Zompist Bboard Again

European keyboards (not including organs, accordians, etc) use mechanical devices to play strings, so that multiple strings can be played at once, without needing as many fingers as normally necessary. You can do this by plucking the string, or by hitting it. This gives two different keyboard families.

Plucked keyboards are generally defined by the orientation of the strings and keyboard. If they're parallel, it's a virginal. If they're perpendicular, like a modern piano, it's a harpsichord. If they're at an angle, it's a spinet. This is a relatively simple mechanism, and it's easy to make a relatively loud, clear instrument. But there are two huge downsides: there's very little control over volume (indeed, if you could play much louder, you'd also be changing the pitch of the note unpredictably), and there's no sustain (partly because it's an inherently sharp plucking sound, and partly because devices in the instrument cut off the sound to prevent blurring, and there's no way to control those devices from the keys). These problems could theoretically be overcome, but it would require a lot of ingenuity and nobody's ever done it.

Struck keyboards, however, have an even bigger problem: they don't work. If you hit a string with a hammer, it doesn't make a sound, because the hammer is then lying on the string, damping it. Human string-hitters hit the string and then pull back the hammer, but that's very, very not easy mechanically.

So instead, what people used were 'tangents': you don't so much exactly "hit" the string as hit it and slide past it. It's that sliding that provides the sound. And it also does something really weird: because the initial hit and the sliding hold the string in place, as it were, the tangent both plucks the string and defines its length at the same time. This instrument is the clavichord, and this is why wobbling the key the right way lets you wobble both the volume and the pitch of the note. And unlike a sharp 'pluck', you can scrape past the string more or less quickly, or even changing the speed partway through the note, giving you vastly more control over the volume and contour of the sound. Magical! And because the mechanism is very simple indeed (it's basically just a lever with a pointy bit at the end), it directly mirrors the fingers of the player and is very quick, with no confusing lag between action and sound - and it's cheap to make! And it can also do something else other keyboards can't: because the string length is defined by the tangent, it doesn't have to be predefined, which means you can play multiple notes on the same string. Theoretically you could play all the notes on the same string - though that would negate the whole point of a mechanical keyboard, and in practice "fretted" clavichords tended to just have two or three notes per string. (some clavichords were 'unfretted' like pianos or harpsichords, to increase the ability to play many notes at once - but fretting means you need fewer strings, so it reduces the price and the size of the instrument, making fretted clavichords ideal for domestic and travel purposes).

BUT: you can't play too loud, because otherwise you change the pitch. And no matter how loudly you play, most of the energy is wasted: you lose all the energy of the initial hit (which just defines the string) and have to rely on the much less efficient process of sliding past the string to generate sound. And what's more: because only the string on one side of the tangent speaks, you end up wasting at least half your energy on the mute string. So the result in an inherently quiet instrument, no matter what you do to it.

Therefore a new invention arose: the tangentenfluegel, or 'tangent piano'. Actually, a bunch of inventions arose, but the tangent piano is the notable one (with one exception - see below). The tangent piano abandons the clavichord idea, and is basically a harpsichord where the harpsichord action is adapted to striking rather than plucking. The vital part is that rather than the key in some way hitting the string, instead the key fires a projectile at the string from below, which hits the string and bounces back into place. This is only a little more complicated than a harpsichord.

...and although it's a mechanically ingenious device with a unique and interesting sound, the tangent piano is now also obsolete, because some bloke called Bartolomeo Cristofori invented an entirely new mechanism, by which hammers could hit strings and then be retracted - and all it took was a couple of dozen moving parts. This immediately meant you could play louder, softer and with more control than the tangent piano, and the new instrument - once people swallowed the high price tag - quickly made all other keyboards obsolete.