Never mind about all this synthesiser nonsense, tell us about... PIANOS. Uncle Andy Honeybone reveals the birth and workings of the string, wood and ivory thing that started it all.

Very few subjects of this grammatically dubious "When Is?" series can be defined in one short phrase, but when the interrogative is applied to the piano — as in, "When Is a piano?" — the answer is, "When it's a struck chordophone."

This month, 'When is?' has gone acoustic — which is to the microprocessor what wholefood is to MacDonalds. The Editor nearly collapsed at the proposal, but recovered enough to ordain that electronics re synthesis should be a recurring theme throughout. I did try.

Chordophones are a class of musical instrument which possess strings (chords). The Rhodes "piano" is therefore not a piano because it has no strings — it is classed as a struck idiophone because of its internal tuning forks. On the subject of classification, many electronic instruments are lumped together with membranophones (drums), because it is deemed that the loudspeaker is the sound-producing medium and is a "skin". The difference between members of the chordophone family lies in the way in which the strings are set in motion. They may be plucked, struck, or bowed (guitars, zithers, and violins respectively).

The origins of the piano are confused, and vary according to the nationality of the authority you consult. Both the Germans and the Italians are keen to take the credit.

Even more obscure, however, is the origin of the keyboard. An apocryphal account begins with the fact that pipe organ actions were so heavy that they required a fist to be hammered on to the key. The keys were necessarily large planks and, as at this time chromatic harmony was considered the work of the devil, only the "white" keys were required. Two fists and two feet were the reasoning behind four part harmony.

As actions became lighter and a greater musical range had to be squeezed within a given space, so the key width was reduced. The additional chromatic notes were added some time around the 15th century.

The German hackbrett (dulcimer struck with held mallets) appears to be the forerunner of the piano — it set many harpsichord manufacturers in search of a striking mechanism. The appeal was touch sensitivity, something that had been lost in the development of the plucked harpsichord from the quiet "hammered-on" clavichord. Bartolomeo Cristofori of Florence was commissioned by Prince Ferdinand de Medici in 1707 to make a harpsichord with dynamics (opera at that time was a very refined public entertainment and dynamics were expected of all the performing instruments).

The striking action is complex as it has to set the strings in motion, as well as damp them on key release. The hammer is flung at the string; the velocity of this free flight determines the loudness of the note. Of all the component parts in a piano — some 6000 — the majority is associated with the action. Bits with strange names such as "bridle straps" and 'wippens" are linked together with springs and felt bushings to knock the string into vibration with every nuance of the key depression. Although the action is designed for silent operation, the bangs and bumps are all part of the piano sound. Because the decay time is very short, the top octave of the treble does not usually have dampers.

It is important for the hammer to hit the string somewhere between one-seventh and one-ninth of the total speaking length. This has the effect of damping out the 7th, 8th and 9th partials which appear "out of tune".

Piano hammers are covered in felt, but this is a fairly recent introduction. Cristofori used rolled parchment, and leather-covered wood was much used after that. Felt becomes compacted with constant striking and the piano's tone becomes brighter.

A piano can have its tone regulated by skilled use of sharp needles on the hammers, but Henri Pape, a man who had 120 piano-improvement patents to his credit, hit on the idea of chopping up hats for hammer-covering material. The felt from this source was too thin but, using custom-made felt, he proved the principle in 1826.

It seems that Pape was full of ideas but was less than methodical. Toward the end of his career he became obsessed with making cycloid and hexagonal pianos which, strangely, were never popular.

Piano strings have seen much development from their origins in brittle cast iron to the more recent refinements of wound steel. If the same gauge wire used for the upper treble was used for every piano string, the lowest note would be some 20 feet long. To make things more practical, various gauges are used with the lowest strings formed by wrapping a secondary wire around a central core. This second approach gives a completely different tonal balance and the real depth of a bass note is absent.

The total string tension is some 30 tons for a grand and 15-18 tons for an upright. Until Babcock's iron frame of 1825, pianos had far less tension and the strings were known to break and to be knocked out of position. A reserve piano was a must at a public concert and the unreliability, coupled with damning statements regarding tonal quality from leading exponents of the harpsichord, gave the early piano a poor reputation.

In later years the non-speaking length of a string was found to be of some importance and the distances from the tuning pins to the bridge (the equivalent of a guitar's nut) are set at an octave-related interval to the speaking length of the strings. This "duplex" system was invented by Theodore Steinway and can also be found in Yamaha instruments. For most modern pianos, three strings per note are usual for the top four octaves, but Bluthner introduced a method of "Aliquot stringing" where a fourth unstruck "sympathetic" string was added.

Soundboards are the equivalent of their acoustic guitar counterparts. A vibrating string has such a small profile that little noise is produced and acoustic amplification is necessary. Very little scientific fact is in evidence for piano soundboards, but spruce is widely used. Yamaha's CP80 "electric grand" has no soundboard as the amplification is electronic via piezo transducers. The same model uses artificial leather-covered hammers and the strings are half the length of those found in a "real" six-foot grand. Double-stringing is found only in the treble.

So far we've considered the grand piano as this was the earliest form. But there was a configuration known as a square (which was actually rectangular) and which maintained the shape and layout of a clavichord — the keys are on the longest side. The square was very popular in America where it was produced for the domestic market and where its space-saving made up for its lack of tone. In a spectacular public relations exercise, the manufacturers Association in Atlantic City piled remaining stocks of squares 50 feet high and set them on fire. Thus in 1904, the square died.

The first upright was built around 1780, but it was not until 1826 that reasonable instruments were available. The problem was with the action; the upright has been variously described as a child of necessity and a remarkable bundle of inventions. The fact is that the upright goes against all acoustic and mechanical sense.

Uprights are classified according to their height — studio pianos are the tallest, consoles take a middle position, and spinets come well down the list. In the case of the spinet, for the hammer to strike the string at the correct position the action has to be sunk beneath the level of the keyboard. This results in many mechanical problems.

Overstringing is a method of obtaining maximum string length within a case of given height. The bass strings run diagonally from top left to bottom right and the treble run from bottom left to top right. The changeover point is always a weakness. Underdamping means that the damper acts below the hammer — as this is nearer the middle of the string it is more effective than the alternative over damping which damps the string ends. A piano which is under damped and overstrung has, despite the terminology, desirable features.

In these days of Japanese domination of the instrument business it is hard to imagine that jolly old England was once the hub of the piano business. Broadwood is the most famous name and, in 1818, this company sent a grand to Beethoven across the Alps by cart. According to Dolge, Beethoven replied, "I shall regard it as an altar upon which I shall place the most beautiful offerings of my spirit to the divine Apollo." One can speculate what he may have said if Yamaha had sent him a DX1.

Bechstein is another highly acclaimed firm (testimonials by Liszt, no less) who, to promote sales, built a concert hall in London. In 1917, in a wave of wartime anti-German feeling, the building was renamed the Wigmore Hall.

Steinway can take most of the credit for consolidating all the known improvements of the day into one fine instrument, which has become the present day grand piano. Technology has not been ignored, Teflon being used in present day Steinway actions and since 1973 an Act of Congress has forbidden the use of ivory — so plastic is now used to cover the wooden keys. In 1972, Steinway was bought by CBS and so the notion of a pre-CBS Steinway is not so daft.

Bosendorfer make the largest piano available today. The Imperial is nine-and-a-half feet long and covers eight full octaves (standard range is seven-and-a-quarter). The lowest note is 16.5Hz and has to be tuned electronically because it is too low to be heard.

Yamaha have been making pianos since 1899 and their sales combined with those of Kawai put Japan at the head of the volume production league (273,000 in 1970). As with most orientals, copying the best of everything is part of Yamaha's ploy. Unheard of automation was also introduced by that company, such as a multiple saw which cuts the keyboard from one block of silver fir in one pass.

So, before I forget, synthesis. A piano boasts over 200 years of development, a lot of wood and metal, and, not to be ignored, part of an involved relationship including the player and the ambience of the room. Sampling has only proved partially successful and, by all reports, the only way to get a grand into a box of electronics is to resort to artificial intelligence techniques (AI — not artificial insemination), as applied by KurzweiL. When is artificial intelligence? Have you ever seen the One Two Testing editorial team?