7 seven-string guitar

Ibanez custom, fender, Gibson, ESP, Epiphone: Guitar Seven String.
A (7) seven-string guitar is a guitar with seven strings instead of the usual six. Such guitars are not as common as the six-string variety, but a minority of guitarists have utilised them for at least 150 years.
Most 7-string guitars add a low "B" string below the low "E". Both electric and classical guitars exist designed for this tuning. A high "A" string above the high "E" instead of the low "B" is sometimes used. Another less common seven-string arrangement is a second G string situated beside the standard G string and tuned an octave higher, in the same manner as a twelve-stringed guitar (see below). Jazz guitarists using a seven-string include veteran jazz guitarists George Van Eps, Bucky Pizzarelli and his son John Pizzarelli.
Seven-string electric guitars were popularized among rock players in the 1980s by Steve Vai. Along with the Japanese guitar company Ibanez, Vai created the Universe series seven string guitars in the 1980s, with a double locking tremolo system for a 7 string guitar. These models were based on Vai's six string signature series, the Ibanez Jem. Seven-string guitars experienced a resurgence in popularity in the 2000s, championed by Slayer, KoRn, Fear Factory, Strapping Young Lad, Nevermore, and other hard rock/metal bands. Metal musicians often prefer the seven-string guitar for its extended lower range. The seven-string guitar has also played an essential role in progressive rock, and is commonly used in bands such as Dream Theater and by experimental guitarists such as Ben Levin.

Today, the seven string has emerged as somewhat of a niche instrument. Drop-tuned six-string guitars have taken the places of 7's for bands that primarily engage in low-end riffing, and the seven has begun to grow in popularity amongst many of the same sort of bands who were using them in the early 1990s , progressive-oriented metal and rock guitarists (such as Jeff Loomis of Nevermore and Jasun Tipton of Zero Hour). Additionally, seven-string guitars were popular and considered cutting edge in the 80s and into the 90s with the shred scene. Now players such as Rusty Cooley, Francesco Fareri and Ricky Graham attempt to "bring back" the shred scene of the 80s which was called "speed metal". Matt Bellamy from Muse uses a custom red Manson 7-string to play just one song, Citizen Erased, with a AADDGBE tuning (the song was originally recorded on a detuned six-string).
This guitar was originally made for a jazz musician, but they decided they were going down a more acoustic route and Matt Bellamy decided he'd buy it instead. Besides being used by solo artist, seven-strings are also used by Mathcore bands and in other progressive genres. Band such as Textures, Unearth, Periphery, Novembre, and Grethor use seven-strings because of the low palm-mutes it produces and the extra range it provides. Dino Cazares of Divine Heresy, Asesino, and formerly of Fear Factory and Brujeria is notable in the metal genre for his custom 7 string ibanez guitars. His custom guitars typically utilise just one bridge pickup, feature reverse headstocks and he often tunes them down one step to A. Amongst his new guitars is a Ibanez Xiphos 7 String.
Triumphant Return guitarist Matti Ice uses 7-string guitars tuned A,D,A,D,G,B,E. Christian Olde Wolbers of Fear Factory (who became the guitarist in 2004) has his own signature Jackson 7-string guitar, offered in Soloist and Dinky forms. Trainwreck of Kritic Kill uses Ibanez 7-string guitars tuned down two whole steps. Stephen Carpenter of Deftones, as well, has several of his own models released by ESP. They have also been used by artists such as Devin Townsend and Lacuna Coil and are available in both regular size and baritone. Deathcore bands such as Suicide Silence, Oceano, and Whitechapel, favoring a low sound, use guitars tuned to drop A.