Posts tagged tension

The History of Piano String Tension

Blah! The title of this sounds to most as exciting as watching paint dry.  Operative words being “to most”… to me however this is one of the more interesting charts i’ve seen in a long time.  Back in 2005, published by Europiano, Juan Más Cabré wrote this article showing the differing string tensions over the last few hundred years. Everything i know about string tension i learned as a child with a bread pan and rubberbands. Hahaaa… i used to make musical instruments when i was a kid. What fascinated me though was the thickness of the rubber band and the sound that would happen at a certain pitch. This is exactly what’s going on in pianos. The graph shows the earliest of pianos from Cristofori (in 1726). That string tension is little more than that of a harpsichord. It became evident that a stronger frame would be neccessary to implement higher tension. With higher tension comes more singing tone. Next on the list is Silbermann who asked Bach for some input. Silbermann contributed the damper device (similar to a damper pedal) to the piano. Shortly thereafter in the Classical era (Beethoven’s time) more and more iron was added to the wooden frame so as to boost the string tension – again with more singing, sustaining sound and also more resonance and power. Enter the famed Steinway and Bosendorfer. Interesting to note is that “more is not always better”. There have been pianos that have had higher string tensions (as in Ibach) but manufacturers decide what sound is pleasing. This is part of the backbone of ‘scale’ – the trade secrets of piano makers. Length of string, thickness of wire and tension of string all add to the sound. To get a mini idea of this, play around with a bread pan. It really is a fascinating exercise in string tension. And after that… just make some fresh bread. Nothing beats music and food together :)

Piano Soundboard Tension???

It was a funny afternoon of visitors in my piano shop.  One such visitor was a friend of mine… another guy named Glenn (although i keep reminding him that 2 ‘n’s are redundant… but then again, i named my youngest son Quinn…)  ANYWHOOOO… he comes in, sits down and states “Glen… i have a REALLY hard time reading information from piano ‘authorities’ when in the first paragraph, there are GLARING errors. It’s rubbish”.  Now you have to bear in mind that most of my friends are critical thinkers.  Glenn is no exception – structural engineer by trade but also piano lover.  He continued “I was reading from a leading expert who was writing about piano soundboards being under tension”.  Me being the non-intellect of my friends… i get dragged by my collar into such discussions… i’m a little slow to the draw and reply… “Ya… uh huh and your point?”  (I’m surprised he didn’t have my head at that response.)  “Glen think about it!!!  Tension by definition means to pull apart.  Take a rubber band. Stretch it apart. THAT’s tension.  Compression means pushing together.  He held one of my business cards bending it slightly – THAT’s compression.  It’s ridiculous that a soundboard would be under tension… it would be KINDLING! Pull apart a soundboard??? Pianos aren’t under tension at all… they’re under compression.  The Roman arches were designed with compression – pushed together”.  After thinking about it for awhile i recognized how he was right.  Piano soundboards are compressed – slightly arced with a crown.  The more i think of that concept, the error in logic almost seems humourous.  We’ve somehow slipped into bantering terms about that incorrectly define the piano.  We then have a scenario of the blind leading the blind don’t we? When the so-called experts are educating their followers down a slippery slope.  Starts to make one wonder however as to the validity of other information given. Just sayin’.

Piano Trivia

Tri-Chord Piano Strings


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?” 

Bi-Chord Piano Strings


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).  

Mono-Chord Piano 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!

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