Mike K post_id=50783 time=1506466611 user_id=1773 said:
What is the best way to play an augmented chord on a stradella bass?
The short answer is: you cannot.
On stradella major = major third + minor third, minor = minor third + major third, 7 = major third + 7, missing 5 and
dim = minor third + minor third.
For C it means major = C E G, minor = C Eb G, 7 = C E Bb and dim = C Eb A (which is also A C Eb, two minor thirds).
There is no way to play a chord with C E G#.
There are non-stradella accordions that have a different arrangement giving 7 = two minor thirds as C7 = E G Bb and that also acts as Gdim, and then the 4rd row of chord buttons is available and used to so an augmented fifth: C E Gis.
On our standard Stradella instruments, alas, we cannot play a chord consisting of C E G# (without adding at least one other note like an augmented 7th). You can play C E G# B for instance by using C base note + E major. But you cannot do it without adding that B or some other note in the mix.