Commonly referred to as the Cello-Guitar, the Brahms guitar was invented in 1994 by classical guitarist Paul Galbraith in collaboration with the luthier David Rubio. It was originally conceived in order to perform Johannes Brahms' Theme and Variations Opus 21a. David Rubio's protégé, luthier Martin Woodhouse, has innovated the design and continues to build Brahms Guitars.
The instrument is an eight string guitar, adding both a high and a low string to the conventional six string guitar. The tuning continues in fourths and the frets are fanned to allow for the different string lengths.
Galbraith's method is to play the Brahms guitar in the cello position adding greater freedom to both hands and incorporating a resonating box.
Other practitioners include the young guitar virtuoso Joseph Ehrenpreis, Everton Gloeden and Luiz Mantovani of the Brazilian Guitar Quartet and Galbraith's former students Redmond O'Toole and Matthew Korbanic. Brahms guitar is also in use by the Dublin Guitar Quartet who use the instrument in their arrangements of Philip Glass, Kevin Volans and Arvo Part string quartets.