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2/14/2013

Miked drum set at Drumrec (drumrec.com), a facility that records and delivers custom drum sessions

Whether you record each part separately or the entire band at once is up to you. For many years, it was de rigueur to record everything separately to a click track, but for musical and musician-interaction reasons, I recommend recording the rhythm section (drums, bass, rhythm guitar, etc.) together whenever possible, then overdubbing the lead parts and vocals. Although recording multiple musicians together requires more input channels on your audio interface and possibly some baffling to reduce leakage, it’s usually a more natural process for the musicians, and allows them to “play off” of each other.

We’ll assume that you have at least a four-channel audio interface; fewer than four channels places too many restrictions on recording drums, and you’ll need at least an eight-channel interface to record the rhythm section together. (Sixteen channels would be even better.) You’ll also need enough microphones, mic preamps, and stands, along with a direct box or two, maybe some amp sim pedals, headphones, and of course, plenty of cables.

Ready? Let’s start with a boom.

Fig. 1. The most common way to mike a kick. If the kick doesn’t need to be highlighted, sometimes engineers will pull the mic back a bit to get more of the “kit sound.”

Fig. 2. When placing the snare mic, aim it at the snare’s center, but also try placing it a bit off-center before making a final decision.

• Capture the kit’s main “picture” with a stereo pair of overhead mics, and then fill in the sound with the use of a few “close” mics.

• Capture the individual elements of the kit with close mics, then fill in the sound with the overhead and room mics.

These approaches may seem similar on the surface, as they both involve combining overhead and close mics. However, the philosophical difference is considerable. Emphasizing the close mics gives a more detailed, precise sound, whereas relying primarily on the overheads captures more ambience and leans toward a “live performance” vibe.

Neither approach is right or wrong, although each does have some advantages over the other. For example, it’s simpler from an equipment standpoint to use your overheads to capture the main drum sound. This generally requires fewer microphones, but it also places greater demands on the drummer’s ability to control the dynamics and relative balance of the kit elements. It also works a lot better in a room that sounds good (which usually, but not always, translates into having good acoustics), because you’re recording the room almost as much as the drums.

The close-mic approach, with each mic recorded to a separate track, is excellent when you want lots of control. It’s also useful if you plan to use drum-replacement software to “change” or augment some of the kit’s elements later on, particularly during mixdown.

Let’s consider each part of the kit, and some recommended mics and placements.

Kick The Electro-Voice RE20 and RE320, Heil PR48, Shure Beta 52, Audix D6, and AKG D112 are all popular choices. Start with the mic placed just inside the hole in the kick drum’s front head, aimed halfway between the spot where the beater hits the head and the tom side of the drum shell (Figure 1). For more attack, aim the mic more toward the beater; for more resonance, angle the mic more toward the shell.

Snare Small-diaphragm moving-coil dynamic mics like the Shure SM57, Audix i5, and Audio-Technica ATM650 are the usual choices, but both large and small condenser mics can work well. (You may need to engage a pad switch on the mic to avoid overload.) The Audio-Technica Pro 37, Røde NT5, and AKG C-414 are good condenser choices for snare.

Fig. 3. The “side capture” option isn’t always about the sound—if the drummer has sketchy stick control, it can save your mic by taking the hit.

Fig. 4. With toms, it’s particularly important to place the mic where it won’t get hit by an errant stick.

Positioning is a matter of taste. Top-miking the head is the most common approach, with the mic placed a few inches above the drum’s rim, and angled in so it’s aimed toward the center of the head, or a point two-thirds of the way toward the center (Figure 2). Some engineers place a second mic a few inches under the drum, aimed at the snares themselves. To avoid cancellation, this mic normally needs its polarity (phase) inverted when combined with the main snare mic at mixdown.

An alternative approach is to use only one mic, pointed at the side of the snare drum (the shell) instead of the head (Figure 3). This technique can result in a very even sound, with a nice balance of crack, resonance, and snare rattle. However, avoid aiming the mic directly at the air vent on the drum’s side.

Toms Dynamic mics usually get the nod for toms, and their ruggedness gives them a better chance of survival if they are subjected to an unexpected stick hit. The Audix D2 and D4, Sennheiser MD421 and e604, Audio-Technica ATM25 and ATM250, and Shure SM57 are all common dynamic mic choices for toms. The CAD M179, AKG C-414, Neumann TLM102, and Audio-Technica Pro 37 are suitable condenser alternatives, assuming the drummer has good stick control. You may also need to use the mic’s built-in pad with condensers. With either mic type, the placement approach is similar to snare—usually with the mic above the edge of the rim, and angled in so that it points roughly midway between the rim and the middle of the drum (Figure 4).

Overheads Small-diaphragm condensers are common for drum overhead duties. Good choices include the Mojave MA-101, Audio-Technica AT4041, Oktava MK012, MXL 603, and AKG C-451B. Ribbons like the Royer R-121, Beyer M160 and Cascade Fathead II can also work very well for drum overhead miking, especially if you’re trying to tame overly bright or enthusiastically played cymbals.

Fig. 5. Note the mics in the upper-left and lower-right corners of the photo.

Placement options are numerous. I really like the classic Glyn Johns technique, which places one mic over the center of the kit— usually above a spot somewhere between the rack tom, snare drum, and hi hat, with the second “overhead” mic placed much lower, near the far side of the floor tom, aimed “across” it toward the hi-hats (Figure 5). An important point with this technique is to keep the two mics equidistant from the center of the snare drum. A tape measure, or three-or four-foot length of twine or even a cable, can come in handy to check to make sure the spacings match. Doing this will ensure that the snare drum hits remain “centered” in the stereo sound field, as captured by the overhead mics. Adding a kick drum mic, and possibly a snare mic, to this type of overhead arrangement is often all you need to capture a great drum sound with only three or four microphones.

Hi-hats You’ll usually get more than enough of the hi-hats in the overheads, or in bleed into the snare mic; but if you need a bit more hi-hat in the mix, a small-diaphragm condenser is usually the go-to choice. Ribbon mics can also work well here—especially if you’re trying to subdue an overly bright or aggressive pair of hats. Try to avoid miking the very edge of the hats or miking them from the side, as these locations can suffer from air blasts. I normally start with the mic placed four to six inches above the hi-hats, and about three to four inches in from the outer edge.

Bass is typically recorded either “direct,” or by miking the speaker cabinet. Many engineers use both methods, with each mic signal recorded to a separate DAW track. To use a direct box, insert it inline by plugging the bass into the direct box, and patching the DI’s “through” output into the bass amp. Route the Direct Box’s line output to a line input on your mixer or audio interface, and thereafter to its own recording track. On a second track, record the miked bass amp. Combining the two at mixdown gives you the flexibility to use the best aspects of each to build your final bass “sound.” Direct recording also allows makes it easy to use reamping techniques and amplifier-modeling plug-ins.

If you take this approach (or can’t use an amp for some reason), most audio interfaces have high-impedance instrument inputs that are optimized for use with passive pickups. These are equivalent to active DI boxes, and because they reproduce the bass sound very faithfully, subsequent plug-ins can impart their full effect. As most bass sounds don’t rely on distortion to the same extent as guitar amp plug-ins, and as the toughest task for any amp sim is to reproduce distorted sounds, bass amp plug-ins can often sound exceptionally life-like.

Miking the Bass Amp Miking a bass amp is somewhat similar to miking a guitar amp, except bass usually means dealing with a wider range of frequencies. Unlike guitar amp speaker cabinets, which typically reproduce frequencies in the 100Hz to 6kHz range, bass amps can extend considerably lower and higher. Many bass rigs even have onboard high frequency tweeters to complement their extended low-frequency bass drivers, and the trend for many years has been toward full-range bass amplification systems. These are especially important not only for giving you a great sense of the fundamental, but also for the harmonics and attack that are so important for modern bass playing—especially with slap and pop playing techniques.

Fig. 6. Close, on-axis miking tends to give the “roundest” sound when miking a bass amp.

Fig. 7. Off-axis miking can yield a tighter sound, but here, it’s also being used to pick up the sound from the amp’s tweeter.

Experiment with moving the mic back a bit further from the bass cabinet than you would with guitar. While near-contact distances from the grille can work just fine, bass wavelengths are considerably long (often measuring many feet), and getting the mic back a bit to where the waveform has “developed” more can sometimes result in a better sound.

Microphones that work well on bass cabinets tend to have good low-frequency response, along with enough mids and highs to provide a balanced sound. Some common “big studio” choices include the Neumann U47 FET condenser, and for dynamics, the Electro-Voice RE20 and Sennheiser MD421. Other condensers that have worked well for me include the Neumann TLM102 and Rode NTK. Dynamic microphones such as the Heil PR40, AKG D112, Audio-Technica ATM250, and Electro-Voice RE320 are also excellent choices on bass cabinets. You can certainly experiment with ribbon microphones on bass, but watch the proximity effect! Ribbons—and mics with figure-8 polar patterns in general—tend to have abundant bass boost due to proximity effect; if placed too close to the speaker, a ribbon mic can sometimes be “too much.”

If the bass-amp rig is bi-amplified, with separate speaker enclosures for the lows and highs, consider using separate microphones for each of the cabinets. In this case, I’d recommend optimizing the microphone choices for each cabinet—e.g., using a dynamic mic such as the RE20 for the low frequency cab, and maybe a condenser for the horn. Once again, by recording each mic to a separate track, you can retain control over their relative balance in the final mix.

Timing Issues When miking an amp and recording DI simultaneously, there will be a slight delay between tracks that depends on how far the mic is from the speaker (Figure 8). As sound travels at a approximately 1 foot per millisecond, if the mic is six inches away from the grille, the delay will be about half a millisecond. Although this isn’t enough delay to create an effect like an audible slapback echo, it can cause comb filtering due to phase differences. The solution is to look at both waveforms, and move the miked sound forward somewhat so its peaks and dips match those of the DI sound.

Fig. 8. The top track is the DI bass. The second track is the miked bass amp; the black band indicates the time difference between a peak in the top signal and the same peak in the signal below it. The lowest track shows the second track moved forward in time so that it lines up with the direct track.

Phil O’Keefe is a multi-instrumentalist, recording engineer/producer and the Associate Editor of Harmony Central. He has engineered, produced and performed on countless recording sessions in a diverse range of styles, with artists such as Alien Ant Farm, Jules Day, and Voodoo Glow Skulls. His articles and product reviews have also appeared in Keyboard and Guitar Player magazines.

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