Guitar chord for chords having their root note on the third, fourth, fifth, and sixth strings. For a six-string guitar in standard tuning, it may be necessary to drop or omit one or more tones from the chord; this is typically the root or fifth. The layout of notes on the fretboard in standard tuning often forces guitarists to permute the tonal order of notes in a chord. The playing of conventional chords is simplified by open tunings, which are especially popular in folk, blues guitar and non-Spanish classical guitar (such as English and Russian guitar). For example, the typical twelve-bar blues
String vibration or, perhaps more easily, by adjusting the machine heads, to obtain the same, or a multiple, of the AC frequency to achieve the same effect. For example, in the case of a guitar, the 6th (lowest pitched) string pressed to the third fret gives a G at 97.999 Hz. A slight adjustment can alter it to 100 Hz, exactly one octave above the alternating current frequency in Europe and most countries in Africa and Asia, 50 Hz. In most countries of the Americas—where the AC frequency is 60 Hz—altering A# on the fifth string, first fret from 116.54 Hz to