Concertina Music Common Keys

Taking as a sample the Czech Area Concertina Club sheet music, I checked to see what kind of key signatures are the most common.

No surprise, the most common keys are G and D.
In fact, of the roughly 200 pieces of music on the CACC website, about 140 of them are written either in the key of G or the key of D, and they are about evenly split with about 70 apiece.

A few pieces are in the key of A, and one piece is in the key of C but changes to G al fine [to the end].

This doesn't mean that you aren't playing other notes not in those keys, this is just referring to the key signatures.  Other notes and chords get played, but they play by the rules of composition.

There are a number of pieces that change keys during the song.  To clear up confusion here: when a composer writes a song, they must pick a key to put their melody in (unless writing crazy modern keyless music a la Arnold Schoenberg).  Sometimes, the song or musical idea will require a change in the music, or there is a change in the music to keep the listener interested.  One musical trick is to change the key by "modulation: most commonly the act or process of changing from one key (tonic, or tonal center) to another."

Technically, a chord progression is a modulation as well, but that is more of a minor modulation, because the music will keep the same tonic, and resolve according to that tonic.  When music modulates keys, you change the tonic.

It's easiest to modulate to a similar key, which is to say, one that has only one more or one less sharp or flat.

Concertina music is fairly simple, speaking from a music theory standpoint.  Not very many pieces actually do a chord progression to modulate to the new key - mostly, they simply finish one section of the song, and start the next section in the new key.  In the example below from Angel Polka, the first line is in the key of G (one sharp).  You can see that the bass line (left hand) is D7 which resolves to G, in the classic V-I resolution.  The second line then opens up with A7, which is not even a common chord with G because of the C# in the A7 chord.  A7 then alternates with D, in the V-I progression again.

This isn't a bad thing, of course.  The V-I progression is one of the strongest in all music - Dominant to Tonic.  Concertinas and the music that's played on it takes full advantage of this - so its no surprise to me that the key changes that I see in the music at CACC are D to G, G to D, and occasionally D will go to A, back to D, and sometimes down to G.  A will change down to D.

If this is all over your head, don't worry about that either - what this pretty much means is:

Learn the keys of G and D inside and out.  The key of A, yeah learn it eventually, but concertina music is written to suit the construction of the concertina, which itself was pretty much built to play around the keys of G and D.  Maybe 10% of the concertina music out there will use the key of A at all - the other 90% is all D and G.

For me, I'd like to expand the world of the concertina some - but first I have to learn the keys of G and D!!