by our wider audience.


First photo shows the inner rim (actually 4 rims, stored side by side). As you can see, solid wood, cut to shape, glued and joined to create the curve. The only laminated wood is used on the shelf for the leg plate.


Here is the underside of a Bösendorfer 280VC - certainly one of the newest designs. Again, nothing vertically laminated. It's nice to see the beam joints, too. You can also see the outer rim, with the kerf cuts filled and puttied.


Here, zoomed in, you can see the vertical kerf cuts a little better.


The last photo is another detail of the rim, this time a model 225 (old design, same solid spruce inner rim, solid spruce outer rim with kerf cuts). This is an art case, so part of the outer rim is cut away to better install the carvings into the rim, not just apply them to the outside. Easy to see the construction details.

I cannot provide photos of the VC rims, but I have seen the details and discussed this in other threads. In the VC models, not only is the soundboard designed differently, its connection to the rim is designed differently. The concept is that the soundboard terminates into a hardwood (in their case solid beech) hoop. The hoop is then embedded into the solid spruce inner rim. The solid spruce outer rim is added later. Again, the solid spruce is kerf cut to provide relief to match the contour of the inner rim. This results in the new soundboard/beech hoop still carrying the sound through the resonant solid spruce rim. New + Old, and still without vertical laminations.

You can analyze all you want, when I play on a Bosendorfer I know I like the sound and touch very very much.

Thanks for all great information here!

As a novice, I have some questions, is it true that when the sound board is cracked, the sound is not affected like many people (sellers?) claim? I always suspected that the claim was not true because if it was so, the piano manufacture would not even bother gluing the pieces of the sound board together. If the sound got affected when the sound board was cracked, then how and in what way it would?

DreamPiano80,

Your question is related, but takes this old thread in a different direction. My suggestion is to pose the question in a new thread.

Well what more is there ? That is enough surely ? So I do not really understand?

Thanks! I'll start a new thread for that question.

I’ve only played two Bösendorfer grands in my life, for much too short a time on each occasion. I love both the sound and the feel.
Because of where I live in the US, I haven’t gotten the chance to try many other great European makers like Bechstein, Blüthner, Sauter, or Steingraeber. I’ve only tried Bösendorfer, Schimmel, Estonia (only one which I purchased), and Petrof (my friends that wasn’t for sale). I guess analysis of what makes a Bosendorfer sound and feel like it does is useful. The only way I can describe it is when I’m playing a Bosie , it feels as if the whole piano is responding and singing as I play. It reminds me of riding my horse when we would canter down the trail. I could feel his breathing and response to my cues.

I love that description. I've had customers describe the sound like going from stereo to surround sound. And often, we talk about the relationship between the tool and the pianist...some great pianos are like very sharp knives in the hand of a trained chef, and it is the skill that shapes the music. However, the analogy I used is that the Bösendorfer is like a well trained dance partner, that if you lead, it knows where to go.

Per this discussion, I would propose that Bösendorfer's rim means more to its soundboard design than with any other current maker.

With a laminated rim construction, the rim certainly affects the design of the soundboard, but makers like Schimmel & Kawai have demonstrated their designs substituting plexiglass for wood rims altogether. Having experienced the plexiglass Schimmels, the performance is objectively better...wider dynamic range, flatter sustain while maintaining an excellent tonal range vs. the identical instrument in wood. For that design, the added density of the plexiglass is the obvious factor.

With a less dense laminated rim, both the soundboard and string scale would be optimized differently to achieve wider dynamic range and flatter sustain. Anecdotally, it does seem to me that with a laminated rim, denser rims have an advantage in producing more (or a greater percentage) of the fundamental tone. I see many examples of this, but you can never isolate the one variable with so many other variables.

I've mentioned this before, but the piano by which I measure all others is an old Bösie! It's in the choir room at my hometown church. I love it.

PianoWorks ATL
What do you mean by a "flatter sustain" ?
I like a good sustain even a "rather lively one ".,What I do not like is if the decay of sound is sudden.
Although I do not think anyone wants that.

There might be another explanation. Perhaps the plexiglass version is better and clearer because the plexiglass is not only denser but vibrates and transmits sound much less than wood, which is why it was used by some high quality hi-fi turntables. Thefore we might suspect that a plexiglass rim would contribute less to the overall sound and let the dynamics of the soundboard stand out for themselves. Maybe.



I find it difficult to believe that any sort of wide band or even sound production from a rib can be achieved. It will have frequencies at which it resonates and reinforces the overall sound so maybe careful choice of heavier materials that resonate at lower frequencies will benefit (some of) the lower notes where the soundboard response is rolling off, but I doubt very much if there is any improved dynamic range or flatter sustain generally, only for the notes where the rim might resonate.

By flatter sustain, I mean that the sustain decays less after the initial attack. Many pianos have a strong attack, but the initial decay is very strong, such that the long sustain is at a much more quiet level. Bösendorfer seeks to have their sustain to be of a flatter level, more like the sound of a bow across a stringed instrument. This gives the pianist more control over the overall expression.

This discussion echoes another thread about sound barriers. If the rim is designed to be very dense, then less of the sound is transmitted to the rim. In simple terms, more of the vibration energy is reflected back to the soundboard from the edges. But the soundboard and string scale have to be designed around this. In the case of the turntable, the density is isolating the vibrations on the turntable.

I'm not sure if you meant "rib" or "rim". I'll presume rim. You can design around a less dense rim in several ways by changing the shape of the soundboard and the string scale. Perhaps one with less crown and higher tension (or lower wire gauges and less tension) will pair better with a less dense rim. Crown and downbearing make the soundboard behave under stress. You can instead design a soundboard that operates under different forces, and I safely presume that the rim and rim connection would be optimized differently.

Bösendorfer speaks about the resonating box principle. If the soundboard on a laminated rim works similarly to the head of a drum, the rim construction of the drum (laminated wood or other materials) has some affect on the tone. But in the resonant box principle is what guides the construction of a violin or cello...the rim is an extension of the soundboard.

Because these are simplified explanations, the details make the result. Bösendorfer's methods make their design work. Using a laminated rim as a design platform can be executed better or worse, depending on the goals of the manufacturer. You can successfully make a laminated rim out of maple, beech, birch, oak, plexiglass, etc.). You can make it beautifully, or you can mass-produce it and the results will vary.

But if any maker tried to take a shortcut in the steps that make a Bösendorfer soundboard & rim construction, the result would automatically be poor. Bösendorfer's methods, including how they cut, season and dry the wood, make it an all-or-nothing result. Though there used to be other makers that employed this type of construction in Europe, there will never be a copy or "knock-off" of a Bösendorfer. There are no shortcuts.

I guess it’s the no shortcuts that make Bösendorfers so expensive.

There is so much bad information regarding piano design/acoustics here I almost don't where to begin. I understand completely if someone likes the Bosendorfers (and I've played on a few nice ones) but to perpetuate their resonant box theory is a little over the top.

This was stated:
"Bösendorfer speaks about the resonating box principle. If the soundboard on a laminated rim works similarly to the head of a drum, the rim construction of the drum (laminated wood or other materials) has some affect on the tone. But in the resonant box principle is what guides the construction of a violin or cello...the rim is an extension of the soundboard"

So lets just use some simple common sense here. EVERY instrument that IS based on an resonant box has a trait in common. ITS a thin walled Box. The violin for example the back is a thin walled piece of maple behaving as a membrane.
Lets compare that to a Bosey. A membrane on top, and on the bottom - a massive criss cross beam structure. One would have an easier time in court proving its meant NOT to resonate.

Both the laminated rim and the Bosey style of rim are both behaving as drums. They're just built differently and each offers its own tonal spectrum.
-chris

The "newer" Bosendorfer scale designs have laminated rims. (I am talking about the 5'8" and 6'7" and newest 9' models compared to the older 7' foot and two 9' and 9'6" models).

So evidently Bosendorfer doesn't think the pieced up spruce rim used in the good old days of Ignats and Ludwig Bosendorfer is vital for the entire brand.

I think the old rims were kept in place because they couldn't afford to invest in converting the old scales to laminated rim construction. And the sales department had to generate a "reason" to explain the inconsistency.

I’ll ask again for perhaps an explanation for an amateur. I played a 6’7” in 2012 and the newer 214 VC Bösendorfer in 2019. Both pianos gave me the feeling that the whole piano was responding to my playing. I was told when I tried them about the special rim design. What gives those pianos the feeling that the whole piano is responding and resonating with my playing? The laminated spruce rim? The scale design with the laminated spruce rim?

Stiffness and flexibility are 2 ways to express the identical thing. Mathematically, they are just the reciprocal of each other.

Roy 123,

You missed the point. Other rebuilders seem to be "focused" on just Stiffness. Almost as if the more the merrier. What I'm saying by throwing flexibility into the conversation is to say that there are limits. The purpose of scalloping is to induce flexibility and to adjust and center the driving point under the bridge (no one else does this but that is its purpose) Most boards I have studied exhibit too much mass. And trying to gain stiffness via mass acoustically has a high price to pay in the form of added weight. Then trying to solve the weight problem, the size of the board is reduced. And on and on down the designer rabbit hole until the end product resembles a Bongo Drum instead of a Timpani Drum. Nothing against Bongo Drums. The resonance I am achieving right now is ten fold what i was getting a year ago. And that makes me happy.
-chris

I never heard someone say a soundboard should be as stiff as possible, though there may be some people, who are ignorant of how soundboards work, that may tout that. It's easy to do a reductio ad absurdum on that belief--a steel reinforced concrete soundboard could be very stiff. I also never heard anyone say that soundboards should be made small to solve the weight issue. What I typically hear is people talking about impedance and balancing stiffness with weight so the board provides sufficient sustain and doesn't produce a "pingy" sound with rapid decay. I previously discussed how soundboards can be made both stiffer and lighter at the same time by introducing the concept of how the aspect ratio of ribs can be so tailored. If I recall correctly, you poo-pooed that idea as worthless. I have heard people discuss the distribution of the area of soundboard as is best for various portions of the pianos scale, which sounds like a sensible idea.

BTW, the last thing you want in a soundboard is resonance--various resonances will amplify and suppress various notes across the scale, producing an uneven response. Perhaps you are calling some other parameter resonance--I'm not sure, but it would be useful if you clarified what you mean by soundboard resonance.

Yes because a tall and narrow rib introduces irregularities that induces strong spatial localization in some specific frequency.
-chris

That seems rather a strange claim--especially stated without explanation or data. A rib is a linear stiffening element that contacts the soundboard in a narrow width. It stiffens the board and therefore raises its resonant frequency, and, of course, also adds mass to the soundboard assembly. Because the stiffness of a rib is so highly dependent on its height, it is easy to imagine that someone, without doing the calculations that I showed in the spreadsheet I provided free to anyone that was interested, could make ribs that were too stiff, and therefore push the parameters of the soundboard too far from its optimal values. That sounds like a plausible scenario that in no way denigrates selecting the stiffness and mass of the rib to provide the desired result. There's really nothing too magical about ribs--their mass and stiffness have to be optimally selected to achieve the tone and sustain that one desires.

You tout compression-crowned boards as being able to provide the desired stiffness while keeping weight down. I guess we could call that optimizing the stiffness-to-weight ratio. One could take another soundboard, equal in all other respects, but not compression crowned, and by adjusting the aspect ratio of the ribs, create the same stiffness-to-weight ratio. It likely wouldn't take much change in the rib's dimensions to accomplish that goal. Would that create " irregularities that induces strong spatial localization in some specific frequency," I doubt it, but I guess I'd need to understand what you mean by that phrase, and hear some test results.

Of course there is nothing magical about the ribs, but they do more than you suggest. First, you can can have two pieces of wood that are the same dimension and they will deflect differently. Then the scalloping. Do you scallop 3 inch out, 4", 5"? Symmetrically or asymmetrical? You can have the same piece of wood and scallop it, measure its deflection, then scallop it some more and you've changed its deflection value. Then there is the relationships between the ribs. This is important to create a smooth stiffness curve. Just controlling the size of the area of a rib ignores their acoustic function. BTW, the scalloping is in a cause and effect relationship with the bridge. And needs to be adjust accordingly. No one talks about that. I have already hinted at the spacing in between the ribs and the relationship to rib count.

All the best.
-chris

Ed, you are mistaken. Bösendorfer did not change to laminated rims. Not for new models. It's just not the case. I included the photos. I'm not sure what you saw that led you to believe this was otherwise.

In the new VC models, the rim uses the same principles as before but with the addition of a "transition" layer. Bösendorfer's soundboard is mated with a hoop made of beech. The beech is solid, not laminated, and the hoop follows a more ideal shape of the soundboard while offering a solid connection to the cut/block construction of the solid spruce rim.

And Chris...the difference in a laminated rim made of non-acoustic hardwoods to create rigidity and density to isolate the soundboard more from the rim...is specifically different than using a rim with less density made from acoustic wood designed to continue the transmission of the sound.

Perhaps you might investigate the use of softwoods in drums? Or the use of laminated/dense rims in violins? These are major departures from what is traditional, and could have merit...but illustrate the difference in basic sound design philosophy.

Since the total sound energy is determined by the energy in the hammer, presumably if the sustain is flatter, and so maintains its loudness for longer, it must die away quicker?

Your ribs are doing just as I suggested--they are providing stiffness as needed, and there's no reason to assume that the stiffness has to be the same everywhere. You describe scalloping, and tapering ribs at the ends has been standard practice. Nothing I said would suggest that ribs couldn't be scalloped, spaced as required, or be of different height or thickness. I was merely reacting to your statement that "tall and narrow rib introduces irregularities that induces strong spatial localization in some specific frequency." I still believe that's a statement devoid of analysis or evidence. Besides, how tall, and how narrow? Tall enough to be too stiff? Tall enough to provide just the right stiffness at the right place? Of course, as you say, scalloping a rib will change its deflection under force--the scalloping reduces stiffness. Given that, other things being equal, the stiffness of a rib goes up as the cube of its height, ribs would seemingly never have to be particularly tall. In some cases, maybe you want a rib to be lighter, but not lose stiffness. A slight increase in height combined with a reduction in width could fulfill that need. Perhaps your poor success with "tall" ribs is a result of making them taller, or too tall, without sufficiently reducing their width? I surely don't know. As your post suggests, there are benefits to tailoring the stiffness of ribs both within a given rib and across ribs. Manipulating the height and thickness are 2 strong parameters that need to be carefully controlled to provide the sound you seek.

Roy123,
You may believe that there is little evidence or analysis, but that just means you're behind the current research. As an example, The Department of Mechanical Engineering in France did a nice study about rib spacing and the influence thereof. Even though the computer modeling is cool, it's really not needed as I have mentioned before, you can hear its effects in a piano once you know what to listen for. Especially the ones where spacing was done horribly.

My thoughts on rib spacing is simple. If there is not enough ribs to the size of the board, tonal problems occur. Too many ribs and you introduce more weight than needed. Get the rib count right and the spacing takes care of itself without the tonal issues or excess weight. However, the Rib Count formula i use is proprietary because i use it in my soundboard software.

-chris

First you said that ribs that were too tall created " irregularities that induces strong spatial localization in some specific frequency." Now you are talking about rib spacing, and yes, I am aware of the study you mentioned. It's a separate issue, and you had no basis on which to claim I am behind the current research. Come on, man! Honest arguments can be useful because they can expose various sides of an issue in a hopefully thoughtful way. Your last post shows this is not an honest argument. I have nothing more to say--the floor is yours.

Roy123,
*ad hominem attack deleted by moderator*
The phrase i used " a tall and narrow rib introduces irregularities that induces strong spatial localization in some specific frequency" is a direct quote from the study.

-chris

Really? Some time ago, I read a study that described how the ribs influence and can interrupt the modes in a soundboard--but because of a fault in my character, I didn't memorize every sentence in it. Maybe it was a different article from the one you read. I just searched and found this study from France .

Is that the study you are referring to? Well, son of a gun, I used a search function to locate anything about tall ribs. Guess what? There was nothing in there. I wasn't going to contribute further to this topic, but you called me a liar. You need to be REALLY, REALLY, REALLY careful about making an accusation like that. I deserve an apology from you, and we will all see what kind of person you are as to whether one is forthcoming

Let's keep it civil folks.