Since a large part of the vihuela repertory consists of arrangements of vocal polyphony, vihuelists necessarily had to see their instrument in some intervallic relationship to a source composition in order to associate its pitches with the frets of the vihuela.
Thus there are some players who always imagine the vihuela in one way, and when the music does not turn out according to how they imagine it, because it leads beyond the [range of its] frets, they change the music so that it can be played easily.
In the proper chapters that follow the prologue, he first describes the tuning and location of pitches at the respective frets of a vihuela in an imagined tuning of gamma-ut, then a more sophisticated method of tuning, and finally how to draw graphs of the finger-board to illustrate the pitches found at the frets in various imagined tunings.
Bermudo begins his suggestions for improving the instrument by describing an easy procedure of dividing a string with the help of a quadrant in which frets for semitone steps are moved slightly up or down, depending on whether they are meant to serve as mi or fa frets, respectively.
The advantage the tuning of his seven-course instrument offers is that mi or fa positions occur across all strings at one respective fret. As illus.3 shows, the first, sixth and eighth frets serve as mi accidentals and are moved closer to the next higher fret, whereas frets three and ten are set as fa accidentals and are closer to the adjacent lower frets.
Bermudo seems to have realized that his new vihuela might not find general acceptance, and for those players who continued to play the common six-course instrument he included descriptions of how to adjust the frets for better intonation on that instrument (see table 2, B2).
By adjusting the frets in order to obtain minor semitones, Bermudo has effectively given up on the idea of imagined tunings.
In this temperament, he promises, the frets are fixed and have 'all the six voices' so that they can accommodate all the modes [ILLUSTRATION FOR ILLUS.
Among them figure prominently his seven-course vihuela, the adjustment of frets with the help of a compass, and his just temperament that 'plays all the semitones'.
The fifth string of the banjo can be tuned to the first string of the guitar played at the third fret, and, finally, the banjo's first string should sound like the guitar's second string played at the third fret.
This is accomplished by fretting the second string at the third fret (push your finger down just behind, rather than on, the metal strip itself, so that the string is pressed against the third space on the neck).
To tune the third string to the second string, fret the third string at the fourth fret, and make it sound like the second string played open.
The numbers on the strings are the fret you play on that string.
Remember: After each melody note (which is played with the thumb), you'll play the pinch (1st and 5th string played together at the same time.) When you're fretting the strings, you should use your left index finger on the 1st fret and your middle finger on the second fret.