Yes, i know it isn't a bass, but it is similar to one. I need to know how this is tuned, where the different notes are, just some basic guitarron stuff. If you could help me, that would be great, because my schools Mariachi Band is suffering from the lack of one.
Tuning is A, E, C, G, D, A. I've only played one of these once, but I will warn you the action on them makes the usually Epi standard of high action from the factory look effortless to play.
Well I'm not mexican but i've seen a lot of mariachi bands playing and i've always wanted to play one, it's not technically a bass guitar because is not an octave lower than a guitar is kinda a baritone so it's tuned A - D - G - C - E - A (i know that because i asked a mariachi guitarron player XD)
To play the guitarron in mariachi music you play chords in 5ths, the guitarron is fretless
but we can imagine the positions by ear, mariachi musicians as many traditional and popular music proffesionals in latin american, usually don't have formal studies they play by ear and it's hard to find anything extensive even in spanish for this kind of study, so it found this:
Chords used on the mexican Guitarron (Basic)

Low High
Note String "Fret" String Fret
C 6 3 3 0
D 5 0 3 2
E 5 2 2 0
F 5 3 2 1
G 4 0 2 3
A 1 0 6 0
B x x 6 2

i hope this can be helpful