A Piano with Tricks: The Remarkable Schmahl Square Piano

At first glance, the eighteenth-century square piano can seem like a relatively straightforward instrument: a small wooden case, a keyboard, strings and hammers. But some early pianos conceal an extraordinary amount of ingenuity. A particularly fascinating example is the square piano attributed to Johann Matthäus Schmahl of Ulm, represented in the collection of the Museum of Musical Instruments of Leipzig University.

Schmahl (1734–1793) belonged to an important family of southern German instrument makers. His early pianos were very different from the large grands that would dominate the nineteenth century. Indeed, some of his instruments were deliberately made in the unusual form of a “lying harp” (liegende Harfe), a distinctive type of early hammer instrument associated with the German pantalon.

What makes the Leipzig instrument particularly interesting is not simply its shape, but the remarkable number of ways in which the player could alter its sound.

An instrument with several personalities

The instrument has a series of levers which allow the player to introduce different effects between the hammers, strings and soundboard.

At the centre of the key-slip is a lever for operating the dampers. Behind this apparently simple control is a surprisingly elaborate mechanism: the lever acts upon a series of double-armed levers through a rail guided in diagonal slots.

But this is only the beginning.

Four further levers are positioned on the fixed front panel above the keyboard. Each produces a different effect.

The first introduces a silk strip between the hammers and strings. Instead of allowing the bare hammer to strike the string directly, the silk softens the contact and changes the character of the sound.

The second operates in a similar way, but introduces a strip of leather or cloth. Contemporary and later descriptions differ over the precise material. The result is nevertheless another distinct colour.

The third lever operates the dampers, allowing the player to control the resonance of the strings.

The fourth is particularly intriguing. It causes a leather-covered wooden mallet to strike the underside of the soundboard.

In other words, the instrument does not simply make the sound of a piano louder or softer. It gives the player a collection of different timbres — almost like a miniature eighteenth-century sound laboratory.

The piano that imitates a harp

Schmahl's instruments have often been connected with the tradition of the pantalon, a large hammered dulcimer popular in eighteenth-century Germany. The pantalon was valued for its shimmering resonance, and early hammer pianos could borrow something of this sound while offering the expressive possibilities of a keyboard. The Metropolitan Museum notes that Schmahl's “harp pianos” were probably intended partly to imitate the hammered dulcimer tradition.

This helps explain why such an apparently modest piano could require so many different devices.

The bare hammer could produce a bright, percussive sound. A silk or leather moderator could soften it. Damping could shorten the resonance. And the additional soundboard mechanism could produce yet another colour.

The effect is remarkably close to the eighteenth-century fascination with registers and “stops” found in harpsichords and other keyboard instruments. Rather than having one fixed piano sound, Schmahl's instrument gives the player the ability to modify the voice of the instrument.

A piano that changes key

Perhaps the most ingenious feature, however, is the transposing mechanism.

The keyboard and its action can be moved approximately 4 mm into the instrument — essentially the distance between two adjacent strings.

When the mechanism is moved, the hammers no longer strike the strings they normally correspond to. Instead, they strike the next higher string.

The result is that the entire instrument sounds a semitone higher without the player having to change the fingering.

This is a beautifully simple solution to a problem that has confronted keyboard players for centuries: how to change the pitch of an instrument while continuing to play the same music.

The idea depends upon an exceptionally regular arrangement of the strings. Because the strings are evenly spaced, moving the keyboard and action by exactly one string spacing shifts the hammers onto the neighbouring set of strings. The mechanism can then be secured in its new position.

It is an extraordinary piece of mechanical thinking.

The same principle is documented in another Schmahl “lying harp” preserved in the Piano Museum Haus Eller, which has a 61-note keyboard but 62 strings specifically because of its half-tone transposing mechanism.

Why transpose a piano?

Today, transposition is something we usually associate with electronic keyboards: press a button and the entire instrument moves up or down by semitones. On Schmahl's piano, however, transposition is a completely physical process.

There is no electronic shortcut. The whole action is moved.

This would have been particularly useful for accompanying singers or other instruments. An eighteenth-century musician might need to accommodate a different pitch requirement without forcing the performer to learn a new fingering.

It is also a reminder that transposition is not a modern convenience. Instrument makers were devising ingenious mechanical solutions to it centuries before digital keyboards made it effortless.

A glimpse into the experimental world of early pianos

Schmahl's instruments are important because they demonstrate that the early piano was not simply a primitive version of the modern piano.

The instrument was still being invented.

Makers were experimenting with different actions, materials, string arrangements, dampers and methods of modifying tone. The boundaries between the piano, clavichord, harpsichord and hammered dulcimer were not yet as firmly established as they would become later.

The surviving Schmahl instruments are especially revealing because they seem to have been made in relatively small numbers and with considerable attention to individual requirements. The Piano Museum Haus Eller notes that around twenty instruments of this distinctive “lying harp” type are known, with considerable variation in keyboard compass and in the number and type of sound-changing devices provided.

That makes each surviving example particularly valuable.

Rather than being a standardised product from an eighteenth-century piano factory, it is better understood as an individual experiment in musical engineering.

More than a piano

Perhaps the most appealing thing about Schmahl's instrument is that it challenges our assumptions about what an early piano was supposed to do.

It could be a piano.

It could imitate something of the sound of a hammered dulcimer.

It could produce different colours through silk and leather moderators.

It could suddenly silence the strings through its damping mechanism.

It could even make the soundboard itself part of the instrument's tonal palette.

And, with one ingenious movement, it could transpose itself by a semitone.

All of this was achieved with wood, leather, silk, metal, strings and a remarkable amount of mechanical imagination.

The Schmahl piano therefore represents an exciting moment in the history of the keyboard: a period when the possibilities of the hammer mechanism were still being explored and the “piano” had not yet settled into the form we recognise today.

The next time we see a small eighteenth-century square piano, it is worth looking beyond its apparently modest exterior. Inside may be an entire world of mechanical invention — and, in Schmahl's case, a piano with considerably more tricks than first meets the eye.

Instrument: Square piano attributed to Johann Matthäus SchmahlMaker: Johann Matthäus Schmahl (Ulm, 1734–1793)Date: c. 1770Collection: Museum of Musical Instruments, Leipzig UniversityCredit: Museum of Musical Instruments, Leipzig University