So you’ve noticed the soundboard of your piano has a crack…or perhaps many cracks. Perhaps it looks less like a smooth, machined piece of carpentry and more like a freight pallet.
I can’t count the number of times someone has said to me: “I don’t think my piano is worth anything…the soundboard is cracked.” Or: “I need you to take a look at this piano and tell me if I should buy it. I want to be sure the soundboard isn’t cracked–I don’t want a heavy piece of junk in my living room.”
Mind you, these statements usually come from the mouths of pianists–and while some of them may be very good musicians, they tend to be suckers to the old myth that cracked piano soundboards equal immediate piano death.
For those of you wondering what the heck a “soundboard” is–don’t worry. You aren’t unobservant or ignorant, soundboards, as important as they are, hide within the belly of the piano.
What is a Soundboard, and Where is it?
If you crack open the lid of either your grand or upright piano and look down, you will see a shiny piece of wood behind the iron plate that runs the entire area of the bottom (or back) of the instrument. This is the soundboard. The soundboard is imperative for the projection of any piano, seeing as how it is the part of the instrument that actually turns the vibrations of the strings into sound. This is accomplished by creating the movement of air through wave vibrations. The physics behind this are complex, but just know this–music boxes work around the exact same concept.
Remember when you were a kid and undoubtedly got to play with a little tinny crank music box? These boxes involve the turning of a cylinder with small raised bumps that strike small metallic tines in order to produce a tune, much like the one pictured below. Perhaps during the course of playing with one of these contraptions, you may have noticed that the sound it produced got much louder when you placed it on a table top or other hard surface.
The same holds true for pianos. The strings within the instrument do not produce much sound by themselves when stuck by the hammers. The soundboard acts as the “table top” from the music box example. It takes the vibrations from the strings and greatly amplifies them in order to produce sound that can be projected.
So how is a soundboard constructed? Well, it’s simple enough in theory. Soundboards are constructed with 4 or 5 pieces of 5/8 of an inch thick spruce, glued together and attached to the back bracing of the piano. The pin block and iron plate are then mounted on top of the soundboard, and the piano is strung. The tolerance for perfect balance throughout the soundboard has to be very strict, and the wood cannot contain any knots or other imperfections that could potentially have a negative effect on the sound. In the early 1900’s, Steinway and Sons introduced their “diaphramatic” sound board–a board that stands at around 5/8″ thick in the middle, and gradually tapers to around 1/4″ at the sides, allowing greater air movement and projection. Other piano makers followed suit with many different conceptual designs.
So what’s the big deal with cracked soundboards? The truth is, I can name about 100 worse things that could potentially happen to grandma’s upright.
Oh No! Is That a Crack I See!? Help!
Nearly all pianos develop cracks in the soundboard over the course of their lives, and rarely are these cracks serious enough to cause any bother. Small cracks, especially along the seams where the wood pieces are joined together, occur after the board has had many years of vibration coupled with cyclical changes in the weather, usually accompanied by the drying of the wood and the glue used to hold the wood together. Split seams are quite common, and usually do not become a worry. The boards themselves may also crack along the grain of the wood between seams.
More serious cracks may occur when the piano has received substantial shock, as in a drop or particularly rough relocation. These cracks may be cause for concern; however, a crack only becomes a problem when the separated pieces of wood pull far enough apart to rattle or buzz against each other or against the rear bracing of the piano. Usually, the diagnosis is easy. If an instrument has a pronounced rattle or buzz when played, a deep crack may have split the soundboard into different pieces. These cracks are usually roughly the width of a penny or wider.
Even in this case, a quick and easy repair may be done using little more than wood wedges and screws in order to prevent extraneous noise.
When the soundboard has received extensive damage, i.e. in a drop, flood, or other major incident, the only way the sound can be preserved would be to remove the plate from the piano and replace the soundboard with a newly manufactured one that closely mimics the original construction.
So ultimately, does a cracked soundboard sound any different from one that isn’t? The answer is yes…however, the change in the sound is so slight, it is all but imperceptible to the human ear. The overall construction and materials used in a soundboard are more important than anything else, including decaying integrity.