There are essentially two ways electric guitarists and bassists can go about recording; you can either go the old-fashioned amplifier to mic route or through Direct Input, also known as DI. Both offer their share of pros and cons but deciding on which of the two is best for your own situation is not as tough as you might think – as long as you know what you’re looking for and what you’re working with. The choice is actually a lot easier for guitarists, as you’ll soon find out, meaning bassists have a little more thinking to do but remember – the key to any great recording starts off with two critical components; a reasonable quality instrument and good skill of the instrument. And once you have those two out of the way you can decide on which route is best for you. But before we get started, a little background on what exactly is DI: For those of you unfamiliar with the term, DI is a means of recording directly to a mixer or DAW just like you would with vocals. While guitarists almost always prefer recording off a miked amplifier due to the specific tonal and natural colorations added by the signature sound of the amplifier, bassists and recording engineers are a little more split on the subject of bass DI.
Ever since I got into recording on my own so many years ago, I agreed with the general consensus that electric guitars should always be captured using amp to mic. Similarly, popular conventions also convinced me that the best way to capture a great bass sound was to go DI. Sure, I still agree with the first part about guitars but with the bass, not nearly as much as I used to. I find that I get the best, most life-like bass sounds by recording my bass just like a most electric guitarists record their guitars: by miking the amp.
The Benefits of DI
The conventional wisdom about recording electric bass has long been to "go direct." The advantage of DI is that the signal never passes through the open air. It moves from the pickups, through the direct box, to the mixing console. Assuming you have quiet pickups, you can minimize noise and eliminate interference between the bass and any other instruments or ambient sounds. The direct box is a necessary middle-man since the signal level coming off the pickups, even on an active bass, is a bit low. The DI brings the "instrument level" signal up to "line level," which is what the mixing board wants. Using the direct box to raise the signal minimizes the amount of preamplification that is necessary, which in turn reduces noise (having to add a lot of gain at the pre-amp stage to correct a low incoming signal is a sure formula for adding noise to your track).
Mic to Amp
DI works, there's no doubt about that. But what if your bass isn't particularly quiet? What if it doesn't sound amazing right off the pickups. What if you use your amp to color your sound? If any of these considerations apply, then you might want to do as the guitarists do and put a mic on your cab. After all, if you've spent money on a decent amp and a decent cab and have spent years dialing in your live sound, why not use that as a basis for your recorded sound? The advantage of using a mic is that you get, with minimal effort, the sound that you hear off the cab itself. While expensive mics with really wide dynamic ranges can capture every nuance, you'd probably be surprised how good even something as commonplace as an Shure SM 57 sounds. A mic is practically the only way to go if you use guitar-style effects like distortion, as distortion-based effects tend to sound terrible when recorded direct to the console (since distortion relies on the speaker to help create the distorted or over-driven sound).
There are drawbacks, of course. You have to experiment a bit with mic placement (I prefer it close up to the speaker, just a bit off axis but still aimed, more or less, at the center of the speaker). The same mic that picks up your bass can also pick up other sounds in the room, including such undesirable sounds as your air conditioner or cell phone – be aware! If you're recording more than one instrument at a time, you're likely to have some of the other instruments, especially drums, bleed into your bass mic.
If you use your computer as a platform for home recording and you're just recording one track at a time, you can do without a mixing console. But you will need a pre-amp or audio interface of some sort. These boxes come in several varieties. Some are plug into your USB2 or FireWire ports. Some plug directly into the microphone port on your laptop or desktop sound card. Some are even cards that replace your entire desktop sound card. A few install in an extra front bay on your desktop PC. Be sure not to confuse audio interfaces with MIDI interfaces. Some boxes function with both types of input. In general, if you're trying to record live sounds, including guitars, basses, and vocals, you'll need an audio interface. If you're exclusively recording MIDI-capable keyboard performances, you'll need a MIDI interface.
Which One is Right For You?
Recording is an art and a science. The only way to really tell what works for you is to experiment. Your recording style will change over time, just as your playing style has. You'll throw out old techniques in favor of new ones. You'll learn from trial and error and from books and other recordists. As with playing, let your ears be your guide. If you can get the sound you like, it doesn't really matter how you get it. The only thing that really matters is the sound of the final product.