Part 2: You might think that the layout of your studio is determined purely by where your monitors go and where you sit, but as Paul White explains, there are a few areas where you have exercise a bit of care. This is the second article in a five‑part series.
Good studio layout is largely a matter of ergonomics, but what feels comfortable for you may not necessarily be the best place for the equipment. The purpose of this article is to examine the 'position‑sensitive' parts of a typical project studio, so that you can 'design out' potential problems at the planning stage. For example, it's fairly well known that speakers need to be set up symmetrically, and that they shouldn't be positioned too close to corners — but what other items of studio equipment are sensitive to where you put them?
Looking first at the mains electricity side of the installation — it's always wise to run all your audio equipment from the same ring main or spur; the golden rule is not to share this with any piece of equipment that create large surges of current, such as central heating systems, coffee machines, fridges and freezers, electric cookers, air conditioners and fan heaters with thermostatic switches. Failure to follow this rule can result in random clicks or pops on your recordings, and can conceivably cause computer crashes.
You should also avoid running signal cables, especially unbalanced feeds or mic cables, alongside mains cables, as hum may be induced from the alternating magnetic field that surrounds all current‑carrying mains wiring. If a signal cable must cross a mains cable, it's best to ensure it does so at right angles — like this, the induced hum current due to magnetic interaction will be at a minimum. Serious induced hum problems usually only arise when mains cables and signal cables are bound together in the same bundle, but it's always good practice to keep them as separate as possible anyway, just to be on the safe side. It's also a good idea to keep cables as short as is practical, and to use balanced connections wherever equipment has balanced inputs and outputs (see the 'Balancing Act' box for more on balanced inputs and outputs).
Large transformers also generate significant electromagnetic fields, which can induce hum in nearby sensitive equipment (for example, guitar pickups, mic amps and record turntable pickups) — and, sadly, amongst the greatest hum‑inducers are the transformers belonging to large power amplifiers or mixing console power supplies! As a rule, never put mic preamps or instrument preamps right next to a power amplifier in an equipment rack, and ideally, leave a unit or two of space above and below power amps and Power Supply Units (PSUs). Not only does this reduce the risk of picking up hum, it also helps provide good ventilation.
Conventional light bulbs don't normally cause interference, but fluorescent lights can induce hum and buzz into sensitive equipment. Fluorescents can be useful for maintenance work between sessions, but it's best to turn them off when you're working, unless you're absolutely sure they're not contributing to the background noise. Electronic light dimmers are even worse, so avoid these, both in the studio and nearby rooms.
Interestingly, the currently popular energy‑saving bulbs are also based on a type of miniature fluorescent tube, but I've installed five in my studio and can't detect any difference in background noise level whether they are on or off. Even so, if you're thinking of doing the same, I'd recommend you check carefully to see if they're having any adverse effect. I moved over to this type of lamp because conventional filament bulbs last, on average, only a couple of weeks in my studio, possibly something to do with the vibration. Furthermore, the heat output from five ordinary bulbs is around 300 Watts more than from the same number of 'equivalent light output' energy‑saving bulbs. In summer, this can make quite a difference to the comfort of your studio, especially if you don't have air conditioning.
It's hard to imagine making modern music without involving computers in some capacity, but if you've ever tried to record a guitar in the same room as a computer monitor, you probably know already that the resulting hum and buzz problems are far worse than you get from fluorescent lights. Single‑coil pickups (of the type used on Stratocasters) are the most vulnerable, and in extreme cases, you have to sit ten feet or more from the monitor to reduce the background buzz to an acceptable level — and even then, you might still need to use a noise gate.
Tape recorders should be kept away from strong magnetic fields. Sticking cute fridge magnets on the side of your recorder is definitely not a good idea...
You may already have noticed that interference is worse at some angles to the monitor's axis than at others, and the same is true if you rotate the guitar. By finding a relatively 'quiet' angle to work at, and by maximising the distance between guitar and monitor, you should be able to get the interference down to an acceptable level, but if not, the only viable options are to either record the guitar while it is played in another room, or to run your computer with the monitor turned off for a while (if it will let you!).
Humbucking pickups are less susceptible to radiated hum and buzz, but you shouldn't let your monitor force you into changing your guitar. Note: if you use a notebook computer with an LCD screen, you won't suffer from this problem.
Before leaving the subject of computer screens, another uncomfortable combination is loudspeakers and computer or video monitors — unless the speakers are magnetically shielded. This time it's the monitor that suffers, as the magnets in the speakers may be powerful enough to deflect the electron beam inside the monitor tube, causing the monitor display to become distorted and the focus to deteriorate. With colour monitors, you often find coloured patches on an otherwise white screen — a sure indication of a nearby magnetic field. In extreme cases, you can end up with a permanent magnetic charge on the display tube, and picture quality won't entirely revert to normal when the speakers are moved away. If this happens, try switching the monitor on and off a few times so that the automatic degaussing circuit operates, but if the problem still persists, you may have to get the tube professionally demagnetised (I've actually degaussed a TV screen using a tape head demagnetiser, but I'm not guaranteeing it'll work every time! To avoid this problem, either work with magnetically‑shielded monitor speakers, or keep your speakers at least 18 inches away from your screen.
It's worth noting that smoking doesn't only damage your health, it also significantly shortens the life of your faders, pots, switches and patchbay jacks. Other enemies of electrical equipment include soft drinks; the sugars and acids contained in most soft drinks have a very corrosive effect on circuit boards and component leads, so if you do spill a mug of orange juice into your faders, or into your favourite reverb unit, expect the worst!
Banning clients from standing drinks on your mixer or effects racks is the obvious thing to do, but if disaster does strike, turn off the affected gear at once, unplug it from the mains, and soak up as much liquid as you can using paper towels. If you have electrical knowledge, you can try removing the cover (but note that you may well invalidate any warranty still in operation by doing this — and please make sure the unit is unplugged!) and cleaning the circuit board with a cloth dipped in distilled water. Once the equipment is cleaned and allowed to dry, you'll probably find it works OK, but if in any doubt at all, get the equipment professionally cleaned and serviced by a competent service engineer. This needs to be done at once, before serious corrosion sets in.
In the case of contaminated faders, carbon types are best replaced, whereas conductive plastic models can usually be taken apart and cleaned with washing up liquid and water. Squirting WD40 through the slots may make you feel better, but is unlikely to cure the problem.
I think I've covered all the main points, and I think you'll agree that it shouldn't be too difficult to avoid most of the above problems once you realise that a problem exists in the first place. A studio is a complex system involving many pieces of electrical equipment and a great deal of wiring, so if you just sling it all together and expect it to work properly without giving the overall system any thought, on your own head be it!
I used the terms balanced and unbalanced when talking about leads and connectors in the first part of this series last month, they've cropped up again this month, so perhaps they're worthy of a few words of explanation.
Analogue audio signal connections can either be balanced or unbalanced. An unbalanced connection relies on a two‑conductor cable, and in the case of screened audio cable, this comprises a central core surrounded by woven or foil conductive screen. Though the screen (which is generally connected to ground), offers a degree of protection against electromagnetic interference, it is still possible for traces of outside interference to become superimposed on the wanted signal.
Balanced systems were developed to provide increased immunity to electromagnetic interference, and the principle is very simple. Instead of a two‑conductor system, balancing involves using three conductors, one of which is still an outer screen, the other two being inner wires used to carry the signal. The reason for having two signal cables is that one has to be fed with a phase‑inverted version of the signal, and if you look at the wiring details for a balanced connector (usually an XLR or stereo jack), you'll see that the normal signal connection is usually referred to as 'plus' while the inverted signal is 'minus'.
At the receiving piece of equipment, the 'minus' signal is inverted once again to bring it back into phase with the 'plus' signal and the two are added together. Why does this help? As the two signal wires are physically very close to each other, it's reasonable to assume that any interference will affect both conductors pretty much equally. When the 'minus' signal is reinverted at the receiving end, any interference on that line will also be inverted, so when the 'plus' and 'minus' signals are added, the overall result is that the two interference signals cancel each other out, while the wanted signals combine. Even this isn't quite perfect, as you don't get exactly the same interference signal on each conductor, and the phase‑inverting circuits at either end of the line aren't 100% accurate either, but even so, the amount of interference remaining on the final signal is a tiny fraction of what it would be on an unbalanced connection in similar conditions. The diagram shows both balanced and unbalanced connections.
Naturally, you have much less control over signal interference emanating from outside your studio than you do over interference that stems from your own equipment or mains supply. If you're unfortunate enough to live next door to a radio ham (or worse still, a commercial radio transmitter or taxi depot), you might find that nothing you do can keep stray broadcasts out of your audio chain, short of turning your whole studio into a Faraday cage (an earthed, metal‑lined box or cage) and filtering all incoming mains! Unfortunately, there's no legal recourse to this menace providing the transmitter is licensed, so if you can't afford to take the Faraday cage approach, all you can really do is to try to come to some kind of arrangement as regards transmitting times (in the case of radio amateurs) — or move!
Other problematic outside sources of interference include welding equipment (particularly gas welders), and any heavy industrial plant that uses high‑powered motors. Nature isn't entirely guilt‑free either, and it's as well to unplug all your gear in the event of a thunderstorm, because a lightning strike anywhere in the near vicinity could easily vapourise every semiconductor device in all your electronic equipment if it's been left plugged in, even if it's switched off!
Tape recorders should be kept away from strong magnetic fields (like those associated with large transformers) as the signal coming off a playback head is so small that any interference can add considerable noise and hum to the output. It's also important not to bring any form of permanent magnet into contact with any part of the tape transport, or you could end up with a magnetic charge on the heads and tape guides, which will not only affect the quality of new recordings, but may also cause existing recordings to deteriorate when they are played back on the machine. Some charge build‑up is inevitable, which is why regular demagnetising is recommended, but strong magnets such as guitar pickups, magnetised screwdrivers, loudspeakers and so on should be kept well away. Sticking cute fridge magnets on the side of your recorder is definitely not a good idea!
Tapes, particularly analogue tapes, can suffer permanent damage if stored near a strong magnetic field. Digital tapes are less susceptible, but there's no point in pushing your luck, so look after these too! Avoid storing tapes near to, or on top of, monitors, close to power cables or transformers, or indeed near any other obvious source of magnetism. Tapes also need to be kept at a relatively stable room temperature, in a low humidity environment, and must be protected from dust by means of suitable packaging or self‑seal plastic bags. Direct sunlight is particularly damaging to tape. Giving your studio a regular clean with a vacuum cleaner will help to prolong the life of both your tapes and your tape heads.