Guitarrón Tuner

Five strings that ascend, and one that does not

The guitarrón is tuned A1–D2–G2–C3–E3–A2. Read it from the low end and the first five climb in a pattern any guitarist would recognise — fourths, then a third — 55.00, 73.42, 98.00, 130.81, 164.81 Hz. And then the last string does not continue to A3 at 220 Hz, where the pattern points. It drops to A2, 110 Hz: a perfect fifth below the string beside it, and exactly one octave below where almost every new player puts it.

This is not a quirk to be corrected. It is the reason the instrument works. The guitarrón is the only bass in a mariachi — no amplification, no frets, standing up, outdoors, against two trumpets — and it gets its weight by playing the bass line in octaves. The part is written as single notes; the right hand plucks two strings at once, most often A1 and A2 together. That octave pair is only reachable because the high A was brought down to where the same hand can take both.

The proof is in the string set

If the tuning still looks like a typo, the gauges settle it. A La Bella guitarrón set is nylon-wound on the three high strings and metal-wound on the three low ones, and its gauges run:

Within each half of the set, thicker means lower, without exception — and the 1st string is thicker than both strings it sits next to. A .107 nylon string is built to sound A2. Wind it up to A3 and you are asking it to carry four times the tension it was made for, on an instrument whose top is already under more load than a double bass’s.

Which string is the “first”? The sources disagree

There is a second, quieter trap here, and it explains a lot of contradictory advice online. String makers number the re-entrant A2 as the 1st string — the guitar convention, where the 1st is the one nearest the floor in playing position. Several reference works instead count upward from the lowest-pitched string, which makes that same physical string the 6th. Both descriptions are of one string; only the counting differs.

So instructions that say “tune the sixth string to A” are ambiguous in the worst possible way, because both ends of this instrument are an A. Name the note with its octave, and check the gauge if you are unsure: metal-wound means it is one of the three low strings, nylon-wound means it is one of the three high ones.

Tuning routine

1. Set the dial to A=440 and leave it there. A mariachi contains trumpets and violins; the strings tune to fixed pitch, not to each other. There is no negotiation.
2. Start with the 2nd string, E3. It is the highest and clearest note on the instrument, so the tuner locks onto it fastest, and it gives you a reference to sanity-check the rest against.
3. Then the 3rd (C3) and the 1st (A2). Take the 1st slowly and watch the octave number the whole time. If the display shows A3 at any point, stop and come back down — you are on the wrong octave and the string is telling you so through your fingers.
4. Now the wound strings: 4th (G2), 5th (D2), 6th (A1). Mute everything else with your forearm, pluck with the flesh of the thumb, and give each note two full seconds before reading it. At 55 Hz a tuner needs time; a fast pluck-and-glance produces a number that has not settled.
5. Check the octave pair by ear. Play the 6th and the 1st together — A1 and A2. They should lock into one thick note with no beating. This is both a tuning check and the sound the instrument exists to make; if it wavers, one of the two is off even if the needle centred on both.
6. Go round again. Six heavy strings on a lightly braced top move the top itself, and the guitarrón is more sensitive to this than a guitar because the loads are so much larger.

The guitarrón in the ensemble

A mariachi’s rhythm section is three instruments doing three different jobs. The vihuela plays the offbeat, high and dry, with its own re-entrant tuning running in the opposite direction to this one. The guitar fills the middle. The guitarrón plays the root and the fifth in octaves, and between them the vihuela and the guitarrón mark out the mánico, the strum pattern that tells a son from a ranchera from a bolero.

It is worth hearing what the two re-entrant tunings do together. The guitarrón brings its top string down an octave so one hand can span an octave pair; the vihuela sends its bottom three up an octave so its strum sits above the guitar rather than doubling it. Neither instrument ascends string by string, and both of them make more sense the moment you see what the other one is doing. Our mariachi instrument tuners page lines up all three.

Where a dial stops helping on a fretless instrument

The guitarrón is fretless, which changes what a tuner is for. On a guitar you tune six open strings and the frets take care of the rest; here the open strings are the only notes the dial can help you with, and every stopped note is your left hand’s responsibility. That is not a hardship — the parts stay low and use a small number of positions — but it does mean the dial is a starting reference rather than a verdict.

The other limit is inharmonicity, and no instrument on this site has more of it. The heavier the winding, the further a string’s overtones drift above exact multiples of its fundamental — so a perfectly centred reading can still sit a shade under the ensemble, and the two strings where this bites hardest are precisely the two you sound together. If the A1/A2 octave beats while both read centred, trust the beat and nudge the upper string a cent or two. Our guide to cents covers why the two answers differ.

Frequently asked questions