This may be of interest..

The soundboard in not only a diaphraghm but a resonator, so any cracks in the soundboard will divide the surface into separate resonating areas with their own 'pitch' as opposed to a continuous resonating membrane where the resonant frequencies are blended in a more uniform manner

http://www.youtube.com/watch?v=04KCRWlaMS8

Don't the ribs keep it all as one unit? Just asking.

That was an interesting video. I'll admit I don't like the thought of a cracked soundboard, but the demonstration of scraping fingernails across the two separated areas really didn't convince me of much. You have to consider all other factors of the piano sound board construction... bridge construction, downbearing, rib construction, etc...

It seems to me that I've read the biggest problem with a cracked soundboard is possible buzzing while playing...

Interesting topic though.

Rick

The ribs and bridges make the entire unit work as a single diaphragm. Although each single plank has it's own "resonant frequency", as does everything in the universe, this does not have any audible effect on the board's performance as a diaphragm.

Rich, as usual, is right on this one.

Sigh...where do these ides come from?

ddf

That's kinda what I was thinking.

although it might be inconvenient for the piano repair guys who are preaching the 'soundboard as a loudspeaker, the proof is in the pudding..

I shimmed a long thin crack on my piano thinking I was going to get a slight improvement but the improvement was instantly noticeable..

the ribs only do so much.

as you can hear on the video, the soundboard, if separated in pieces will have discrete resonances. Once the soundboard is joined together as a whole then the resonances of the soundboard change becoming more uniform from one section of the board to the next.

although the ribbing of the board does influence the overall resonance, there are also resonances in the spaces between the ribs, like on a drum..

This concept of a 'soundboard' as a speaker or pure diaphragm is not scientifically sound. The soundboard does not move up and down like a piston, it vibrates in function of the dissipation of the mechanical energy of the string in MANY DIFFERENT WAYS.. the inertia of the vibrating string as it moves laterally or vertically, oscillation in tension, the interaction between the vibrations of the other strings, the reflections of vibrations off of the rim etc.etc.

the waves travel on the soundboard surface as well as the ribs, although we are talking about higher frequencies.

Alfred Dolge, Sievers and other piano manufacturers have already stated that soundboard design is purely empirical, and that many things were tried, from one-inch soundboards with no ribs, to paper-mache ribbed soundboard, parchment etc..

no piano made today can be said to be RADICALLY different than the steinways of the late 1800's, and the design of the steinways is based upon tradition.. solely tradition and empirical judgement based on MUSICAL aesthetic..

sorry for the rant,

if you believe that soundboards don't vibrate as resonators as well as diaphraghms then why don't you use some other material than wood? perhaps something that has such high internal damping that it would NOT resonate on the surface at any frequency? (by the way it is physically impossible for a stiff membrane of any type NOT to have resonances.. loudspeaker manufacturers have invested countless resources in trying to do this but never achieved perfection)

You would have to use rubber, or something similar because the stiffer the membrane the more likely it will resonate.

my guess is you would have a bland and boring instrument..

you cannot 'erase' hundreds of years of instrument-making tradition with your 'scientific affermations' guys..

prove it with science if you want to be scientific..

Dear Acortot,

The industry has advanced tremendously since the days of Alfred Dolge. We have all read his texts and yes, at that time, piano design certainly was largely empirical. It is not today though.

There have been many CAD simulations, experimentation using modern applied physics and algebra (the algebra has been applied to the action)

Please do not misunderstand me. I did not say that a soundboard is only a simple piston, but it does act as a diaphragm. Our company has worked on thousands of grand pianos over the years, have replaced soundboards, repaired soundboards, and redesigned them. My opinion has nothing to do with an empirical observation.

But I am not discounting your opinion and I am not at your piano. If you perceive an audible difference and you are certain that the sliver of spruce that you have used to shim a crack has produced that difference, then so be it.

Just for fun, here is a virtual demo. of the behavior of an imaginary soundboard based on what we know about behavior and physics of sound. It is clearly not a simple piston. This demo. is based on Mensurix, which is a computer program that is used to determine the best balance of string mass used in a given piano design.




All the best,

For hundreds of years the world was also flat.

Jonathan

Acortot, I'm not doubting what you heard but I am intigued. What did you do with the strings so that you had a clear space while you shimmed the soundboard?

This does point to the common idea that these repairs are not individual and isolated. Usually when something as significant as soundboard repair is done, so are other beneficial repairs like new strings, action repair, bridge repair, etc. The cumulative benefit is absolutely dramatic.

Not coincidentally, these "dramatic results" often justify a reasonable, moderate repair over a better, more thorough ($$$) approach. When to repair and when to replace...that is the question.

I think that we can safely say that the sound of a piano is a much easier thing to grasp than the shape of the earth.

And from a musician's point-of-view, or from an audience's point of view, the only concern is how PLEASING the sound is.. there is no science behind the aesthetics.


I can understand that someone might want a louder more powerful sound, or they might want to increase a specific technical characteristic through a scientific method, but in the end the listener has to like the result..

often the most pleasing result is a result of distortion or added resonances.. we see this in all kinds of instrument building: from violins to electric guitar amps.

just sayin..

Hi,

I shimmed the soundboard with the strings on, nothing changed..

I have a small tool I use to open-up the crack, like the one you buy from piano supply stores but much smaller.

then I stuck a shim I bought from a piano supply store with some glue.

before the soundboard to the left of the crack had a sound, a resonant peak, which was different than the one on the right..

then, when they were joined mechanically by the shim, there was no 'break' in the resonance of the soundboard. The resonance frequency changed smoothly as you approached the rim or went towards the other side..

the sound changed, becoming less 'chimey' or 'jangly' and it sounded more 'whole'..so to speak.. please don't take my adjectives too seriously because they are subjective..

what I can guarantee is an audible change.. I heard it immediately (that crack had been there for years, and was so fine that I didn't bother to fix it until now). Record lows have caused extra-low humidity in my house and the piano soundboard went 'CRACK' three separate times this week!!

My GF who plays also heard it, although she said she liked it more before!

I think it sound more 'solid' now, and am curious to see what happens when I shim them all.

I disagree totally. The shape of the earth is simple- it can be measured scientifically and with great accuracy.

Try this with a sound - we all hear differently.

Jonathan

As can any sound. In fact, it's much easier to measure a sound than measuring the shape of the earth. No rockets, no satellites, no radar, no GPS etc. - just a decent microphone and frequency analyser, and you've measured the sound scientifically and with great accuracy.



What we measure and what we perceive are sometimes two very different things. The fact that we hear things differently doesn't mean we can't measure them exactly. If the outcome of a measurement depends on the operator, it's not very scientific to start with.

My point exactly .. The end result of sound measurement - since we all hear differently is not scientific. Sure we can show sound waves, but once it hits the human ear the measurement depends on the listener.

Jonathan

Even more problematic are our differing likes and dislikes of tonality.

I like a boomy, fat bass, others would label that distortion.

Or muddy...

I like a boomy, fat bass too.

Rick

Yes, one man's fish is another man's poisson..

A little update.. I've shimmed a big crack from above, taking off some strings and have found an improvement, although not as evident as the last one..

Then I realized that I could get a good effect for the cracks that were unreachable from above by sticking a few very tiny shims, like flat wooden nails with a bit of glue in the tighter cracks. Basically it's not the crack itself that has a sonic effect but the decoupling of the soundboard on either side of the crack, in areas between the ribs mostly.

as long as the soundboard is joined in a few places and the vibrations 'cross the gap' to the other side, the sound changes.

obviously, if the shims are rammed too hard, they will encourage further splitting, so the ideal is still the traditional method, or at least to fill the crack completely with glued shims.

it obviously would have been nice to have the strings and the plate off, but maybe in 20 years..

No, exactly not my point. To call hearing a "sound measurement" is flawed to start with. Rather, it's sound perception. That's why it differs from one person to the other, even in the same person from one day to another.

In contrast, a sound measurement will not differ from one device to another (provided they're accurate enough).

Should you not have some sort of humidification?

With most things perception is reality. It does not matter what someone tells me I hear. It is what I hear that matters.

Jonathan

What you hear, is not what matters per sé, it's only what matters to you. Your perception is not reality per sé, it is your reality. In itself, there's nothing wrong with that.

But in the context of scientific measurements - which you yourself cited...



... in the context of such scientific measurements, personal perception is not only irrelevant, it can be downright dangerous.

To stay with this example: I perceive the earth to be flat. But scientific measurement has taught me that it's round. So, tell me, what shall my "reality" be?

I can see this is going nowhere - have a great day.

Jonathan

I bought my Baldwin L knowing it had a long hairline crack in the soundboard. It's still one of the best sounding L's of the dozens I looked at before I bought it. It has not widened or lengthened in the 6 years I've owned it. Dampp-Chaser probably helps keep it stable.

Of course it was going somewhere - but that's OK, no answer is also an answer.

Have a great day too.

We all have to trust our own perceptions at some point in any artistic pursuit.