Here's an interesting quote from a 2002 interview :
"Interviewer:
Tell me about the factors in your decision to transition from double bass to the electric upright.
Eberhard Weber:
The regular bass doesn't have many possibilities. The reason I switched to electric bass is because music became very loud in the late '60s and the double bass couldn't be heard anymore. I realized I could put pick-ups on my double bass, but found out when you play at a certain volume, you suffer from feedback because of resonance from the body. So, it was only logical to find an instrument which has no feedback. There was a solid body I saw in an antique shop. It was totally broken but I got it repaired. I added a pick-up and thought "From now on, this is my instrument." I discovered that it was absolutely wrong because I still played the way I played on the double bass.
Initially, I didn't change the attitude with the electric bass. It took one year before I felt comfortable on this kind of instrument. I found you are a different bass player because now you can lead. You can tell people where to go onstage which you couldn't do before. The drummer and trumpeter could always lead, but the bass player couldn't simply because of volume. But even though you can put an amplifier on double bass and it can play loud, it still cannot lead because it still has this kind of background-ish sound that is not meant to lead. But with the instrument I have, you can play background, in the middle or foreground. Whatever you do, it can be heard. So they have to deal with you. Many musicians don't like that, certainly not the conservative ones.
Frankly spoken, the bass is kind of a silly instrument. How can someone pick an instrument that is not meant to play solos or be a leader? Even Charlie Mingushe was an excellent bass player, but he didn't lead from his bass, but from himself, from his ego. And of course, after I had discovered the kind of electrical bass I use now, I noticed that I can also lead acoustically in terms of sound with the bass, in a way that even Mingus couldn't. When someone played full force in his time with the bass, you couldn't hear it. Nowadays, you can do whatever you want on the bass or any instrument. Sometimes, when I play with a German all-star group which does a sort of jazzy music, the front line complains about my volume because they're not used to hearing the bass. So, I'm in between the lines or in between the seats as they say in Germany. [laughs]"