Fanned-fret guitar

A multi-scale fingerboard is an instrument fretboard which incorporates multiple scale lengths. The scale length is the vibrating length of the strings.

Guitars, including bass guitars, generally employ a single scale length for all of the instrument's strings, though the employed scale length varies significantly between manufacturers (electric guitar scale typically falls between 24" and 25.5"). This measure is the effective length of each of the vibrating strings, not counting compensation for adjusting intonation.

A multi-scale fingerboard or fretboard is typically based on two scale lengths, but could potentially incorporate more. The most typical use is one (long) scale length for the low string and a different, usually shorter, scale for the highest string. This could be achieved by angling the nut, and bridge, and fanning the frets. Strings between the highest and lowest would also each have a unique scale length.

The bandora is a late 16th century instrument with a longer string length for its bass strings than for its trebles. It is depicted in Praetorius' music dictionary Syntagma Musicum published in 1619.

The concept of the multiscale fingerboard goes back to at least 1900, when the first patent for such a fingerboard was filed by E. A. Edgren. (Patent #652-353, E. A. Edgren)

In his 1900 patent Edgren describes in his claims: “… a musical instrument the combination with a sounding body or box, of the following instrumentalities, to wit: a neck approximately in the form of a double convex in cross section…” a plurality of frets secured to said neck, said frets being positioned at an angle one to the other so that the first and last frets incline in opposite directions “... it will be noted that the bottom flange of the head C runs at an angle so that one side of the neck B will be longer than the side opposite. The frets diverge, running from the center outward, so that the lower frets extend slightly in a direction opposite to the upper frets”. This patent is no longer in force. When it was, it affected only instruments with a curved fingerboard, such as most steel-string guitars.

Possibly the first modern multiscale fretboard was used on an instrument called a StarrBoard, invented by John D. Starrett in 1977. Starrett developed a tapping instrument that employs a matrix of halftones, fretted horizontally with strings spaced vertically, to allow one fingering to cover all scales. Because of the large range of notes from low B below E on a bass, to high B four octaves above, however, he needed a way to have a long scale for the low B, but a shorter scale for the high B. He simply laid out the two scales he thought would work and connected the dots.

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