Dead Low B fix?
Maybe this should be in "Strings", but it is applicable to the dead B syndrome on some basses. On my Fender P5 I've never been happy with the low B string. The notes below E seemed to be dead thuds and notes above that are okay, but nothing great. Last night I was messing around with it and I noticed that B string wasn't really straight across the saddle, it seemed to hump upwards. So I pressed on the B string at the bridge to make sure it has the propper witness point and it had a very noticeable improvement to the B string. I think it's less of an issue with other strings because they have more tension and will fall into place better. So if you're trying out a bass at a store and it seems to have a dead B string, just give it firm press at the saddle, tune it and see if that helps.