This section explains how to do an on-location stereo recording of a classical music ensemble. We cover both equipment and procedures.
Equipment
• Microphones (low-noise condenser or ribbon type, omni or directional, free field or boundary, stereo or matched pair).
• Multitrack recorder or stereo recorder. These were described in Section 1 in the sections "Multitrack Recorder" and "Stereo Recorder."
• Low-noise mic preamps or low-noise mini mixer (necessary if the mic preamps in your recorder are low quality).
• Phantom-power supply (necessary if your mixer or mic preamp lacks phantom power).
• Stereo bar.
• Mic stands and booms, or fishing line to hang mics.
• Shock mount (optional).
• Mixer (necessary if you use more than two mics).
• Mid-side (MS) matrix box (if you are recording with the MS technique).
• Headphones and/or speakers.
• Power amplifier for speakers (optional) or powered Nearfield monitors.
• Recording medium: hard drive or flash memory.
• Power strip and extension cords.
• Notebook and pen.
• Talkback mic and powered speaker (optional).
• Tool kit.
• Fresh batteries.
First on the list are microphones. You'll need at least two or three of the same model number or one or two stereo microphones. Stereo and surround microphones are listed in Section 12 under the headings "Stereo Microphones" and "Surround Microphones." Good microphones are essential, for the microphones-and their placement-determine the sound of your recording. To achieve professional-quality recordings of music, you should expect to spend at least $100 per microphone or $1000 for a stereo microphone.
For classical music recording, the preferred microphones are con denser or ribbon types with a wide, flat frequency response and very low self-noise (explained in Section 7). A self-noise spec of less than 20dB equivalent SPL, A-weighted, is recommended.
If you want to do spaced-pair recording, you can use either omni directional or directional microphones. Omnis are preferred because they generally have a deeper low-frequency response. If you want to do coincident or near-coincident recording for sharper imaging, use directional microphones (cardioid, supercardioid, hypercardioid, or bidirectional).
Mics with those polar patterns tend to roll off in the low frequencies, but you can compensate for this with equalization.
You need a power supply for condenser microphones: either an external phantom-power supply, a mixer or mic preamp with phantom power, or internal batteries. A low-noise stereo mic preamp (or low-noise portable mixer) lets you make recordings free of electronic hiss.
You can mount the microphones on stands or hang them from the ceiling with nylon fishing line. Make sure that the fishing line's tensile strength exceeds the weight of the mics. Check legal safety issues with hanging mics; different rules apply in different places. Stands are much easier to set up, but more visually distracting at live concerts. Stands are more suitable for recording rehearsals or sessions with no audience present.
Neumann makes tiltable "auditorium hangers" that suspend mic capsules of the KM 100 system from their cables.
The mic stands should have a tripod-folding base and should extend at least 13 feet high. Some suitable products are telescoping photographic stands (available from camera stores such as prostudiousa.com).
They are lightweight and compact. Other examples are the Shure S15A (shure.com), Quik Lok A85 (quiklok.com), AEA-13MDV (wesdooley.com), K&M 21411B, and various models at micsupply.com. You can use baby booms or stand extenders to increase the height of regular mic stands.
A useful accessory is a stereo bar (stereo microphone adapter, stereo mic mount). This device mounts two microphones on a single stand for coincident or near-coincident stereo recording. Along stereo bar can accommodate spaced-pair miking. Some examples are given in Section 12 under the heading "Stereo and Surround Microphone Adapters." Another needed accessory in most cases is a shock mount to prevent pickup of floor vibrations. Some models are the On-Stage MY410 (various vendors), Sabra Som SSM-1 (sabra-som.com), Shure A55M (shure.com), and AKG H85 and H100 (akg.com).
In difficult mounting situations, boundary microphones may come in handy. They can lie flat on the stage floor to pick up small ensembles or can be mounted on the ceiling or on the front edge of a balcony. They also can be attached to clear Plexiglas panels that are hung or mounted on mic stands. Boundary mics are made by most microphone companies.
To monitor in the same room as the musicians, you need some closed cup, circumaural (around the ear) headphones, or isolating earphones to block out the sound of the musicians. You want to hear only what is being recorded. Of course, the headphones should be wide-range and smooth for accurate monitoring. A better monitoring arrangement might be to set up powered Nearfield loudspeakers in a separate room.
If you're in the same room as the musicians, you have to sit far from them to clearly monitor what you're recording. To do that, you need a pair of 50-foot microphone extension cables. Longer extensions are needed if the mics are hung from the ceiling or if you monitor in a separate room.
A mixer is necessary when you want to record more than one source- for example, an orchestra and a choir, an orchestra with spot mics, or a band and a soloist. You might put a pair of microphones on the orchestra and another pair on the choir. Connect the insert sends from the mixer to a multitrack recorder, then mix the tracks to stereo back in the studio. If your budget doesn't allow a multitrack recorder you could mix the mic signals live to a stereo recorder.
For monitoring an MS recording, bring an MS matrix box that converts the MS signals to left-right signals, which you monitor. MS matrix devices are listed in Section 12 under the heading "MS Matrix Decoders." Selecting a Venue
If possible, plan to record in a venue with good acoustics. It should have adequate reverberation time for the music being performed (about 2 seconds for orchestral music). This is very important, because it can make the difference between an amateur-sounding recording and a commercial sounding one. Try to record in an auditorium, concert hall, or house of worship rather than in a band room or gymnasium. Halls with wooden surfaces and a shoebox shape tend to sound best.
You may be forced to record in a hall that is too dead: that is, the reverberation time is too short. In this case, you may want to add artificial reverberation from a digital reverb unit or plug-in, or cover the seats with plywood sheets or 4-mm polyethylene plastic sheeting. Strong echoes can be controlled with carpets, RPG diffusors, or drapes.
If the venue is surrounded by noisy traffic, consider recording after midnight. Turn off noisy air conditioning if possible while recording.
Call the venue manager and ask that the circuit breakers for the stage outlets be turned on the day of the session. Ask where you can load-in your equipment. Also make sure that the load-in door will be unlocked when you plan to load in.
Session Setup
Be sure to test all your equipment for correct operation before going on the job. If you are using battery-powered devices, install fresh batteries in them just before the concert. Keep your equipment inside your home or studio until you're ready to leave. A recorder left outside in a cold car may become sluggish if the lubricant stiffens, and batteries may lose some voltage.
Make sure your hard drive or flash card has enough capacity for the session. Table 3-1 in Section 3 shows the storage required for a 1-hour recording.
Arrive at the venue a few hours early to allow for setup and for fixing problems.
First, power-up the equipment. You can use batteries or an AC extension cord plugged into an outlet near the stage. Make sure this outlet is live. Gaffer-tape the extension cord lengthwise or cover it with mats to prevent tripping. Tie your outlet strip's AC cord to the extension cord, so that they can't separate if someone pulls on the extension cord.
If this is a session, listen to the ensemble playing on the stage. Is the sound bad? You might want to move the musicians out onto the floor of the hall.
Mounting the Mics
Place your microphones in the desired stereo miking arrangement. As an example, suppose you're recording an orchestra rehearsal with two crossed cardioids on a stereo bar (the near-coincident method). Screw the stereo bar onto a mic stand and mount two cardioid microphones on the stereo bar. For starters, angle them 110° apart and space them 7 inches apart horizontally. Aim them downward, so that they'll point at the orchestra when raised. You may want to mount the microphones in shock mounts or put the stands on sponges to isolate the mics from floor vibration.
Basically, place two or three mics (or a stereo mic) several feet in front of the group, raised up high (as in FIG. 1). The microphone placement controls the acoustic perspective or sense of distance to the ensemble, the balance among instruments, and the stereo imaging.
As a starting position, place the mic stand behind the conductor's podium, about 12 feet from the front-row musicians. Connect mic cables and gaffer-tape them to the top of each mic stand for strain relief. Raise the microphones about 14 feet off the floor. This prevents overly loud pickup of the front row relative to the back row of the orchestra. It also reduces audience noise by mounting the mics farther from the audience.
Gaffer-tape the mic cables to the bottom of the stand to keep it from being pulled over.
Leave some extra turns of mic cable at the base of each stand, so that you can reposition the stands. This slack also allows for people accidentally pulling on the cables. Try to route the mic cables where they won't be stepped on, or cover them with mats.
FIG. 1 Typical microphone placement for on-location recording of a classical
music ensemble: (a) top view and (b) side view.
Live, broadcast, or filmed concerts require an inconspicuous mic placement, which may not be sonically ideal. In these cases, or for permanent installations, you probably want to hang the microphones from the ceiling rather than using stands. You can position a stereo bar with three nylon fishing lines spaced apart. Make sure that the tensile strength of the fishing line exceeds the weight of the mics and stereo bar. Hang individual mics by their cables and attach two fishing lines to the front of each mic to aim it. Another inconspicuous mic placement is on mic stand booms projecting forward of a balcony. For dramas or musicals, directional boundary mics can be placed on the stage floor near the footlights.
If you are uncertain which mic technique to use, you could set up two or more mic arrays and record them to multitrack. When you master the program, choose the best-sounding technique. You might even mix the signals of two or more mic pairs.
Connections
Now you're ready to make connections. Here are some connection methods for just two mics:
• If your stereo recorder has high-quality mic preamps and phantom power, plug the mics directly into the recorder mic inputs.
• If your recorder lacks phantom power (or the phantom voltage is lower than the mics require), plug the mics into a phantom supply, and from there into your recorder mic inputs.
• If your recorder lacks high-quality mic preamps, plug the mics into a low-noise mic preamp or mixer with phantom power. Connect cables from there into your recorder line inputs.
Here are some connection methods for more than two mics:
• Plug the mics into a stage box (described in Section 1) and run the snake back to your mixer. Plug the snake mic connectors into your mixer mic inputs. If you are recording to two-track, plug the mixer stereo outputs into the recorder line inputs. If you are recording to multitrack, plug the mixer insert-send jacks into the recorder line inputs.
• If you have a multichannel audio interface with mic preamps, plug the mics into the interface. Connect the interface USB or FireWire port to a laptop computer.
• If you want to feed your mic signals to several mixers-recording, broadcast, PA-plug your mic cables into a mic splitter or distribution amp (described in Section 2 under the heading "Splitting the Microphones"). Connect the splitter outputs to the snakes for each mixer. Supply phantom from one mixer only, on the direct side of the split. Each split will have a ground-lift switch on the splitter. Set it to ground for the mixer supplying phantom. Set it to lift for the other mixers (or to ground if that results in the least hum). This pre vents hum caused by ground loops between the different mixers.
• If you're using directional microphones and want to make their response flat at low frequencies, you can run them through a mixer with equalization for bass boost. You might prefer to equalize the recording during mastering instead. Boost around 50-100Hz until the bass sounds natural or until it matches the bass response of omni condenser mics. You won't need this equalization (EQ) if the micro phones have been factory equalized for flat response at a distance.
Monitoring
Put on your headphones or listen over loudspeakers in a separate room. Sit equidistant from the speakers, as far from them as they are spaced apart. You'll probably need to use a Nearfield arrangement (speakers about 3 feet apart and 3 feet from you) to reduce coloration of the speakers' sound from the room acoustics. Play CD tracks 1-4 to set up your monitor speakers correctly for stereo listening.
Turn up the recording-level controls and monitor the signal. When the orchestra starts to tune up, set the recording levels to peak around +/-15dB, so that you have a clean signal to monitor. You can set levels more carefully later on.
Microphone Placement
Nothing has more effect on the production style of a classical music recording than microphone placement. Miking distance, polar patterns, angling, spacing, and spot miking all influence the recorded sound's character.
Miking Distance
The microphones must be placed closer to the musicians than a good live listening position. If you place the mics out in the audience where the live sound is good, the recording probably will sound muddy and distant when played over speakers. That is because all the recorded reverberation is reproduced up-front along a line between the monitor speakers, along with the direct sound of the orchestra. Close miking (5-20 feet from the front row) compensates for this effect by increasing the ratio of direct sound to reverberant sound.
The closer the mics are to the orchestra, the closer the orchestra sounds in the recording. If the instruments sound too close, too edgy, or too detailed, or if the recording lacks hall ambience, the mics are too close to the ensemble. Move the mic stand a foot or two farther from the orchestra and listen again.
If the orchestra sounds too distant, muddy, or reverberant, the mics are too far from the ensemble. Move the mic stand a little closer to the musicians and listen again.
Eventually, you'll find a sweet spot, where the direct sound of the orchestra is in a pleasing balance with the ambience of the concert hall.
Then the reproduced orchestra will sound neither too close nor too far.
Here's why miking distance affects the perceived closeness (perspective) of the musical ensemble: the level of reverberation is fairly constant throughout a room, but the level of the direct sound from the ensemble increases as you get closer to it. Close miking picks up a high ratio of direct-to-reverberant sound; distant miking picks up a low ratio. The higher the direct-to-reverb ratio, the closer the sound source is perceived to be. Play CD track 25 to hear how miking distance affects the direct-to-reverb ratio.
If the recording venue is "live" because of hard surfaces-brick, glass, stone-chances are you will need to mike closely. On the other hand, if the venue is "dead" because of soft surfaces-carpet, drapes, stuffed seats-expect to mike farther away.
An alternative to finding the sweet spot is to place a stereo pair close to the ensemble (for clarity) and another stereo pair distant from the ensemble (for ambience). According to Delos recording director John Eargle, the distant pair should be no more than 30 feet from the main pair, otherwise the signal might simulate an echo. You record the two pairs to a multitrack recorder and mix them back in the studio. The advantages of this method are as follows:
• It avoids pickup of bad-sounding early reflections.
• Close miking reduces pickup of background noise.
• After the recording is finished, you can adjust the direct/reverb ratio or the perceived distance to the ensemble.
• Comb filtering due to phase cancellations between the two pairs is not severe because the delay between them is great and their levels and spectra are different.
Similarly, Skip Pizzi recommends a "double MS" technique, which uses a close MS microphone mixed with a distant MS microphone (as shown in FIG. 2). One MS microphone is close to the performing ensemble for clarity and sharp imaging, and the other is out in the hall for ambience and depth. The distant mic could be replaced by an XY pair for lower cost.
FIG. 2 Double MS technique using a close main pair and a distant pair
for ambience. Spot mics also are shown.
If the ensemble is being amplified through a sound-reinforcement system, you might be forced to mike very close to avoid picking up amplified sound and feedback from the reinforcement speakers. In that case you will need to add high-quality artificial reverberation or convolution reverb.
For broadcast or communications, consider miking the conductor with a wireless lavalier mic or stand-mounted mic.
Stereo-Spread Control
Concentrate on the stereo spread. If the monitored spread is too narrow, it means that the mics are angled or spaced too close together. Increase the angle or spacing between mics until localization is accurate. Note:
Increasing the angle between mics will make the instruments sound farther away; increasing the spacing will not. Play CD track 9. The mics are angled and spaced too close together, so the stereo spread is narrow.
If off-center instruments are heard far left or far right, that indicates your mics are angled or spaced too far apart. Move them closer together until localization is accurate. Play CD track 20. The mics are too far apart, so the stereo separation is exaggerated.
If you record with an MS microphone, you can change the monitored stereo spread either during the recording or after.
To change the spread during the recording, connect the stereo mic outputs to the matrix box and connect the matrix-box L-R output to the recorder. Use the stereo-spread control (M/S ratio) in the matrix box to adjust the stereo spread.
To alter the spread after the recording using a matrix box: Record the mid signal on one track and the side signal on another track. Monitor the output of the recorder with a matrix box. Back in the studio, run the mid and side tracks through the matrix box, adjust the stereo spread as desired, and record the left and right outputs.
To alter the spread after the recording using a digital audio work station (DAW):
1. Record the mid mic on track 1; record the side mic on track 2.
2. Copy or clone track 2 to track 3. Be sure the waveforms are aligned.
3. Pan track 2 hard left; pan track 3 hard right.
4. Reverse the polarity of track 3 or use an "invert polarity" plug-in.
5. Group tracks 2 and 3, so their faders move together.
6. To change the stereo spread, vary the levels of tracks 2 and 3 relative to track 1.
If you are set up before the musicians arrive, check the localization by recording yourself speaking from various positions in front of the microphone pair while announcing your position ("left side," "mid-left," "center"). Playback the recording to judge the localization accuracy provided by your chosen stereo array. Recording this localization test is an excellent practice. Play CD tracks 8-24 to hear the localization of several stereo mic techniques.
Monitoring Stereo Spread
Full stereo spread on speakers is a spread of images all the way between speakers, from the left speaker to the right speaker. Full stereo spread on headphones can be described as stereo spread from ear to ear. The stereo spread heard on headphones may or may not match the stereo spread heard over speakers, depending on the microphone technique used.
Due to psychoacoustic phenomena, coincident-pair recordings have less stereo spread over headphones than over loudspeakers. Take this into account when monitoring with headphones or use only loudspeakers for monitoring. Play CD tracks 9-10 alternately over loudspeakers and headphones.
Compare the stereo spread.
If you are monitoring your recording over headphones or anticipate headphone listening to the playback, you may want to use near-coincident miking techniques, which have similar stereo spread on headphones and loudspeakers. Play CD tracks 13-14 alternately over loudspeakers and head phones. Compare the stereo spread.
Ideally, monitor speakers should be set up in a Nearfield arrangement (say, 3 feet from you and 3 feet apart) to reduce the influence of room acoustics and to improve stereo imaging. On the wall behind the monitors, attach a panel of acoustic foam that extends a few feet beyond the speaker spacing.
If you want to use large monitor speakers placed farther away from you, deaden the control-room acoustics with acoustic foam or thick fiber glass insulation (covered with muslin). Place the acoustic treatment on the walls behind and to the sides of the loudspeakers. This smoothes the frequency response and sharpens stereo imaging. You might include a stereo/mono switch in your monitoring system to check for mono compatibility.
Soloist Pickup and Spot Microphones
Sometimes a soloist plays in front of the orchestra. You have to capture a tasteful balance between the soloist and the ensemble. That is, the main stereo pair should be placed so that the relative loudness of the soloist and the accompaniment is musically appropriate. If the soloist is too loud relative to the orchestra (as heard on headphones or loudspeakers), raise the mics. If the soloist is too quiet, lower the mics. You may want to add a spot mic (accent mic) about 3 feet from the soloist and mix it with the other microphones. Take care that the soloist appears at the proper depth relative to the orchestra.
If a sound-reinforcement system is in use, place the soloist mic 8-12 inches away to prevent feedback. Use a foam windscreen on a vocal mic.
To make the soloist mic inconspicuous, you could place a small-diaphragm mic at about chest height aiming at the mouth, and use a slender mic stand such as the Schoeps Active Tube RC.
Many record companies prefer to use multiple microphones and multitrack techniques when recording classical music. Such methods provide extra control of balance and definition and are necessary in difficult situations. Often you must add spot or accent mics on various instruments or instrumental sections to improve the balance or enhance clarity (as shown in FIG. 2). In fact, John Eargle contends that a single stereo pair of mics rarely works well.
A choir that sings behind the orchestra can be miked separately with two to four cardioids. You might place the choir in the audience area facing the orchestra, and mike the choir.
If the recording mics are also used for sound reinforcement, place the choir mics about 3 feet out front and 3 feet above the head height of the back row. Add piano mics and wind-screened soloist mics about 8 inches from their sound sources. Record all the mics to multitrack, and mix the tracks back in your studio. Add reverb and EQ as needed.
Pan each spot mic so that its image position coincides with that of the main microphone pair. Using the mute switches on your mixing console, alternately monitor the main pair and each spot mic to compare image positions.
You might want to use an MS microphone or stereo pair for each spot mic. Adjust the stereo spread of each local sound source to match that reproduced by the main pair. For example, suppose that a violin section appears 20° wide as picked up by the main pair. Adjust the perceived stereo spread of the MS spot mic used on the violin section to 20°, then pan the center of the section image to the same position that it appears with the main mic pair.
When you use spot mics, mix them at a low level relative to the main pair-just loud enough to add definition but not loud enough to destroy depth. Operate the spot-mic faders subtly or leave them untouched. Otherwise the close-miked instruments may seem to jump forward when the fader is brought up, then fall back in when the fader is brought down. If you bring up a spot-mic fader for a solo, drop it only 6dB when the solo is over, not all the way off.
Often the timbre of the instrument(s) picked up by the spot mic is too bright. You can fix it with a high-frequency rolloff or by using a mic with that characteristic. Adding artificial reverb to the spot mic can help too.
To further integrate the sound of the spots with the main pair, you might want to delay each spot's signal to coincide with those of the main pair. That way, the main and spot signals are heard at the same time. For each spot mic, the formula for the required delay is:
T = D/C
where
T: delay time in seconds
D: distance between each spot mic and the main pair in feet
C: speed of sound, 1130 feet/second.
For example, if a spot mic is 20 feet in front of the main pair, the required delay is 20/1130 or 17.7 milliseconds. Some engineers add even more delay (10-15 milliseconds) to the spot mics to make them less notice able (Streicher and Dooley). As a rule of thumb, 1 foot corresponds to about 1 millisecond of delay.
A suggested track assignment for multitrack concert recordings is shown below:
Tracks 1-2: main pair Tracks 3-4: distant pair Tracks 5-6: "outriggers" or widely spaced pair
Tracks 7-8: spot mics and conductor's mic (for announcing takes).
Once the microphones are positioned properly, gaffer-tape the mic-stand legs to the floor, so that the stands can't be knocked over.
Setting Levels Now you're ready to set recording levels. Ask the conductor to have the orchestra play the loudest part of the composition, and set the recording level for the desired meter reading. A typical recording level is +/-6dB maximum on a peak-reading meter for a digital recorder. The level can go up to 0dB maximum without distortion, but aiming for +/-6dB allows for surprises. Bass-drum and tympani hits produce the highest peaks.
If you plan to record a concert with no sound check, you have to set the record-level knobs to a nearly correct position ahead of time. Do this during a pre-concert trial recording, or just go by experience: set the knobs where you did at previous sessions (assuming you are using the same microphones in the same venue). Another way to pre-set the recording level is to aim for a peak meter level of +/-15dB when the orchestra tunes up.
Before going on-location, you could play loud orchestral music over your studio monitors or home stereo, set up your mics and recorder, and set approximate recording levels. If you need to set the level less than one-third up to get a 0-dB meter level, you probably need to insert a pad or set the mic-gain switch to low gain.
Recording a Concert
Before the concert obtain a printed program of the musical selections. On this program, next to each piece, you will write down the recorder counter times of the beginning and end of that piece. That will help you locate and identify the pieces correctly when you edit the recording later.
Start recording when the conductor walks out (or sooner). Record the concert nonstop if your recording medium allows. Document your mic placement and recording level for future jobs.
Editing
At this point, the recording is finished and you've brought it back to your studio. The concert recording has long applause after each piece. Suppose you want to edit the applause shorter and insert a few seconds of silence between the compositions. Here is a suggested procedure for editing a stereo recording using a DAW:
1. Connect a USB cable between the computer and recorder. Then the computer recognizes the recorder as a storage device. Click-drag the recorder's wave file of the concert to your hard drive. If you recorded to DAT, copy the program in real time through your sound card or audio interface (ideally in digital format).
2. In the audio editing software, start a new project and set up an audio track.
3. Import the concert file from the hard drive into the audio track.
4. Play the track and locate the first piece. Refer to the counter times you wrote on your session notes or concert program.
5. Delete the part of the recording before the first piece but do not close up the space.
6. Find the applause at the end of the piece. About 10 seconds into the applause, split the clip or region. Also split the clip a few seconds before the start of the next piece. Cut out the audio between the split points, but do not close up the space.
7. Label the clip of the composition with its title.
8. Repeat Step 6 for the rest of the pieces.
FIG. 3 A DAW screen showing an applause fade-out, a 4-second gap, and
a fade-in before the next piece.
Now each musical piece is in a separate clip or region on your screen.
Slide the first piece to the beginning of the program. Next you will add fades and adjust the spacing between the pieces (refer to FIG. 3):
1. At the end of each piece, let the applause play for 3 seconds then fade it out over about 8 seconds Use a fade that starts quickly and ends slowly.
2. If there is background noise such as air-conditioning rumble, insert a fade-in about 2 seconds before the beginning of each piece (FIG. 3). Or you may want the track to start right when the music starts; that is, with no ambience before it starts.
3. Time-slide the clips to create a 4-second gap between them (or what ever interval sounds right).
If you don't want total silence between pieces, do not fade out the applause.
End each piece's clip where the applause stops, and leave about 4 seconds of recorded "room tone" between clips.
To edit a session that has no applause, set the beginning of each clip just before the first note. Set the end of each clip just after the reverberant tail fades to silence. Leave about a 4-second silent gap between clips (or whatever sounds right).
When you're finished editing, note the start time and duration of each clip. You will use this information to write a cuesheet that deter mines the start IDs when burning a CD. Export the edited program to a 24-bit stereo file.
Sometimes, despite your best intentions and the finest microphones, the spectral balance of the recording might be poor. The bass might be weak, the strings strident, and so on. Room acoustics play a strong part in this. Fortunately, a recording having a skewed tonal balance can often be salvaged with equalization. An effective tool for this purpose is Harmonic Balancer (har-bal.com), which shows the spectrum of the recording and lets you equalize it as needed.
Once the program is equalized (if necessary), import the equalized file and normalize it, so that the highest peak reaches +/-0.1dBFS. Finally, enable dither and export the normalized mix to a 16-bit stereo file. You will burn a CD from this file.
A Real-World Example: Recording an Orchestra in a Concert Hall
To illustrate what an actual concert recording might be like, I'll describe an on-location project that I did recently. The promoter of a local sym phony orchestra phoned and asked me to record the group live in concert.
She wanted 25 CDs of the concert for the musicians.
Preproduction
In talking with the promoter, I got this information:
Performance date and time: May 9, 2006, at 7 p.m.
Load-in time: 6 p.m.
Length of performance: 1 hour, no intermission.
Venue and venue address: Superb Theater, 110 S. River St., Elkhart, IN.
Instrumentation: Symphonic orchestra with no soloists.
Directions to venue: I used Google maps.
Next I drew a block diagram of the recording system. I planned to record the orchestra with a pair of mics and a flash-memory recorder. From the block diagram, I generated an equipment list:
2 Neumann KM140 cardioid mics; Stereo mic adapter; Tall foldable mic stand and boom extender; Two 15-foot mic cables and a spare mic cable; ART Phantom II battery-powered phantom power supply
Behringer UBB 1002 battery-powered mixer
Edirol R-09 battery-powered flash-memory recorder
AKG K240 headphones
Spare batteries
Carrying case
Gaffers tape
Pen, notebook, and flashlight
All this fit into a cloth bag and a carrying case.
In the studio, I set up all this equipment to test it. I screwed the stereo mic adapter onto the boom extender, and taped the boom extender temporarily to the folded mic stand to make carrying easier.
The Recording Session
I arrived at the session an hour before showtime. Setup for this gig typically takes 20 minutes.
I have recorded at this venue before and have found that the best spot for the microphones is in the 3rd row center, raised about 14 feet. That places the mics about 12 feet behind the conductor. In this particular venue, placement closer than 12 feet gives a dry, bright sound and overemphasizes the front-row strings. With the mics farther than 12 feet, the recorded orchestra sounds too distant and less engaging.
After unpacking, I mounted the two Neumann KM140 cardioid mics in the stereo mic adapter in the NOS configuration, aiming down to where the orchestra would be when the mics are raised. After plugging the cables into the mics, I formed a sideways "U" out of the mic cables and taped the cables to the boom extension to act as a strain relief. Next, I screwed the boom extension onto the mic stand and raised the mics all the way.
The mixer, phantom supply, and recorder were in a carrying case in my lap. I plugged the mic cables into the phantom supply, which was plugged into the mixer and from there into the recorder line input. Why were those devices necessary? The recorder mic input was a little noisy and did not provide 48V phantom, which the Neumann mics required.
The battery-powered mixer had quiet mic preamps, but it also did not provide 48V phantom, so I needed an external 48V phantom supply.
Once everything was connected, I powered up the recording devices and listened to the mic signals over headphones. I verified that the left and right channels were not reversed. When the orchestra tuned up I set the recording level to peak at +/-15dB.
Finally, the conductor walked onstage. I started recording and noted the counter time of each piece. The concert was recorded nonstop for editing later.
Editing/Mastering
Back in the studio, I set up my DAW to edit the concert. I followed the procedure given in this section under the heading "Editing." I burned a master CD and a safety copy. Finally, I duplicated the master CD several times, put on CD labels, and delivered a box of CDs to the conductor.
References
Pizzi, S. "Stereo Microphone Techniques for Broadcast." Audio Engineering Society Preprint No. 2146 (D-3), Presented at the 76th Convention, October 8-11, 1984, New York.
Streicher, R., and Dooley, W. "Basic Stereo Microphone Perspectives--A Review." Journal of the Audio Engineering Society, Vol. 33, No. 7/8 (July/August 1985), pp. 548-556.
Eargle, J. The Microphone Book. Boston: Focal Press, 2001.