STRINGS ATTACHED Recording Strings

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STRINGS ATTACHED Recording Strings HUGH ROBJOHNS The art and the challenge of recording is all about capturing the best possible rendition of the musical performance without colouring the tonal quality of the instruments or swamping their subtleties in undesirable mechanical noises. In this workshop I shall be looking at some of the techniques and pitfalls involved in recording violins, cellos and basses, be it as solo instruments or in the context of quartets and larger string sections. As regular readers will know, one of my hobby horses is that ﬁnding the best position for the microphone is far easier with an...

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STRINGS ATTACHED Recording Strings HUGH ROBJOHNS The art and the challenge of recording is all about capturing the best possible rendition of the musical performance without colouring the tonal quality of the instruments or swamp- ing their subtleties in undesirable mechanical noises. In this workshop I shall be looking at some of the techniques and pitfalls involved in recording violins, cellos and basses, be it as solo instruments or in the context of quartets and larger string sections. As regular readers will know, one of my hobby horses is that ﬁnding the best position for the microphone is far easier with an understanding of how the particular instrument works - in other words, where the sound is produced, how it radiates into the room, and what its fre- quency spectrum is. With that in mind, let’s start with an overview of the characteristics of stringed instruments. The String Family The string section as we know it today — violins, violas, cellos and basses — emerged around the beginning of the 17th centu- ry. Before that, stringed and bowed instruments tended to be of the vertically held viol and lyras da braccio form, the latter super- ﬁcially resembling a modern violin, but typically having ﬁve played strings and two or more drone strings. The early and unwieldy bass violin, also with ﬁve strings, was displaced by the grandfather of the modern four-stringed cello at about the same time. One of the most important characteristics “It is the independent vibrato produced by each member of a string section, all shared by all instruments in the string family with random frequency and phase relationships, which contributes so much is the wide range of tonal colours that differ- towards the rich, full symphonic sound…” ent instruments are capable of producing. This is principally due to the individual qualities of the wood used in their construction, the details of their internal design and the skill and technique of the performer. The basic source of sound is obviously a vibrating string which is encouraged into oscillation by dragging a bow across it. The bow is traditionally formed from horsehair made slightly ‘sticky’ with rosin. The frequency of oscillation is determined by two things: ﬁrst, the tension of the string (set by the tuning pegs or nuts), and second, the length which is free to vibrate. The free length extends between the bridge (towards the bottom of the instrument) and the position of the ﬁngers on the ﬁngerboard which ‘stop’ the string to a desired length. Unlike guitars, there are no frets on the ﬁngerboards, so correct tuning is determined solely by the skill of the performer. However, the lack of frets makes it possible to introduce vibrato on sustained notes with a gentle  rocking action of the hand, effectively alter- ing the length of the string in a cyclic manner. It is the independent vibrato produced by each member of a string section, all with ran- dom frequency and phase relationships, which contributes so much towards the rich, full symphonic sound associated with the best orchestras and string sections — an effect which is hard to achieve by artiﬁcial means. The vibrations from the string alone are far too weak to stimulate enough air to be loud enough, so an acoustic ampliﬁer is employed. The body of the instrument is, in effect, a res- onant box designed and tuned to amplify the sound from the vibrating strings across their working range — hence smaller bodies for higher pitched instruments and larger bodies for deeper ones. String vibrations are passed to the body through the bridge, setting up sympathetic vibrations in the various body panels, as well as in the enclosed volume of air. These resonances are inherently ﬁxed in frequency due to the physical size of the panels and cannot translate with the played pitch, as tends to happen in wind instruments. The tonal character of stringed instruments, therefore, changes from note to note as different resonances are stimulated. Also, since different body panels, and sections of panels, resonate and therefore radiate
sound in different frequency bands, the direction in which the strongest sounds emerge from the instrument also varies with dif- ferent notes (see the diagrams of the polar responses of the violin and cello, above). The nature of the body resonances also has a strong effect upon the harmonic structure of stringed instruments. For example, in the upper registers of a violin, the fundamental of any particular note is generally the strongest component (the highest note being around 2.6kHz). However, in the lower registers the fundamental is typically 20 to 25dB lower than its strongest overtones, which are usually either the octave or the third harmonic. This is primarily because the body is not sufﬁciently large to resonate at the true fundamental frequency. The lowest open string vibrates at 196Hz, with a wavelength of around 0.6 metres. The effect of this weakened fundamental is that the upper strings tend to have a slightly more mellow and fuller sound than the lower ones. The viola is tuned a ﬁfth lower than a violin and so generates frequencies with a wavelength 1.5 times larger (the lowest funda- mental note being 130Hz). However, the viola body is typically less than 1.2 times bigger than the violin, so it has even more trou- ble resonating at the fundamental frequencies of the lower registers. This results in even weaker fundamentals compared with the overtones, the outcome being its characteristic ‘nasal’ quality of sound. The cello is tuned an octave below the viola, with the bot- tom, open C string producing a fundamental at 65Hz. Like the violin and viola, the body of the instrument is poor at amplifying such low fundamentals. The air cavity of the body actually resonates at around 110Hz, amplifying the ﬁrst overtone extremely well. The double bass produces fundamentals as low as 41Hz for a four-stringed instrument and 31Hz for the ﬁve-stringed version, but, as with the cello, the lowest resonance peak in the body (which is the air resonance) is an octave above this. Hence the funda- mental is a relatively weak component of the sound of the lowest strings, and the majority of the sound energy is contained in the band between 70 and 250Hz. In terms of the high-frequency spectrum created by these stringed instruments, the double bass has harmonics which extend to around 2.5kHz and the cello produces little above about 3kHz. The violin can generate surprisingly strong harmonics up to around 10kHz or even higher, but the range of overtones produced by all stringed instruments is strongly affected by playing technique. The length of an open string (that is, one played at its full length) is precisely deﬁned by the nut at the top of the neck and the bridge at the bottom, and so tends to have a richer harmonic structure than a stopped string. However, if the player presses the string harder against the ﬁngerboard, the number and strength of upper harmonics can be increased considerably. The use of the bow also inﬂuences the sound quite substantially: if drawn over the string close to the bridge, the resulting vibra- tions are rich in harmonics, whereas bowing nearer the ﬁnger board gives a softer timbre. Interestingly, the mechanical noise components created by the bowing action are actually a vital element of the sound of the string family and, relative to the harmonic components, can be as much as 25dB stronger than the mechanical noises associated with most wind instruments. Usually, these bowing noises are masked by the harmonic sequence of the played notes but, in the case of the double bass (and, to a lesser extent, the cello) the mechanical noises often extend to higher frequencies than the har- monic content of the played strings, creating an audible and characteristic buzzing effect.  The starting transient of a bowed string is extremely complex, taking 30mS to 60mS to complete, depending on the string. Cello and double bass transients often last as long as 100mS on the lowest strings (higher strings start vibrating quicker than the lower ones). An added complication is that during this transient phase, the pitch of the played note can be up to 20 cents ﬂatter than the ﬁnal steady tone, although it is rarely perceived as such. No wonder synthesized strings often sound such a poor imitation of the real thing! “In general, assuming the circumstances permit, it is best to position string players In terms of dynamic range, a violin can typi- in a relatively large environment which has fairly reﬂective surfaces — and the cally produce sound extending between 45 more wood on the ﬂoor and walls the better!” and 80dB SPL (measured at a rather distant six metres). Unlike wind instruments, the full expanse of harmonics can be retained across this whole range, as they are more dependent on ﬁnger pressure and the position of the bow than the energy provided by the bowing action. The cello has a sim- ilar dynamic range to the violin, although the top strings tend not to be quite as strong as the lower ones, and the double bass is roughly 3dB louder across its whole frequency range. Although the viola can play as quietly as the violin, it can not perform as loudly, peaking at about 72dB SPL at six metres. Recording Strings — The Basics As can be seen from the diagrams of the polar responses of the violin and cello, the large frontal surface of each instrument is the main radiator of sound across most of the frequency range. However, the width of the projected sound beam varies with fre- quency, as does its axis, even emerging predominantly behind the player in some parts of the spectrum! The precise radiation pattern will depend on the nature of the particular instrument, and although the diagrams suggest microphone positions which have been optimised to capture the most uniform balance of the instrument’s frequency range, these should only be taken as a guide. There is no substitute for taking the time to move around the instrument in the studio listening carefully for the position where the optimal balance exists. Indeed, because of their varying polar response, strings afford great scope to alter the balance
of the recorded sound with different microphone positions — for example, to capture a more brilliant, detailed sound, or a smoother, darker tone. In general, assuming the circumstances permit, it is Signal Processing best to position string players in a relatively large String sections normally require relatively little processing. Equalisation may be environment which has fairly reﬂective surfaces — required when close miking, but rarely for the more distant techniques. and the more wood on the ﬂoor and walls the Compression is also rarely required, although this depends a lot on the nature of better! Like most instruments, the sound generat- the music, style of the performance, and the rest of the track’s instrumentation. ed by strings ideally needs space to become prop- Usually, if compression is needed it is just to apply a little gentle squashing to the erly balanced and coherent, so relatively distant louder peaks. Something worth avoiding is trying to bring up the level of quieter miking in a large and pleasantly reverberant room passages with a compressor, particularly when a distant miking technique has been used because the necessary gain make up will tend to emphasise the room is usually an important factor in a successful noise and ambience. Far better to have a word with the conductor to see if the recording. dynamics can be changed by the players themselves. Every recording engineer has their own view on The most common form of signal processing needed is reverb, especially when a the most appropriate mics to use for strings, but close-miking technique has been used, and here it really is a case of matching the most favour condenser microphones. The high reverb to the material. I would tend to favour medium to large room presets, ide- sensitivity permits a more distant placing than ally with a dense, smooth and ‘woody’ quality to their programming. The most dynamic microphones could cope with, and Wooden Room preset in Yamaha’s REV 500 and 03D is very good for this. Try to create a suitable and believable virtual room for the instruments to perform in. the wide frequency response, combined with Decay times need not be very long - perhaps between 1.5 and 2.5 seconds to suit tonal accuracy, suit the complex sound character the music, although longer times up to four seconds can sometimes be useful if of string sections very well. However, take care to you want that ‘swimmy strings’ kind of sound! Whatever you do, don’t go over- avoid condenser mics with pronounced presence board on the reverb level. Most people add far too much reverb in the mix, peaks as they will tend to over-emphasise the resulting in a muddled and imprecise mix. My handy tip here is to bring up the upper harmonics, particularly on violins, produc- reverb return fader until the fake acoustic is obvious, then back it off about 5dB. ing an unpleasantly hard sound quality. The larger professional studios would typically opt for large-diaphragm mics on string sections, such as the Sony C800G valve microphone, the Neumann U47 and U87, or the AKG C414ULS. At the project end of the market there are several large- diaphragm mid-price microphones which would be equally suitable, such as the AKG C4000B, the Rode NT1 and the Audio Technica AT4033a, for example. There are plenty of other microphone models which could be used, as long as you remember that, essentially, the aim is to use a smooth-sounding but detailed microphone — and ideally one which has a very controlled off-axis response so that the room ambience does not become coloured. Large-diaphragm mics aren’t the only way of recording strings, and many engineers prefer the sound of smaller capsule micro- phones like the Neumann KM84, and KM100 series, Sennheiser MKH20 and MKH40, AKG C460, and the Schoeps Collette series. These are all particularly smooth-sounding mics which are capable of capturing a lot of detail too. I have had a great deal  of success with the MKH20 and MKH40 (omni and cardioid respectively), which are really lovely microphones for this kind of application. Some engineers still favour ribbon microphones for string sections, as these share many of the desirable qualities of condensers without the tendency to harshness which some of the latter exhibit. They also almost always have ﬁgure-of-eight polar respons- es, which affords a great deal of control over separation from unwanted spill. However, ribbon mics are notoriously fragile beasts and tend to be relatively rare these days. Recording Large String Sections There is nothing to beat the sound of a full string section. While the London Philharmonic is above the budget of most SOS read- ers, virtually every town has at least one amateur orchestra, and most can turn out a pretty decent sound given half a chance. There is invariably a budding orchestrator in their midst who would probably be only too willing to help translate your ideas into the appropriate notation. There are three basic approaches to recording an orchestra in ‘living’ stereo, and the concepts do not change signiﬁcantly whether you are working with a full complement of musicians, or just a string orchestra. The most difﬁcult solution is ‘multi-miking’ the orchestra, typically using one mic per two rows of violins and violas and one per pair of cellos and basses — all panned into a fake stereo image of your own design! Even if you have enough mics to cover the orchestra and enough inputs on the mixing desk, creating a well-balanced natural orchestral sound from the component parts is no easy feat, although it can be done given the time. There are obviously occasions where multi-miking is the best, or only, solution — such as when working in poor acoustics or with a string section live on stage. The trick is to ﬁnd a good compromise between the inherently unnatural sound quality derived from close mics, and the need to minimise spill from the other musicians. Although often overlooked these days, microphones
with ﬁgure-of-eight polar patterns can be a godsend in this situation as they allow the mic to ‘look’ down on the wanted instru- ments from above whilst rejecting unwanted spill coming in from the sides. Another increasingly popular multi-mic approach is to use bugs. These are usually contact mics temporarily ﬁxed to the bridge of each and every instrument. Of course, this means lots of cables, dozens of desk channels, loads of panning, and plenty of grief because they will never, ever all work at the same time! A recent popular alternative uses miniature electret mics on goosenecks which mount on the bridge, but allow the capsule to be positioned over the soundboard (eg. the Accusound system), or even inside the body cavity through an f-hole. Some live performers have bugs ﬁtted all the time anyway, but they can also be hired from most of the major pro-audio hire companies. As you might expect, bugs give superb separation from spill, but tend to sound pretty horrid in isolation and need a lot of corrective equalisation, not to mention room ambience and reverberation. If the room acoustics and situation permit, I think most engineers would agree that far better results can be obtained by employ- ing a technique which leaves the musical balancing up to the performers themselves, with the mics capturing the collective orchestral sound. The ‘purists’ prefer the classic Blumlein coincident pair, whereas most commercial classical music engineers tend to favour spaced arrays — both techniques have their own advantages and disadvantages for any given situation. The coincident technique involves mounting a pair of cardioid or hypercardioid microphones such that their capsules are aligned vertically above one another, but angled outwards between 45 and 65 degrees from the centre line (this is called the ‘mutual angle’). Altering the mutual angle, polar pattern and distance of the array from the orchestra provides a great deal of ﬂexibility in balancing the perspective, image width and ambience of the recording, although precise details are a little too complicated to go into here. A typical starting point might be with a pair of hypercardioids (my preferred pattern) around three metres above the ﬂoor and perhaps four metres behind the conductor, although this is very dependent on the required image width and per- spective. The coincident microphone technique provides excellent mono compatibility (which is to say that the sound doesn’t change too drastically if the stereo recording is auditioned in mono), and tends to present a lot of precision and detail in the stereo image. Some hold these qualities in high regard. The inherent drawback of the technique, however, is that directional microphones have to be used. All pressure-gradient mics suffer to some extent from coloration to off-axis sounds as well as a limited and uneven bass response. Since the mics are aimed left and right of centre, the middle of the orchestra is inherently off-axis to both mics and this can present problems in obtaining a natural and consistent quality of sound for all sections of the orchestra. The alternative approach involves variations on spaced microphone arrays. The stereo imaging created by spaced mics relies on sound arriving at each microphone at different times which produces imprecise imaging, but a fuller and, to some people’s ears, a more natural soundscape. The technique also favours omni-directional microphones which generally have a very well-extend- ed and smooth low-frequency response, together with near freedom from off-axis coloration. One very common technique is the Decca Tree arrangement, involving three omni-directional mics arranged in a triangle of roughly 1.2 metres on each side and with the central mic forward of the two outriggers. The mics are then panned fully left, right and centre to match their physical positions. Depending on the size of the orchestra, it may be necessary to add further outriggers to reinforce the distant edges.  Since omni mics pick up more ambience than their directional relations they have to be sited much closer to the orchestra — say three metres above the ﬂoor and only a couple of metres directly behind the conductor as a typical starting point. Yet another approach is the ‘dummy head’ idea where omnidirectional mics are placed up to 10cm either side of a vertical bafﬂe (the whole array usually being positioned as for the Decca Tree).The bafﬂe is typically a wooden or Perspex disc of about 25cm diameter (representing the human head) covered in felt to reduce the amount of high frequency reﬂections reaching the mics (which equate to the ears). Although intended for use with binaural headphones, the technique also creates a lovely amorphous string sound on loudspeakers which sits nicely behind foreground instruments without offering any distracting imaging detail. Both of these spaced microphone techniques employ time differences between the channels to relay positional information for stereo imaging and, if auditioned in mono, can often sound coloured or even phasey. This used to be of serious concern to broad- casters in particular, but these days mono compatibility is far less of an issue (try and buy a mono CD player!) Soloists And Quartets Recording string soloists is relatively simple. Choose a recording environment which has a reasonably lively but warm acoustic, select a smooth-sounding condenser microphone, ﬁnd the best-sounding position about two metres above and in front of the instrument, and record it! Naturally, cellists and bassists tend to stay put relative to the microphone as their instruments are spiked to the ﬂoor, but violinists often twist their bodies back and forth as they play. This shouldn’t be a problem with relatively distant miking technique, but when close miking, it often produces tonal variations as the high-frequency components of the sound are directed toward and away from the microphone. The only practical solution is to make sure the musician is aware of the issue… and hit them with a big stick whenever they start to sway! If the recording venue sounds nice, it can be worthwhile recording a soloist in stereo, purely for the natural perspective and ambi- ence. I would personally tend to favour a coincident technique in this situation for its more accurate imaging qualities. However,
if the room sounds horrible, it might be as well to close-mike the instrument and rely on equalisation and artiﬁcial reverb — not ideal, but sometimes the best way of handling a difﬁcult situation. You might even try a commercial bug, or even a DIY bug. I have had some success using an oversized foam windshield to wedge a miniature electret mic into an f-hole on violins or the fretwork holes in the bridges of cellos and basses. It is important to take care arranging the cable so that it does not rattle against the instru- ment body, or could get caught up and pull the mic from its recess. Also, be warned that applying gaffer tape to the instrument in an effort to secure the mic cable may result in sudden death when the owner discovers that removing the tape also dislodges the varnish — Blu-tack is often a much safer bet! A quartet or other small string section can “…be warned that applying gaffer tape to an instrument in an effort to secure a be approached in a variety of ways, most of mic cable may result in sudden death when the owner discovers that removing which are a cross between close-miking as the tape also dislodges the varnish — Blu-tack is often a much safer bet!” described above, and the orchestral miking techniques already discussed. Assuming space and room acoustics permit, good results can be obtained by siting a microphone between 1.5 and 2 metres in front and above the violins. With chamber-sized string sections, try using one mic positioned to the front and above each group of four violins. In a smaller ensemble where a more intimate sound is required, use one mic for each pair of violins, positioned a little closer and aimed more or less between them. The exact positioning depends on the width of the mic’s pickup pattern, and how well balanced its response is to off-axis sounds. Narrower pattern mics obviously need to be located further away than wide-pattern mics. A similar approach can be used for the cellos and basses in a large section, but with one mic covering each pair. Alternatively, try mounting a microphone on a banquet stand raised about 0.5 metres above the ﬂoor (roughly at the height of the bridge), and positioned about 0.6 metres in front of a solo cello. As might be expected, this provides a far more intimate sound. Published in SOS April 1999 
LOCATION RECORDING Recording On Location Cheshire Youth Orchestra Recording a large orchestra can be fairly tricky, even in the most well- equipped of studios, but trying to get a great sound on location, using only the gear you can ﬁt into your car, adds challenges all of its own. MIKE SKEET A 420-mile round trip was required to get to Anglesey, North Wales, where I was to record the Cheshire Youth Orchestra. The 63-piece orchestra was to be in residence at the site for two days of rehearsals before I arrived late on the second day (Friday) with all the recording kit. Saturday and Sunday were to be the recording days, with two sessions per day from 10am to 1pm and from 2pm to 5pm, with a break in each — a very professional approach, which I thought augured well. I had been advised by the orchestra’s manager (and the producer at the sessions), Valerie Hayward, that we were to record in the chapel on the site. I had ascertained that the chapel was relatively long and that the orchestra would ﬁll nearly the whole length and certainly the whole width. Orchestral layouts are very predictable, albeit subject to any restrictions imposed by the plan of a given venue. You have the strings close up to the conductor, with the ﬁrst violins, second violins, violas and cellos spread out from left to right, and with double basses to the rear of the cellos on the far right. Behind the second violins and violas you usually have the woodwind — two each of ﬂutes, clarinets, oboes and bas- soons. Behind these, hopefully on risers, you ﬁnd the brass section — trumpets, trombones, horns and possibly a tuba. Behind these loud instruments, the equally loud percussion section is usually found. At this site, the four players involved had their kit ﬁlling the narrower sanctuary area distant from the conductor — including timpani, glockenspiel, xylo- phone, cymbals and a conventional drum kit. Lone operators like myself usually work with a main stereo pair above and behind the conductor, covering the strings and the rest of the orchestra in general. However, I knew that this particular venue and resultant layout would not be well suited to only having a pair behind the conductor, even though this method can undoubtedly work when there’s an effective tiered setup. I ﬁgured it would probably be necessary to focus on the woodwind with another pair of some sort, and although I suspected  that the sheer volume of the brass would mean they’d need no separate cover, I decided that I should prepare for the possibility that I might need to adjust the percussion balance against them. I packed a ﬁgure-of-eight and a hypercardioid for this purpose, as they could both be set up with their pickup nulls angled to reject the brass — cardioids are not the answer in such situations. Knowing that there was to be a movement from Rachmaninov’s second piano concerto, and also an item with violin and harp soloists, I knew I would also need a moveable stereo pair available, placed in the space in front of the orchestra to help in bal- ancing these soloists. I also included a couple of outrigger omnis in case I wanted to reinforce the left and right extremes of the soundstage. All these mics, and a variety of cables, accompanied three tall stands with booms and one smaller set into a Cavalier saloon. Having enquired that a small separate room was available to monitor in, two stands for a pair of small BBC-designed Rogers LS35A loudspeakers accompanied the mic stands, along with a Quad 405 ampliﬁer. I do not like loudspeakers on tables — I use them up in the air, clear of rear walls and room corners, and having stands on which to place them usually ensures these requirements can be met. The two homemade mixers used for the recording ses- I used one of the mixers I designed and built myself; one with eight chan- sions. The main mixer is on the left, with Frank Fox’s The nels in a briefcase, including talkback, Frank Fox’s The Box visual soundstage Box visual display above it, and the mixer on the right monitor and two Sharp Minidisc recorders. These act as backups to the dealt with the feed from the Pearl DS60 microphone, separate Sony DAT and allow instant playback without disturbing the DAT. allowing it to be used in place of an M&S stereo pair. Also They also provide the producer with a take-home copy of the sessions for in shot are the portable master DAT recorder, backup the edit planning. Minidisc recorders, and Sennheiser HD600 monitoring headphones.
Setting Up On Location The hour and a half up to midnight on the Friday when I arrived at the venue was spent carrying in all the kit, setting up and checking that everything was functioning. For the main microphone I used a unique Pearl DS60, made in Sweden, with its four rectangular capsules — I have a dedicated DIY desk which means I can use it as if it were an M&S pair (see the ‘Middle & Side Mic Technique’ box for details of M&S recording). The woodwind had another M&S pair, comprising a Schoeps CCM4 cardioid and CCM8 ﬁgure of eight, held in place by a neat M&S mount. For balance reasons I favour a semicircular woodwind layout, when I can get away with it — I did so here by mov- ing the music stands and seats around at 10 minutes to midnight, while no-one was looking! The percussion area was covered by a couple of Beyerdynamic ribbon mics in another M&S rig — an M160 hypercardioid cou- pled with an M130 ﬁgure of eight. I like to use ribbon mics with percussion, and the low output levels associated with most rib- bon mics don’t tend to cause any problems with such loud instruments. I was able easily to set up the mic nulls to ignore the brass just behind the mic stand. I usually make sure that I leave some spare mic cable under spot pairs, so that they can be easily moved to suit different works being recorded. In this case, I knew that there was to be a James Bond theme selection, and that I’d have to move the position- ing to suit the drum kit for this. The soloists, near the conductor, were covered with another M&S pair of Schoeps mics, this time with a soft cardioid CCM21 as the middle. Efﬁcient Cabling I had packed a 16-way 75m Klotz multicore, but with the short distances involved I preferred to use separate cables for each pair of mics — if I’d used the multicore, I’d probably have had to saw the centre corners from the doors to the playing area in order to prevent damage to the cable! I exclusively use dedicated four-core 25m cables, with ﬁve-pin XLRs, for each of my M&S rigs, each mic feed using opposite wires of the screened quad. The desks have ﬁve-pin XLR inputs ensuring each pair is correctly connect- ed each time. I had packed eight reels, making 200m in total. An important regime to follow when running cables through an orchestra to your control room is to tape down the cables with white gaffer at sensible intervals. I also use the gaffer tape to protect the cables wherever they pass through doorways which need to be shut so as not to compromise the loudspeaker monitoring. Creating The Best Balance Homing-in On A Soloist The ﬁrst thing I do, during the warm-up at the When it came to recording the piano concerto movement, we had to ﬁnd the best start of the ﬁrst session, is to set the gains and the way to balance the soloist, Fergal O’Mahony, with the orchestra. This involved get- faders for the main pair. For setting up the ting the piano sensibly positioned and employing the soloist M&S pair. There were Middle channel, the conductor will always oblige a number of factors to take into account here, not least that Tim Redmond had to  by rehearsing a loud bit. I try to allow a caution- be able to see Fergal’s hands at some crucial moments. In the end they decided that ary headroom of about 6dB on the DAT, as the the baby grand piano should be to the right of the conductor, in front of the cellos, which meant that Tim didn’t need to turn too far to see Fergal’s ﬁngers. players’ enthusiasm tends to rise as sessions pro- ceed. The piano lid was fully raised and the spot pair was placed 2m from the centre of the strings at about 2.5m above the ground. The level balance and perspective, along The stereo width then needs to be set by the with the apparent width of the piano image, was quickly established as they played amount of Sides mic in the mix. Apart from through the whole of the eleven minute movement. I favoured a ‘slightly to the left’ loudspeaker and Sennheiser HD600 headphone stereo position for the piano, with a width related to that of the orchestra. The spot judgment, I also rely on The Box’s display, which pair was angled to get the slightly left-hand image, this having the advantage that helps reassure me that things are not too wide or spill from the cellos behind and to the right of the piano was captured to the right of centre, coinciding with the main pair’s perception. Conﬂicting spill can create too narrow. You can see its diamond-shaped grid imaging problems, as well as balance difﬁculties. of LEDs at the top of my suitcase mixer in the picture, and a full diamond display is the aim. With the main pair muted I then individually set the gains and the faders for each of the other pairs in the rig. Each also has its width provisionally set. Having got the ball-park settings, the main pair is brought in again and the balance and perspective inﬂu- ence of the other pairs is judged, with levels and widths being trimmed. There is an argument for including time delays in the feeds of ‘spot’ mics, but this recordist remains to be convinced of this when relatively distant stereo spot pairs are used. The dominant source of peak levels will generally remain the main pair and, overall, the balance should give the impression of strings nearest, woodwind behind, brass and percussion behind them. It will be the main mic which will give the more ambient pick-up of the woodwind, brass and percussion — the spot pairs adding focus and clarity in the mix. The producer’s ears also assisted here. Valerie had the scores of the works and advised me on the balance, as this particular engi-
neer can’t (and doesn’t want to!) read musical scores — I take the view that an alternative judgement from a listener’s perspec- tive is a good thing. Finally, once we had a balance, the conductor, Tim Redmond, was invited in to hear a test take. We must have got the sound pretty good, as he felt he could make any further changes merely by working with Middle & Sides (M&S) Mic Technique the orchestra. M&S stands for Middle and Sides, which is a powerful stereo miking technique. Two Taking, Editing & Mastering mics are required. The Middle mic faces the centre of the soundstage, and can be an The four sessions went by without any technical omni, cardioid, ﬁgure of eight, or any pattern in between. The Sides mic faces side- ways to the soundstage, and must be a ﬁgure of eight. The mics should be as close problems. There was some subtle rebalancing and together as physically possible and vertically coincident. mic repositioning, especially for some of the ﬁlm scores. By the end, we had a total of 124 takes When the signals from these two mics reach your mixing desk, the Middle mic is fed recorded on three DATs, with four Minidisc back- at equal levels and in phase to the left and right of your master stereo buss — con- ups. The backups were given to the producer necting it to one channel of a desk and panning it centrally takes care of this. The Valerie, who had to listen through in excess of Sides mic is also fed to the left and right of the stereo buss at equal levels, but with four hours of music in order to plan the editing. the phase of the right channel inverted. This can be done by splitting the mic feed She was assisted in this by Simon Roach, who has to two channels of a desk, panning one full left and the other full right, and having a a degree in recording and who was then to come phase inversion in the right-hand feed. If the desk can’t do the phase inversion, it can be incorporated in the splitter lead. down to North Bucks with the scores in order to guide me in getting the edits right. The level of the Middle mic is decided according to the headroom of your master recorder in the usual way, depending on what is being recorded. On the other hand, The editing program we used was Minnetonka the level of the Sides mic determines the width of the stereo image — it shouldn’t Audio Software’s Fast EdDit, which I ﬁnd quick really exceed that of the Middle mic, and should usually be a maximum of around and tactile to use. The appropriate takes or parts three decibels below, due to its out-of-phase nature. of takes were loaded in as straight digital feeds via S/PDIF from a Tascam DAP1 DAT. After some I have been sold on the use of M&S microphone rigs for years. For a start, you get hours of copy-and-paste editing, involving over instant control of stereo width on your desk, as just mentioned. In addition, the 50 edits within the music, the 16 works were stereo image starts between the loudspeakers, as the centre of the soundstage is focused on axis by the Middle mic — compare that with any crossed or spaced pair assembled in a provisional ﬁnal order. — and the imaging is very clean, clear and coherent, with a depth of perspective. It was not too difﬁcult to come up with an open- Mono compatibility is second to none, as the Sides mic contribution is simply can- ing number, the music from Star Wars, and the celled when summing the stereo to mono, and if you have suspended a pair upside ﬁnal track was to be Ron Goodwin’s 633 down on location, as is usually convenient, ﬂipping the sides of the stereo is as sim- Squadron, with which the orchestra always ends ple as changing the phase-inversion settings on the desk. Another reason I like M&S their concerts. The piano concerto movement is because I can use all sorts of combinations and makes of mic from my armoury — and the other piece with soloists (John Williams’ even the BBC-designed long-ribbon ﬁgure of eight microphone, the Coles STC4038.. music from the ﬁlm Schindler’s List) were spaced  apart in the middle, with the other works between. Each piece was trimmed to about two seconds at the start and about three seconds at the end. Fade-ins and fade-outs were then made, and an appropriate number of seconds of digital silence placed in between — classical music needs around six to 10 seconds between works. Then we sorted out the track IDs, and these were placed at the start of the ambience fade-ins (rather than right up against the music) as is the norm for classical CDs. The mastering technique we used was to output the entire playlist from the S/PDIF output of the editor to an Audio & Design DMM1 digital mas- tering desk. From there it went to two master DAT machines in parallel. This setup allowed the levels of the Minnetonka Audio Software’s Fast EdDit, which was used in compiling and editing the recorded takes into a ﬁnal playlist.
quieter items to be raised manually, making them much more interesting to listen to. Increases of around 6dB were common, with one or two particularly low-level deliveries going up as much as 9dB. By watching the cursor move along the editor’s waveform display we could gently get the level back to 0dB where necessary, thus preserving the impact of the orchestral dynamic range. This ‘musical’ approach is something which cannot be done with compressors or limiters! I had noticed that we might need to add reverberation while on location, but I usually do this after the editing to leave my options open. In this case, I mixed in reverb from a TC Electronic M2000, though the send was ﬁrst passed through a TC Electronic Finalizer in order to add some low-frequency lift and high-frequency cut as a means of warming up the sound. I also increased the stereo width of the reverb send in the Finalizer. Finally, the tapes from the editing session were passed to fellow engineer and producer, Patrick Allen (of Opera Omnia Productions) who discussed it with the conductor, and put ﬁnishing touches to the track ordering, adding a touch more reverb using Patrick’s TC Electronic M5000 system. Published in SOS February 2002 