This section describes some ways to conduct a multitrack recording session of a concert.
You've arrived at the venue. After parking, offload your gear to a holding area, rather than onstage, because gear on stage will most likely need to be moved.
Learn the names of the PA company crew members and be friendly.
These people can be your assets or your enemies. Think before you comment to them. Try to remain in the background and do not interfere with their normal way of doing things (e.g., take the secondary side of the split). A successful remote engineer makes others feel comfortable and exudes confidence.
Power and Grounding Practice
At the job, you need to take special precautions with power distribution, interconnecting multiple sound systems, and electric-guitar grounding.
Power Distribution System
Consider buying, renting, or making your own single-phase power distribution system (distro). It will greatly reduce ground loops and increase reliability. FIG. 1 shows a suggested AC power distribution system. The amp rating of the distro's main breaker box should exceed the current drain of all the equipment that will be plugged into the distro system. Ask the house electrician to hook up the distro's power cable to the breaker box.
Furman makes a model ACD-100 AC Power Distro. It distributes a 100-amp feed (from a breaker box) to five 20 amp, 120V outlets with circuit breakers. The unit works on 120, 240, or 208V three-phase circuits and provides spike and surge suppression. Furman's Website is furmansound.com.
FIG. 1 An AC power distribution system for a touring sound system.
Power Source
If your recording system is a multitrack recorder that will connect to the PA mixer's insert sends, simply set up next to the PA mixer and plug into the same AC outlet strip that the PA mixer is using.
If you split the mic signals, you can run your recording snake up to the front-of-house (FOH) position and set up your mixer or mic preamps there. Get AC power from the PA mixer's power outlet strip so that your mixer and the PA mixer have the same ground voltage. This prevents hum when the two mixers are connected. Of course, you might prefer to locate in an isolated area for better monitoring. If you plug into a local AC outlet there, you should be able to make connections without ground loops and hum if the house power distribution system is well designed.
Otherwise, run one or two thick (14 or 16 gauge) extension cords from the PA mixer's outlet strip to your recording system. These cords may need to be 100-200 feet long. Plug AC outlet strips into the extension cord, then plug all your equipment into the outlet strips.
If you're using a remote truck, find a source of power that can handle the truck's power requirements, usually at a breaker panel. Some newer clubs have separate breaker boxes for sound, lights, and a remote truck.
Find out whether you'll need a union electrician to make those connections (US only). Label your breakers.
Check that your AC power source is not shared with lighting dimmers or heavy machinery; these devices can cause noises or buzzes in the audio. You might want to use a power conditioner with an AC isolation transformer.
The industry-standard power connector for high-current applications in the US is the Cam-lok, a large cylindrical connector. Male and female Cam-loks join together and lock when you twist the connector ring. Distro systems and power cables with Cam-lok connectors can be rented from rental houses for film, lighting, electrical equipment, or entertainment equipment. One such rental house is Mole-Richardson (mole.com.).
The standard power connector in Europe is the C-form.
Use an adapter from Cam-lok to bare wires. Pull the panel off the breaker box, insert the bare wires, and connect the Cam-lok to your truck's power. Some breaker boxes have Cam-loks already built in. (Caution: Have an electrician do the wiring if you don't know what you're doing. A union electrician might be required anyway.) Measure the AC line voltage. If the AC voltage varies widely, use a line voltage regulator (power conditioner) for your recording equipment.
If the AC power is noisy, you might need a power isolation transformer.
Check AC power on stage with a circuit checker. Are grounded outlets actually grounded? Is there low resistance to ground? Are the outlets of the correct polarity? There should be a substantial voltage between hot and ground, and no voltage between neutral and ground.
Some recording companies have a gasoline-powered generator ready to switch to if the house power fails. If there are a lot of lighting and dimmer racks at the gig, you might want to put the truck on a generator to keep it isolated from the lighting power.
Interconnecting Multiple Sound Systems
If you hear a hum or buzz when the systems are connected, first make sure that the signal source is clean. You might be hearing hum from a broken snake shield or an unused bass-guitar input. If the hum persists, experiment with flipping the ground-lift switches on the splitter and on the direct boxes. On some jobs, you need to lift almost every ground; on others, you need to tie all the grounds. The correct ground-lift setting can change from day to day because of a change in the lighting. Expect to make some trial-and-error adjustments.
If the PA has serious hum and buzz problems, offer help. You might hear buzzes in your quiet control room or isolating earphones that the PA people can't hear over the main system with noise in the back ground. Maybe the PA company is using balanced line-level audio cables that are grounded at both ends, which can cause ground loops and hum. You might want to use some cable ground-lift adapters (FIG. 2) to float (remove) the extra pin-1 ground connection at equipment inputs.
A radio station or video crew might want to take an audio feed from your mixing console. If so, you can prevent a hum problem by using a console with transformer-isolated inputs and outputs. Or use an XLR Y-cable with a ground lift. Other options are a direct box or a line-level transformer splitter, such as the Whirlwind Line Balancer/Splitter (LBS) or the ProCo IT-1 Isolation Transformer Unit. For best isolation, use a distribution amp with several transformer-isolated feeds. Lift the cable shield at the input of the system you're feeding.
We recommend the article, "Sound System Interconnection" on the Rane Website, http://rane.com/note110.html. It describes how to connect balanced and unbalanced equipment and prevent ground loops.
FIG. 2 A ground-lift adapter for balanced line-level cables.
Mic Connections
You have previously created a mic list, so you know what to plug in where. Make some copies of the mic list. After unpacking, place one list by the splitter, another by each stage box, and another by each mixer. The list will act as a guide to help you keep things organized.
Attach a strip of white console tape just below the mixer faders.
Use this strip to write down the name of the instrument that each fader affects.
Based on the mic list you made, you might plug the bass direct box into snake input 1, plug the kick mic into snake input 2, and so on. Label fader 1 "bass," label fader 2 "kick," etc. Also plug in equipment cables according to your block diagram.
Have an extra microphone and cable offstage ready to use if a mic fails.
If you unplug a mic plugged into phantom power, it will make a popping noise in the sound-reinforcement system. Be sure to mute the mic channel first.
Running Cables
To reduce hum pickup and ground-loop problems associated with cable connectors, try to use a single mic cable between each mic and its stage box connector.
Avoid bundling together mic cables, line-level cables, and power cables. If you must cross mic cables and power cables, do so at right angles and space them vertically.
Plug each mic cable into the stage box or splitter (if used), then run the cable out to each mic and plug it in. This leaves less of a mess at the stage box. Leave the excess cable at each mic stand so you can move the mics. Don't tape down the mic cables until the musicians are settled.
It is important that audience members do not trip over your cables.
In high-traffic areas, cover cables with rubber floor mats or cable crossovers (metal ramps). At least tape them down lengthwise with gaffers tape.
It helps to set up a closed-circuit TV camera and TV monitor to see what's happening on stage. You need to know when mics get moved accidentally, or when singers use the wrong mic, etc.
Setting Up the Recording Mixer
If you are using mic splitters and a recording mixer, here is a suggested procedure:
1. If the mixer is set up in a dressing room or locker room, add some acoustic absorption to deaden the room reflections. You might bring a carpet for the floor plus acoustic foam or packing blankets for the walls.
2. Turn up the recording monitor system and verify that it is clean.
3. Plug in one mic at a time and monitor it to check for hums and buzzes.
Troubleshooting is easier if you listen to each mic as you connect it, rather than plugging them all in and trying to find a hum or buzz.
4. Check and clean up one system at a time: first the sound-reinforcement system, then the stage-monitor system, then the recording system.
Again, this makes troubleshooting easier because you have only one system to troubleshoot.
5. Use as many designation strips as you need for complex consoles.
Label the input faders at the bottom and top. Also label the monitor mix knobs and the meters.
6. Verify that left and right channels are correct and that the pan-pot action is not reversed audibly.
7. If you are setting up a separate recording monitor mix, do a preliminary pan-pot setup. Panning similar instruments to different locations helps you identify them.
8. Make a short test recording and listen to the playback.
Mic Techniques
Normally the PA company chooses and places the mics, but you might do it yourself or collaborate with the PA company. This section offers some tips on miking instruments and vocals.
In a quiet recording studio with good isolation between instruments, you have the freedom to mike instruments 1 or 2 feet away if you want.
But in a noisy club or auditorium, with band members close together on stage, separation is a serious problem. Usually you need to mike a few inches away to reduce background noise, room acoustics, leakage, and feedback. Here are some other ways to control these problems:
• Use directional microphones, such as cardioids, supercardioids, or hypercardioids. These mics pick up less feedback, leakage, and noise than omnidirectional mics at the same miking distance. For example, the Audix OM5, OM6, and OM7 vocal mics (audixusa.com) have a tight hypercardioid pattern that controls leakage.
• If possible, hang drapes or other acoustical absorption material on the rear wall to reduce sound reflections into the mics. Consider moving the instruments and vocals farther apart to improve isolation and reduce phase interference between mics.
• Use direct boxes. A direct box (DI box) is an interface between an unbalanced electric instrument and a balanced mixer mic input. Bass guitar, electric guitar, and keyboards can be recorded direct to eliminate leakage and noise in their signals. However, nothing beats the sound of a miked guitar amp. You could record the guitar directly from its effects boxes, then use a guitar-amp emulator during mixdown. That is especially helpful if the guitar amp is noisy. Note that sequencers and some keyboards have high-level outputs, so their direct boxes need transformers that can handle line level.
• Use contact pickups. On acoustic guitar, acoustic bass, and violin, you can avoid leakage by using a contact pickup. It is sensitive only to the instrument's vibration, not so much to sound waves. The sound of a pickup is not as natural as a microphone, but a pickup may be your only choice. Consider using both a pickup and a microphone on the instrument. Connect just the pickup to the PA and monitor speakers to prevent feedback, and connect the mic and pickup to the recording mixer. If the mic has too much leakage during mixdown, you can either use the pickup track or overdub the guitar.
• Choose mic positions carefully. Close miking affects the tonal balance of a recorded instrument. When you change the mic position, you change the tone quality. For example, an acoustic guitar miked near the sound hole is bassy, near the bridge is mellow, and near the fingerboard is bright.
Listed below are some typical miking methods for vocals and instruments. These are just some suggested starting positions--experiment and use your ears.
Vocal: Use a condenser, ribbon, or dynamic vocal mic about 0-3 inches from the mouth. To reduce breath pops with vocal mics, be sure to use foam pop filters. Leave a little spacing between the pop filter and the mic grille. It also helps to switch in a low-cut filter (100Hz high-pass filter). If the mic is a cardioid, aim the "dead" rear of the mic at the floor monitors to reduce feedback. If the mic is a supercardioid or hypercardioid, angle the mic to be more nearly horizontal so that its zone of least pickup aims at the monitors. Caution the performer not to cover the grille with a hand because it could color the sound and cause feedback.
Acoustic guitar: Option 1--Mount a mini mic at the edge of the sound hole and turn down the excess bass with the mixer's equalization (EQ).
Option 2-Mount a mini mic inside the guitar under the 17th fret. Option 3-Mount a mini cardioid mic a few inches from where the fingerboard joins the body, or place a boom-mounted mic there. Option 4-If you can't get enough gain-before-feedback with a miked acoustic guitar (as often happens with a rock band), use a pickup or a pickup mixed with a mic.
Plug the pickup into a direct box. During mixdown, you might roll off some highs around 10-12 kHz to make the pickup track sound less "electric." Sax: Place a dynamic or condenser mic a few inches above the bell, aiming at the tone holes. For more mobility and a brighter sound, clip a mini mic to the bell.
Electric guitar or electric bass direct: For a clean sound, plug the guitar into a direct box. Plug the direct-box output into a mixer mic input. For a distorted sound, plug the instrument into a guitar signal processor, and connect the processor output into a mixer line input.
Electric guitar amp: Place a dynamic mic with a presence peak 1 inch from a speaker cone, slightly off-center.
Synthesizer or drum machine: Use direct boxes. Flip the ground-lift switch on the boxes to the position where you monitor the least hum.
Drum set: Try two cardioid condenser "stick-type" mics about 2 feet above the cymbals (see Section 8 for stereo miking techniques). Add a dynamic mic or mini condenser mic just above the snare-drum rim, and a large-diaphragm dynamic mic in the kick drum. Put some dynamic mics just inside the tom-tom rims if necessary. Stuff a pillow or blanket in the kick to get a tight sound, and use a wood or plastic beater for extra "click." The kick drum often requires some EQ to sound good. You might cut a few dB around 400Hz and boost around 4 kHz.
Bongoes or congas: Try a dynamic mic midway between the drums a few inches away, or mike both drums up close.
Grand piano: Raise the lid. Gaffer-tape a mini mic or boundary mic to the underside of the lid in the middle. For stereo, use two mics: one over the bass strings and one over the treble strings. If you need more isolation, close the lid and tweak EQ to remove the tubby coloration (usually cut 1-4dB around 250Hz).
Another method: raise the lid and place two condenser mics 8 inches over the bass and treble strings, about 8 inches horizontally from the hammers. Or place the bass mic about 2 feet toward the tail. If necessary, cut 1 or 2dB around 250Hz to reduce tubbiness.
Upright piano: Face the soundboard toward the room (not next to a wall). Mike the soundboard a few inches from the bass and treble areas with two dynamic or condenser mics.
Banjo: Tape a mini omni mic to the drum head about 2 inches in from the rim, or on the bridge. Or place a cardioid dynamic or condenser mic about 6 inches from the drum head.
Fiddle: Try a dynamic, ribbon, or condenser mic about 8 inches over the top. For a fiddle player who sings, place the mic about 6 inches over the fiddle, aiming at the player's chin. Some players use a pickup into a direct box.
Mandolin, bouzouki, dobro, lap dulcimer: Place a dynamic, ribbon, or condenser mic about 6 inches away.
Hammered dulcimer: Place a dynamic, ribbon, or condenser instrument mic about 8 inches above the top edge aiming at the soundboard.
Acoustic bass: Mike about 3-6 inches away, just above the top of an f-hole or a few inches above the bridge. For more isolation, wrap a cardioid dynamic mic in foam (except for the grille) and stuff it behind the bridge. Many players use a pickup, which they plug into a bass-guitar amp. Plug the pickup into a direct box and connect the phone-jack output in the direct box to the amp. Some amp heads have an XLR direct out and a ground-lift switch to prevent hum. The pickup will need some EQ to sound natural.
Flute: Place a dynamic, ribbon, or condenser mic halfway between the mouthpiece and the tone holes, about 6 inches away. Or wear a headworn mic, and place the mic capsule between the mouthpiece and tone holes.
Harmonica: Mike up close with a dynamic vocal mic. Or plug a hand held mic into a guitar amp, and mike the amp.
Accordion, concertina: Tape a mini mic onto the tone holes on each side (two mics total). You might prefer to locate a dynamic mic 6 inches from the tone holes on the keyboard side. Some players use a pickup into a direct box.
When you're recording a band that has been on tour, should you use its PA mics or your own mics? In general, go with its mics. The artists and PA company have been using their mics for a while and may not want to change anything. Most mics currently used in PA are good quality anyway, unless they are dirty or defective.
If you're not happy with their choice, you could add your own instrument mics. Let the PA people listen to the sound in the recording truck, or in headphones. If it sounds bad because of the mic choice, ask, "Would it be okay if we tried a different mic (or mic placement)?" Usually it's all right with them-it's a team effort. Make sure every instrument is miked.
If not, add your own microphones.
Electric-Guitar Grounding
While setting up mics, you need to be aware of a safety issue with the electric guitar. Electric-guitar players can receive a shock when they touch their guitar and a mic simultaneously. This occurs when the guitar amp is plugged into an electrical outlet on stage, and the mixing console (to which the mics are grounded) is plugged into a separate outlet across the room. If you're not using a power distro, these two power points may be at widely different ground voltages. So a current can flow between the grounded mic housing and the grounded guitar strings.
Caution: Electric-guitar shock is especially dangerous when the guitar amp and the console are on different phases of the AC mains.
It helps to power all instrument amps and audio gear from the same AC distribution outlets. If you lack a power distro, run a heavy extension cord from a stage outlet back to the mixing console (or vice versa). Plug all the power-cord ground pins into grounded outlets. That way, you prevent shocks and hum at the same time.
If you're picking up the electric-guitar direct, use a transformer-isolated direct box and set the ground-lift switch to the minimum-hum position.
Using a neon tester or voltmeter, measure the voltage between the electric-guitar strings and the metal grille of the microphones. If there is a voltage, flip the polarity switch on the amp (if any). Use foam wind screens for additional protection against shocks.
Audience Microphones
When you make a live recording, audience-reaction mics are essential.
They help the recording to sound "live." Without audience mics, the recording may sound too dry, as if it were done in a studio. And there's nothing like cheering and clapping to add excitement to a live recording.
One easy method is to aim two good cardioid condenser mics at the audience. Hypercardioid or shotgun mics are even better. Put them on regular mic stands, on the stage floor, on either side of the stage. If those mic stands must not be seen, hang some mics or put a stereo pair at FOH (FIG. 3). Section 8 describes stereo mic techniques.
If the audience mics are far back in the hall--100 feet from the stage, or at FOH, for example-they pick up the band's sound with a delay.
When mixed with the close mics, the audience mics add an echo. You can prevent this echo if you mix the recording using computer software: slide the audience tracks to the left (earlier in time). Align the waveforms of big peaks.
What if you don't have enough tracks for the audience mics? Record them on a two-track recorder. Load this recording into your digital audio workstation (DAW) along with the other tracks. Align the two recordings in time as just described. Another option is to turn up some stage mics in the mixdown when the audience applauds.
If the audience mics are run through the PA mixer's preamps, leave the audience mics unassigned in that mixer to prevent feedback.
To get more isolation from the house speakers in the audience mics, use several mics hung close to the audience. Some engineers put up 4 audience mics maximum; some use 8 to 10. Use directional mics and aim them away from the house speakers.
Another option is to not mike the audience or not use the audience tracks. Instead, during mixdown, you could simulate an audience with audience-reaction CDs. Simulate room reverb with an effects device or plug-in.
FIG. 3 Some audience miking techniques.
Setting Levels and Submixes
Now that the mics are set up, you might have time for a sound check.
That's when you set recording levels. Have the band play a loud song. Locate a mixer input module that is feeding a recorder track. Set the input trim (mic preamp gain) to get the desired recording level on each track.
You might set each track's level to peak around +/-10dB maximum, which allows some headroom for surprises.
Check all the keyboard patches and guitar effects because some may be much louder than others. You might put a limiter in line with some insert sends to prevent excessive levels.
You often encounter PA consoles where some insert sends are tied up with signal processors. You must use those channels' direct-out jacks instead, which usually are post-fader (unless they can be switched to pre fader). Another option is to "Y" the insert send to your recorder and to the processor input. Or, assign those channels to unused groups (buses) and get your recording signals from there.
If you don't have enough tracks for all the mics, you could set up a two-track drum sub-mix. Ideally you would do this with the recording mixer rather than the PA mixer, and monitor over headphones or Nearfield monitors in a separate room. Assign each drum mic to buses 3 and 4 (for example), and pan each mic as desired. Put the sub-master faders for buses 3 and 4 at design center-the shaded area about 1/2 to 3/4 up.
Have the drummer hit each drum repeatedly, one at a time, as you adjust the input trims to prevent clipping. For example, ask the drummer to bang on the kick drum. Turn down the kick-drum's input trim all the way. Slowly bring it up until the clip LED (overload light) flashes. Then turn down the input trim about 10dB to allow some headroom. When all the drum trims are set, do a drum mix with the faders. Try to adjust all the faders up or down by the same amount so that the recording level is correct when the submasters are at design center.
Recording
If your recording will be synched later with a video recording by using SMPTE (Society of Motion Picture and Television Engineers) time code, record the video time-code feed on a spare recorder track.
A few minutes before the band starts playing, start recording. Keep a close eye on recording levels. If a track is going into the red, slowly turn down its input trim and note the counter time where this change occurred.
Caution: If you are recording off the PA mixer, turning down its input trim will affect the PA levels. The PA operator will need to turn up the corresponding monitor send and channel fader.
This is a touchy situation that demands cooperation. Ideally, you set enough headroom during the sound check so you won't have to change levels. But be sure the PA operator knows in advance that you might need to make changes. Ask the operator whether he or she wants to adjust the gain trims for you, so the operator can adjust corresponding levels at the same time. Thank the operator for helping you get a good recording.
If you are recording with a splitter and mic preamps on stage, assign someone to watch the levels and adjust them during the concert. Preamps with meters allow more precise level setting than preamps with clip LEDs.
Keep a track sheet and log as you record. For each song in the set list, note the counter time when the song starts. Later, during mixdown, you can go to those counter times to find songs you want to mix. Also note where any level changes occurred so you can compensate during mixdown. It helps to note a counter time when the signal level was very high. When you mix the recording you can start at that point in setting your overall mix level.
Record each set nonstop so that you don't miss anything. You can edit out unwanted material later.
Teardown
After the gig, because your mics might be stolen or damaged, pack them away first. Refer to your equipment list as you repack everything. Note any equipment failures and fix broken equipment as soon as possible.
After you haul your gear back to the studio, it's time for mixing and editing, covered next.