Regarding https://www.guitartricks.com/lesson/19898
"half step from 12>13 fret looks actually to be the 13 to 14th fret."
It looks like this one is fixed. Is there another part of the riff or song you're referring to?
Regarding https://www.guitartricks.com/lesson/19898
"half step from 12>13 fret looks actually to be the 13 to 14th fret."
It looks like this one is fixed. Is there another part of the riff or song you're referring to?