The Optima Chrome 4099 RL set I purchased (brand new, btw) played with a more-than expected muted sound on the E and A strings (which was OK), but a completely opposite bright sound on the D and G strings. I too was expecting these strings to be somewhat like the original Ric type flats. I am not saying that they do not sound as expected. I am saying that the set I have played unevenly. Whether they were dull and thuddy or somewhat bright, at least I could use them if all four strings played similarly.
Optima Chrome Flatwound Bass Strings
Electric Bass Flatwound chrome strings, sized 0.045 to 0.100 Long scale.