CHAPTER 9

The Studio Environment

9.1 Some Human Needs

Much has been written in the preceding chapters about the studio rooms being, first and foremost, rooms for musicians to play in. Obviously, all the individual tastes of every musician cannot be accommodated by any one studio design, so the ‘ultimate’ environment cannot be produced. Nonetheless there are a few general points which are worthy of consideration. Light colours, for example, make spaces feel larger than they would do if finished in dark colours. In general, they tend to create less oppressive atmospheres in which to spend long periods of time. Daylight in studios is also widely recognised as being very popular.

9.1.1 Daylight

Traditionally, it has been the out-of-town studios which have been more inclined towards allowing daylight into the recording areas. Initially it was probably easier to do this in the relative tranquillity of rural life, as the sound isolation problems of inner city locations were not so great. The knowledge of the changes from day to night, and more unpleasantly, after very late sessions from night to day, along with an awareness of the changing seasons, are all instrumental in helping a person’s well-being. This fact is perhaps more medically recognised now than it was only a few years ago. Once it had been established that the sound isolation in studios with outside windows was adequate, daylight soon became widely accepted as a desirable asset for studios.

9.1.2 Artificial Light

The use of imaginative lighting to create moods can be highly beneficial to the general ambience of a studio. Fluorescent lighting, apart from the ‘hardness’ of its light, is generally taboo in recording studios because of the problems of mechanically and electrically radiated noises. The mechanical noise problem can sometimes be overcome by the remote mounting of the ballast chokes (inductors), which prevent the tubes from drawing excess current once they have ‘struck’ (lit), but the problem of the radiated electrical noise can be a curse upon electric guitar players. In some large studios, fluorescent lights can be used without apparent noise problems in very high ceilings (6 m), well above the instruments, but in general they are likely to be more trouble than they are worth.

Lighting is a personal thing, of that there is no doubt, and the design of studio lighting systems is quite an art form in itself. Many people do not like the small, halogen lights, as they find their light too stark. Argon filled, tungsten filament bulbs are still a very practical solution, though interior designers seem to eschew them. Figure 6.2 shows a room with floor-level, concealed, tungsten strip-lights, illuminating the stonework and casting shadows of the surface irregularities up the wall. The down-lighting is provided by old theatre floods. Figure 6.3 shows the use of wall lights and an ‘old’ candelabrum, to create the effect of an old castle. The room in Figure 6.7 was expected to be used by many session musicians, so in its ceiling it had both tungsten 60° down-light reflectors and a skylight to allow in daylight. These forms of lighting would facilitate the reading of sheet music. If desired, for more mood, the skylight could be covered, and daylight would then only enter via the stained glass window, which could also be externally lit at night to great effect. ‘Mood’ lighting was also provided by electric ‘candles’ on the walls.

In all of the above cases the lighting was controllable not only by the switches of individual groups of lights (or even single lights in some cases) but also by ‘Variacs’. The Variacs are continuously variable auto-transformers, which despite their bulk and expense (roughly €80 each for the 500 VA [watts] variety, and 15 cm in diameter by 15 cm deep) are the ideal choice of controller in many instances. They cannot produce any of the problems of electrical interference noise, which almost all electronic systems are likely to create from time to time. Variacs simply reduce the voltage to the bulbs, without the power wastage and heat generation of rheostats, which dim by resistive loss. It is possible by more complex means to produce a ‘clean’, variable AC, but the methods of doing so tend to be even larger and more costly than Variacs, whose pure simplicity is a blessing in itself.

Electronic dimming systems using semiconductor switching can be a great noise-inducing nuisance, both via the mains power (AC) and by direct radiation. It is simply not possible to switch an AC voltage without causing voltage spikes. So-called ‘zero voltage switching’ may still not be zero current switching, as the loads which they control will be unlikely to be purely resistive. A theoretically perfect sine wave can only exist from the dawn of time to eternity, and cannot be switched on or off without transient spikes. Even if you find this hard to understand; believe it! (A positive-going half-cycle of a sine wave starts as a gradual continuation of the previous negative-going half-cycle. On a plot it can be seen as a smooth transition. On the other hand, if the positive half-cycle begins from zero, it has to begin from a horizontal line on the display. There will therefore be an abrupt change in the direction of the plot, and this can only be achieved by the inclusion of multiple higher frequencies in the overall signal.)

From the early 1970s to the mid-1980s many studios installed coloured lighting as well as the white light for music reading and general maintenance. Suddenly, they became passé for a decade or so; but recently they have again begun to occasionally emerge. Such are the cycles of fashion. Anyhow, whatever lighting system is used, the general rule should be ‘better too much than too little’. One can always reduce the level of lighting by circuit switching or by voltage reduction; but if there is insufficient total lighting for music reading or maintenance, work can become very tiresome.

9.1.2.1 Low-consumption lighting

Since the beginning of the twenty-first century, the pressure has increased on designers to try, where possible, to use lighting of low consumption. The most common types of such bulbs tend to be of the mini-fluorescent type, or LEDs (Light-Emitting Diodes). Whether these are suitable in any given studio environment may be a question of trial and error, and may depend on the ceiling height and the types of instruments to be recorded. Many old, classic, electric guitars and amplifiers are very high impedance devices which do not reject interference very well. A useful test of the suitability of various types of lighting can be to make a cable with a power (mains) plug on one end and a bulb-holder on the other end. The bulb under test can be mounted in the holder, the plug can be connected to an AC power socket and then brought close to the guitar and the amplifier, with the volume set to a realistic level. Some of the low-consumption lights will give rise to buzzing sounds, either by injecting interference into the guitar pick-ups or into the amplifier circuitry. Clearly, an array of 20 or more of such lights in the studio ceiling would be a very likely source of problems.

In many countries, modern electrical regulations seem to be demanding the use of low-consumption lighting, but in almost all cases there are ‘get out’ clauses for special circumstances. Unfortunately many professional electricians are unaware of these exemptions, and so insist on using the low-consumption bulbs and telling the clients that the exemptions do not exist. This seems to be a growing problem with the ever-changing and expanding regulations, and the general ‘dumbing down’ of training programmes. In 2011, tungsten filament bulbs such as R63s are still being routinely fitted into new studios under the full view of the inspectors where alternatives can be shown to be unsuitable. In fact, it can also be shown that the use of appropriate lighting, even with filament bulbs, can often use no more power than the indiscriminate use of unsuitable low-consumption bulbs. What is more, there is a question of health. Inappropriate lighting can lead to headaches and eye fatigue. The colour of some of the LED lighting can also be rather harsh and unpleasant.

As with so many ‘green’ issues, the reality of whether any ostensible energy-saving measure will really save energy is often very difficult to calculate.

9.1.3 Ease and Comfort

General comfort is also an important issue, as again, comfortable musicians are inclined to play better than uncomfortable ones, and few things seem to kill the sense of comfort and relaxation more than an untidy mess of cables and other ‘technical’ equipment. Musicians should never be made to feel in any way subservient to the technology of the recording process. The studio is there to record what they do; they are not there to make sounds for the studio to record. Sufficient sensitivity about this subject is all too frequently lacking in studio staff, especially in many of those having more of a technical background than a musical one.

Easy access to the studio, for the musicians, is another point worth considering well when choosing the location for a studio. Studios have been sited on the fourth floor of buildings with no lifts, but their existences have usually been rather short lived. Especially for musicians with busy schedules, easy access and loading, together with easy local parking, can be the difference between a session being booked in a certain studio or not. It is also useful to have some facility for the storage of flight cases and instrument cases, outside of the recording room. Apart from the problems of unwanted rattles and vibrations which the cases may exhibit in response to the music, when a studio looks like a cross between a warehouse and a junk room it is hardly conducive to creating an appropriately ‘artistic’ environment in which to play.

The points made in this section are not trivial, though they are not given their due attention in all too many designs. Experienced studio owners, operators, engineers, users and designers, appreciate these points well, but in the current state of the industry, a large proportion of studios are built for first-time owners. As so many of them fail to realise the true importance of these things, they are frequently the first things to be trimmed from the budget, especially when some new expensive electronic processor appears on the market midway through the studio construction. Most long-established studios do provide most of these things though, which is probably one of the reasons why they have stayed in business long enough to become long-established.

9.2 Ventilation and Air-Conditioning

It is certainly not only in studios that people complain about the unnatural, and at times uncomfortable, sensation of air-conditioned rooms. Unfortunately though, with sound isolation usually also being good thermal isolation, and given that people, lights and electrical equipment produce considerable amounts of heat, air-conditioning of some sort is more or less a mandatory requirement in all studios. In smaller rooms, such as vocal rooms, where few people are likely to be playing at one time, sometimes a simple ventilation system is all that is required. In fact, it can be advantageous in many instances to provide a separate, well-filtered, ventilation-only system in addition to any air-conditioning. It is remarkable how many times these systems have refreshed the musicians without having them complain of dry throats.

9.2.1 Ventilation

In order to get the best out of a ventilation system there are a few points worth bearing in mind which are of great importance. One of the greatest rules is never to only extract air from the room. If an extraction-only system is used, the room will be in a state of under-pressure; a partial vacuum. Whenever a door is opened (or for that matter, via any other available route), air will be drawn into the room. This air will be dirty, because it cannot be filtered. Dirt and general pollution will also enter the room along with the air, perhaps affecting the throats of singers and leaving dust everywhere.

In rooms which only require a low volume of air flow, such as vocal rooms, it is often possible to simply use an input-only fan, with the air being allowed to find its own way out via an outlet duct of suitable dimensions. When high volumes of air flow are necessary, extraction fans are usually fitted, but there are some basic rules which should be followed. For the reasons mentioned in the previous paragraph, the extraction fans should never be operating without the inlet fans, as they would constitute an extract-only system and would suffer all the drawbacks. What is more, the flow rate of the extraction system should never exceed that of the inlet system, as this would still produce an under-pressure in the room. It is prudent to restrict the flow rate of the extraction system to between 60 and 80% of the inlet flow, dependent largely upon the degree to which air can find its way out of the rooms by routes other than the intended outlet system. In purpose-designed studios, the extraction flow rate can usually be almost as high as the inlet flow rate, because the rooms are normally more or less hermetically sealed at all points other than via the air-change system(s). However, multi-functional rooms, which may serve as studios from time to time, are often somewhat more leaky through their doors, windows and roofs, in particular. In these cases a proportionally lower extract flow rate would be desirable (or even none at all), as over-pressures may be more difficult to achieve.

The normal way to ventilate is to draw air in from outside through a filtration system. This would usually consist of either a single filter or a series of filters, with removable elements which can easily be cleaned and/or replaced. Air will then pass to an in-line fan and on to a silencer, or series of silencers, before entering the room. This way, the room is kept in over-pressure, so, any time a door is opened, the clean, filtered air in the room will escape through the door, keeping the dirty, outside air from entering through the doorway. Such systems keep the rooms cleaner, and ensure that the air which enters the rooms is always clean. Outlets will normally pass first through silencers (both to prevent street noise from entering and studio noise from leaving) and then on out to the outside air, perhaps via a back-draught damper. The damper is a one-way flap arrangement which only allows air to flow out. If the ventilation system is switched off, and the wind is in an unfavourable direction, then should air attempt to enter via the outlet, the flaps close off the ducts. This also prevents dirt from entering via the unfiltered outlets. Fire dampers are sometimes also installed, which close the air ducts completely should the room temperature rise above a predetermined limit. By this means, if the temperature rise is due to a fire, the oxygen supply to the fire will be cut off, thus slowing the spread of the fire even if not extinguishing it completely. Another point to remember is to turn off the ventilation system when the studio is unoccupied, so that if a fire should begin it will not be supported by a constant supply of oxygen. A typical ventilation system outside of a studio with three rooms is shown in Figure 9.1.

The ventilation ducts will often be of the ‘acoustic’ type, such as Decflex Sonodec, having a thin, perforated aluminium foil liner, then a wrapping of 5 cm of fibrous absorbent material, and finally an outer metalised foil covering. In this type of ducting the air is allowed to pass through a relatively smooth inner tube, which presents only minimal friction, and hence loss of air flow. This smooth inner lining must be as acoustically transparent as possible to allow the sound to be absorbed by the fibrous layers around it. If the sound cannot easily penetrate the inner lining of the duct, it will travel very effectively along the tube. Sound can travel along kilometres of smooth bore tubing with remarkably little loss, as no expansion of the wave can take place. (The double distance rule [see Section 2.3] does not apply.) This is the principle by which the speaking tubes of the old ocean liners were able to provide excellent communications, often over long distances and in noisy surroundings; bridge to engine-room, for example. Figure 9.2 shows an installation of acoustic ducts running through the back of an absorber system.

Figure 9.1:

The ventilation system of a studio with three rooms. On the shelves are, from left to right, the filter boxes, the axial inline fans, and the 90 cm long silencers. All the flexible ducting is of the acoustic type, which itself acts as an in-line silencer, except for the extensions on the outlet ducts to the right, which are simple, flexible aluminium tubes. The air inlet is where the cable tubes can be seen, at the bottom left of the picture. Normally, to comply with building regulations, the inlets and outlets should be at least 5m apart, to prevent recirculation of exhausted air. Audio Record Studios (now ‘El Estudio de Domi), Morón de la Frontera, Spain (2001).

Duct size is also very important. For any given quantity of air to pass, the air flow down a duct of large diameter will be much slower than down a narrower duct. A 20 cm diameter duct has an approximate cross-sectional area of 315 cm², and a 30 cm diameter duct an area of 709 cm², which is more than double. Therefore, for any given rate of air flow, the speed of the air down the 30 cm duct need only be just under half of that down the 20 cm duct. As the noise caused by turbulent air flow follows something like a sixth-power law, then for any given flow rate, ventilation system noise will rise rapidly with falling duct diameters. For adequate air flow, even in the smaller rooms, 20 cm seems to be about the minimum usable duct diameter. Appropriate fans with a flow rate of about 700 m³ per hour on full speed will usually suffice for this diameter of tube. Speed control should again be provided by variable or switchable transformers, and not by electronic means, to avoid interference.

Some local authorities may demand that ventilation systems meet certain building regulations, but common sense can usually be applied. In many cases, the incorporation of some of the regulations intended to save energy can often consume more energy than necessary. Ten litres per second per person is absolutely adequate for ventilation systems in recording studios, especially now that in many countries people no longer smoke in studios. This equates to about 35 m³ per hour. A room for four persons would therefore suffice with an air change of around 150 m³ per hour, yet the building regulations may require 10 times this figure. This can be enormously wasteful, especially if the ventilation system is of the constant loss variety, which means that outside air is simply pumped through the room, from inlet to outlet. With an unnecessarily high flow rate, any heating or cooling in the room will be severely reduced in efficiency, but such is the blind stupidity of many regulations. They are meant for more normal circumstances, which recording studios are not.

Figure 9.2:

‘Acoustic’ ventilation tubing passing through the absorbent rear ‘trap’ of a control room, during construction, before the mounting of the principal absorption materials. Sonobox, Madrid, Spain (2001).

Heat recovery systems are also sometimes required, which pass the incoming air and the outgoing air across heat exchangers, but once again they are not always as ‘green’ as they seem. In principle, if the air outside is cold, the outgoing air at room temperature can warm the incoming air to some degree (and cool it if the air outside is hot) if the two are passed across different surfaces of the exchanger. However, when flow rates are low, the power used in the motors of the recovery systems, plus the additional flow resistance to the air which can lead to increased power being required from the ventilation fans (which may then produce more noise and require more silencing) can consume more energy than they save. Studios can frequently be much greener when some of the ‘sledgehammer’ green regulations can be avoided (legally, of course).

9.2.2 Air-Conditioning Systems and General Mechanical Noises

Traditionally, professional recording studios have used conventional, ducted air-conditioning systems, and noise floors of NC20 or less have been achievable, even with quite high rates of air flow. Such systems are still the only way to properly air-condition a studio, but as has always been the case, they are relatively expensive.

Since the early 1980s, the real cost of studio equipment has been falling. Partly as a consequence of this, and somewhat unrealistically, the charges per hour for the studios have plummeted. At a time when €100,500,000 are spent on the recording equipment for a studio, to have to pay €150,000 for an air-conditioning system may not seem too disproportionate. On the other hand, when manufacturing technology has made it possible to buy for €150,000 an entire set of equipment that will not perform far short of the equipment costing €1,500,000, people seem to baulk at similar charges for good air-conditioning. Competition between studios has forced real prices ever downwards, and a state of affairs has now developed where the cost of ducted air-conditioning systems, for most of the mid-priced studios, has become insupportable. It must be said, though, that this is a situation driven by commercial realities, and that the need for good, conventional air-conditioning systems is as much a professional requirement today as it ever was.

It is a strange situation, exactly analogous to that which exists with sound isolation costs. People seem to expect sound isolation to be cheaper if they ‘only’ want to use a room to practice drums, as opposed to the more ‘serious’ purpose of recording. Similarly, people seem to expect to have to pay less for the air-conditioning systems if they are paying less for the recording equipment. There is simply no logic in any of this.

Largely for economic reasons, therefore, there has been a great increase in the number of ‘split’ type air-conditioning systems coming into studio use. Although these are by no means ideal for this purpose, they are many times cheaper than the ducted systems, but as the heat exchangers and their fans are in the studio, with only the compressors remaining outside, there is an attendant noise problem. In control rooms the units can usually be left running in ‘quiet’ mode, as the noise which they produce is often less than the disc drives and machine fans which may also be in the room (but which really should not be there), but in the studio rooms they usually must be turned off during quiet recordings. Unfortunately this intermittent use can lead to temperature fluctuations which may not be too good for the consistency of the tuning of the instruments. Nevertheless, despite their problems, there are now many split systems in studio use. The use of multiple, small, quiet heat exchangers is normally preferable, where practicable, to the use of larger, single units. Some small units now produce less than 30 dBA of background noise at a distance of 1m when used on low speed. Such a unit is shown in Figure 9.3.

Studio customers have become used to inexpensive recording, and all too few of them now want to pay for facilities which can provide all the right conditions for optimal recordings. Unfortunately, as this has become widespread, it has also apparently become acceptable in these ‘market forces’ days. Air-conditioning systems have in very many cases been tailored to a ‘reasonable’ proportion of the recording equipment budget, which has led to unsatisfactory air-conditioning, but this reality exists. On the other hand, market forces have led to much competition between manufacturers of split-type systems on the subject of noise, which has been gradually reduced in level.

Some of the Daikin units have now become just about acceptable for control room use when running on low speed, even for critical listening, but it often requires that they should be mounted in front of absorbent surfaces. Nevertheless, the marketing wars have led to some rather confusing publicity battles regarding the quoted noise figures. Customers should take great care when choosing systems because some that are quoted as having extremely low noise figures on their ‘quiet’ settings have air flow rates that are so low as to be almost useless in a studio. There seems to be missing any means of readily correlating noise with air flow when looking at the publicity material. For example, one machine withthree speeds may have a marginal, but acceptable performance on low speed, with a quoted noise of say 23 dBA at 1m. Another machine, with five speeds, may quote the same maximum heating and cooling but with a noise figure on low speed of only 20 dBA. However, the low speed of the second machine may be so low that it is not adequate for the room, and on higher, more practical speed, it may make more noise than the first machine. Therefore, in reality, the first machine would be the quieter option, despite the publicity for the second machine claiming a lower noise performance.

Figure 9.3:

Towards quieter, split air-conditioning. If split air-conditioning systems must be used, then it is wise to choose units with aerodynamically streamlined inlet and outlet vents, to avoid the higher levels of turbulence noise associated with the more common grills.

All this can be very confusing for inexperienced people to sort out. It can be very difficult to make choices based on publicity material alone unless a more in-depth study is made of the specifications (which also may not be very clear). What is more, subjectively, not all dBs of noise are equal. In fact, two machines can produce equal noise figures yet one may be subjectively noisier than the other. It may all depend on the type of noise and in which frequency bands it is concentrated. Studio designers may often have their own preferred choices of split air-conditioning systems, based on experience, but it can sometimes be difficult to convince clients of their superiority when faced with a small army of sales representatives from air-conditioning suppliers who are all trying to sell their own products. It is lamentable how so many studies operate with totally inadequate ventilation and air-conditioning. The owners are such easy prey for the sales representatives.

There are limits, however, below which the lack of suitable environmental control will pose serious problems, not only for the musicians but also for instruments such as pianos and drums. Draughts of air are generally disliked, most musicians would agree about that, but there may be some considerable differences in their preferences of optimal temperature for their own comfort. If a studio is block-booked for a week or so, then the chosen temperature can be selected at the start of the session and maintained, but pianos should not be tuned until the temperature has had time to stabilise. With shorter bookings, the temperature should be kept at a suitable compromise, as frequent changes in air temperature will cause great problems with the tuning of any permanently situated pianos, and many other instruments for that matter.

Humidity is another factor which needs consideration. If maintained too low it can dry out the throats of singers, and may cause piano sound-boards to crack. If it is too high it can be uncomfortable for the musicians and corrosive to instruments. Sixty or seventy per cent humidity is a good level for most purposes, and in the better studios regular attention is paid to the maintenance of the appropriate levels. Unfortunately, in an enormous number of smaller or less professionally operated studios, little or no attention whatsoever is paid to humidity control. Once again, the relentless driving down of studio prices has rendered it impossible for many ‘professional’ studios to provide the sort of environmental controls that are musts for truly professional studio operations.

There is now a huge ‘consumer’ recording market, which, although providing standards below what the ‘professional’ market was accustomed to, has blurred with the professional market to such an extent that the lower sets of standards have begun to influence the professional world. Some of this has no doubt been due to the enormous influence of electronically based music, where studio acoustics and air-conditioning noise have not been problems. But it is difficult to understand how some people can hear any detail at all in control rooms whose noise floors are made ridiculously high by the presence of hard disc drives and numerous equipment fans. Fortunately though, there seems to be a swing back to the use of acoustic and electrified (as opposed to electronic) instruments, which is just as well if much of the passed down experience that exists in the recording industry is not to be forgotten through the loss of a whole generation of recording staff to the computer world. The provision of acoustically isolated machine rooms, with good temperature control, is now an important feature of many studios in order to keep the control room background noise level below acceptable limits. In these cases the ‘split’ air-conditioning systems are ideal, and the background noise levels which they may add are of no practical consequence. In fact, given their efficiency they are probably the preferred option.

When very low noise levels are required in studios, a very viable option is to employ batteries of water coils in the ventilation ductwork. Figure 9.4 shows such a system above a film dubbing theatre, and Figure 9.5 shows the noise inside with all systems running. The rise towards 1 kHz is due to – somewhat perversely – the Dolby processors; when the requirement for low noise in the room was made by Dolby, themselves. The low frequency noise from the HVAC (heating, ventilation and air-conditioning) system can be seen to be around NC10 (approximately 10 dBA). Normal, ‘split’ air-conditioning systems, and other systems using ammonia or similar halogen-free refrigerants, tend to operate in the cooling mode with very low temperatures, often below 0˚C in their heat exchangers. These low temperatures are efficient coolers, but they tend to condense too much of the humidity out of the air. This is what often gives rise to the well-known discomfort which many people feel when working long hours in air-conditioned rooms, and it can also badly affect the voices of singers and actors. When water is used to cool the heat exchangers, and high flow rates can be allowed, temperatures as high as 14˚C can be employed in order to cool rooms down to 20˚, even in relatively hot weather. High volumes of relatively cool water dry the air much less than low volumes of refrigerants operating below zero. Where possible, when water systems are used, it is best to try to site the heat exchangers in places where leaks will not cause disasters (i.e. not directly over the studio rooms) and where there is no danger of them freezing up in winter conditions, which will probably split the pipes and spring leaks once they thaw out. Turning them off during the winter, weekends or holidays, is not an option if outside temperatures dip below 0˚C, unless the systems are first drained of their water. Nevertheless, using water as a temperature controlling medium can be beneficial. In winter, the systems can be reversed to provide heat for the rooms, and normally the sensation is of a very pleasant, natural heat. In general, these systems are very effective, but they tend to be more expensive than some of the other options, especially as all the water pipe work usually needs to be made of stainless steel. All the ductwork shown in Figure 9.4 is Sonodec, which is both flexible and also acts as a silencer. The inner tube must be stretched as much as possible to open the ‘accordion’ folds and avoid the introduction of turbulence noise into the system at higher air flow rates.

Figure 9.4:

In the system shown, the air enters through the rectangular filter boxes, on the extreme right of the photograph, before passing through the fans. The ‘water battery’ heat exchangers are in the large rectangular boxes, which also act as expansion chambers and quite effective silencers. The air then loops round through the ‘acoustic’ ducting before entering the room. An external heat pump controls the water temperature between about 28˚C in winter and 12˚C in summer (depending upon the outside air temperature) in order to maintain a constant temperature of around 20˚C in the studio. Stepped transformers control the fan speed, thus regulating the air flow through the room.

9.3 Headphone Foldback

The topic of foldback will be discussed in detail in Chapter 24, but it is also relevant in this chapter because it is an extremely important part of the studio environment. It can be the entire acoustic reality for the musicians during their performances, because in by far the majority of cases musicians will record whilst wearing headphones. In these instances, the acoustics of the studios can only be heard via the microphones, mixing console and headphones, so the musicians can find themselves in a totally alien world if due consideration is not given by the recording engineers to the creation of the right foldback ambience.

Figure 9.5:

The above plot shows the noise level inside the dubbing theatre whose temperature control system is shown in Figure 9.4. The upper trace shows the noise level with all systems running. The middle trace shows the noise floor of the measuring microphone. Somewhat ironically, the noise in the region around 500 Hz was due to the ventilation fan in the Dolby processor, mounted close to the mixing console. Without the processor the noise floor, below 1 kHz, remains always less than NC I5.

If musicians need to hear what they need to hear in the studio, then they need to hear it in their headphones as well. Many musicians play off their own tone, so if they cannot hear themselves with their usual sound they may ‘force their tone’, or perhaps hold back, and neither is satisfactory for optimal recording. If musicians need to hear richness in the direct sound, then they ideally would need to hear it in their headphones; if they need the reinforcement of lateral reflexions, then they need to hear those in the headphones also. At times, it can be considered beneficial to put up ambience microphones which will be used in the foldback only. If this helps to improve the sense of ‘being there’ for the musicians then it is surely worthwhile, though it is rarely done.

There are two big problems with the optimisation of foldback. Firstly, few recording engineers have spent enough time as recording musicians to be sufficiently aware of the complexities and importance of the requirements of different musicians in terms of foldback. They cannot be blamed for this, as they cannot spend their lifetimes doing two things at once. The reverse of course applies. So many musicians are used to poor foldback that they fail to realise what could be achieved. As with the case of the recording engineers, the musicians have also not spent a working lifetime doing the other end of the foldback job. There are times when musicians are given their own foldback mixer for use in the studio, but they rarely have access to the reverberations that are available from the control room which can greatly aid their perceptions of space.

Secondly, however, if too much of the foldback burden is loaded on to the musicians, then they can become distracted from their primary job: playing. In fact, one significant restriction on foldback balance is time. The foldback mix cannot be set up until the musicians are playing, but once they are playing, too much time cannot be spent setting up the foldback before they ‘go off the boil’, and lose their motivation to play. Furthermore, too much fiddling with the foldback, with levels going up and down and things switching in and out, is absolutely infuriating for the musicians. Remember, effectively it is their whole audible environment that is being disturbed. For them, it is like an artist trying to paint a picture with the lights going on and off randomly.

Where possible, foldback should be very carefully considered. A stereo foldback system is much easier to hear clearly than a mono one. In stereo, even things which are perhaps a little too low for the ideal balance for a mono mix can be perceived much more easily due to the spacial separation which stereo provides. Whenever possible, it seems beneficial to provide the facility of systems where the recording engineer can monitor exactly what the musicians are hearing, which includes listening at the same level. Obviously, on systems where all, or at least many, of the musicians are in a position to make their own balances, this is hardly practicable, but in cases where many headphones are driven from a common power amplifier, it is. In these cases, it can be beneficial for the engineer to have a line in the control room which is connected to the same power amplifier output as the studio headphones, and, where possible, to monitor on the same type of headphones that are being used by the musicians. There can in this way be little doubt that the engineer is monitoring the selfsame space that the musicians are immersed in, and there is therefore much less chance of misunderstandings.

In many cases where the control room foldback monitoring system is only via headphones plugged into the mixing console, or where it is heard on loudspeakers, the recording engineers can never truly know what the musicians are hearing. This has often led to time wasting, or, if the problems have not been pursued, to the musicians having to try to play with the problems still unresolved. In either case, the musical performance will probably suffer. The musicians also seem to feel an added sense of being understood and appreciated when they feel that their environment is being shared by its controller, and this helps to allay any insecurities which they all too frequently feel.

It is imperative that the design of any studio extends to ensuring that sufficiently flexible foldback systems are available, because the ‘virtual’ spaces in which the musicians may have to perform can be just as important to the recording process as the very real spaces in which they physically play. A full understanding of this is a fundamental requirement of being a good studio designer or a good recording engineer, and good foldback systems are an equally fundamental part of a good studio. In effect there are therefore three aspects to the acoustics of a recording space. Firstly, the acoustic as heard in the room; secondly, the acoustic as collected by the microphones and thirdly, the combination of the two as perceived by the musicians if they must use headphones. All should be considered very carefully in both the design and the use of the rooms.

Choice of open or closed headphones can also modify this environmental balance. Closed (sealed) headphones tend to add to the feeling of isolation, and take the musicians one step further away from their ‘real’ acoustic space. Nonetheless, there are times when closed headphones are very necessary. Drummers, for example, may need closed headphones in order to avoid having to use the painfully high foldback levels which may be necessary so that the other instruments can be heard over the acoustic sound of the drums. In this case, closed headphones are used to keep unwanted sounds out. Conversely, vocalists, or the players of quiet, acoustic instruments and, in particular, those instruments which require the positioning of a microphone close to the head of the musician, may also need to use closed headphones. This is especially the case during overdubbing, when the ‘tizz tizz’ reminiscent of sitting next to somebody using a personal stereo system may be picked up by the microphone. It may subsequently be difficult to remove these sounds (especially timing ‘clicks’) from an exposed track. In this instance the closed headphones are used to keep the unwanted sound in.

It is a pity that foldback is so often subject to so much compromise, but in a way such is its nature. As so much modern music has developed out of domestic recording technology it is not surprising that aspects of the limitations of the prior technology should be carried along. The simple headphone systems often used in small studios get used in bigger studios, for which they are often inappropriate, when studio companies expand without the necessary experience for a larger operation. It is quite amazing how many people in relatively large studios are totally ignorant of many excellent practices that were well-established 40 years ago. So many people are now self-taught, and they can lack so much knowledge of many simple things which make recording practices so much more effective. But it is imperative to remember that whatever wonders may be created in the acoustic design of the studio, often for the benefit of the musicians, as soon as they put on a pair of headphones those musicians can be in a different world, and it is best not to leave them feeling lost in it. This is one very important difference between designing live performance spaces and designing recording spaces. In the latter case, it is not only how the musicians hear the space which predominates in the design considerations, but how microphones react to the space. This point should never be forgotten.

9.3.1 Loudspeaker Foldback

Many studios and musicians find the facility of being able to provide foldback via a loudspeaker a useful asset. The concept of the ‘tracking loudspeaker’ goes back almost to the dawn of electrical recording. Many vocalists found that it was easier for them to perform without headphones, so that they could clearly hear their own, natural voices. A loudspeaker would be positioned facing the vocalist, and the backing track would be played back through the loudspeaker at the minimum level needed to allow the singer to perform well, but not so loud that the overspill into the microphone would cause problems. The directional characteristics of a cardioid microphone were employed in order to reject as much of the loudspeaker output as possible. This was further aided by placing non-reflective screens behind the vocalists, to prevent the playback signal from bouncing off a wall behind and subsequently entering the microphone.

These loudspeakers also became useful as a means of playing a recording back to the musicians without them having to leave their positions and go into the control room, which would in any case perhaps be too small to house them all. This was never a particularly good means of assessing the sound of the recording, but was a useful tool for discussing performance quality or mistakes with the producer, conductor, or musical director. They were also useful in orchestral recordings, when the conductor needed to highlight some point in the performance to the musicians, as taking a whole symphony orchestra into the control room would clearly be out of the question. Once again, ease and comfort go a very long way towards getting the best performances out of musicians, so they should be given great attention when designing, or operating, a studio. The recording process begins with the musicians, and they are the foundation on which the rest of the process is built. If these foundations are weak, then all the subsequent proceedings may never achieve their potential strength or quality.

9.4 Colours and General Decoration

These are the areas over which a studio designer often has least control. They are very subjective; very personal. Each studio owner or manager seems to want to make their own input to the design, and this is an area where they feel free to do so.Nevertheless, some guidance can be given by the designers, based on previous experiences, which may help the studio chiefs to avoid making any great errors.

Dark colours tend to make spaces feel smaller. In large studios this may help to create a more intimate atmosphere, but in small studios the effect can be claustrophobic. Very often, of necessity, the ceilings of control rooms and small overdubbing booths are not very high, and light colours can go a long way towards lifting any sense of oppression. Light colours also reflect more light back into the room, so they tend to diffuse the light, making it less hard on the eyes. Also, the extra reflected light means that less overall power of lighting is needed, therefore less heat is generated and less air-conditioning is necessary.

In a studio in Watford, England, the owner began seriously running out of money towards the end of the construction. Wisely, and it was a decision he never regretted, he continued to invest more in the acoustics than the decorations, which he felt could be easily improved at a later date. He went to a local outdoor market, looking for inexpensive fabric, and returned with several short rolls of leftover material which he had bought cheaply. The comments of the building crew when he showed them the fabric that they were to work with would not be printable in any decent publication. He had bought white fabric with yellow stripes, blue flowers on a white background, red dots on a white background, and various other designs. Nevertheless, once the different fabrics had been juxtaposed carefully, the result was a small studio with a spacious feel and a remarkably happy and pleasant atmosphere to work in. Even the most severe of the original critics admitted that the result was, surprisingly, very agreeable.

The other extreme of this situation is when a studio owner employs the services of an interior designer who is allowed to severely compromise the acoustics. This happens in a great number of cases, especially when marketing and financial people, in their customary absolute ignorance of recording needs, believe that if a studio looks absolutely great, but sounds only mediocre, it is a better business option than sounding fantastic but perhaps lacking the ‘designer’ touch. It must also be said that some studio designers will bend to such compromises if it ensures more work for their business, and hence more profit.

There is, of course, no law against any of this, and some adherents to market forces philosophies may even applaud the existence of this state of affairs, but it really does nothing for the advancement of studio functionality. This is being mentioned here to stress the fact that a studio which looks great in publicity photographs, and has the name of a reputable studio designer attached to it, does not necessarily mean that it is either a good studio, or that the named designer had as much control over the acoustics in the way that the publicity is implying. One of the problems of the ‘low profile’ of acoustic work is that good acoustics can be easily sacrificed to other, more visible trivia. Cases abound such as where money has been short for good anti-vibration mounts for an air-conditioning system because the owner decided to spend €60 each on 24 door handles. Or there is an inadequate electrical installation, because the owner spent €100/m² on a hardwood floor that would largely be covered by a mixing console and effects racks. These are examples of common occurrences.

There is perhaps a philosophically different outlook between studio designers who make money from building good studios, and studio designers who are in business to make money. The latter will probably be more easily swayed into being subjugated by interior designers. For a proposed studio owner looking for a designer, it is perhaps a case of caveat emptor – let the buyer beware – because he or she alone is responsible if the results are disappointing. It also must be said that some owners do want something which looks great, even if the acoustic and operational results are compromised, but how to achieve that would be a totally inappropriate subject for discussion in a book such as this.

The aesthetics of recording studios are a very important aspect of studio design, but good design can incorporate aesthetically pleasing ideas. However, the aesthetic demands of some interior designers are frequently acoustically insupportable. An air of respectful cooperation between the specialists is the obvious solution.

9.5 AC Mains Supplies

Appropriate AC mains supplies are a fundamental part of the infrastructure of any good recording studio, but general electrical contractors are often totally unfamiliar with the needs of high quality recording studios, and they are often greatly resistant to suggestions which they consider to be out of the ordinary. Sometimes there is good reason for this, because standardised systems of installation and power distribution have been developed as a safety measure. Standardised systems also mean that any qualified electrician can make modifications or tests on a system which will not upset the rest of the installation, or show up as fault conditions.

However, standardised industrial or domestic power installations may be inadequate for highly sensitive recording equipment. Hospital power supplies which feed delicate equipment upon which lives depend are another example of installations where normal power distribution techniques can be inadequate. The life or death circumstances which exist in medical facilities ensured that hospitals and the like have had exemptions in many countries, for many years, which have allowed special AC supply techniques to be used. Electricians who work on medical installations will be trained in the use of these special techniques. However, wiring systems in recording studios are generally not so well regulated or supervised. The recording industry is not usually perceived as being a particularly responsible or necessary profession, so such exemptions have been slow in arriving.

Indeed, there have been many cases where special AC power installations have been incorporated into new studio designs, and where much care and attention has been paid to detail. Nevertheless, within a few months of the opening, perhaps where a studio manager or head of maintenance has been replaced, other electricians have arrived, working to ‘the book’. Under such circumstances, chaotic systems have begun to develop, sometimes with dangerous results. Studios have not done themselves any favours by this sort of lax behaviour, so it is little wonder that they have not been granted their technologically necessary exemptions. Even in a technically advanced country like the USA, electrical codes were not modified until the 1990s to allow balanced power installation, and even these were restricted to studios with a competent, qualified electrical supervisor. It was recognised that despite its advanced technology, the USA was also the home of the very market forces which would seek to cut costs by not employing a qualified electrical supervisor if at all possible. Technological advancement does not always go hand in hand with responsible business attitudes.

It is therefore quite dangerous and irresponsible in a book such as this to try to explain how to make AC power installations. It is also not practicable, because the rules and regulations in not only each country, but often in each state or region, can be very different. What can be done, however, is to discuss a few of the ideal requirements, and these will be discussed in further detail in Chapter 25. Nevertheless, it would still be up to any individual wishing to pursue these to find a knowledgeable and flexible electrical engineer or contractor who could then interpret them in such a way that would not break local installation rules. Whilst it is true that many qualified electricians are neither knowledgeable of electrical engineering theory nor are they willing to change their habits, it is usually possible to find specialised electrical engineers who can make the appropriate arrangements. Remember also that a non-standard installation can be dangerous if it is worked on during later visits by electricians who, quite justifiably, expect the installation to be standard. Adequate and permanently accessible documentation that will not be lost when staff change is not something which one can expect to exist in 99% of the recording industry. Technologically advanced countries such as the UK, France and the USA are no exceptions, either, but Chapter 26 will look in detail at audio wiring systems which are generally tolerant of use with more standard power wiring installations.

9.5.1 Phase

The ideal number of phases to which all the audio equipment should be connected in any studio, or complex of studios which can be interconnected, is ONE! All audio equipment, together with any other equipment to which it may be connected, including computers, video, film or radio equipment, should all be connected to the same power phase. The only exceptions are where equipment, such as radio transmitters, are fed via galvanically isolated audio connections; i.e. through transformers with adequate insulation. Electricians often do not like to put all the equipment on one phase, because they prefer for good power engineering reasons to balance the load. Nevertheless, the reasons to connect to one phase only are first, safety, and second, noise.

In countries where the nominal mains supply voltage is in the 230 volt region, the voltage between the live connections of any two phases will be in the region of 380–400 volts. Under certain fault conditions, connecting the audio cables between two pieces of equipment on different phases can have instantaneously lethal results. Under normal circumstances this should not happen, but with weak insulation on two devices, even if the insulation holds on monophase operation, the extra potential when two pieces of such equipment are connected together can initiate a fatal breakdown.

What is more, when audio signals (analogue or digital) pass repeatedly through equipment with different ground plane potentials, as is almost inevitably the case if interconnected pieces of equipment are connected to different mains supply phases, signal contamination is likely to result. It is true that extremely well designed equipment can be immune to these effects, but unfortunately even some very expensive audio equipment does not come under the heading of ‘extremely well designed’. Capacitive coupling in power supply transformers, for example, can easily lead to fluctuating ground plane voltages. In general, the higher the gain of any equipment, the more sensitive it will be to supply-phase differences.

If three phases are available it is best to dedicate the cleanest, most stable phase to the audio equipment. Lighting, mono-phase air-conditioning systems and ventilation equipment can use a second phase; and refrigerators, coffee machines and general office equipment can be connected to a third phase. General-purpose wall outlets outside of the recording area can be connected to the least heavily loaded of the second and third phases, but some local regulations may modify this. Although this may not seem to balance the phases very well in terms of equal current drain on each phase, electricians frequently fail to realise just how variable is the current drawn by a recording studio. Equipment such as power amplifiers often draw current in pulses, dependent on the musical drive signal. Musicians connect and disconnect their instruments and amplifiers, lighting gets turned up and down, air-conditioning currents are temperature dependent, tape recorder motors stop and start (although there are less of them, these days); many things change during the course of a session. There is a tendency for non-specialist electricians to look at the maximum power consumption of each piece of equipment, and then try to distribute it presuming that the current drain is constant. The reality is nothing like this, and phases sensibly balanced for technical reasons can easily be made to give a distributed average load that is better balanced than many electricians would achieve by distributing things according to their ‘standard’ calculations. The problem is often how to convince them about this when they perceive themselves as being the experts on such matters. There is more on this subject in Section 25.6.1.

9.5.2 Power Cabling

Guitar amplifiers and audio power amplifiers have a tendency to draw current in pulses. For this reason oversized cable sections are often specified. General electricians will size cable according to the heat produced by the cable resistance in response to the power being consumed by the equipment. To many electricians, anything much beyond what such power requirements would need for reasons of safety is usually seen as a waste of money. However, pulse-drawing equipment needs oversized cables. There are two reasons for this. Excess resistance in the power supply cable may restrict the peak level of the required current pulse, which can limit the high-level transient response of audio power amplifiers. Furthermore, cables lacking sufficient cross-section for the current pulses can create problems in other equipment, and can even crash computers. If a current pulse causes a voltage drop on a power cable, then even if this cable is not shared by any other piece of equipment, the voltage drop can cause harmonic distortion on the supply line. This can then bypass the power supply filtering of some sensitive equipment and interfere with the proper operation.

In fact, the problem of harmonic induced interference can also be caused by uninterruptible power supplies (UPSs) which do not have waveform feedback. Not all audio computers are happy working on all UPSs. It would seem a pity for a UPS first to save a recording when the mains power fails, only to subsequently crash the computer due to its bad voltage waveform. Many computer crashes that are blamed on software problems can be traced to bad power installations or inappropriate UPSs.

9.5.3 Balanced Power

In some hostile power line environments, one of the best solutions to avoid interference problems coming in via the electricity supply can be to balance the power. This involves the use of power transformers with centre-tapped secondary windings, producing, for example, 115 V–0– 115 V in place of a single 230 V supply. Electricians should be consulted if this sort of measure is needed, in order to avoid making any illegal installations, but the technique can reject interference in exactly the same way that balanced audio lines are less sensitive to interference than unbalanced lines.Signal-to-noise ratio improvements of 15–20 dB have been reported as a result of power balancing.

In many countries, it may be illegal to supply balanced power to normal wall-socket power outlets. Special installation work may be required, by expert engineers. Many electricians may simply refuse to do it, as they cannot justifiably put their signature to something with which they are not familiar. Nevertheless, specialist engineers can usually find legal ways of installing such systems if there appears to be no other option for interference suppression. It should also be stressed that with such a specialist job as studio electrics, it is all really a job for electricians with some experience in this field if the highest standards of performance are required.

9.5.4 Mains Feeds

It is important to try to ensure that the main cables feeding the studio in-coming fuse-board are connected as close as possible to the main distribution board for the building. This ensures that the large-section cables will continue to the street, and onwards to the principal supply. If this is not done, then any common cable between the point of connection of the studio to the mains supply of the building, and the main feed connecting the building to the street, will be a common impedance. Any currents and noises generated elsewhere in any part of the building which shares the same feed cables will superimpose themselves on the supply to the studio, and the supply will not be clean. In addition, if these cables are only rated in terms of the power consumption, they may not have the cross-section sufficient for the non-distortion of surge currents, as described in Section 9.5.2. A low impedance supply is highly desirable.

Once again, independent supply cables to the main feed to the building may be inconvenient for the electricians, and they may resist it on the grounds of being unnecessary because they are still thinking in terms of power consumption and standard cable sizes. Nonetheless, it needs to be impressed upon them that a recording studio is no ordinary installation in terms of its power cable requirements. Again, an experienced specialist electrical engineer may need to be called in, if only to convince the electrical contractors that the necessity is a very real one.

9.5.5 Earthing

A good earth is essential as a safety measure, and it is normally also needed for a good signal-to-noise ratio, but if very elaborate earthing systems seem to be the only way to reduce noises the implication is that there are problems in the system wiring; either the power wiring or the audio wiring. Normally, in buildings with steel frames or steel reinforced concrete in the foundations, connection of the earthing (grounding) system to the steel provides an excellent earth (ground).

In the book by Giddings¹, on wiring in general, the first 113 pages are dedicated to power and grounding systems, so it should be evident that a few paragraphs, here, cannot deal with the subject. However, what can be made clear is that similar rules apply to the earthing cables as to the power feed cables. The studio power system, and its technical earth, should be connected to the best earth point via the shortest cable run and with the largest practical cross-section of cable.

Another point worth mentioning, which is often overlooked, is the degree to which the earthing system of a studio may be being polluted from within. Obviously, sharing the long tail of an earth cable with other users of a building may result in a lot of electrical noise on the common (shared) section of the earth cable. The studio earthing system therefore needs to be connected directly to the building safety earth, and not via any shared lengths of cable. However, even from within the studio, the earth can be polluted by bad choices of electrical filters. Many filters of inappropriate design, which frequently still find use in studios, do little other than remove the interference from the live and neutral cables and dump it all on the earth, which in some cases is more sensitive to the noise than the live and neutral are. Power balancing can be a big help in these cases, because the noises on the live and neutral cancel on their way to earth. This will be discussed at greater length in Chapter 25.

Very well designed systems using well-designed equipment can often work well with the most simple of earthing systems. Unfortunately, all recording equipment is not so cleverly designed, so in buildings with earth noise problems, and on ground which is geologically bad for earthing, expert advice may be needed. Standard electrical contractors may only know of safety earths, and perhaps a little, learned by hearsay, about technical earths. It is not always wise to rely on their advice. In cases of persistent problems, a specialist engineer should be sought.

9.6 Summary

In the majority of cases, the presence of daylight in a studio is a desirable asset.

Choice of artificial lighting should be made carefully, so as not to risk compromising the electroacoustic performance of a studio.

Variable transformers tend to be the best form of lighting control.

Good ventilation, air-conditioning and humidity control is usually essential. Extraction-only ventilation systems should not be used.

There has been a great increase in the number of split air-conditioning units being used in studios. These are not ideal, but if they must be used, the quietest, aerodynamically profiled ones should be chosen.

Foldback systems are very much part of the studio environment for the musicians, and the necessity of seeking the most appropriate systems for the musicians’ needs should not be neglected.

Colours and general decoration are a very important part of a studio environment, but interior design should never be allowed to degrade or limit the work of the acoustic designer.

Studio power wiring needs are often beyond the experience of normal electrical contractors. Specialist advice may be needed.

When any non-standard installation is completed, documentation should be thorough, and available for consultation by any electrical contractors who may do work in the studio in the future.

Electrical regulations can change from country to country, and even from state to state or region to region, so local advice should always be sought.

It is strongly advisable to connect all audio and associated equipment to the same electrical power phase. This is for reasons of both safety and noise.

The main studio breaker-board/fuse-board should be connected to the incoming supply of the building, without sharing any cable runs with other tenants. Oversized cable sections should also be used, to help to provide the lowest possible source impedance.

In very problematical installations, from the point of view of electrical supply noise, balancing the power can be a very effective cure, but it should only be done under the supervision of an electrical engineer experienced in such techniques.

Good earthing systems should be installed, again avoiding common cabling with other tenants. Direct connection to the steelwork in building foundations can make a good technical earth. Despite concrete being perceived to be a good insulator, it still grounds well the steel buried inside concrete foundations.

Many mains filters can often be a source of noise on the earthing system.

Reference

1  Giddings, Philip, Audio Systems – Design and Installation, Focal Press, Boston, USA, Oxford, UK (1990)