Phantom Power: Lower the Boom
Jun 1, 2008 12:00 PM, By Doug Eisengrein
CONTROL THE SOUL OF YOUR MUSIC WITH THESE BASS-RECORDING AND MIC-PLACEMENT TIPS
Capturing and mixing bass is one of the finest arts in the music-making process. Although bass occupies a relatively limited frequency range at the low end of the human-audible spectrum (roughly 40-50 Hz to 250-300 Hz), without proper care, it can mix with other instruments in the lower registers such as kick drums, guitars or synth pads, resulting in an unappealing sonic soup. And while bass may not be the spotlight of most songs (in the way vocals often are), it typically provides the driving bedrock of rhythm and soul. Your job as engineer or producer is to properly capture and clearly translate that energy into the mix. The following tips cover the initial recording phases of bass — both electric and upright.
WHO ARE YOU?
Unlike higher pitched sounds such as hi-hats, bass frequencies are big and nondirectional in nature. They can travel through walls and floors with ease, are heavily affected by structures (hence bulky bass traps) and elicit a somatic reaction in ways that higher frequencies simply cannot. When was the last time you came out of a club stoked about the feel of the cymbals?
No matter how good the gear is on hand, pause before just slapping a mic on the bass amp or upright body. Perhaps the most important ingredients for recording bass are first, to communicate with the player, and second, to spend some time getting to know his or her particular instrument and desired sound. For example, the dub-infused rhythmic sound of Jah Wobble (Public Image Ltd., Bill Laswell) differs decidedly from legendary Jaco Pastorius' (Weather Report, Joni Mitchell) trademark higher pitched fretless soloing. Furthermore, if you asked a seasoned upright player such as Ron Carter (Miles Davis, A Tribe Called Quest) to describe the sound he is after, or from where on his bass the best sound emanates from, he'll surely have an answer. If you're in the studio with an electric player, ask the bassist about the sound of his or her pickups. Listen to the sound of the amp closely from many different angles. If it's an upright bass, is the player plucking the strings or using a bow? Walk all the way around the instrument as they play, put your head close to the floor, near the bridge, next to each F hole and listen closely. These simple, attention-to-detail exercises will show you where to place your mics and which mics to choose. You will also gain the respect of the player involved. If it's a member of your own band, you may be surprised how much better you will get to know the bassist's particular sound.
THE BASS-ICS
Although some engineers favor simplicity when recording bass, I say capture the maximum sonic colors to work with during mixdown time. In almost all cases, it's wise to record the electric bass' direct signal through a quality active DI, a preamp with an instrument-level input or a bass amp's mic or line-level direct output, if available. This will give you a clean — ahem — base to start with. The same goes for upright bass, if it has a pickup and an output. In addition, mic the amp for its particular color and separately, the player's fingers on the frets — capture those subtle rhythmic and finger slide nuances that the pickups may not translate. For upright bass, find the instrument's “sweet spot” and use your best mic on hand for that, but also try miking in front of the bridge, in front of the preferred F hole, between the hands and perhaps even the lowest part of the bass' body near the floor, where low-frequency energy may be greatest. However, when taking this multiprong approach, be sure to record each source to a separate track; you can then carefully mix them all later. But when that time comes, don't be afraid to throw parts out if they don't enhance the final product.
MICROPHONE CONTROLLER
When it comes to microphones, choose wisely. While dynamic mics can work, condensers are generally the best choice for bass due to their quicker, natural transient response. Large-diaphragm dynamics, such as those that are used on kick drums, can also work well. That is particularly true on bass cabinets due to their ability to handle high sound-pressure levels (SPLs) and in live scenarios where feedback can be a big issue.
The first rule to remember when miking bass is proximity effect, the phenomenon in which low frequencies are enhanced as the mic is brought closer to the signal source. That can sometimes be used to your advantage, but you want to keep enough distance as to avoid distortion, excessive boominess or misrepresentation of the real tone. With a bass cabinet, start by placing a nice large-diaphragm condenser four to six inches away from the speaker; my preference is a little off-axis. Move the mic away as necessary, to increase airiness, or if there are multiple speakers involved. For fingers on the frets, also try a condenser (though even a typical dynamic such as a Shure SM57 can do the trick here) set six to 12 inches away, pointed right between the bassist's two hands. In the case of upright bass, try a nice ribbon or large-diaphragm condenser directly in front of the bridge, 12 to 18 inches away to accommodate for bowing and movement of the bass, and also place a second mic about the same distance away, pointed at the better-sounding F hole. The bridge mic is likely to produce a more level tone, while the F-hole mic will often capture boomier dynamics. To compensate for the latter, use some light compression. Finally (or alternatively), try another condenser set about bridge level, 18 inches away, but pointed between the bottom of the bass and the floor. Try various angles and alter proximity to taste, or until you find the strongest bass response. As with any miking application, some experimentation with microphone choice and placement is always necessary, but even when you think you've found “the way,” remember that it probably won't work in all scenarios.
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