Capturing dulcet tones from hard-to-record strings.
When I started recording in the late 1970s, it was not uncommon to see a violin or cello as part of a group, whether the music was progressive rock, jazz, or a folkie jam band. These days, most of the string players that come through my Guerrilla Recording studio are not members of a band, but are hired for a particular session and may play on only one or two songs.
When I get advance notice of such a session, I always stress the importance of bringing in musicians that own (or can borrow) good instruments, and that can play in tune and read music. In addition, I advise clients to have well-written charts ready and, ideally, to put in some rehearsal time with the musician in advance.
With this minimal groundwork, even a student-level string player can provide good results in a quick overdub session. But if there is no preparation, be ready to cool your heels for a few hours while the group rehearses, waffles, argues, and/or does take after awkward take before realizing that it has neither the right part nor the right player for the song.
FINICKY LOTMost of the string players I know will freely admit that they and their peers have a reputation for being a bit, well, "high-strung." Therefore, any extra effort that you make to ensure their personal comfort in the studio may well figure into whether you get a good performance.
When the session day rolls around, be sure to have a sturdy music stand, a reliable tuner, good lighting, and a comfy armless chair on hand. Offer the most accurate, smooth-sounding headphones you have available, and start the monitoring level at about half of what your rock 'n' roll clients are accustomed to. Also, if you have more than one recording room available, ask the musician which room he or she would prefer to play in. (In most cases, string players will wisely choose the largest, woodiest, and most reverberant room you have - more on this later.) Be aware that the room needs to be kept at a stable, warm temperature for the benefit of both the instrument and the player's fingers.
SIZE MATTERSOnce all of these preliminary details have been taken care of and your performer is settled in, it's time to put on your engineering cap and review rule number one: as with most acoustic instruments, microphone technique and the contributions of room ambience are crucial components of a great string sound. Particularly with strings, the instrument must interact favorably with the room, and the mic has to capture the subtleties of that interaction without exaggerating any negative qualities such as bow noise or boomy lows.
It's no secret that strings sound best in a big, wood-paneled room, whether it's a concert hall, a parlor, or the barn out back. A small, dead, and/or boxy room will rarely make a string player happy - and an unhappy string player is surely not going to make you happy. So open up the room as much as possible and then spend a few moments in the space listening to the smoothing effect that the room reverberation contributes, especially in the high ranges of the string sound.
Bear in mind that the location of the instrument within the room is another important factor in the recorded sound. Positioning the player near a wall or reflective surface will produce more early reflections, brightness, and immediacy. This excited, short-decay ambience may also be the best way to get a good recorded sound out of a less-than-ideal room. But with this added character comes the possibility of phase cancellation and midrange coloration, resulting from sound waves that bounce off a nearby wall and arrive at the microphone with a short time delay. A softer, more neutral timbre is achieved by putting the player in the middle of the room and miking at a distance that nicely blends the direct tone of the instrument with the room's reflected sound.
FAVORED STATUSTo my ear, the best mic for recording any stringed instrument, regardless of style, is almost always a ribbon mic. My first choice from the Guerrilla vault is usually the Royer R-121 or Coles 4038 (both classic, bidirectional ribbon designs). But even the modestly priced beyerdynamic M 260, M 160 (see Fig. 1), or M 130, or the Oktava ML 19, can outperform prestigious tube condenser mics. The main reason for this is the ribbon mics' inherently soft and high-end response, which works perfectly to alleviate screechiness and bow noise in all members of the string family. Ribbon mics are also noted for their warm low end, and in this application they have a magical ability to "reach inside" an instrument and capture the woody tone. In addition, the bidirectional (or figure-8) pickup pattern of most ribbon mics seems to capture an ideal amount of lush room ambience.
In contrast to the ribbon mics' soft timbre, most condenser mics - even highly regarded tube models - pick up much more high-end "scratch" on bowed strings because of presence boosts and capsule resonances above 6 kHz. Of course, sometimes you need more high-end definition (or pattern control) in an ensemble situation, particularly on jazz bass. Additionally, in some situations the relatively low output of a ribbon microphone is a hindrance, particularly on viola. In these instances I would not hesitate to use a large-diaphragm condenser that is set, if possible, to an omnidirectional or subcardioid pickup pattern for a more natural, roomy tone.
With only one notable exception (a Neumann KM 140 used on a very nice viola), I have not found small-diaphragm condensers to be the best choices for close-miking strings. However, classical recordists generally favor small-diaphragm condensers for distant stereo-miking applications.
As for dynamic mics, models such as the AKG D 112 and the Sennheiser 421 and 441 can produce decent results on acoustic bass. But on the higher strings, dynamics don't offer the full frequency response or sensitivity required for adequate reproduction.
RESULTS MAY VARYEvery stringed instrument sounds a little different, of course, due to a complex set of factors including its construction, age, and upkeep, as well as the current humidity and temperature. Also, the conventions of various musical styles place their own unique demands on both instrument and player. These variables make it hard to predict the best mic placement for a particular instrument. Nevertheless, here are some general guidelines, including tips that can be useful in dealing with any type of bowed string instrument.
DON'T SCRATCH HEREMost violinists want to sound lively and bright but not scratchy. If the instrument doesn't have enough high overtones and "cutting power" at around 3 kHz, it may end up sounding like a viola. And if the instrument has too much high end on the recording, it can be nearly impossible to soften the edges without killing vital ranges of the upper harmonics. In other words, it's best to get the sound right at the mic rather than to count on being able to fix it later.
Start by miking the violin at least 1 foot above the top of the instrument (see Fig. 2). Remember that closer placement with a unidirectional mic yields more low-end (from the proximity effect) and high-end detail, whereas distant placement produces fewer lows, more room sound, and a better midrange blend of the violin's complex harmonics. The low string on the violin is tuned to G below middle C (196 Hz), so you don't need a mic with a big low end for this job.
If the tone of the violin seems thin, angle the mic toward the wide lower half of the instrument's body, by the performer's chin. If you need more highs and/or definition, orient the microphone above the neck of the violin and the narrow upper half of its body. In any case, it's best to avoid placing the microphone directly above the spot where the bow meets the strings, as this position is likely to emphasize bow sound, inhibit the violinist's movement, and/or result in the mic getting hit by the tip of the bow.
If your microphone sounds too scratchy from any position above the top, try miking the instrument from the side - or, as a last resort, from underneath. Though placement underneath will certainly diminish bow sound, be aware that it will also pick up a balance of frequencies that is very different from what the violinist is used to hearing.
Whatever approach you settle on, let the performer hear the first good pass, solicit his or her suggestions, and take advice about the recorded tones seriously. I've learned a lot about these instruments by relying on the players' expertise, figuring that good performers have spent many thousands of hours with their ears right next to the real thing! (By the way, these guidelines are also applicable to foreign stringed instruments, such as the Chinese erhu and the East Indian sarangi.)
OH, FIDDLE STICKSThe instruments may look the same, but the sound and attitude of the fiddle and the violin are a world apart. If you can't tell the difference between the two, ask yourself these questions: Is there a banjo, mandolin, or steel-string guitar in the mix? Is the song about a woman, a truck, or the open road? Is the player drinking beer? If you answered yes to any of the above, you almost certainly have a fiddle on your hands.
The fiddle, a familiar component in numerous forms of American and international folk music, doesn't need much help to cut through the mix. Also, it is generally less dependent on room sound to complement its tone, relying instead on heavy, aggressively accented bowing to make a strong rhythmic statement. This is no background instrument, friends. Get in close for an extra measure of bow sound, and don't be afraid of a little high-end grit. Be warned, though, that fiddlers are more apt to want to stand and move around, especially when they're soloing (which is most of the time).
GETTING CLOSERThe viola is a bit larger than the violin and is similar in shape, with a low note of C3 (130 Hz), which is a fifth down in pitch from its more popular cousin. In the classical repertoire, the viola typically provides rich middle voicings in string quartets and symphonic works; it is not commonly regarded as a solo instrument. Even in the studio, it is usually heard in conjunction with the violin, either adding a lower harmony or doubling an octave down.
In principle, the viola can be miked the same way as the violin, with a few notable differences. Compared with the violin, the viola has a darker tonal character, is not traditionally played as aggressively, and does not "cut" as much. Therefore, positioning the mic closer to the instrument than you would with a violin is usually helpful (if not necessary). Closer miking will yield the multiple benefits of richer lows, a little extra bow sound to aid in mix definition, and a hotter level (which can be a substantial concern in itself). Proceed carefully, though: as you get closer to the top of the instrument, microphone placement becomes more critical because the mic will start to reject some resonant areas and lose the blend of overtones.
The need to mic a viola closely brings up another recording problem common to string players: audible breathing. In an isolated passage or solo, particularly with a relatively quiet instrument like the viola, the sharp intakes of breath (which unfortunately tend to occur during rests) can be very apparent in the final mix. Gating may help in some cases, but the only good solutions I've found are to mic from a different angle, such as from behind the performer's head, or to use a figure-8 or tight cardioid pattern with the null side of the mic oriented at the player's mouth and nostrils. Of course, adding high EQ or reverb in the mix only makes the problem worse, so you'll breathe easier if you deal with this issue in advance.
DEARLY BELOVEDThe cello is one of the most beloved instruments. There's just something about its soothing sound and evocative, human quality that adds a blend of soul and class to any recording. And in the right hands, it can be a wonderfully expressive solo voice.
A world-class cello will have an abundance of desirable sonic qualities, including solid lows below 250 Hz; a rich, woody tone at 400 Hz; a smooth midrange; and clean, clear highs - all focused right in front of the bridge. That's the first spot I usually try, being careful to keep the microphone away from the f holes (because of the excessive low-end buildup that occurs there) and at least 6 inches from the top of the instrument. Moving the mic higher up the cello's neck increases the highs, detail, and proportion of bow sound, whereas lower placement in front of or slightly below the bridge enforces the fundamental tone and reduces scratchiness.
A mediocre cello can give the unwitting engineer all sorts of trouble, including scratchy highs, nasal-sounding midrange at around 800 Hz, uneven lows, and a basic lack of tone due to poor instrument quality and/or an improperly placed sound post. (The sound post is an internal wooden dowel that is wedged between the top and bottom surfaces of any stringed instrument. It must be adjusted properly so that the instrument can resonate evenly throughout its range.)
To get around one or more of these problems, microphone selection and experimenting with placement and distance are key. If you have exhausted those options, equalization can also be used to compensate for defects in an instrument. But a good instrument is surprisingly easy to mic once you find the sweet spot, and it will often yield good results with a large-diaphragm condenser mic as long as the lowest note (C2 at 65 Hz) is well represented and the highs are relatively smooth.
COVERING THE BASSESBowed bass can be approached in much the same way as cello by initially miking in front of the bridge and then carefully adjusting placement and distance to refine the balance of frequencies at the mic. Of course, for many forms of popular music, the bass is played with the fingers (pizzicato, or pizz, pronounced like pits), opening up a whole new world of challenges for the engineer.
The bottom note on this instrument is a low E at 41 Hz, and most good basses have no trouble projecting ample lows to the mic placed close in front of the strings, about 3 to 6 inches above the bridge. The problems I encounter most often with bass recording, even with professional players, are dull sound (or a lack of high-end detail) and booming notes in the low end.
Additional issues worth mentioning here include stereo miking, pickups and amplifiers, and fluctuating tone or level caused by player movement. Due to the size of the upright bass, a single mic may prove insufficient for capturing the "bigger picture" of the instrument's complex range of tones - especially if the instrumentation for the song is relatively sparse or if the bass is prominently featured. In this case, try a ribbon mic near the bridge and a condenser mic (preferably a large-diaphragm model) up above the instrument, aimed downward to pick up "air" and higher-end content from the strings (see Fig. 3). Remember to heed the three-to-one rule, and make sure the condenser mic is positioned so as not to pick up the musician's breathing. (For a more detailed discussion, see "Recording Musician: Recording Upright Bass" in the December 1997 issue of EM.)
Many jazz bass purists frown on using the sound of a pickup, whether routed through a direct box or an amplifier, in the studio. But moderate levels of direct or amp signal can help fill in the high end, stabilize mix level, and add note definition, especially on dense and up-tempo pizz numbers. If I'm taking a direct signal from the pickup, I'll usually roll off quite a bit of high end above 4 kHz, as this range is often unnatural in tone and particularly bothersome to bassists. (Subtractive high-end EQ, combined with a generous dose of reverb, can also work wonders on electric violin and cello tracks.)
After making all the adjustments needed to capture a good bass sound, you'll find that normal side-to-side or back-and-forth movements of the instrument - even as little as 2 inches - can change the balance of acoustic to amplified sound, and can even negate all of your careful miking refinements. Therefore, keep a "watchful ear" on your bassists and don't hesitate to remind them that the tone will suffer if they stray too far from the ideal mic position. A round pop filter is a good visual aid for keeping an animated player "in the zone" (see Fig. 4), and it will also help protect the mic from being hit with the bow.
THE FUTURE IS BRIGHTIn a future column, I will address techniques for recording multiple string ensembles (including classical quartets) and methods of combining live and sampled string tracks as well as esoteric bowed-sound sources ranging from guitars to gongs to blocks of Styrofoam. In the meantime, I hope you will have the opportunity to refine your recording chops on individual stringed instruments, using techniques detailed in this column and those you discover on your own.