By contrast, most open major or open minor tunings provide only octaves, fifths, and either a major third/sixth or a minor third/sixth—but not both. Don Helms of Hank Williams band favored C6 tuning; slack-key artist Henry Kaleialoha Allen uses a modified C6/7 (C6 tuning with a B on the bottom); Harmon Davis favored E7 tuning; David Gilmour has used an open G6 tuning. Modal tunings Modal tunings are open tunings in which the open strings of the guitar do not produce a tertian (i.e., major or minor, or variants thereof) chord. The strings may be tuned to exclusively present a single interval (all fourths; all fifths; etc.) or they may be tuned to a non-tertian chord (unresolved suspensions such as E–A–B–E–A–E, for example). Modal open tunings may use only one or two pitch classes across all strings (as, for example, some metal guitarists who tune each string to either E or B, forming "power chords" of ambiguous major/minor tonality). Popular modal tunings include D Modal (D-G-D-G-B-E) and C Modal (C-G-D-G-B-D). Lowered (standard) Derived from standard EADGBE, all the strings are tuned lower by the same interval, thus providing the same chord positions transposed to a lower key. Lower tunings are popular among rock and heavy metal bands. The reason for tuning down below the standard pitch is usually either to accommodate a singer's vocal range or to get a deeper/heavier sound or pitch. Common examples include: E♭ tuning Rock guitarists (such as Jimi Hendrix on the songs Voodoo Child (Slight Return) and Little Wing) occasionally tune all their strings down by one semitone to obtain E♭ tuning. This makes the strings easier to bend when playing and with standard fingering results in a lower key. It also facilitates E shape fingerings when playing with horn instruments. D tuning D Tuning, also called One Step Lower, Whole Step Down, Full Step or D Standard, is another alternative. Each string is lowered by a whole tone (two semitones) resulting in D-G-C-F-A-D. It is used mostly by heavy metal bands to achieve a heavier, deeper sound, and by blues guitarists, who use it to accommodate string bending and by 12-string guitar players to reduce the mechanical load on their instrument. Among musicians, Elliott Smith was known to use D tuning as his main tuning for his music. It was also used for several songs on The Velvet Underground's album The Velvet Underground &