For contemporary players, the DAD tuning or the Mixolydian Mode, as Harpgirl has said, is the standard tuning. In the 1970's, the Ionian Mode or "sol-sol-do" was standard. There has been a major shift in thinking about dulcimer tunings in the past 30 years. In the earliest years of the dulcimer revival, players thought in terms of modal tunings and referred to the "do-re-mi, etc" names for string relationships. They commonly used the Ionian mode since it is the equivalent of what we commonly refer to a major scale. For the past 20 years or more, however, players are more likely to refer to tunings by the key in which the instrument is tuned and the "do-re-me" scale is rarely mentioned.

There are several reasons for this shift of emphasis. The most important one is the presence of the 6# fret. Although it was being put on dulcimers in the 1960s (possibly due to Howie Mitchell) it took a few years for players to discover the many possibilities which were created by that innovation. The 6# fret enabled one to play a major scale in the Mixolydian tuning and get a flatted seventh note as well. The length of the fret board can vary by makers, but the most common length which was used by McSpadden and others gave the brightest and best sound when tuned to the key of E in the Ionain tuning. The Mixolydian tuning sounded best in D. Since many fiddle tunes in American and British folk tradition were played in D or A, the DAD tuning on instruments with the 6# fret become more popular. Another bonus with the DAD or Mixolydian tuning was the rich chords that could found on the fretboard. I began using the Mixolydian tuning because it best suited my singing voice and the nice chords which were available, which I think was true of others as well. A further bonus of the DAD tuning was that with the use of bar chords the dulcimer could at least accompany other instruments playing in other keys and thus eliminated the need for much retuning. The more proficient players could also play melodies in keys other than D with the accompaning bar chords, again adding to the versatility of the DAD tuning. One could also switch into the Aeolian or minor mode from Mixolydian by using bar chords.

That's my lecture for the day. Now I can start thinning the bed of lettuce in the garden.