If your bass has a flabby sounding B string or a weak sound, do not despair, there may be an easy fix for this problem. There are some things that you might want to try before throwing the bass away, just because the B strings sounds weak and flabby.
First: Experiment with different types of strings. While round wounds will have the brightest sound, they are not always the best sound for punch. I would try two different types, specifically, a bare core type round wound, and a ground wound string. Ground wound have lots of midrange and some highs, but have a lot more punch than round wounds. Below is a photo of some LaBella Super Steps, which are a bare core type of round wound bass string.
When using the bare core string for this problem have as little of the bare core past the bridge saddle, on the pickup side. The more bare core which is exposed past the bridge saddles, the less bass the B string will have. The more exposed core on the pickup side, the thinner sound the string will be. You may need to use a string ferral, and feed the string through the back side of the bass body. This is what I did on my five string Warmoth Jazz Bass.
Changing the gauge of B-string another consideration. There are typically about four or five sizes, 0.125, 0.128, 0.130, 0.135 inch. There may be some trade offs here, but this may fix the flabby sounding B-string.
Second: I would try installing a different bridge. Certain bridges have a very weak disposition, and they do affect the attack of the strings significantly. Try using a Leo Quan Bad-Ass type or a Carvin Hipshot (some are aluminum and some are brass…brass is generally better). See my story on the hardware page. Below is photo of my Jazz Bass with the Carvin Hipshot Bridge and the LaBella Bare Core Strings as described above.
Third: If you have a bolt on neck, consider swapping out the neck with a different neck or a longer neck (say 35 inches). The extra inch will improve the B string and may solve your problem entirely. However, you may need to get a new case for your bass! If you do decide to go this route, give some thought about using a maple neck with a maple finger board, since these often have a very nice and warm sound. Ebony or rosewood fret boards will often have a very bright sound, with some of the midrange attenuated.
Fourth: Make sure that your low-end EQ is boosting the bass sound at 80Hz, and not at some other frequency like 35Hz. 80Hz give all basses a very punchy feel and presence.
Fifth: If the above methods did not work, you may be better off with a different bass. Sometimes, it is just not possible to correct this problem. If that is the case, then consider some of the following basses:
Modulus (35 inch graphite material),
Schecter (35 inch neck through body)