<https://www.concertina.net/forums/index.php?/topic/21213-new-to-concertina/#comment-197072>
<http://schema.org/text>
"The patterns of notes on the push and pull of the C and G rows are closely related to the patterns of notes on a C and G harmonica, and for the same reason of harmonizing while playing in the home keys.   That doesn't necessarily mean you should just play any given tune up and down one row separately depending which key you are in, since there are advantages to crossing rows to get better fingering and phrasing.  But it may help you understand the logic of the patterns.\n \n\n\n\tWith the 20 button, you won't have the 30 button's outer row of accidentals and reversals which does seem more random.   That also means there are a few notes which simply aren't available at all, and if you are looking to play Irish session tunes the first one you will miss will be the C# needed for tunes in D major.   But no worries, there are a great many tunes in C and G major, and the related minors, and modes, and if you have the option to choose the key to play in then you can transpose to a key for which you do have all the notes.  That may not be so true for jazzy tunes with lots of accidentals and blues chords, but you can still play partial chords, if someone else is playing the missing notes at least part of the time.  Most often a light touch on the harmony is better anyway.\n \n\n\n\tFinding your way around the combination of melody and available harmony notes is part of the charm of the Anglo.  I love my 20 button. \n \n"
<https://www.concertina.net/forums/index.php?/topic/21213-new-to-concertina/&tab=comments#comment-204116>