February 01, 2013, by Bruce Bartlett
Remote recording is exhilarating. Musicians, excited by the audience, often put on a stellar performance. Usually you only get one chance to get it recorded, and it must be done right.
It’s on the edge, but by the end of the night, especially if everything has gone as planned – what a great feeling!
Challenges abound. Monitors can feed back and/or leak into the vocal microphones, coloring the sound. Bass sound can leak into the drum mics, and the drums can leak into the piano mics. Then there are other mic-related gremlins such as breath pops, lighting buzzes, wireless system glitches, and more.
How to get around the potential problems? Let’s have a look at some effective mic techniques that work well when recording in the live realm. And note that these are tailored more to “pop-style” music performances.
Position omnidirectional mics close to the source. Close miking increases the sound level at the mic, so less gain is needed, which in turn cuts background noise and leakage.
Use unidirectional mics. Cardioid, supercardioid, hypercardioid models reduce leakage and feedback by attenuating off-axis sounds. Also, their proximity effect boosts the bass up close, without boosting the bass of distant sounds.
Use direct boxes and guitar pickups to eliminate leakage. Or use pickups mixed with mics.
Use a pickup for the stage monitors and a mic for the house loudspeakers. Here’s a trick to reduce feedback while attaining quality sound. If miking an acoustic instrument that has an internal pickup, send the pickup signal only to the monitor loudspeakers, and send the mic signal only to the house loudspeakers.
Specifically, in the mixer’s pickup channel, turn up the monitor send and turn down the fader. In the mixer’s mic channel, turn down the monitor send and turn up the fader. That way, the pickup prevents feedback from the floor monitors, while the mic provides a natural sound to the audience.
Try headworn noise-canceling mics on vocals. A noise-canceling or differential mic is designed to cancel sounds at a distance, such as instruments on stage or monitor loudspeakers. These mics can provide very good gain-before-feedback and isolation. Note that the mic must be used with lips touching the foam windscreen, or otherwise the voice is cancelled.
Use wireless mic systems correctly. If dropouts can be heard, move the wireless receivers (or remote antennas) where a stronger signal can be picked up. It may also help to put the receivers on stage. If distortion occurs with loud yelling, turn down the gain-trim pot in the affected mic.
Prevent hum and buzz. Keep mic cables well separated from lighting and power cables. If the cables must cross, do so at right angles to reduce the coupling between them, and separate them vertically. If hum pickup is severe with dynamic mics, use models that incorporate humbucking coils. Routinely check cables to make sure shields are connected at both ends. Tape over cracks between connectors to keep out dust and rain.
Try mini mics and clip-on holders. Nearly all manufacturers offer miniature condenser models, and sometimes these tiny units offer sound quality comparable to larger studio mics. If clipped on musical instruments, they reduce clutter on stage by eliminating boom stands, while also allowing performers to move freely around the stage. And because a miniature clip-on mic is very close to its instrument, it picks up a high sound level.
Often, omnidirectional mics can be used without feedback, and generally, they offer a wider, smoother response and pick up less mechanical vibration than unidirectional models.
As always, there is no one “right” way to mic voices and instrument for live recording purposes – or any other application for that matter. The suggestions here are techniques that have been proven to work, but never hesitate to use what feels best for your situation.
Vocal. It’s usually best to stick with a cardioid dynamic or condenser, maybe with a presence peak around 5 kHz, and perhaps with a foam windscreen to reduce breath pops. Lips should touch the grille/foam for best isolation. Aim the rear of the mic at stage monitors to reduce monitor pickup and feedback.
Also, try using a 100 Hz low-cut filter and some low-frequency roll-off to reduce pops and to compensate for proximity effect.
If more isolation and gain-before-feedback is needed, try a hypercardioid model such as an Audix OM7 and aim the mic horizontally.
Acoustic guitar. Consider using a cardioid condenser positioned about 3 inches to the neck side of the sound hole, a few inches away (Figure 1). Roll off excess bass. Aim the mic downward to pick up less vocal.
Another approach is a direct box on the guitar pickup. In addition, some mini mics are specially designed to clip onto a guitar. And, taking the feed via DI box is another possibility.
Figure 1: One way to mike an acoustic guitar. (click to enlarge)
Electric guitar. To add some guitar amp distortion, mike the amp about 1 inch from its speaker cone, slightly off center, with a cardioid dynamic model. A leakage-free alternative is to use a DI box and process the signal during mixdown through a guitar-amp modeling processor or plug-in.
Electric bass, synthesizer, drum machine. Go with a DI box.
Leslie organ speaker. Place a cardioid dynamic with a presence peak a few inches from the top louvers, then add another mic on the lower bass speaker.
Grand piano. Tape a mini or boundary mic to the underside of the raised lid in the middle. For stereo, use two mics: one over the bass strings and one over the treble strings. For more isolation, close the lid and tweak EQ to remove the tubby coloration (usually cut around 125 Hz to 300 Hz).
Figure 2: Two methods for miking a grand piano. (click to enlarge)
Or, raise or remove the lid. Place two flat condensers 8 inches over the bass and treble strings, about 8 inches horizontally from the hammers, aiming at them (Figure 2). One other approach is to put the bass mic about 2 feet nearer the tail, aiming at the sound board.
Upright piano. Place two cardioids facing the sound board, a few inches away, dividing the piano in thirds.
Drums (toms/snare). Place a cardioid dynamic with a presence peak – or a clip-on cardioid condenser – about an inch above the head and 1-2 inches in from the rim, angled down about 45 degrees to the head.
Drums (cymbals). Using one or two boom stands, place cardioid condensers (flat or rising high-frequency response) 2 to 3 feet over the cymbals. The mics can be spaced 2 to 3 feet apart or mounted “XY” style for mono-compatible recording. A stereo mic can also be used effectively.
Drums (kick). Remove the front head or go inside the hole cut in the front head. Inside, on the bottom of the shell, place a pillow or blanket pressing against the beater head. This dampens the decay portion of the kick drum’s envelope and tightens the beat.
Place a cardioid dynamic with a presence peak and a deep low-frequency response inside a few inches from the beater. For extra attack or click, use a wooden beater and/or boost EQ around 3 kHz to 6 kHz. Cut a few dB around 400 Hz to remove the “papery” sound.
Drums (simple miking). For jazz or blues, sometimes great results can be had with one or two large-diaphragm condensers (or a stereo mic) overhead, and another mic in (or in front of) the kick. There may be need to add another mic near the snare drum.
As an alternative, clip a mini omni to the snare drum rim, in the center of the set, about 4 inches above the snare drum. With a little cut around 200 Hz or so, the sound can be surprisingly good. This can be enhanced with another mic in the kick.
Bongos and congas. Place a cardioid dynamic near each drum head.
Xylophone and marimba. Deploy two flat-response condensers 18 inches above the instrument and 2 feet apart.
Acoustic bass. There are several options. For the best isolation, use the player’s pickup if available. Plug it into a DI box. Or mike the player’s amp up close up (if one is being used). A mini mic just inside the instrument’s f-hole provides excellent isolation but tends to sound “hollow,” while taping a mini near the f-hole can work if excess bass is rolled off.
Figure 3: An AMT S25B for acoustic bass. (click to enlarge)
Another approach is a flat-response cardioid a few inches out front, even with the bridge. The Applied Microphone Technology AMT S25B clamps onto the bass body and mounts a directional mic on a gooseneck (Figure 3). One more: wrap a cardioid dynamic in foam and stuff it in the tailpiece aiming up. Cut EQ around 700 Hz for tailpiece miking.
Banjo. Tape a mini omni to the drum head about 2 inches in from the rim, or on the bridge. Or, place a flat-response condenser or dynamic 6 inches from the drum head, either centered or near the edge.
Fiddle/violin. Some mini mics are specifically designed for violin. Another approach is to use a cardioid dynamic or condenser about 6 inches over the bridge.
Mandolin, bouzouki, dobro, lap dulcimer. A flat-response cardioid condenser about 6 to 8 inches away from a sound hole is often the best option.
Saxophone. Mount a shock-mounted cardioid on the instrument bell (Figure 4). Or, try a mini omni or cardioid condenser clipped to the top of the bell, picking up both the bell and tone holes a few inches away.
Brass. Place a ribbon or cardioid dynamic about 8 inches from the bell, or attach a mini gooseneck mic to the bell.
Woodwinds. Use a flat-response cardioid condenser placed 8 inches from the side – not in the bell.
And again, a clip-on mic from a source such as AMT is another approach.
Flute. Try a cardioid with a foam pop filter near the mouthpiece, or, use a mini omni clipped on the instrument resting about 1.5 inches above the zone between mouthpiece and tone holes.
Harmonica. A very closely placed or handheld (literally) cardioid dynamic is usually the way to go.
Figure 4: An SD Systems LCM 8g clipped securely to the bell of a sax. (click to enlarge)
Accordion, concertina. Employ a cardioid about 8 inches from the tone holes on the piano-keyboard side. Tape a mini omni near the tone holes on the opposite side (because it moves).
Audience. This is an interesting one! It can be done with two spaced cardioids on the front edge of the stage aiming at the back row of the audience (Figure 5).
Another method is the use of two spaced cardioids hanging over the front row of the audience, aiming at the back row.
Or, try two mics at front-of-house. To prevent an echo between the stage mics and FOH mics, slide the waveform of the FOH mics to the left (earlier in time) until it aligns with the waveform of the stage mics.
Figure 5: Getting the audience into the action. (click to enlarge)
In other words, look for high signal peaks and align them in time.
Keep in mind that each of these techniques involves some compromises in order to fight background noise and leakage, but with some careful placement and EQ, they can put you well on the way to a quality recording.
AES and SynAudCon member Bruce Bartlett is a recording engineer, audio journalist, and microphone engineer (http://www.bartlettmics.com). His latest books are Practical Recording Techniques (6th Edition) and Recording Music On Location.