RECORDING LIVE TO 2-TRACK
by Bruce Bartlett © 2006
Bruce Bartlett is a recording engineer, microphone engineer, and technical writer. He has written 800 articles and eight books on audio topics, such as "On-Location Recording Techniques" and "Practical Recording Techniques 4th Ed." published by Focal Press. Bruce is a member of the Audio Engineering Society and Syn Aud Con.
Before the mid-sixties, all recordings were mixed live to stereo or mono. Many of them sounded fantastic. These days we record everything on multitrack, but we ought to rediscover the art of 2-track recording. Why? The sound can be more transparent and punchy, and the performance can be more exciting because all the musicians play at once. If you mix directly to a 2-track recorder, the signal goes through your mixer only once -- during recording -- not twice during recording and mixdown. There's only one A/D conversion. The signal path is as short as possible, so the sound is extra clean and clear. What's more, you save recording time because you omit the overdubs and mixdown. Recording live to 2-track is exhilarating. The band you record has to perform well all the way through the song, so they must be well rehearsed. And you have to do a flawless mix as the band plays. All the musicians must play or sing at the same time; you can't overdub. But this can be a blessing in disguise. Musicians often play better when they can interact and feed off each other's energy.
As for drawbacks, you may have a problem with leakage. Suppose you have to record loud and quiet instruments at the same time with a mixer, such as a drum set and an acoustic guitar. The sound from the loud instruments will leak into the mics for the quiet instruments. This leakage can make the loud instruments sound distant or muddy. Another drawback is that you can’t re-record a single musician’s performance if they make a mistake; you need to re-record the entire group. You could re-record starting from a few seconds before the mistake, then edit the takes together.
If you want to try recording live-to-2-track, you’ll need some sort of 2-track recorder. Currently the main types are:
• MiniDisc recorder
• Flash-memory recorder
• Laptop computer with a sound card and sound editing software
A Hi-MD MiniDisc recorder lets you record uncompressed CD-quality wave files on low-cost Hi MD MiniDiscs. You get up to 94 minutes recording time on a 1 GB disc. Examples include the Sony MZM10 ($300) and MZM100 ($400). They come with a stereo microphone and earbud headphones. Because MiniDiscs cost little and are removable, a MiniDisc recorder is a good choice if you're recording in the field for a long time and can't dump a flash-memory recording to a computer. You must use the provided Sony software to copy MiniDisc files to a computer. MiniDisc recorders can skip if bumped, so you need to hold the recorder steady.
A flash-memory recorder (Figure 1) is a portable digital recorder with no moving parts. Also called a solid-state recorder, it records into a flash-memory card such as a Compact Flash or Secure Digital (SD) card. A 2 GB card, which records 2 hours of 24-bit/44.1kHz wave audio files, cost about $65 when this article was published. Flash-memory recorders can record MP3 or uncompressed PCM wave files (which are CD quality or better).
Figure 1. Edirol R-09, an example of a flash-memory recorder.
(from Edirol website)
These recorders have a number of features to consider. Power comes from replaceable or rechargeable batteries. Available mic connectors are XLR, ¼" phone (6.35mm socket), or 1/8" phone (3.5mm socket), with or without 48V phantom power or plug-in power. Some units come with built-in or plug-in stereo microphones. Price ranges from $400 to $2000. After making a recording, you connect the USB port in the recorder to the USB port in a computer. The recorder shows up as a storage device on your computer screen.
You drag-anddrop the recorded sound files to the computer's hard drive for editing and CD burning. The files
transfer in a few minutes. Then the flash-memory card is empty, free to make more recordings. Nearly all flash-memory recorders include a mic-gain switch to accommodate both quiet and loud sound sources. Low gain or low amplification (0 to 15 dB) is for recording loud sounds (rock concerts); medium gain (25 dB) is for recording medium sounds (acoustic music, lectures, or
rehearsals); high gain (50 dB) is for recording quiet sounds (nature, quiet talking). Most recorders have AGC (automatic gain control), which sets the recording level automatically depending on how loud the sound is. Some units include a limiter to prevent recording above 0 dB level, which otherwise would cause distortion.
Some examples of flash-memory recorders are the Sony PCM-D1; Marantz PMD660, PMD670 and PMD671; Core Sound PDAudio® System, AEQ PAW-120, Edirol R-1 and R-09, M-Audio MicroTrack 2496, Nagra Ares-M, PocketRec software, Sound Devices 722/744T, Fostex FR-2, Roland CD2, Mayah Communications Flashman, and Tascam HD-P2.
Laptop, Recording Software and Audio Interface
Another stereo recorder is a laptop computer with recording software (Figure 2). To get audio into the computer, use a two-channel audio interface. This is a mic preamp with two mic inputs and a USB or FireWire port, which connects to a similar port in your laptop. If your computer lacks that port, get a USB or FireWire PC Card adapter. It is a PCMCIA card with a USB or FireWire port.
Plug the card into your laptop, and connect its port to the audio interface. Another option is a CardBus card, which is an advanced PCMCIA card with faster speed.
Figure 2. An audio interface plugged into a laptop computer via a USB connection.
Some examples of a two-channel USB audio interface are the M-Audio Transit and Fast Track Pro (www.m-audio.com). USB or FireWire PC Card adapters and CardBus adapters can be found in a Google search. Some examples of recording software are Adobe Audition, MOTU Digital Performer (Mac only), Steinberg Cubase SX and Nuendo, Digidesign Pro Tools, Apple GarageBand, Cakewalk Music Creator, Home Studio and Sonar; Emagic Logic (for Mac only), Sony Pictures Digital Vegas and
Sound Forge, BIAS Deck, Pro Tracks Plus, Magix Samplitude, Mackie Tracktion, Magix Sequoia, RML Labs SAW Studio, and Audacity (which is freeware). When a laptop recording is done, you are ready to edit it. You don’t have to transfer the wave files
from recorder to computer as you do with other methods.
2-TRACK RECORDING STYLES
We’ve looked at 2-track recorders. Now let’s consider how to use the microphones. Two ways to record to 2-track are with multi-miking or stereo miking. With multi-miking, you mike each instrument and singer, and mix them live to 2-track. This method works best with rock, pop, folk or jazz. With stereo miking, you record a musical ensemble with a stereo mic or a matched pair of mics. You pick up the group as a whole, along with the room acoustics. This method works best for an orchestra, symphonic band, choir, pipe organ, string quartet, or soloist. Sometimes it works well for a folk group or acoustic jazz group. Stereo miking sounds relatively muddy when used to record a rock band indoors, but it can be done. In fact, at some performers’ concerts, tapers sections are set up in the audience area for the purpose of recording the show in stereo.
Connections for 2-track recording are simple. If you're stereo miking, either plug the mics directly into the recorder's mic inputs or into a mic preamp. The best portable recorders have XLR mic inputs with phantom power for condenser mics. If you use a mic preamp, plug its outputs into your recorder's line inputs. Outboard mic preamps, or good mixer mic preamps, tend to sound
cleaner than the low-cost preamps built into recorders. Also consider using an outboard A/D converter for better sound. Connect your mic preamp outs to the converter ins. Then connect the converter outputs to your recorder’s or sound card’s digital
inputs (if available).
Some companies make combination mic preamp/ converters. You could even connect a compressor/limiter between the mic preamp and recorder analog line in. The compessor will prevent excessive peaks from overloading your recorder. This is a useful feature when you record live concerts, where you can't predict the recording level. Many portable
recorders have a limiter built in. If you're multi-miking, plug your mixer's bus 1 and 2 outputs into your recorder's line inputs. If
you're grouping inputs on your mixer, plug the stereo bus out to recorder line in. The sound will be slightly cleaner if you don't set up groups, so consider mixing everything directly to busses 1and 2.
Here are some techniques for multi-miking a band and recording it live to 2-track. First set up to monitor busses 1 and 2. It's hard to monitor clearly over headphones because the band's live sound leaks through the headphones ear seal. Try to use a snake so you can monitor in a separate room. If you must be in the same room as the musicians, use headphones with good isolation, such as Etymotic earphones. Connect the insert sends (or pre-fader direct outs) from the PA mixer's mic channels to the line inputs of a separate recording mixer (Fig. 3). Or split the mics to feed the PA mixer and your recording mixer (Fig. 4).
Figure 3. Connecting PA mixer insert sends to recording mixer line inputs.
Figure 4. Splitting the mic signals to feed the PA mixer and recording mixer.
Mike each instrument and singer. You can reduce leakage by miking close and recording direct. Have vocalists sing with lips touching the foam pop filters on their microphones. Use direct boxes or guitar simulators instead of mics.
Direct boxes give a clean, tight sound since they pick up no background noise or leakage. In the studio, don't use a bass amp; record the bass guitar direct and monitor it with headphones instead. This keeps the muddy-sounding bass notes from bouncing around the room.
What if you don't have enough mics? Sometimes you can pick up two instruments with one mic. Try miking the drum set with one mini omni condenser mic, about 4” above the snare rim in the middle of the set. Boost the bass and treble a little. Another mic goes in the kick. Now set the master faders to design center (0 dB, about 3/4 up). While listening to the mixer output, bring up the bass-player's fader and ask him or her to play the loudest part of the song.
On the mixer, set the bass fader to design center. Adjust the gain-trim pot to get a 0 level on the mixer's meters. Listen carefully to check for hum, noise, and buzzes.
Repeat these steps for each instrument and vocal. The lead vocal might need a compressor; patch it into the vocal channel's insert jacks. Next, have the musicians play the tune while you set up a mix. You might start by raising all the
faders to about -10 dB. Pan each mic as desired. Then adjust the faders so you can hear everyone about equally. Make sure you can hear each instrument in the mix.
With the balances roughed in, tweak up EQ. Close-miked vocals will need some bass rolloff to sound natural, about –6 dB at 100 Hz. You might have to turn up the monitors or headphones to hear the mix better. When the band stops, do a quiet playback so you can check your EQ settings at home-stereo levels.
Keep the mixer level peaking around 0 maximum. Set your recorder's input level so its meters peak at –6 dB maximum. That setting allows a little headroom in case the band plays louder.
Finally, add effects.
Once you're happy with the mix, record about a minute of the tune. Then play it back. Make any adjustments needed and re-record. Note that you can't fix mistakes by punching in. but you can always do another take. Or do several takes, and edit together the best parts of all the takes.
STEREO MIKING CLASSICAL MUSIC
When you stereo-mike a classical ensemble, try to record in a venue with good acoustics. The reverb time should be fairly long, and the background noise should be quiet. Set up two identical mics on a stereo bar, or use a stereo mic or dummy head. One stereo mic
technique that works well in most situations is called ORTF. Take two cardioid mics, angle them apart 110 degrees (±65 degrees off center), and space their grilles 7 inches apart horizontally. An alternative with less off-axis high-frequency rolloff is NOS: mics angled 90 degrees apart and spaced 12 inches horizontally. You might prefer to use two omni mics spaced 2 to 3 feet, or a
Place the mic stand about 12 feet in front of the front-row musicians and raise it about 14 feet high (Fig. 5). The mics should aim down toward the ensemble. Run a long pair of mic cables to your recorder.
Figure 5. Miking an orchestra.
As the group rehearses, monitor the input signal. If the sound is too edgy, dry, or detailed, move the mics a foot or two farther away and listen again. If the sound, however, is too distant and muddy, move in a foot or two. Try to find a spot where you hear a pleasing blend of the group and the hall acoustics.
If you use good mics, you'll be amazed at the realism and purity of sound you can get with this method.
With any type of music, you need to set your recording levels carefully. If you're recording a rehearsal, ask the group to play the loudest part of the music. Adjust the recording level to peak at about –6 dB maximum. At a live concert, if there was no sound check, you may have no idea where to set the recording level. You might start by turning up the record-level knob 2/3 up, check your meters, and slowly adjust the level up or down as needed. Once it's set, try to leave it alone. It's better to set the level a little too low than too high. To prevent excessive levels, switch on your recorder’s limiter if it has one.
What if the sound is distorted, even though you did not reach 0 on your meters? Chances are that the mics put out a signal strong enough to overload your mic preamp. To prevent this, switch on the pad (attenuator) on your recorder or mic preamp. If you find that you're setting the recordlevel knob less than 1/3 up to prevent excessive meter peaks, you probably need to use the pad. Always turn on the pad when you record a rock concert.
STEREO MIKING ROCK MUSIC
You might try recording a rock concert from the audience area. If a taper's section is set up in the audience, as in the Grateful Dead concerts, it's legal to record the concert. Otherwise, it's not -- unless you have the artists' permission. You'll need a portable recorder and a stereo mic or a matched pair of mics. A few recorders have mics built in. Some people use a binaural set of mics that fit on the head (such as made by www.core-sound.com). Or you can clip mini omni mics to your shoulders. Small electret mic capsules can be powered with a battery, and can plug directly into your recorder or mixer mic inputs. If you can, sit fairly close to the band so the mics will pick up less room reverb. But don't sit too close, or you'll be far off-axis to the PA speakers, where the treble is weak. Some people get a good result by putting a stereo mic at the PA mixing console. They mix that mic with a direct feed from the console.
STEREO MIKING FOLK OR JAZZ
Often you can get a realistic sound by miking a folk group or jazz combo in stereo. Start by mounting your stereo mic, or pair of mics, on a mic stand at ear height. If you use omni or unidirectional boundary mics, place them on the floor about 3 feet apart. Put the mics as far from the group as the group is wide. For example, if the group is 5 feet wide, place the mics 5 feet away. That way you'll pick up everyone in the group about equally.
Do a trial recording and play it back. Is anyone too quiet? Have them move a little closer to the mics and try again. Do you want to hear more room acoustics? Move the mics a foot or two farther from the group and re-record. Check the playback and decide if the sound is okay.
If you're recording a concert, try to mike close to get the clearest sound. Close miking lets you pick up more of the group and less of the PA speakers. Ask whether you can put your mics on stage; some musicians prefer that you don't. Often the best you can do is sit in the front row, and put your mic stand near you.
You can edit your recordings by copying the desired songs to a digital audio workstation (DAW). This is a personal computer in which you installed a sound card and sound editing software. Using that software, copy the recording onto your hard drive. If you made your original 2-track recording directly on a laptop’s hard drive, just open the file for editing in your editing software.
After editing the program, save it to a stereo wave file. Ideally, you'd send the sound files on a CD-R to a mastering house. If you want to master the program yourself, here are the main steps:
- Import each song mix into a multitrack session, one song per track. Trim the start and end of each mix.
- Add a few seconds of silence between songs (unless it’s a live concert).
- Make the loudness consistent from song to song.
- Use EQ to make the tone quality of each song consistent. Har-Bal (www.har-bal.com) is an effective tool for matching levels and optimizing EQ of finished mixes.
- Note the start time of each song for use in writing a cue sheet for CD burning.
- Maybe apply a little multiband compression to the stereo bus and raise the overall level.
- Peak-limit and normalize the stereo bus.
- If your songs are 24-bit, turn on dithering. Export the mix (the mastered program) to a 16-bit/44.1 kHz stereo wave file.
There's your finished recording, ready to copy to a CD-R.
© 2006 Deltamedia International Inc.
No reproduction in any way without written permission.