Even if you used a tuner, you should check the 5th fret harmonic of E (sixth string) against the 7th fret harmonic of the A string, which should be a smooth unison sound (no waves or dips in the sustain of the two notes). Then check the 5th fret harmonic of A against the 7th fret of the D string, etc. Another method of checking tuning by harmonics uses octaves: the 12th fret harmonic of the E string with the 7th fret harmonic on A, etc. Again, both systems break down between the G and B, but if your ear is a little more advanced, you can check the tuning by striking the major third interval that exists between the 12th-fret harmonics of the open G and B strings, again checking for a nice, smooth sustain. Always double-check tuning by playing the four chord forms shown in Ex. 1-4, listening for nice, smooth sympathetic vibrations between all the roots and fifths and open strings. Don’t forget that the guitar is an instrument of EQUAL TEMPERAMENT, and therefore n...