Q: “A friend of mine has a 12-string guitar, but he took 6 off because he said he didn’t know how to tune a 12-string. I guess I always thought it was a normal way, but we would like to put 12 strings back on. Can you tell us how we go about tuning it? I have a guitar tuner.”
A: “Standard” 12-string tuning is pretty simple. For your four lower pitched strings (E A D G) you will tune their 12-string counterparts to the same note one octave higher. For your two highest pitched strings (B & E) you will tune their 12-string counterparts to exactly the same pitch so they play in unison. It’s that simple.
While simple in concept, actually making a 12-string guitar sound “in tune” is not always so easy. When strings are tuned to octaves of one another it is very easy to hear slight mistunings or intonation problems. Further, getting two dissimilar strings, such as the big E string and it’s little counterpart to play nicely together over the range of the neck is something only the higher quality 12-string guitars are up to. In fact, I’ve seen a number of people remove the high octave G-string off of their guitars for just this reason, leaving 11 total strings. That’s always a tough string to keep in tune, partly because it is tuned so high.