The guitarrón mexicano, which means "big Mexican guitar" in Spanish (the suffix -ón makes something bigger), is a large, deep-bodied six-string acoustic bass guitar used in Mariachi groups. It is similar to the guitar but was not developed from that instrument. Instead, it was created independently from the sixteenth-century Spanish bajo de uña, a type of plucked bass. Its large size allows it to produce loud sounds, so it does not need electric amplification for small performances. The guitarrón has no frets and uses heavy strings, usually nylon for the top three and wound metal for the bottom three. It is often played by repeating notes an octave apart, a practice made easier by its standard tuning: A1 D2 G2 C3 E3 A2. Unlike a guitar, the pitch of the guitarrón strings does not always increase as you move downward. For example, the lowest string (A2, the sixth string) is a perfect fifth below its neighboring string (E3). The guitarrón inspired Ernie Ball to create the first modern acoustic bass guitar, which was released in 1972.

Use

The guitarrón is a large instrument used in Mexican Mariachi groups. These groups usually have at least two violins, two trumpets, one Spanish guitar, a vihuela (a five-string, high-pitched guitar-like instrument), and the guitarrón. A strap is often used to hold the instrument up so it can be played easily. The guitarrón is the main rhythm instrument in the group and acts as the bass instrument, playing deep, low notes. The steady rhythm created by its basslines helps the other instruments stay in sync. It is rare for a group to have more than one guitarrón player.

To play the guitarrón, musicians need strong left hands to press the thick strings against the fingerboard and strong right hands, especially the index, middle finger, and thumb, to pluck the heavy strings (usually a metal and a nylon string). The right hand usually plucks two strings at once to create a bassline in octaves, even though the music is written as a single note. Because the strings are thick, the player must play slightly ahead of the beat instead of behind it. The instrument is used to play basslines that move through chord progressions with rising and falling patterns. Triads are often used in songs. The guitarrón also plays more detailed lines to add decoration during changes in the music’s key, rhythm, or speed.

• Mexican composer Julián Carrillo modified the guitarrón to play microtonal music by adding extra frets. He used the instrument, called the octavina, in several compositions, including Preludio a Colón (1922).
• The guitarrón is played by Roy Estrada on the 1966 album Freak Out! by the Mothers of Invention.
• Randy Meisner of the Eagles plays the guitarrón on the song New Kid in Town from the album Hotel California (1976; the instrument is called "guitarone" in the credits).
• Aaron Goldsmith, a member of the New York-based group Luminescent Orchestrii, uses a modified guitarrón with an extended neck to play melodies.
• Simon Edwards played the guitarrón for the 1980s British folk-pop band Fairground Attraction. He also played it on the Talk Talk album Spirit of Eden (labeled "Mexican bass" in the liner notes).
• Conrad Lozano has often played the guitarrón with his band Los Lobos.

Design

The back of the guitarrón is made from two pieces of wood that form a shallow V shape. This design makes the instrument larger and deeper. The curved shape helps the instrument produce a strong, deep sound. The sides and back are made from Mexican cedar, and the top is made from tacote, a wood that is light and strong. Tuning machines with worm gears change the tension on the strings, which adjusts the instrument's tuning.