Big bands didn’t travel much because of their size, and because of that bassists never seemed too upset about their instruments. That was until the electric revolution hit instruments. Soon the electric organ, the electric guitar, and affordable microphones and amplifiers made it so a club owner wanting to fill his dance hall didn’t have to book a 25 piece brass band, each wanting musician’s union wages for the night, good show or not, they could instead hire three or four teenagers, a drummer, a guitarist, and a bassists, one of them sings, and you end up paying a 25th the cost. The issue now was, record companies would buy up these combos, and then tour them around the country, and that string bass started to have some issues. They would warp, they would suddenly make next to no sound, and we’ve even heard stories about them exploding coming out of an air conditioned night club, just the tension and the glue couldn't hold together anymore.
Then, in steps Leo Fender, yes that Fender, who looks into this problem. He realized that the size of the instrument had nothing to do with the instrument it had to do with the volume that it needed, and the deep tones it had to project. Story goes that one night out in southern California, he happened past a mariachi band, and there was a guy plunking away on a Guitarron, it is pitched almost as low as an upright bass, but it is much, much smaller. He had just started producing what would eventually come to be known as the telecaster, and he realized that he could make an instrument pitched as low as an upright bass, but it could be as compact as a guitar, thanks to its body not having to actually amplify the sound. He added frets because he also heard from a lot of the swing and country bassists around southern California that with them never having properly taken lessons or learned the instrument to the level that many of their contemporaries, the jazz players and the big band guys, that they often found themselves playing out of tune. Thanks to this information, in 1951 the modern bass guitar was born with the introduction of the Fender Precision bass.
over the years the bass has, like the guitar, evolved with musical trends getting flashier or more subdued visually, getting a higher 5th string to help big prog rock bands in the late 70's, or getting a lower 5th string to compete with synthesizer basses in the mid 80's, eventually adding them both on at the same time to make the wide necked modern 6 string bass and helping define the sound of modern jazz R&B. The bass has defined modern music, with its growling voice, and handsome aesthetic, it will surely define the music of the future just the same.