Welcome to SOTW! Play them one-step higher (the guitar being a concert pitch instrument and your tenor being a Bb instrument). To match a concert-pitch instrument, you must play a step higher . . .
B = your C#, F# = your G#, etc. DAVE

 

One of the challenges of playing gitar music is the tunes are often shown in guitar friendly keys EADG which is F#, B E and A ...lots of sharps

 

Here is a transposition chart for most instruments:

Chart of Key Transposition

 

Am trying to figure out which chord on my alto sax matches up with the A Chord on guitar

 

F#

 

Or...buy him a capo.

 

I hope it goes without saying that you can't play a chord on a sax, although you can play an arpeggio of the notes of the chord. The guitar chord of A major ( A C# E triad) on an alto (3 half steps down) is F# major chord triad of F# A# C#.

 

A rookie question:

Would the alto sax play F# for just the duration of the guitar’s A chord or could it play the F# A# C# arpeggio for the duration of the guitar’s chord?

 

Is it an A major chord, minor chord, +5, diminished, 9 or #9 or b9, etc.? Alto sax could play a F# major scale or a pentatonic scale or some other scale or groups of notes depending a lot on what type of A chord the guitar is playing and what chords come before and after the A chord. It could play passing notes on the way to or from the F#. It could play the melody, if there is one. It could play lots of things. Search "voice leading" on the internet or in this forum.

 

What to play obviously depends on context-- including whether arpeggiating the chord would be boring for the listener-- it might even be overplaying, let's say there's a singer and 3 other horns. We don't have enough information to say what is right to play.

 

I agree with Zasterz. I played a gig today with a band I sometimes sit in with. Some of the songs are country-ish. All I could do on some tunes was just hold the tonic note of the chord until the chord changed and then play the tonic note of that chord. So basically I was playing whole notes on, for example, A, D, and E chords. If I tried to play anything more, it just sounded wrong. Then the next tune would be a fast blues in A and I could play all over the place, doing a lot of pentatonics but also ripping through passing notes and playing scales or even chromatically up or down to the chord change. What notes to play over an A guitar chord depends entirely on the tune and the changes and the context.

 

Exactly- country, folk, singer-songwriter-type stuff— I’ve played in plenty of situations where you can barely sneak in an inoffensive 2 or 6 over the major triad!