Wormy Chestnut for dulcimers - Clifford Glenn
Instruments- discuss specific features, luthiers, instrument problems & questions
I won't call a 1975 dulcimer "vintage" -- that would make me an "antique"! Those earlier post-revival instruments, for the most part, weren't designed with DAd home tuning in mind. That doesn't mean that the pegs won't hold that tuning. It just means that if you are absolutely set on DAd as the home tuning you will want to experiment with different gauges of melody strings -- instead of the .012 which comes in a package set, you may want to try .011 or a .013
If you are playing with others, then DAA or Ddd would be good home tunings. If you play mostly by yourself, as I do, then the key of C (CGG or Ccc) might fit your voice better.
I find that those Bagpipe tunings (Ddd/Ccc) have an advantage on dulcimers without 6+ frets, similar to the advantage that the 6+ fret gives to players who prefer DAd/Chord Melody. Ccc/Ddd gives us the ability to easily play in two or more Modes without re-tuning.