I believe that in the early days of the piano, there was no such thing as a crowned soundboard.

Soundboard ribbing could be quite complex, such as in early Pleyels, or quite simple, like Broadwood but there wasn't really an incentive to arch the soundboard until the late 1800's because of the lower string tensions and because of tradition.

Is there any particular manufacturer which can claim to have invented the 'arched' or 'crowned' soundboard?

I don't know, but Steinway didn't have the 'diaphragmatic' soundboard until late on. maybe 1930s.

Bluthner I've no idea about, Bosendorfer or Bechstein I've no idea about, although I'm sure there was some sort of crown on most of the pianos.

I suppose it's an issue for piano restorers who want to bring the instrument to what it was when it was new rather than try to incorporate improvements in the design.

Hurstwood farm for instance, often rebuild pianos with carbon fibre actions and soundboards. I've never tried one, but while they are probably very good, excellent rebuilds, you couldn't really say they were anything like true to the original piano. They may be better, for instance, but they wont sound the way pianos did 100 years ago. Mind, it's not as if we have any real way to know how they sounded 100 years ago, because nobody can remember!

The crown, or curvature of a soundboard is an elementary part of piano design, also of harpsichord and clavichord design. This bend pressing against the tension of the strings strung across is what creates vibration and tone.

How crown is achieved and to what degree it exists in any given instrument changes from design to design - and has changed over time.

To avoid confusion, it is difficult to assess crown after the tension of the strings have been applied to a given instrument. Also, older instruments may not show crown at all when they are unstrung (it that a word?) but the assembly is designed to fail and the downbearing from the strings will eventually cause the board to lose crown.

We have had very nice experiences over the past decade or so using rib crowning as opposed to compression crowning, but that might be best left to another post.

I am not sure that it is part of harpsichord and clavichord design

Can you please tell me where you got this info?

I believe that it was a relatively late invention, probably late 1800's.

There are many patents which try and improve soundboard construction as it relates to string-pull

One noteable solution about 1830ish was to place half the strings pulling upwards and the other half downwards.

My own personal research, traveling with Bill Shull as Technical Consultant and Photographer is leading me to believe that in approx 1858, Steinway was recognizing this potential and has started to use it at least in their Grands. They likely used it everywhere, I have not personally inspected squares and uprights for this.

The Monitor Grand, Prototyped in about 1868 shows direct evidence Steinway understood crown from a compression point of view.

I have in my shop now an 1872 Production Monitor, the very first production B scale.
This piano clearly relies on Crown and compression.

As always, the world being what it is, someone somewhere may have used it prior to 1858. I have not seen any evidence yet.

I’ve written about this in the past but I don’t know how far back in the archives you would have to go to find it…

Until it’s proven otherwise I remain convinced that soundboard crown is one of those things that just evolved as an unintended consequence of mass production.

Until the middle 1920s the only viable adhesives available for wood assembly—whether for pianos, furniture or whatever—was animal hide glue in all of its various forms. When gluing up large assemblies in production quantities it was common to heat the wood substrates to keep the glue warm and prevent its “skinning over” before the joints could be fully assembled and clamped.

This was also true with the piano soundboard and rib assembly. As the so-called “modern piano” with its relatively thick soundboard panel moved into the era of mass production it became common practice to pre-heat the soundboard panels in special hot boxes for extended periods of time.

As these periods of time grew longer to facilitate production the panels had time to physically shrink as they dried out. When they became dry enough and had shrunk enough it was discovered that the completed assemblies warped when they were returned to the normal factory atmosphere.

Ultimately it was discovered that this characteristic could be used to enhance piano performance if it could be controlled. Although it is impossible to control with any precision—the atmosphere inside the factory and in the homes and halls where the pianos end up cannot be predicted with any precision—working parameters did evolve and are still in use today. Though by a diminishing number of piano makers.

Ironically, the more that we learn about how the soundboard system actually works the more the whole practice of crowning is brought into question.

ddf

Wasn't 'crowning' used in instruments long before the piano come along. Wood working has depended on compression tension to hold glue joints through humidity changes for centuries. Rings true?

I have been told by my tech that my piano and all the other grand Baldwin's with Accu-Just Hitch Pins have perfectly flat soundboards.

Not so. All Baldwin grands from about 1960 on had ribs that were machine-crowned to a radius of 72' (or about 22 m). When initially built the crown probably would have been a little higher than that depending on the relative humidity in the factory and, ultimately, in the home or auditorium where they ended up.

ddf

My thoughts as well, Dave.

In practical terms, we have rebuilt an 1858 Hallet & Davis which was clearly designed with a crowned board and are currently rebuilding an 1860 Steinway - also with a clearly designed crown.

We currently have 2 older harpsichords in stock as well (although we did not rebuild either one). The larger 2 manual appears to be perfectly flat, but it is strung with steel strings. Using my piano head, it would seem that there is still a substantial downbearing on this instrument and that what appears to be flat when strung actually has a little crown during manufacturing.

The smaller 1 manual model may very well have been designed without crown in the soundboard, but this is a spinet with very thin wire.

Again, piano head thinking here - with any type of downbearing, it seems that a board without this design would have a huge disadvantage over time.

Thoughts Del?

Good point about the Hot-Boxes. That would explain much

What feature or design parameter do you see that causes you to reach this conclusion? I have seen older pianos with rib crowned design that were "clearly designed" to have crown but intentions otherwise have not been so evident. At least to me.

Agreed Dale, I am also curious to know what specific observations Rich is making.

The "tell tale" signs would be missed by a sales person.

That is not exactly how it works.

Piano soundboards are an example of breadboard construction. A big sheet of paneling with the grain in one direction is glued to the ribs with the grain in the opposite direction. This is like a breadboard, a cutting board for bread which is made from a panel of wood boards glued together along the grain, capped at each end with a smaller board with the grain perpendicular to the panel. If you glue the smaller boards to the panel, you have a problem.

Wood acts like a sponge in some sense. If it gets moist, even from the moisture in the air, it absorbs some of that moisture and expands. But it does not expand evenly. If you imagine the way that a plank of wood is oriented in a tree, it expands most of all radially, or outward from the center of the tree. It expands least of all up and down. If you dry the wood out, the wood shrinks.

In breadboard construction, if you glue the end pieces to the panel, and the panel dries out, the end pieces, which have the up and down grain which barely shrinks along its length, keep the panel which has a lot of radial grain, from shrinking. With no other way to relieve the tension, the panel cracks.

This is what causes cracks in soundboards. The panel is glued to the ribs in precisely this method.

The method that has been used to mitigate this tendency to split when the panel is dried out is to dry the wood as much as it is ever expected to dry, and then glue it to the ribs. When you do that and the wood is brought to normal humidity after it is glued, the panel expands, but the ribs do not, and this causes the soundboard to crown.

This was probably the origin of the crowned soundboard.

Dale and Larry,

I do not replace soundboards personally. That is not my duty here on the Cunningham team, but I do know about the process. If we are rebuilding a piano with an inner rim that has a pitch to it it seems obvious to me that the piano was clearly designed to have crown.

Tell me if I am missing something here, please.

Some specific examples, such as serial number with a photo of the pitched inner rim would be appreciated.

I am sorry Larry. I do not have those at my fingertips and, perhaps, not at all - but I will check.

We document our work, but only in regards to work completed, materials used, etc. We photograph a piano extensively before we work on it, but we do not regularly record things like inner rim angles during the process.

Hi Rich,

I believe that the problem with understanding your original post was that it wasn't apparent that the evidence needed to be viewed from the perspective of a torn down piano, i.e. soundboard removed. I can see how you would come to that conclusion from looking at an inner rim with an angled top, but not unless the board was out. Now I see where you came from with your earlier statement.

And not all pianos have such rims, I imagine..

In my opinion “crowning” has been quiet amplified as fundamental contributor to the performance of the soundboard when in reality there are other aspects which are much more important. One fundamental factor is rib positioning; the ribs in the soundboard play an essential role in stiffening the soundboard, preventing the board from subdividing in several vibrating pockets (which happens to some degree) which results in energy consumption instead of energy radiation. Ribs positioning equalize the properties of the soundboard along and perpendicularly to the grain (isotropy).
Here is an explanation to how soundboard vibrate: all soundboards have a fundamental pitch; as the frequencies get further away from the fundamental pitch the soundboards tend to subdivide in multiple vibrating areas instead of vibrating as whole unit as when the frequencies get closer to the fundamental pitch. With these subdivisions the board becomes more of an energy consumer than an efficient energy reflector and therefore the need to balance between energy transmission versus energy reflection.

Another fundamental aspect of the performance of the soundboard is the balance of the acoustic properties of the board which for the most part these properties are affected by the quality of the wood, its density, rib positioning and thickness of the board.

Dimensions of the board also have a relation to its performance. As the soundboard becomes larger in proportion with the scale design of the piano , the soundboard happens to be too thin for its size and therefore the importance of stiffen the board. A larger soundboard has higher chances for energy loss. Good examples are concert grand pianos where the tail becomes very narrow and not wider. This is why I say that soundboards are not speakers, because they just don’t project airborne energy (sound) they also consume and recycle mechanical energy (vibration) otherwise the piano would not have any sustain in the tone.

A side note; I want to say that I don’t understand Steinway’s claim of the diaphragmatic soundboard (I will appreciate an objective explanation from somebody) however; by definition all soundboards attached to the rim are a diaphragm, unless there is a definition of diaphragm that I’m not familiar with.

Kurtman,

Steinway Patent US 2,051,633 April 18th 1936 "Sound Board" will give you a rough idea of the diaphramatic sound board they are referring to.

Rich, you are making a strong claim regarding circumstances in the shop you personally, as a salesman, are observing.

For the purposes of reference, I would like even one serial number and some documentation of your claim.

BTW, I will include this documentation in the material I am collecting for Bill Shull.

Your point is well made with the exception that it seems to lump all types of soundboard design together in one fundamental category. The real goal in soundboard design is to achieve a certain stiffness-to-weight ratio that is compatible with the character of the stringing scale. If the original design depended significantly on the compression stiffness of the soundboard panel—and the resultant crown—to achieve its necessary system stiffness than that crown is important. At least as an indicator; when the crown is gone it is an indication (along with the accompanying change in the sound of the piano) that a certain—and necessary—amount of its initial stiffness is also gone.

Other types of soundboard systems—those depending on the stiffness of appropriately designed ribs—do not share this dependency on system crown.




This is a characteristic of speakers as well; when the energy source stops sending (electrical) energy into the system the speaker stops producing sound energy. So it is with the piano soundboard system; when the strings stop sending (mechanical) energy into the system the soundboard stops producing sound energy. Speaker diaphragms also consume energy (friction in the surround and spider and air) and recycle energy (through various resonances). The function of the piano soundboard system is very similar.

ddf

Larry,

Of course I sell, but I have a sales staff that do this full time. As owner of a company that has a 12,000 sq. ft. restoration shop, a full compliment of outside service people, a moving company, a retail store, and a church organ consultation business, I cannot sell full time and I need a working knowledge of all of these aspects of our business.

My love though is the acoustic piano and the restoration center is what drew me into this business in the first place.

I am passionate about learning about it. I always have been. I am involved in decisions in all of our major projects, in production forecasts, and in costing and budgeting for our restoration projects. I have also, along with my partner Tim Oliver, changed the way we do restoration since becoming owners.

I know that does not make me a rebuilder, but I am finding your comments about being a salesman abrasive. Perhaps you didn't mean them that way. Sorry.

Anyway, I will see about getting any documentation tomorrow morning. As you know, I admire Bill's work and would enjoy helping his work in any small way that I can.

Rich,

The documentation would be very good to have. Photo's especially as it clearly documents the observations you mention. Bill will be pleased to have things such as this, especially if it shows the features you mention.

For future reference, it is important to document as much of the original piano as possible. Features such as the beveled inner rim or curved belly rail are important.

Also, preserving any original parts, as artifacts, that have been removed with serial numbers and model's If you do not have room or inclination to store them, there are some Bill and I would like to have and preserve for study and reference.

Well, in truth, Speakers, especially the full-range type used for musical instruments, do not stop producing sound immediately after signal is removed, since they do have resonances, although slight

..another element to consider is that the Speaker is designed from the ground-up to minimize distortion and enhance linearity, in an effort to convert the electric signal waveform into it's corresponding sound..

the pistonic motion of the speaker cone, the shape of the cone, the suspension system of spider and the suspension on the rim of the cone, are all in function of an 'ideal' representation of the waveform..

with Pianos, from a high-fidelity point-of-view, we have a terrible transducer, which does not aim to follow the input waveform linearly, but instead it creates a 'sound' based on the way the soundboard interacts with the string.. including regeneration.

Let me know by email, pm, or by phone what you think you and Bill would have interest in and we are happy to help if we can.

All the best,

Rich,

Steinway from the very beginning to 1884.

Any older instrument prior to 1884

Photo's.,

Plan view, parallax corrected top and bottom of the piano.
Plan view along the same lines of the action bass and treble side, front and top.

Scale measurments, strike distance from the agraffe, capo or otherwise front termination.

As you mentioned the possibility of a beveled inner rim .. photographs of that.

Photographs of anything and everything of interest.

Document the action, orignal key ratio's, spread, weights of parts by sections.

As far as parts from these pianos? Everything. We are interested in all of it.

If you must remove the sound board ... as intact as possible is important. Removing the bridges as carefully as possible.

We will take everything you are not inclined to keep.


Best thing, contact either myself or Bill if you have something coming up.

Bill and I just flew down to San Antonio TX to document an 1868 8' or so Steinway grand in original condition.

We feel it is that important that we pd for the flight, bought lighting specifically for that occasion ... just to spend a day with that piano.