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PART VIII Recording Studios Argon filled, tungsten filament bulbs are still a very practical solution, though interior designers seem to eschew them. Lighting is 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 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 prob- lems 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. 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 believe, believe it! It is possible by more complex elec- tronic means to produce a " clean " , variable AC, but the methods of doing so tend to be even larger and even more costly than Variacs, whose pure simplicity is a blessing in itself. From the early 1970s to the mid-80s many studios installed colored 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 insuffi-