Usually when recording with condensors, people like a large diaphram mic (U87, 414, etc.). But one of the best sounds I ever got was with 2 Neuman KM84s set up in XY mode about 2 feet in front of the bridge. This was for a quiet jazz CD and the bass, recorded solely with this set up (no DI or other mics on it), sounded terrific. The stereo image from the 2 KM84's in XY set up could be panned in such a way as to make the image huge. So much so, in fact, that we had to use a lot of restraint in the mixing so as to not have the bass dominate everything.
The bassist on the session was Mike Richmond, who proclaimed on play back that it was one of the best recorded sounds of his bass that he'd ever heard.
That was both gratfiying and humbling to hear from somebody like him.
This might not work for everyone in all situations though: The very small room where we recorded had a really nice (but subtle) bump in the lower frequencies and we were recording at low volumes with no headphones.
Come to think of it - the most important element in making the bass sound so good had nothing to do with the room, the mic'ing or the session: it was that Mike was playing the bass!
