Edger Meyer mentioned the lowest note on his double bass is a C but I understand it it typically E. Edger’s base uses the ”low C fretboard extension” mentioned, similar to the one pictured in the double-bass Wikipedia article:

(I saw he also had a treble extension on the high string. I once watched him play a violin concerto on the double base, just for fun.)
BTW, Edger is an incredibly nice person. When my middle son, a cello player, was in high school Edger would occasionally visit the high school and spend time with the group of cello and bass players, playing, listening to them, giving them tips and most of all, encouragement. What a guy!
(My son started cello in the 4th grade in the Oak Ridge TN elementary school. I understand Edger’s father started that string program in that school years before.)
You‘ve probably never heard a concert like their first with over 100 4th-grade string players, (mostly violins) who had first touched their instrument a few months before!!!. My son still plays the cello at 41 and thinks it’s cool I just acquired the accordion! Who knows, maybe he’ll pick it up someday.
(Just for background, in our family our mother, starting in the 50’s, insisted a proper education comprised Reading, Writing, Arithmetic, and MUSIC and insisted we ALL take lessons starting with piano. The family tradition continues, some in the family are incredible singers, instrumentalists, and composers; our young grandson is learning sax.)
JKJ

(I saw he also had a treble extension on the high string. I once watched him play a violin concerto on the double base, just for fun.)
BTW, Edger is an incredibly nice person. When my middle son, a cello player, was in high school Edger would occasionally visit the high school and spend time with the group of cello and bass players, playing, listening to them, giving them tips and most of all, encouragement. What a guy!
(My son started cello in the 4th grade in the Oak Ridge TN elementary school. I understand Edger’s father started that string program in that school years before.)
You‘ve probably never heard a concert like their first with over 100 4th-grade string players, (mostly violins) who had first touched their instrument a few months before!!!. My son still plays the cello at 41 and thinks it’s cool I just acquired the accordion! Who knows, maybe he’ll pick it up someday.
(Just for background, in our family our mother, starting in the 50’s, insisted a proper education comprised Reading, Writing, Arithmetic, and MUSIC and insisted we ALL take lessons starting with piano. The family tradition continues, some in the family are incredible singers, instrumentalists, and composers; our young grandson is learning sax.)
JKJ