The Cardboard Guitar: How One Experiment Revealed the Secret of the Classical Guitar

In 1862, in Seville, a Spanish guitar maker built an instrument that should not have worked.

Its back and sides were not made of rosewood, maple, or cypress. They were made of papier-mâché, essentially cardboard. Only the top was proper wood: a thin, carefully shaped sheet of spruce.

The maker was Antonio de Torres Jurado, and he wanted to prove a point. Many people believed a guitar’s voice came from its precious woods and its body. Torres believed something else. If the top, the soundboard, was built correctly, he thought, the rest mattered far less than anyone imagined.

The cardboard guitar sounded remarkably good.

That instrument still survives, in the Museu de la Música in Barcelona. It is one of the strangest objects in the history of music, and it holds the answer to a question guitar makers had wrestled with for centuries.

A quiet instrument in a loud world

For most of its history, the guitar had a problem: it was quiet.

In the sixteenth and seventeenth centuries, the popular guitar in Spain and across Europe had five courses, pairs of strings tuned together, rather than six single strings. It was a lively instrument for dances, songs, and strumming, but it belonged to small rooms and informal gatherings.

By the late eighteenth century, six single strings had become the norm. That gave players more range and more possibilities. It did not give them more volume.

Put a guitar in a large hall and its sound simply faded into the space. Playing harder made it harsh rather than louder. Making the body bigger often made it dull. The instrument needed to project without losing the warmth and sensitivity that made it worth listening to.

That was the puzzle Torres set out to solve.

The secret in the soundboard

A vibrating string carries surprisingly little energy. On its own, it barely makes a sound. The bridge passes that vibration into the soundboard, the soundboard moves the air, and only then does the guitar truly speak.

So the soundboard is the heart of the instrument. It has to be strong enough to resist the constant pull of six strings, yet thin and flexible enough to vibrate freely. Too stiff, and the guitar sounds choked. Too loose, and it can warp or crack.

Torres’s answer combined several ideas. He enlarged the body, especially its lower half. He thinned the top. And underneath it he refined a pattern of light wooden struts spreading out like a fan, supporting the soundboard while still letting it move.

Fan bracing existed before him. Larger guitars existed before him. What Torres did was bring these elements together into a balanced, coherent design, one that gave the guitar a deeper bass, a clearer treble, and a voice that could carry.

The cardboard guitar was his demonstration. Strip away the expensive woods, keep the right soundboard, and the guitar still sings.

A guitar needs a guitarist

A better instrument is only half the story. Someone has to show what it can do.

One of the musicians who played Torres guitars was Francisco Tárrega, a Spanish guitarist and composer who helped lay the foundations of modern classical guitar technique. In his hands, the guitar could carry a melody, an accompaniment, and a bass line all at once, sounding at times like several instruments instead of one.

In the twentieth century, Andrés Segovia took the guitar further than anyone before him. He played in major concert halls around the world, persuaded composers to write for the instrument, and insisted the guitar belonged on the same stages as the piano and the violin.

But Segovia had a problem of his own: strings.

The war that changed the strings

For centuries, guitar strings were made of gut. Gut could sound beautiful, but it was temperamental. It reacted to heat and humidity, went out of tune easily, and varied from one string to the next.

During the Second World War, good gut strings became hard to find. After the war, Albert Augustine, a guitar maker working in New York, began experimenting with a new material from the chemical company DuPont: nylon.

Nylon strings were consistent, durable, and stable. Segovia adopted them, and much of the guitar world followed. By the second half of the twentieth century, the combination we now think of as the classical guitar was complete: Torres’s design, nylon strings, and a concert repertoire that kept growing.

Still unfinished

The story does not end there. Modern makers continue to experiment with lattice bracing, double tops, and new materials, all chasing more power without losing warmth.

But nearly all of them still work in the shadow of a man who built a guitar out of cardboard to prove a point.

The classical guitar never needed to become a different instrument. It only needed to discover what it could already do.