Dana, if you tune your Ginger to GDg, you can play everything you currently do in DAd. You will sound great. You will be in a higher register and a different key. Everything will be wonderful and you'll have fun. You can also tune to AEa and be in an even higher register.
Unless you start to play with other dulcimers tuned DAd, that is, for then you will not be in the same key. There are ways to play in G out of a DAd tuning and in D out of a GDg tuning, but that requires some more understanding of keys and the fretboard.
If you tune a Ginger to DAd you probably will need different gauge strings. McSpadden surely has recommendations for string gauges for a DAd Ginger and you can also use the Strothers String Gauge calculator , inputting the VSL and the desired tuning. That calculator errs on the light side, so feel free to use strings slightly heavier than what it indicates.
When you buy a Ginger from McSpadden, they use a slightly different bridge for DAd or GDg tunings. Can you switch tunings without a compensated bridge? Yes, and you might find it plays perfectly well. If you have a sensitive ear, however, you might find the intonation slightly off. If you want to tune your Ginger to DAd, then try it and see how it sounds. If you notice an intonation problem, you will want to get a compensated bridge.
But you already have dulcimers tuned DAd. Why not keep this one tuned GDg or AEa so that you can play in those keys and the higher register? I think you'll find it a refreshing change.
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Dusty T., Northern California
Site Moderator
As a musician, you have to keep one foot back in the past and one foot forward into the future.
-- Dizzy Gillespie
updated by @dusty: 08/17/17 08:25:27PM