Guitar Lessons by Fretello on Instagram: "CGCFAD is the standard Drop C tuning only with all the strings tuned down an additional step. It s best to use heavy-gauge strings when tuning this low. CGCFAD or Drop C is an excellent tuning for those who wish to play low heavy-metal or grunge riffs. To tune to Drop C, Drop D is a great starting point to get yourself into Drop C, especially if you have no reference tones available. This is because if you tune to Drop D and then drop every string down 1