One of our avid inSync readers (and contributors) had the following follow up to our recent tip on lighting dimmer noise (see the TTOTD from 12/3/99).
“You can eliminate all the hash, noise and most of the buzz by using variacs to dim your lights. They are big, heavy, and expensive (about $160 for 1200 watts). Don’t install them yourself unless you know what you’re doing. Get an electrician. I got mine from McMaster-Carr Supply in Chicago. This will not totally get rid of the hum, but it’s about 90% effective. For a near 100% solution, use an equipotential or balanced line AC source with the variacs. Of course now we’re talking big dollars if you have a lot of lights to control. If you’re a total tweakhead, run a sine wave uninterruptable power supply (UPS) off your AC panel, from there go to the equipotential supply, and from there to the variacs (Ed – okay, this is really overkill). Always watch your wattage and/or volt-ampere ratings. An overload could start a fire!”
Another inSync reader inquired about newly emerging DC dimming technology. In theory these should solve a lot of the problems created by AC dimmers, but at present the cost is prohibitive for most project studios, which also means there is no widespread body of knowledge on how effective they really are.