Strings need to be at the "right" tension to sound like guitar strings. Get a chart of string tension against gauge. If your guitar sounded nice to you with the strings you used to play in the keys you used to play, check the string tensions off the chart at that pitch. Now look up the gauge for the same string tension or a LITTLE bit more at the lower pitch.

If you used to play 13s in standard tuning, you may find you want 14s to go down a semitone. A B string on a set of 13s is likely to be a 17 or thereabouts.


BUT you will find that the ring of chords is somehow less clear, or muddier.   I tried a long-neck guitar that tuned on standard strings to D once, and the sound was not helpful to me.


I have one concert cutaway strung with 9s that I tune up three semitones. Try for 4 and the strings break! But I did need a whole new setup for the 9s in G.

Gordon Newton will make you custom sets but his strings are not standard construction. Strings Direct got me a set of non-standard bass strings to play a 3/4 bass tuned as a violin (GDAE) and they sound just right - but of course it isn't about chords.