I tend to avoid flatwound for my electric bass, as they don't sound as bright to me. I think they're aimed at Jazz players, but I might be wrong

I have a friend with an acoustic bass, and I was disappointed at how quiet it was without amplification. But then the body was quite slim. I assume you have to buy a pretty sizable one to get any volume? I want to buy one, but to me the whole point is NOT having to use an amp