Trygg Tryggvason Decca Tree Classical Music Sound Recording

Trygg Tryggvason Decca Tree Classical Music Sound Recording
CHAPTER FOURTEEN
Classical Music
Tryg Tryggvason
It would be pretentious to suggest that an account of recording techniques
could be in any way definitive. Quite apart from the fact that the variables
involved are so manifold as to defy detailed analysis, the results are judged by
aesthetic standards upon which there is, at best, agreement in only statistical
terms. Furthermore, there is disagreement upon what the ultimate aim of the
balance engineer should be. On the one hand, there is the viewpoint that a
performance should be transcribed as nearly as possible to the original –
that is, the sound as heard by a listener at a certain point in the original
location. On the other, it is suggested that a certain degree of artistic licence
is permissible, provided that this results in an improvement in sound quality,
impact, or whatever.
These are necessarily vague terms and, in fact, there is a range of approaches from one extreme to the other; there are occasions nowadays, for
instance, when a composer writes with technical innovations in mind that
can only be achieved artificially during recording. Nevertheless, for the
most part, ‘serious’ music recording is concerned with traditional music,
for which there is equally a sonic tradition, and it is this aspect of recording
that will be dealt with here.
There are essentially two different circumstances in which such music
recordings take place; with an audience present and without. In the first
case, the performance is presented, whether on record or broadcast, as a
unique event, and there is a psychological tendency for the listener to identify
with the audience and occasion. For this reason, it can be expected that the
listener will not judge matters of balance too harshly, in exactly the same
way that it is not reasonable to condemn a performance because of the
odd musical mishap. This is perhaps as well, as the engineer’s control over
positioning, microphone layout, and other factors is extremely restricted.
It is natural that the listener should expect the perspective of the balance
to reinforce his identification with the audience, and the effect of his involvement in the occasion in terms of his expectations of sound quality
should not be underestimated.
Classical Music 211
However, these observations do not apply equally to recordings made
under session conditions. For the listener, the performance tends to assume
an abstract, timeless flavour, and the actual location may well be unknown
to him. When he selects and plays a record, the performance is for him alone,
in his listening room, and there is no atmosphere, such as audience sounds, to
encourage an identification with the audience in a concert hall. The direct
result of this is a more critical attention to aurally perceived detail, and a
heightened sense of dissatisfaction with any imperfections, particularly
with repeated playing. For these reasons, there arises the need to transcribe
the performance in terms of the recorded medium, with the objective of
idealizing the sound quality in the hall, under listening room conditions.
The mere fact that nearly all recordings nowadays, including those made
with coincident stereo microphones, are made with the assistance of spot
microphones is itself demonstrative of the fact that there is general agreement on this principle, and it follows that any attempt to evolve an ideal
microphone technique theoretically is quite irrelevant to the business of
making records.
Microphone systems
As the usual technique of music balancing is to obtain an overall stereophonic sound image from the main microphones, and to reinforce this as
necessary with spot microphones, it would be as well to examine the two
commonly adopted systems. These are the familiar coincident pair, and the
less well-documented spaced microphone system, both of which can yield
sound of very high quality.
The coincident pair, or stereo microphone, relies on two directional
microphones angled respectively to the left and right, to reproduce the
sound waveforms that would have impinged upon the ear, at a certain point,
from the left and right directions. In spite of the fact that the two signals are
reproduced via two loudspeakers, thus introducing significant cross-talk,
the stereo image produced is excellent, and positional definition outstanding.
Provided that they are used at a reasonable distance from the performance
area, all sources are evenly and realistically picked up, and the close proximity of the two capsules to one another results in negligible phase discrepancy
between them, which accountsforthe positional stability. Any polar response
may be used, subject to certain limitations, but obviously an omni-directional characteristic results in near-mono; some stereo microphones are
equipped with infinitely variable polar characteristics, which may be changed
remotely from the mixer. The two capsules may be angled with respect to
one another and this angle can be chosen to give the desired stereo width
or angle of cover.
272 Sound Recording
The sum and difference signals may be separated electrically, and the
magnitude of the difference signal varied with respect to the sum. By using
this technique, the capsule mutual angle may be set to around 90° to 120°
and width, as well as polar patterns, may be remotely controlled. The larger
angle reduces the risk of degeneration of centre sources as a result of microphone non-linearities off-axis. These facilities make the stereo microphone
invaluable for the recording of live performances in particular; it is unobtrusive and, apart from its initial placement, all manipulations may be
effected from the mixer.
It is not proposed to deal extensively with stereo microphone parameters
here, as they are adequately dealt with in Chapter Thirteen. A cursory
glance at the effective parameters for an included angle of 90° will suffice
to illustrate some observations on their effectiveness in recording.
The polar diagram for the figure-of-eight position is illustrated in Fig. 13.10,
The available angle of cover is 90° at the front, The side quadrants are out of
phase, and therefore not useful. The rear 90° quadrant is useful for reverberation pickup but is in antiphase to the front signal.
In the cardioid position (also shown in Fig. 13.10) the available angle of
cover is 270°, but is generally restricted to the front 180° to avoid any off-axis
non-linearities. The rear 90° is insensitive.
The hyper-cardioid pattern gives a covered angle of 130° at the front;
the side 90° angles are out of phase, and the rear 90° quadrant is not really
useful as the rear hyper-cardioid lobe is small.
Showing how the changing sensitivity of a
directional microphone (a cardioid in this
example) can be used to discriminate between
forward and rear sections of the performance
area
It will be clear that changes in the microphone position, as well as its polar
response, will affect both the stereo width and the reverberation content in
the signal. Furthermore, as the figure-of-eight pattern has the rear quadrant
in antiphase to the front, there can be a certain cancellation of bass reverberation components, which is undesirable. For this reason, that pattern
is not favoured and the remaining patterns, of course, discriminate to some
extent against natural reverberation.
Remembering that polar patterns should be thought of as solid, obtained
by rotating the pattern through 180° on its own axis, a certain degree of
Classical Music 213
discrimination between forward and rear sections of the performance area
may be obtained by tilting the microphone, as shown in Fig. 14.1.
The interdependence of the parameters, together with the fact that the
entire performance area is covered by only two microphones, effectively
means that little control over details of balance within the performance
area is afforded the engineer, and it can be difficult to optimize one parameter without adversely affecting another. It could also be argued that the
discrimination against reverberation may compel the engineer to work at a
greater distance from the source than he would wish, or to reinforce reverberation
with
separate
microphones
for
this
purpose.
On occasions, when recording larger ensembles, the main pickup image
may be reinforced with two omni-directional or cardioid microphones on
the left and right flanks.
Spaced microphone systems
In this approach we are effectively sampling the sound at various points
across the stereo stage, and recreating the wavefronts between the loudspeakers by panning each microphone to a position corresponding to its
physical location. A typical system is illustrated in Fig. 14.2.
Complaint is frequently heard that such a system results in unacceptable
phase ambiguities and, while there is a certain amount of truth in this, a
careful attention to the geometry can minimize the effect, and positional
definition can be very good. The microphones used are omni-directional
types, but they should nevertheless be carefully angled towards the area
that they are intended to cover since most omni-directional types are, in
fact, quite directional at higher frequencies. The central three microphones
are the most important, and should be thought of as a single stereo system;
a correct balance between them must be maintained, as this is fundamental
to correct overall balance and any fader adjustments required are therefore
made equally to all three. The extreme left and right microphones are used
only as a reinforcement of the outer wings of large ensembles.
There are several major advantages offered by this technique. The omnidirectional polar pattern results in a higher and more natural reverberation
pickup than is achieved by directional types; it is interesting to note that
Fig. 14.2
Use of spaced omni-directional
microphones for stereo
214 Sound Recording
these pressure sensitive transducers function on the same principle as the
ear itself, unlike the directional family. This enhanced reverberation sensitivity
effectively means that it is possible to work closer to the source than with
cardioids, for the same reverberation content, resulting in clarity without
excessive immediacy; indeed, the relatively close working distance of 3 to
4 metres (9 to 12 feet) is essential to take full advantage of the high frequency
directional characteristic. It also offers the added benefit that level differentials,
between similar signals received by more than one microphone, tend to
swamp any phase ambiguities. The fact that the microphones are separated
permits quite subtle but worthwhile adjustments to suit each occasion.
Layout is rather critical and unique to each situation much of the work
being done in placing the instrumentalists themselves, after which the
precise microphone placings may be attended to.
These, then, are the two systems in general use; each has its own applications and merits but, for the purposes of records, the spaced system appears
to offer important advantages. Were the coincident system able to offer
higher sound quality than this technique, the loss of control could be
tolerated, but there is no evidence that this is the case; even if the positional
definition is marginally superior, it is considered that the sound quality of
the omni-directional microphones, together with the creative flexibility of
the spaced system, far outweigh this. It is, in any case, open to serious
question whether the integrity of the coincident system can be preserved
at all when spot microphones are used in addition to them.
In the examples which follow, the spaced technique is used exclusively,
but most of the discussions remain valid if a stereo pair is substituted for
overall pickup.
Preparations
It is of great value to study the material to be recorded thoroughly before
the actual session, with a view to forestalling any technical problems which
might arise, The manner in which a piece is written can provide valuable
information as to the optimum placement of musicians for stereo, and it
will be found that the usual positions taken up by the musicians in performance are by no means always ideal for stereo recording. Clearly, it will
be important to create a stereo image in which there is a reasonably balanced
activity across the sound stage, and an examination of the score can often
suggest a suitable layout. Furthermore there may be artifices required,
particularly in opera, which require substantial technical preparation.
Fader work may also be necessary at certain points, for which a cue would
be very useful, and such areas of likely difficulty may be noted in the score,
so enabling the producer to give the necessary cue during the session.
Classical Music 215
The criteria by which a suitable location for a recording is chosen will
not be dealt with in detail here. It should be stressed, however, that a good
and complementary acoustic is the most fundamental requirement for
music recording, without which all subsequent operations are necessarily
compromised. Finding a really good hall, which does not suffer unduly from
noise or other problems, can easily be the single most time consuming factor
with which the recording team must deal; a useful source of information,
in an unfamiliar area, can often be the local fire service, who will be able to
point out the halls of any size that could be suitable.
Usually, a great deal may be learned of a hall’s acoustic qualities by ear,
with the aid of a few judicious handclaps and shouts. Most traditional music
appears to be best complemented by an acoustic having a reverberation
time of between 2 and 2-5 seconds, with a reasonably even decay throughout
the frequency spectrum. Figure 14.3 shows the reverberation/frequency
curves of an excellent recording hall; the increase in reverberation time
Fig. 14.3
Reverberation/frequency curves of a
typical hall often used for recording
towards the bass end is a recurring characteristic of the better halls. Naturally,
it is important to ensure that there are no unpleasant slaps, caused by standing waves between parallel surfaces in a hall.
Much thought must be given to the question of space and layout as, with
multi-microphone techniques, clarity and separation can be obtained only
if it is possible to locate musicians in such a manner that crosstalk between
microphones is minimized; a large, unobstructed floor area is therefore
important. In the case of large scale recordings involving orchestra, chorus
and soloists, accessible balconies and a stage of some kind can be most
helpful, as a set-up of this kind could become extremely cluttered if all the
musicians are at the same level; in particular, contact between sections
could be very problematic.
Turning to the question of microphone types, it must be said that this is
largely a matter of individual preference. Microphone technical specifications,
although valuable, tell us nothing of their sound quality, and microphones
with not obviously dissimilar specifications can sound markedly different.
The main microphones are naturally the most important; in the case of
216 Sound Recording
stereo types, many possibilities exist as, of course, any pair of directional
types may be used. The quality of the Neumann SM69 is excellent, as is
that of a pair of AKG 414 types. For the spaced system, the Neumann M50
is an old favourite, and the KM83 is also very good. Other types may well
yield convincing results, but it is important that they should become somewhat directional at high frequencies.
Spot microphones must usually be cardioid, in order to achieve separation,
but omni-directional types may sometimes be used if well separated from
other performers. The Neumann KM84 is an excellent general purpose
microphone, and some engineers favour also the AKG 451. For some percussion instruments, the Neumann KM88 appears to offer an appropriately
incisive quality. Sometimes it may be necessary to compromise to some
extent in the choice of microphone because of limited availability; if this is
necessary, it is obviously best to do so in some minor area, where the effect
of the particular microphone is minimal.
For the most part, capacitor microphones are used but occasionally
moving coil or ribbon types are selected, either because an engineer has a
particular preference for such a microphone in a certain application, or
where one is pressed into service for a detail effect, in the absence of a
capacitor type.
It is essential that all microphones are connected in the same phase, and
a convenient way of checking this is to use an oscilloscope Lissajous display. The ‘scope is switched to ‘external X’, and an oscillator applied simultaneously to the X and Y inputs, to establish the phase of the instrument
itself. Some oscilloscopes will display a line sloping upward from left to right,
but many indicate the opposite slope, upward from right to left. Whichever
is displayed represents the in-phase direction. The X and Y sensitivities
should be adjusted to give a 45° slope. The instrument can then be connected with the left signal to the X input, and the right to the Y input.
Fig. 14.4
Types of oscilloscope
display produced by
different amounts of
phase shift
If we assume the in-phase display to be as in Fig. 14.4a, any in-phase signal
monitored will be thus displayed. Progressive phase shift of one channel with
respect to the other causes the display to change as in Figs. 14.4b, c, d and e,
according to the degree of shift, providing that sine tones are used.
Thus we have a visual display of relative phase between left and right,
which gives an immediate indication of stereo image width and phase.
Classical Music 217
Naturally., a stereo music signal will be indicated as a ‘splash’, but this should
be discernibly ellipsoid in the in-phase direction, as in Fig. 14.5. If it is ellipsoid
in the other direction, then this indicates an out-of-phase connection at
some point. If the signal is panned towards mono centre, the ‘splash’ will
narrow in width until finally it becomes a straight line.
Fig. 14.5
Ellipsoid shape of oscilloscope trace during
music with microphones properly in phase
It will be evident that the relative phase of a pair of microphones may
easily be checked, using this instrument, by placing them close together
and observing the display. In addition to this, however, the instrument gives
a visual display of many parameters simultaneously; apart from left-right
balance, phase and stereo width, excessive use of spot microphones and
frequency dependent phase problems, resulting from poor layout, are immediately obvious. It is therefore worthwhile to have a Lissajous display
available throughout a recording session, by connecting an oscilloscope to
the left and right signals as described.
We have so far examined some of the more important aspects of recording
in very general terms, and can now proceed to an examination of some
particular examples. The only justification offered for the approaches described is that they have been used successfully, and the results have withstood the test of general critical scrutiny.
Solo performers
There is little difficulty in recording most solo instruments, as there can be
no conflict of interests in the choice of microphones or placement. Microphones of any characteristic may be chosen, according to taste, and used
in pairs to render the random phase reverberation stereophonically. Whilst
a coincident pair may perfectly well be used, there is really no need to angle
the two microphones at all; for example, a pair of omni-directional microphones placed a foot apart, and both pointing at the source, can produce
a richly stereophonic image, as a Lissajous display will show. As the significant
218 Sound Recording
stereo information is contained in the reverberation, the phase difference
at the two points is accepted by the ear as stereo information, and the
direction from which it emanated is unimportant; in these circumstances,
there is a good case for keeping the source on the microphone axes. Omnidirectional types would normally be chosen for their natural quality and, if
it were necessary to resort to directional types, this would tend to imply
that the acoustics were not really suitable.
There may be occasions when it is desirable to create an atmosphere of
space in a solo recording; for example, a solo vocalist may be required to
sound in a rather operatic perspective. This may be achieved by placing a
main microphone system at some considerable distance from the performer, and obtaining focus by the use of a pair of spot microphones, rather
as though the main system were placed to cover an imaginary orchestra.
Singers, generally, are extremely variable in their vocal power and the
differences in the optimum distance from the microphone can be very
considerable. Unfortunately, the closer that it is necessary to work, the
greater become the dynamic variations from the microphones, particularly
between low and high notes, when there is any tendency to dynamic unevenness in the voice itself. There are vocalists who, on certain notes, peak
perhaps 6-8 dB above their average level, and it may be exceedingly difficult
to focus the lower registers without being in constant danger of sudden
overmodulation. In the worse cases, the only answer may be a pair of limiters
with a fast attack time, but matters are rather serious if one is forced to this
resort, which is always to be discouraged. In most circumstances, the voice
is followed on the faders, with the assistance of cues from the producer, and
a good memory!
Some vocal qualities benefit from gentle equalizer assistance, particularly
the rather ‘edgy’ quality encountered with some voices, but it is important
not to turn too readily to equalizers to solve problems, when better solutions
might be found in other areas. It may well be, for instance, that a slightly
different microphone placement, or the choice of a different microphone,
will provide a superior improvement.
The piano is notoriously difficult to record, but again an omni-directional
pair is recommended. Tastes seem to differ widely here, and very different
qualities of sound may be obtained, both by placement of the microphones
and the position of the instrument itself. Experience has shown that different
artists playing the same piano, under identical conditions, may require
different microphone placement to be adopted, and changes in repertoire
often suggest complementary balance changes. Furthermore, the sound
quality of individual instruments, even of the same manufacture, is enormously
variable.
Classical Music 219
All these factors should be borne in mind when seeking a balance, and a
constantly experimental approach is likely to be the most successful. It can
also be very helpful to keep a note of the serial numbers of the various
instruments encountered, and their individual tone quality, so that it may
be possible to obtain one that is known to be good, for subsequent recordings.
Figure 14.6 illustrates recommended microphone positions. Towards the
middle of the piano case, the sound quality is quite bright and it generally
becomes warmer towards the tail end; the exact position between these
extremes may be varied according to circumstances. Worthwhile improvements may be obtained by moving the microphones only a few inches one
way or the other and, by exercising a little diplomacy, most artists may be
persuaded to co-operate in allowing sufficient balancing time without
becoming too impatient.
It is a simple matter to arrange alternative types of microphone simultaneously, in closely grouped pairs, to evaluate the differences in their
sound qualities, and it may even be found that two pairs, of different types,
offer some enhancement of quality when used simultaneously.
Fig. 14.6
Alternative positions for a pair of microphones
for the piano
Chamber music
There are, of course, very many different kinds of ensemble under this
heading, and a beginning can be made by considering the string quartet
or quintet. As with any relatively quiet music, one of the greatest problems
is finding a location which is both acoustically appropriate and free of excessive ambient noise. Really good halls are, in any case, hard to find and one
is fortunate indeed if there is no difficulty with extraneous noises such as
traffic, trains, or aeroplanes, to name a few regular offenders. Even in relatively secluded locations, there may be a great deal of noise from wind,
rain, or even birds. When assessing a possible hall, therefore, any such
noises should be listened for and investigation made of the feasibility of
eliminating them at source. Low frequency noise may be reduced to some
extent by the use of steep cut bass filters, provided that care is taken to ensure that they do not significantly affect the recorded sound quality.
There is little point in placing microphones on individual instruments, as
it is usually important to preserve the intimate character of this kind of
220 Sound Recording
Fig, 14.7
Use of three omni-directional microphones for
a string quartet
music and to avoid any suggestion of sensationalism. The stereo trio of
microphones described earlier can be arranged to cover the group, at a
height of between 2-5 and 3 metres (8 and 10 feet), and the instruments
arranged around it as shown in Fig. 14.7. Finer points of balance may then
be dealt with by moving individual instrumentalists rather than microphones.
In practice, the best grouping may be rather more widely spaced than is
usual for performance, to obtain clearly defined positional information in
stereo; the difference is not great and most musicians adjust comfortably
to it.
In the case of music involving a piano with other instruments, it may be
difficult to control the powerful piano sound in relation to the other instruments. If there are several other instruments, such as in a piano quintet,
the arrangement shown in Fig. 14.8a is safest, presenting the dead side of
the piano to the omni-directional trio on the strings. If, however, there is
only one other instrument, the arrangement in Fig. 14.8b is more satisfactory.
It is possible to use a pair of cardioid spot microphones on such an instrument, discriminating against the piano to some extent. With a little care,
adequate separation may be achieved, the omni-directional pair on the
piano providing most of the bloom. Thus an intimate, integrated sound can
be obtained, whilst at the same time preserving the all-important aural
contact between the musicians.
Fig. 14.8
Possible arrangements for chamber
music with piano: (a) a piano quintet,
and (b) a solo instrument sonata
One factor which is not always considered is the quality of the piano itself.
Apart from the differences between those of different manufacture, there
may well be a case, in some circumstances, for using a rather smaller piano
than the usual full-sized concert grand.
Early secular music can turn up a very large range of instruments, many
Classical Music 221
of which are very quiet, and there may be little relevance in attempting to
create a concert balance; much of the material is very intimate and personal,
and not greatly enhanced by reverberation. The usual omni-directional trio
may therefore be used at a considerably lower height, and very close spot
microphones may be required on some instruments. In such cases, difficulty
may be experienced with finger noises on plucked instruments, or breathing
noises, and optimum microphone positions may be found by standing near
each instrument whilst it is being played, and listening at different points.
The very high degree of amplification required for some instruments can
make the slightest ambient noise obvious, but this is offset to some extent
by the fact that bass filters can be used at higher cut-off frequencies than is
possible with the more modern instruments.
Orchestral music
As with chamber ensembles, a good physical layout is of fundamental
importance and the recording team should set out all seats and music
stands before the arrival of the orchestra. A typical layout is shown in
Fig. 14.9.
Fig. 14.9
One possible arrangement of microphones for a symphony orchestra
Note that the individual string sections are well defined, and the omnidirectional main microphone system arranged so that each microphone
has a definite duty area for which its placement is optimized. It is very
important to provide depth as well as width in the layout, as this will be
reflected in the stereo sound, giving a natural perspective to the orchestra
and a good body of strings in the central area, as well as at the sides. The
basses are best kept well back from the main microphones, and provided
with their own omni-directional spot microphone to locate and clarify
them.
The woodwind layout may be varied according to numbers, and it can
be advantageous to arrange them in two rows, if they are many. It is not a
good thing to place them too far back, as they should be well represented
222 Sound Recording
through the main microphones, whilst some control over their relative
balance may be achieved, without destroying their perspective, by means
of a fairly high pair of cardioid spot microphones, as shown in the diagram.
Incidentally, it is worth noting that the use of spot microphones in pairs,
wherever possible, affords the opportunity of creating stereo images for
sections, rather than relying on a conglomeration of mono panned signals.
The positions of the horn and brass sections, still farther back, may be
interchanged as musically appropriate, but the left position for the horns is
usually chosen as, in this position, their bells are pointing away from the
rest of the orchestra, reducing the risk of their sound quality ‘swimming’.
The use of cardioid microphones, focussed on the bells from the rear of the
players, can enhance the quality of their sound but they should be used
discreetly in order to avoid distorting their perspective. The brass section,
being comparatively powerful, can often be placed in such a manner that
spot microphones are unnecessary; their sound quality is entirely dependent
upon an adequate and focussed main microphone pick-up, and details of
balance may often be dealt with by asking the players themselves to change
their dynamics.
Percussion and timpani may be placed more or less as desired at the back
and sides of the orchestra, the arrangement shown in the diagram being
one commonly adopted possibility. In the case of timpani, a pair of cardioid
spot microphones may be better than one, if there are more than two
instruments used, and a suitable position is above the skin, but not over the
centre where the sound quality is not particularly good. A recurring problem
is a certain thick quality in the timpani sound, which is more a consequence
of the omni-directional technique than anything else. Nevertheless, matters
can often be greatly improved by asking the player to use harder sticks. It is
in cases like this that an ability to relate amicably with musicians is of
paramount importance. Co-operative players may often take an active
interest in their recorded quality during a session, and adjust their technique
accordingly, should this be beneficial.
Similar considerations apply to the rest of the percussion section; the
dynamic latitude in recording is not as great as in performance, and any
corrections necessary must be made by the musicians. Provided that the
dynamics are kept low enough, good detail control over the sound quality
and dynamics should be available, using spot microphones. A further useful
observation is that percussion instruments are frequently bunched together,
to keep them within the reach of a single player. It may be more appropriate,
for stereo, to spread them more, and it may be necessary to be aware of this
well in advance, so that additional percussionists can be made available at
the time of the session.
Classical Music 223
One aspect of recording technique which is well worthy of attention is
the choice of orchestra size. While composers sometimes specify this
precisely, and in other cases it is governed by tradition, it should be remembered that these directives relate to live performance. In the recorded
medium, an orchestra can often sound far larger than it actually is, depending
on the acoustics, and numbers should be chosen with this in mind; authenticity is of little value if the quality of the end result is degraded by the thick
quality characteristic of excessive numbers.
Harpsichord continuo presents an interesting problem; correctly balanced,
it is barely audible – it has been said that one should not hear it but, if it
were missing, one should miss it! For this reason, it is best positioned towards
the rear of the strings, possibly near the basses with which musical contact
is often important. A cardioid spot microphone, placed under the body of
the instrument, can be used for fine control of quality.
Concertos, naturally, demand that the solo instrument be placed at the
front, close to the main microphones; a pair of cardioid spot microphones
can be used to focus the instrument, although omni-directionals can be
effectively used if desired, provided that they are well separated from the
orchestra. It is as well to give consideration to the question of what degree
of soloist dominance is required well before the session, in conjunction with
the producer and artists. Some concertos are very soloistic, with the orchestra
in very much an accompanying role, whereas others are more symphonic
in structure; such differences should be reflected in the balance, and can
be adjusted by means of alterations to the soloist’s proximity to the orchestra,
and appropriate use of his spot microphones.
In conclusion, then, the fundamental balance in orchestral recordings
should be obtained through the main microphone system by means of
sensible positioning and internal balance; any attempt to correct a deficiency
in these areas by means of spot microphones is a certain recipe for disaster.
Opera
A few observations were made at the beginning of this chapter about the
fundamentally different listener conditions pertaining respectively to the
recorded medium and live performance. It is in modern opera recording
techniques that these principles reach their highest development, in terms
of traditional music, for it becomes the clear duty of the recording team to
utilize every available technological artifice creatively, to compensate the
listener for the absence of the visual element, and the consequently depleted
dramatic impact. There are nearly always stage movements in the action
which must be convincingly rendered in stereo; in addition, there may be
various effects, such as off-stage events, which require imagination and
224 Sound Recording
meticulous preparation if they are to succeed without the aid of the visual
factor.
The cost of recordings on this scale can be enormous, and the scheduling
extremely tight. Artists are ever-increasingly internationally mobile, and plan
their commitments sometimes years in advance; key singers may be available
only on a very few specified sessions, during which their performances must,
at all costs, be safely recorded. As a consequence, it is always vitally important to ensure that no time is unnecessarily wasted. The producers and
engineers normally spend lengthy sessions in consultation, long before the
recording, planning the technical and artistic approach to each session.
Often, apart from the main producer, a second producer will remain on the
stage during the recording, co-ordinating the activities of the soloists, with
the aid of a marked-up score and telephone contact with the control room;
there may well be two balance engineers also, one dealing with the orchestra,
and the other the voices. Clearly, a good working relationship between all
involved is of primary importance.
Technically, in order to provide a degree of insurance against balance
imperfections, a multitrack master is taken simultaneously with the stereo,
with such areas as orchestra, soloists, chorus and off-stage locations on
separate pairs of tracks; this also enables the engineers to meter the individual sections as required. However, the aim is to obtain a stereo master
Fig. 14.10
Opera recording in an outside location where three ofi-stage sub-areas
are used, helped by TV cameras and
headphones or speakers
Classical Music 225
in the first instance, and it is therefore this signal which is monitored. Any
reductions which might be required can then be edited, as necessary, into
the stereo master which remains mostly first generation.
Remembering that the recording may be spread over several weeks, or
even months, and that it must be possible to inter-edit the tapes, the entire
technical arrangements must be meticulously logged, so that they can be
reproduced exactly at any subsequent time. In particular, for any session
subsequent to the first, the tape machines should be lined up to the frequency run made during the first session, rather than the standard alignment
tape; this is of paramount important when noise reduction systems are
used.
It has already been mentioned that good recording halls are hard to find
and, in the case of opera, this problem is further augmented by the large
numbers of performers involved and the consequently high sound levels.
The absorption of the performers themselves, together with the enormous
climaxes which occur in some works can result in acoustic saturation of the
hall. This., of course, degrades the apparent reverberation time and adversely
affects the stereo perspective.
In order to overcome these problems, in the absence of more suitable halls,
it has become necessary to exploit existing locations to the utmost, with
the aid of the increasingly sophisticated machinery available.
Figure 14.10 illustrates a set-up in which the available resources of a location
have been exploited in this manner. Three off-stage locations are used, all
of which are in contact with the conductor by means of closed-circuit
television; the musicians are able to hear the main orchestra by means of
foldback feeds from the mixer. Artists may become somewhat alarmed
when these arrangements are suggested, but usually they will co-operate
happily once the advantages are clear to them. While it may be perfectly
possible to achieve the effect required by means of suitable placement
within the main hall, the distance between the off-stage groups and the
main orchestra may well lead to ensemble difficulties as a result of the time
taken for sound to travel between them; the foldback arrangements, of
course, allow all the musicians to hear the main microphone signals. In
addition to this, it is likely that the television picture of the conductor will
be a good deal clearer than the view an off-stage musician might expect
to have in a cluttered hall.
The recording benefits are, of course, enormous; full attention, in terms
of microphone technique, may be paid to each group, without the problems
of crosstalk between microphones, and full advantage can be taken of the
acoustics of the individual locations. Each group may be recorded on separate
tracks of a multitrack machine, to provide for any balance alterations which
226 Sound Recording
may be required later, and their individual autonomy permits the engineers
to place them, spatially or in perspective, in any manner of their choosing.
For larger off-stage bands, it has proved more efficient to use a subconductor to control the ensemble of the group, relaying the main conductor’s beat with the aid of closed-circuit television and foldback; it is
usually quite in order to use a small loudspeaker in place of the headphones,
if this is preferred by the artists.
In the main hall, the orchestra may be laid out more or less as described
earlier, and the stage and chorus sections placed typically as shown in Fig.
14.10, at some distance, and with their own spot-microphone arrays. While
separation is obviously important, it should not be sought to an extreme
degree, as the sound quality of both the stage and chorus sections is dependent upon their adequate representation through the main microphones;
their spot microphones are used to clarify and focus them, but should never
dominate. It is usually helpful, in the interests of musical contact, that all
the vocalists should be raised relative to the orchestra and, to this end, it
may well be necessary to have temporary stage areas or extensions built for
the recording,
The question of stage movements requires some thought and, while it is
possible to achieve this to a certain extent by means of the pan-pots, it is a
rather dangerous method, as the electrical positioning may conflict with the
information given by the main microphones. Usually, the necessary moves
are noted in the stage producer’s score, and he can thus prompt the soloists
to make the moves physically at the correct time. The main producer should,
however, simultaneously prompt the balance engineer, in order that he can
track the moving voice on the faders.
Occasionally, dynamic changes in the vocal quality of a singer might be
required – usually taking the form of a recession into the distance, or vice
versa, Sometimes this kind of change can be satisfactorily achieved by
arranging that the singer moves in relation to his spot microphone, but
frequently, an echo chamber or plate, used exclusively on the particular
voice, can be the most effective solution.
It falls to the producer to co-ordinate the activities of the large number of
participants, in various locations, and this task, in itself, can be formidable in
view of the inevitably high ambient noise between takes. By providing comprehensive talk-back and telephone communications to all locations, from
the producer’s desk, this problem can be greatly eased and, where the facilities are available, closed-circuit television monitoring of the various locations
can be of enormous benefit. A further communication refinement is the
provision of talk-back facilities from the conductor to the stage and chorus
areas, in order to improve the clarity of the conductor’s directions to them.
Classical Music 227
At the mixer, the orchestra section provides the basic sound field, and this
is therefore usually attended to first. Subsequently, the various other locations and sections can be balanced separately within themselves, before an
integration of the overall image is attempted. A really good understanding
between engineers is essential, if fader creep – the process of always increasing the level of the weaker section rather than reducing the excessively
strong one – is to be avoided.
One of the great benefits of using multitrack machines is the possibility of
adding new material subsequently to the main recording. The very considerable scheduling problems have already been mentioned, and there is the
ever present risk that an artist might fall ill at the crucial time when he is
required, and re-scheduling may well be prohibitively expensive. However, it
is quite possible to record the main material in the absence of the indisposed
artist and, at any convenient time later, record the missing information on a
vacant pair of tracks on the multitrack machine. The previously recorded
orchestral tracks may be sent, via the sel-sync facility, to a pair of headphones or a small loudspeaker, and the artist is thus able to synchronize his
performance to the main material. It is by no means easy to record the
orchestral tracks in such a way that ‘space’ is left for the new part, and care
is also necessary to avoid imparting an unnatural prominence to the overlaid
voice. Any shortcomings in this respect will sound offensive, quite apart from
completely giving the game away! The microphone technique adopted for
superimpositions of this kind requires a little thought; in order to render the
artist as he would have been recorded had he been present at the original
recording, it is necessary to simulate the crosstalk between microphones
that would have occurred. It is therefore important to set up the main
microphones, in roughly the position that they would have occupied had the
orchestra been present, in addition to the usual soloist’s microphones.
Naturally this technique need not be used solely as a buffer against illness
and other disasters; there may well be reasons for using it to achieve a
particular brilliance and clarity on an instrument, where the scoring is such
that a worthwhile improvement over normal recording technique can be
effected. This is sometimes the case with percussion instruments, when they
are used in a particularly dramatic or soloistic manner; it can be difficult to
obtain a really incisive quality when such instruments are picked up excessively by the main microphones.
There may be cases when material of some kind must be superimposed
on the original, but no spare tracks are available on the multitrack machine.
Whilst it is perfectly possible to make an immediate reduction to stereo
simultaneously with the superimposition, this may not necessarily be
desirable, as no subsequent remixes would then be possible. In such a case, an
228 Sound Recording
Fig. 14.11
Arrangement for superimposing a
new recording on a multi-track original
and recording a trial stereo mix,
without affecting the original
arrangement as shown in Fig. 14.11 may be used; the multitrack machine is
connected through the mixer as for a normal reduction, and the synchronization tracks sent to the artist in the hall by means of the mixer foldback
circuits. The replay heads are, of course, used in place of the sel-sync
system mentioned earlier. Thus, a stereo reduction is produced at the time,
incorporating the new part, but the new recording is also preserved independently on a second stereo machine. Should further remixing be necessary, it is only necessary to obtain the same stereo and multitrack machines,
and align the tapes for synchronization; good machines can be relied upon to
hold synchronization for at least a few minutes, which is quite adequate for
most superimpositions,
The techniques which have been outlined here serve to illustrate the
increasing complexity of large-scale recordings and, with the imminence of
quadraphony, both techniques and machinery are likely to become still
more sophisticated. It is perhaps pertinent, in conclusion, to observe that
while great fluency in the manipulation of machinery is essential to the
balance engineer, the most gifted engineer will invariably subjugate his
technical fluency and facilities to the needs of the music; any technical
innovation is worthwhile, provided that it serves this master alone.
Acknowledgement
I should like to acknowledge the co-operation I received from James Lock of
the Decca Record Company in the writing of this chapter.
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising