It Plays, It Vibrates, It Sings!
Happy and musical 2009!
Over the course of 2008, we looked at this marvelous instrument, the piano, from its original invention, it’s history & evolution, and its pre-eminence as it flourished in the 20th century. Just before the New Year, we beagn exploring all the components of a modern day grand piano in exploded views and cut-aways, so you can see all the piano’s parts from the hugest to the tiniest, and how they all work together. Now that we have a sense of the major structural parts like the case, pin block and cast iron frame (refer back to the exploded view of a grand in our last post by clicking here,) let’s take a look at how this beautiful contraption actually produces sound. What exactly happens when you strike the keys?
Here’s a great animated cut-away view of one key and its connected action parts in a grand piano. Watch closely and you’ll see all the essential movements and connection that take place when you press down any key.
The key rocks on a central fulcrum called the "center rail," and as you press the down on the front end, the back end of the long wooden key lifts upward. This in turn lifts the complicated triangle shaped (sort of) wooden mechanism with all the sticks of wood and springs, called the "wippen." Towards the front end of the wippen, you’ll notice a stick of wood that pushes the hammer up toward the string, called the "jack," by pushing against the bottom of the hammer shank (the stick of wood the hammer is at the end of.) If you look closely you’ll see the top of the jack isn’t actually pushing directly against the hammer shank, but against a little orange-&-white ball hanging under the shank, called the "knuckle." You’ll also notice how the "L"-shaped jack snaps out from under the knuckle at the last moment, just before the hammer hits the string. That’s called "escapement," as we covered in our piano history posts, and that’s what allows the hammer to fall back away from the string, freely, instead of blocking against the string, which would effectively stop the sound.
Finally, you’ll notice that although the hammer bounces back away from the string, it doesn’t fall all the way back down, being caught momentarily at about half-way down by the "backcheck." the red, white and orange cushion sticking up from the back of the key. The orange color is actually a layer of buckskin covering, which grabs the hammer’s tail and holds it in check. This, plus the spring-loaded repetition lever (the top-most stick of the wippen’s "triangle") lift and hold the hammer aloft just enough to allow the jack to sneak back under the knuckle, fully ready for another play of the key, even though the hammer has only fallen back about half-way and the piano player has only allowed the key to raise back up about half way. In other words, even though when playing, the key is pressed down a full 3/8 of an inch before hitting bottom, this marvelous mechanism allows the player to play that note again when the key has only come back up about 3/16", instead of having to let the key all the way back up before replaying the note (as in the earliest pianos.)
Of course, all the springs, sticks and buttons of this mechanism need to be in perfect adjustment (or "regulation") in order for this to work correctly, and that’s where your expert technician comes in. There’s about 15-20 adjustments to be made on each key action! But a good technician knows exactly how to do this. It takes a few hours if the piano is completely out of "regulation," or just a short routine service call if just to keep every part in perfect adjustment. Here’s another detailed view of all the parts in a grand piano action, also showing the damper and it’s respective levers. The damper lifts off the string when you press the key, allowing it to vibrate freely, then comes back onto the string to mute it as you let the key up.
So now we’ve set the string in motion, free to vibrate until either the sounds dies out, or we let up on the key, letting the damper fall back down on the string. Next, we’ll look at the acoustics of how that string’s vibration gets amplified into the room and your ears, through the bridges and soundboard.
0 comments
Kick things off by filling out the form below.
Leave a Comment