Guitar and Bass by Marc Schonbrun
Guitar can be one of the easiest instruments to record—or at least it used to be. Back in the early days, musicians stuck a microphone in front of the amplifier and that was it. Now we are barraged with different amplifiers, effects processors, amplifier simulators, and realistic plug-ins in the computer-recording arena.
Direct Interfaces for Guitar and Bass
To record guitar and bass without the use of an amplifier, you will need a direct box (shown in Figure 11-1) in order to properly interface with the mixer or recording device. Some studios-in-a-box and computer interfaces feature a Hi-Z (high impedance) direct guitar/bass input. If you have this feature, you won't need a direct interface to record your instrument—you can plug right in with a guitar cable. These are becoming more and more common, especially with studio-in-a-box setups.
Direct instrument signals are usually high-impedance sources, so they can't be plugged into a mixer or recording device. In order to record them, you need to use a direct box to convert the high-impedance, unbalanced signal coming from the instrument to a low-impedance, balanced output. The output of the direct box will be a balanced cable, either XLR microphone or tip ring sleeve (TRS).
If your amplifier is equipped with a line out, you can run a cable directly from the back of your amplifier into your mixer or recording device's line input. The amplifier line out will have the correct output level and impedance. The amplifier's line-out jack is specifically designed for studio setups like this. You can also use this feature for live sound applications.
Unfortunately there's one catch to using an amplifier's line out—you might encounter a ground loop, which can cause some very unpleasant buzz in your signal. If this happens, plug your instrument into a direct box that has a ground lift switch. The direct box will take care of the buzz and you will have a good clean signal to work with.
Miking an Amplifier for Guitar and Bass
Miking a guitar or bass amplifier is pretty simple. Most engineers simply place a dynamic microphone a few inches from the center of the speaker. Placing a microphone close to a sound source is commonly called “close-miking.” Close-miking is typically used with amplifiers, some acoustic instruments, and most drums.
The exact location of the microphone on the speaker will differ from amplifier to amplifier and microphone to microphone. It's common to place the microphone slightly off the center of the speaker. You can get different tones based on the location of the microphone. As you move the microphone farther to the outside of the speaker, the sound warms up. The closer you move to the center, the more grit and high end you can capture. Let your ear be the judge of what sounds best. Be prepared to spend a good amount of time moving the microphone around at first, until you learn what sounds best.
Figure 11-2: Miked guitar amp
Recording engineers employ a few tricks in placing a microphone on an amp that might help you achieve some unique sounds. First, you don't have to use a dynamic microphone. Many condenser microphones can handle high sound pressure level (although not the very highest), so if you're not cranking the amplifier to 11 (as in the movie This Is Spinal Tap), a condenser could be fine. You might get a richer sound by using the full range provided by a condenser.
Another trick is to use two microphones: a dynamic microphone to close-mike, and a condenser microphone farther back to catch ambience. By blending the two signals together, you can get a nice, rich sound. The farther away the condenser microphone is, the more ambience and natural reverb you'll get in the sound. Many engineers employ this technique to fatten up and widen the guitar and bass tracks.
Direct-Recording Preamplifiers
There's a wave of digital technology available to guitar and bass players found in the direct-recording preamplifier. Devices like the Line6 PODXT and the BOSS GT-10 emulate amplifiers and effects in one handy unit. What's even better is that they can output to line level, allowing you to plug them in directly, bypassing the need for an amplifier or direct box. These units are small and compact, and have become a staple for guitar players who record frequently. Many of the guitar sounds you hear on TV, radio, and studio recordings might very well have come from direct-recording preamplifiers or their computer plug-in brethren.
Wet or Dry Effects?
Effects such as reverb, delay, and chorus help give modern guitars and bass their unique tone. Most players come into the studio with a “sound” they always play with. Typically this sound is achieved with added reverb and other effects. The big question is whether or not to record the guitar with effects (wet) or without (dry). Some players consider the effects a signature part of their sound; it would be hard to duplicate those sounds later on when mixing. However, certain tones sound very good by themselves—but how they fit into a full mix is another story.
The biggest disadvantage to using wet effects is that you have no control over the effects after they're recorded. If you suddenly find out during mixing that there's too much reverb and the guitar sounds distant, there's little you can do to fix it. It's usually safer to leave reverb out of guitar and bass signals, because it's easy to add it during mixing. That way you have control over the final sound.
Computer Plug-Ins for Guitar and Bass
Computers have become a mainstay of recording studios. Both at home and in the professional world, plug-ins for DAW programs are being developed at a dramatic rate. Guitar and bass players have not been left out of this party. Companies such as Line6 and Fender feature digital modeling in their guitar amplifiers using DSP (digital signal processing). Computers use DSP to process recorded audio for effects. One of the coolest plug-ins available for guitar is Eleven by Digidesign. Another favorite is Native Instruments Guitar Rig 3, an impressive guitar amp and effects modeler plug-in with foot controller for live use.
As you can see from the screenshot in Figure 11-3, the controls of Guitar Rig 3 mimic what you're used to seeing on amplifiers (they even resemble some of the classic gear). Not only are there a variety of modeled amplifiers, but the effects are built in, too! You simply plug your guitar directly into the computer and Guitar Rig 3 does the rest.
Figure 11-3: Guitar Rig 3
One of the ultimate features of a plug-in like this is its ability to change the sounds after you have recorded them. The audio track contains only the clean audio; it's the plug-in that does the rest of the work. That means you can change the sounds as you go along, without having to rerecord the part. That's something that wasn't possible before these programs were introduced.
Many guitar amplifiers, especially tube amplifiers, sound best when turned up quite a bit—or even turned all the way up—because of how tube amplifiers saturate and create gain. To record with the amplifiers this loud, isolation of some kind is a must. Whether you banish the amplifier to a closet, another room, or a special isolation box, for the sake of your hearing, you need to do something. This is especially true when recording loud amplifiers with a band. Isolation can minimize the amount of bleed-through into the other instruments’ microphones.
