1. Check your acoustics. Small project studio rooms reveal their biggest weaknesses below a couple hundred Hz, because the length of the bass waves can be longer than your room dimensions—which leads to bass cancellations and additions that don’t tell the truth about the bass sound. Fix your room, put in bass traps, and if all else fails, do a reality check with quality headphones.
2. So much is in the fingers. A good bassist makes all the difference in the world. As just one example, fretted notes can give a tighter, more defined sound than open strings (which are often favored for live playing because they give a big bottom— but can overwhelm a recording).
3. Compress, compress, compress. Normally you don’t want to compress the daylights out of everything, but bass is an exception, particularly if you’re miking it. Mics, speakers, and rooms get really weird in the bass range, with uneven responses. Compression can help even these out, giving a smoother, rounder sound. Also, try using parallel compression—i.e., duplicate the bass track, but compress only one of the tracks. Squash one track with the compressor, then add in the dry signal for dynamics.
4. Put highpass filters on other instruments. Clean up subsonics and low frequencies on instruments that don’t really have any significant low end (e.g., guitars, drums other than kick, etc.). A low cut filter, as used for mics, is a good place to start. By carving out more room on the low end, there will be more space for the bass to fit comfortably in the mix.
5. The right EQ is crucial. Accenting the pick/pluck sound can make the bass seem louder. Try boosting a bit around 1kHz, then work upward to about 2kHz to find the “magic” boost frequency for your particular bass. Also consider trimming the low end on either the kick or the bass, depending on which one you want to emphasize, so that they don’t fight. Finally, many mixes have a lot of lower midrange buildup around 200–400Hz because so many instruments have energy in that part of the spectrum. It’s usually safe to cut bass a bit in that range to leave space for the other instruments, and provide a less muddy overall sound; sometimes cutting just below 1kHz, like around 750–900Hz, can also give more definition.
6. Tuning is key. If the bass foundation is out of tune, the beat frequencies when the harmonics combine with other instruments are like audio kryptonite, weakening the entire mix. Beats within the bass itself are even worse. Tune, baby, tune!
7. Edit in context. Because bass is such an important element of a song, what sounds right when soloed may not mesh properly with the other tracks. Work on bass and drums as a pair—that’s why they’re called the “rhythm section”—so that you figure out the right relationship between kick and bass. But also have the other instruments up to make sure the bass supports the mix as a whole.
8. Beware of phase issues. It’s common to take a direct out along with a miked or amp out, then run them to separate tracks. Be careful, though: The signal going to the mic will hit later than the direct out, because the sound has to travel through the air to get to the mic. If you use two bass tracks, bring up one track, monitor in mono (not stereo), then bring up the other track. If the volume dips, or the sound gets thinner, you have a phase issue. Hardware devices like the Radial Engineering Phazer or Little Labs IPB can tune out phase differences; with a DAW, simply slide the later track so it lines up with the earlier track. The timing difference will only be a few milliseconds (i.e., one millisecond for every foot of distance from the speaker), so you’ll probably need to zoom way in.
9. Respect vinyl’s special requirements. If anything you ever do has even a slight chance of ending up on vinyl, pan bass to the exact center. If there’s more than one bass track, pan both to center.
10. Fun with bass amp sims. There are some excellent bass amp sims, like the cabinets in Native Instrument’s Guitar Rig 3 and Waves GTR, as well as the dedicated Ampeg SVX plug-in (from the AmpliTube family) offered by IK Multimedia. These open up the option of recording direct, but then “re-amping” during the mix to get more of a live sound. You’ll also have more control compared to using a “real” bass amp.