Hohner Harmonica Old Standby . These popular beginners harmonicas are also affordably priced. Fine construction and tone with heavy plated covers and sturdy boxes. Diatonic Harmonicas The reeds of Diatonic Harmonicas produce the notes of the scale to which they are tuned. For example a diatonic harmonica tuned to the key of C would produce the natural notes of the C scale without sharps and flats (picture the white keys on a piano without the black keys). Each hole has two reeds; one plays when breath is exhaled (blow) and the other when inhaled (draw). The individual reeds are each tuned to play a different note on the scale.