http://archive.bassplayer.com/artists/jackson1.shtml
There has been some criticism leveled at the 6-string bass guitar. Some players call it a marketing gimmick while others feel they should master the "standard" 4-string before concerning themselves with a six. Your thoughts?
My feeling is: Why is four the standard and not six? As the lowest-pitched member of the guitar family, the instrument should have had six strings from the beginning. The only reason it had four was because Leo Fender was thinking in application terms of an upright bass, but he built it along guitar lines because that was his training. The logical conception for the bass guitar encompasses six strings. As regards the issue of "mastering the 4-string" before moving on to the six, consider that inasmuch as there is no point where one can be said to have "mastered" anything, to make this inane suggestion reveals the speakers to be idiots. As long as we remain seekers, never truly achieving our ultimate goals, we may as well start with the full basic blueprint and enjoy the expanded expressive possibilities of the extended range of the instrument. Of course, the undoubtedly famous-name superstars who utter this nonsense probably regard themselves as masters in their own right. So be it. For the rest of us, their attitude reveals them to be jealous, angry, and frustrated. Too damn bad.
When did the idea for a contrabass guitar occur to you?
As a beginner, I observed proper tuning sequence-fourths-but often brought the entire sequence down a half- or whole-step in order to put certain important bass notes in the lowest possible octave. A typical example would be a song in Eb: Sometimes, especially when playing with bands, I found myself willing to take chances with switching octaves that I might feel too intimidated to attempt when practicing to records. As I progressed, I began consistently observing normal tuning discipline, but I continued feeling constrained when practicing to a particular record whose bass part would drop below low E. The numerous recordings of organist Jimmy Smith were important to me because practicing with them helped give me a firm foundation in swing, but there was one piece, now forgotten, that had an altogether different effect: I heard a significant note, one I simply had to play, that was below my range. I realized by this point that tuning down, while it allowed the note to be played, caused a loss of sonority.
" - Merling