Posts tagged pounds
Pianos are stubborn! There are no two ways about it. If you pull their strings, they’ll pull back. In fact, it’s a little like a tug of war when tuning. The farther the piano has dropped in pitch (remember that there are thousands of pounds pulling whether you play the instrument or not), the more the piano is going to complain when you pull it back up to pitch. For example, there are 100 cents in a semi-tone. A cent is an increment of pitch. So if you pull strings 25 cents, quite often the piano will pull back 8 cents. Raise the pitch 15 degrees (or cents) and it will pull back 5 cents. Why is that? Most of that pull-back is from the soundboard responding to added pressure.
The following are some tuning fun free facts i’ve noticed in recent years:
1. Solid reputable pianos will fall about 3-5 cents per year. It makes sense then that a piano that hasn’t been tuned for three years will be out of pitch 9-15 cents.
2. Pianos will not stay perfectly in tune if they are out more than about 15 cents. Back to the tug-o-war… you tighten the strings and it will pull back. It is impossible to stabilize perfectly a piano on first tuning that is out more than 15 degrees.
3. It’s a good idea then to compensate for this loss of pitch. Let’s say that A440 is “0” and that the piano is 15 cents down in pitch (-15). I usually adjust my strobe to tune +5 and expect that the piano will then drop by that amount. Crossing fingers, the piano will end up at 0 after completion.
4. Pianos farther than 40 cents down and have strings that look old and rusty, expect possible string breakage.
5. When pianos are farther than 15 cents down, it doesn’t mean that the piano cannot be tuned, it simply means that it would be a good idea to do a ‘pitch raise’ first and then do a fine tuning. A pitch raise is a very fast tuning to bring the piano into the ballpark. Once the piano has settled somewhat to the new tension, it is then possible to tune it at which point, the piano should be stable.
6. Piano wire gauge is matched to the pitch of a note. Even though the wires may look all the same thickness, they’re not. And so when pitch has slidden, the piano also won’t sound optimal. Only when the instrument is matched for the pitch will the tone also follow. Pianos that are flat in pitch usually sound dull and lifeless.
Next time you have your tuner over, ask him/her (providing they have a strobe) how many cents your piano is ‘out’.
PS…you’ll look like you’re in the know
Ok time to do the math. Here’s the question of the day: How many pounds of string tension are there on one piano, meaning… each string is tightened to produce tone – how many pounds of tension are the combined strings? Well to answer that, you need some data. First of all, how many pounds are pulling on one wire? The answer – on average, about 160 lbs. Next question – how many wires are on a piano? Well this varies greatly from piano to piano. “IT DOES?”, you ask. Yes – it all depends on the design or “scale” of the piano, the length, and the amount of bass strings there are. “Well aren’t there the same notes on each piano?”
Yes, of course there are 88 notes on each instrument but if you’ve ever looked inside you’ll see that there are Monochord, Bichord and Trichord strings. (Think: Monocycle, Bicycle and Tricycle – need i say more?) Some notes have one string, some two and others three. Depending on the manufacturer, the length of the piano (usually longer has fewer bass strings), string amounts will vary considerably. All pianos have “crossover” meaning that the copper bass strings cross over the steel wire strings. Sometimes that crossover point is quite high on the piano, sometimes it’s lower. Having said ALL that… on average there are about 225 wires on a piano (45 bass strings and about 180 treble strings).
So whipping out my handy dandy calculator… 160 pounds of pressure on 225 strings (on average) = 36,000 pounds! or about 18 tons of string tension. This necessitates having a cast iron frame (which in turn makes the piano REALLY heavy). There…. small piece of trivia you can talk about at the next cocktail party. Enjoy!