While traditional Richter-tuned, 10-hole diatonic harmonicas have a remarkable three-octave range, one can only play a complete major scale spanning one octave in a single key from holes 4 through 6. By contrast, the country-tuned diatonic harmonica with its 5th-hole draw reed voiced a halftone higher (F to F# in a C harmonica), is not only capable of playing 2 complete major scales but can also play one of them from the second hole in two full octaves.

Harmonica enthusiasts who are already f...