So, I want to get a Hammered Dulcimer, what size do I need? The obvious answer is it depends….
Firstly there are practical considerations. Do you want to take the dulcimer out the house? If so, how big is the boot of your car, a monster dulcimer is great in the privacy of your own living space but when transporting it to the local folk club it can be a mammoth task requiring sack trucks and a team of young men to move it for you.
Then comes the question of how complicated to you want to make your life? All these extra notes just make more tuning and unless you are prepared to practice lots these notes are a bit of a pain to play. They interrupt the flow of playing, having to dot across to get that funny note, got to hit the right one and get back again. Not something for the faint hearted.
What tunes do you want to play? Most folk tunes seem to be in C, G and D. Morris tunes mostly avoid too many sharps and flats.
A 12/12 gives you 2 1/2 octaves of G major, 2 octaves of C and an octave of D and F major plus the relative minors.
In addition on a 15/14 you extend to 2 octaves of D, a full octave of A major which is great for playing the A chord for accompanying singing or tunes. This means you can easily play the chords for tunes in D major (D, G and A). A low D# is not something I have ever needed, but I am sure I will find tune that needs it eventually!
In the UK a 12/12 is the standard instrument whereas in the USA the 15/14 seems to be the standard instrument. Most of the US dulcimer books are written with a 15/14 in mind.
Above 15/14 things can get as complicated as you want. My personal view is 58 strings are enough to tune and carry about. You can look at USA makers like Master Works website and look at the vast array of extra string options for there virtuoso instruments. Again, personally life is complicated enough with 58 strings!
I have played a 12/12 for years but have recently changed to a 15/14 and find the extra D octave and the ability to easily play the chords for D major songs very useful. You pay your money, you take your choice!