Seven-string guitar

A guitar with an added lower string, most often tuned to a low B, giving an extra register below the standard range.

The wider neck and additional tension mean the instrument behaves differently: the low B needs a heavier gauge and a longer scale to stay clear and in tune, and the neck must be stiffer to resist the extra pull. Chord shapes transfer directly, since the added string simply becomes the new lowest root, but the physical width demands adjustment for players used to six strings. The design became standard in heavy music, where the extra string supplies a register that does not crowd the bass.

Example: a power chord shifted onto the low B string sounds a fourth below the same shape on the sixth string, filling a gap below the standard range.

Seven-string guitar

See also