The BACH.Bogen® (BACH.Bow) enables string players to play one, two, three and four strings simultaneously and to change easily among these possibilities. The high arch of the bow allows full, sustained chords to be played and there is a lever mechanism that affects the tension and release of the bow hairs.
Mstislav Rostropovich was intimately involved in the development and testing of the BACH.Bogen.
John Cage and Dieter Schnebel have written works which explore the new perspectives and potential of the BACH.Bow.
Even in our own time, the solo violin and cello compositions of Johann Sebastian Bach make singular demands on performers, not least of all in the matter of polyphonic playing.
Although one might think of the curved bow as, somehow, emblematic of string playing, the fascinating world of polyphonic performance and evidence from former times are still open to investigation.
The practice of polyphonic playing using such kinds of bows is documented by the Renaissance era lira da braccio virtuoso Alessandro Striggio (1540-92); the organist, violonist, and gambist Nikolaus Bruhns (1665-97); the German violinist and contemporary of J.S.Bach Johann Paul von Westhoff (1656-1705), who developed a unique notation for polyphonic playing; and last, but not least, Niccolò Paganini (1782-1840), whose polyphonic daredevilry, in some of his works for violin and viola, was studied and documented by Philippe Borer.
The BACH.Bow is especially conceived for polyphonic playing and its research and development phase has been both lengthy and intensive. A variety of disciplines has been called upon: mathematics and geometry, studies of materials, design, building of prototypes, development of playing techniques, composition, recordings and concerts. This whole cycle was repeated several times before a definitive design was arrived at. The new design takes into account the particulars of both human anatomy and the geometry of string instruments.
Ever since the publication in 1905 of Albert Schweitzer's ground-breaking book about J.S.Bach, the question of the curved bow has been widely debated, even among the experts. For Schweitzer, however, use of the curved bow was essential in performing Bach’s string works. Asked to write something for the Bach year in 1950 (Bach-Gedenkschrift), fifty years after his original study, Schweitzer still focused on his ideas about the curved bow; clearly this remained central to his ideas about Bach interpretation.
Certain musicologists (D.Boyden, for example) have questioned the use of the curved bow, but their notions seem to be based more on theory than actual use of the bow itself. Two recent texts, on the other hand, clearly document use of the curved bow: Rudolf Gaehler’s book Der Rundbogen für Violine - ein Phantom? (The Curved Bow for Violin - a Phantom?), and Michael Bach’s article on the Suites for Cello of J.S.Bach, published in the German magazine Das Orchester. Both these studies are supported by the considerable research and concert experience of their authors. It is significant to note that almost fifty years elapsed between Schweitzer’s 1950 article and Gaehler’s highly significant work in our own time. The going has been slow, but the issue is still very much alive and great strides have been made in the recent past.
Rudolf Gaehler summarizes all important texts on the curved bow which have been published in the 20th century. His primary concern is to show the feasibility of Bach’s polyphonic notation and its execution with the curved bow. His CD realease of all six Sonatas and Partitas confirms very convincingly both this thesis and his own mastery of polyphonic playing.
Michael Bach proposes a new interpretative approach to the Suites and focuses on the exceptional variety of sound production afforded by the curved bow. He reveals a farsighted and broad view of interpretation with the curved bow; in particular, the interpreter’s free choice of playing the notated material as chords or as arpeggios. Even the arpeggios can be played with unparalleled variety, far greater than anything imaginable with the conventional concave bow. It is even possible to add successive voices without dropping the preceeding ones. In addition, the tension of the hairs on the curved bow can be controlled flexibly and precisely, permitting heretofore unknown sound qualities on one or more strings in both monophonic and polyphonic textures.