It’s become an all too familiar scenario… A school district is looking to save on energy and maintenance costs and hires an energy efficiency consultant. With all good intentions, the consultant sees three dozen or so 500-watt PAR lamps in the auditorium house lights and recommends they be replaced by 17-watt LED PARs. The district also expects huge savings in replacement lamp costs and increased safety since the custodians won’t need to climb out on planks over the plaster lath ceiling.

Assuming they got the apparent color temperature right (which is yet another topic), the new lamps look great until they try to dim them with their 20-year-old phase control dimmers. Flickering occurs, and then lamps cut out. After that, some lights don’t even come back on.

When it comes time to consider changing over to LED from older style incandescent house lighting, it’s not simply “changing the light bulb.” A holistic approach must be taken. Even if the package on the lamp states it is “dimmable”, it may or may not do so on a stage lighting system. If the lamps do dim they may not fade to black as desired, or they may flicker. Performance lighting venues are one of the few places where lights are actively dimmed in view of the patron; the lights should fade smoothly and to black.

In older stage lighting power and control systems that also drive the venue’s house lights, careful consideration must be given into upgrading or switching the power source. This can mean switching from phase control dimmers to “smart” relays or constant current circuits. Additionally, running a whole new control system is frequently needed (whether DMX-512 or 0-10V). As the accompanying article details, modern LED house lighting dimming and control has many nuances and many possibilities.

Consider this automotive analogy… In the 1970s, radial ply tires were the “hot new thing”. Better handling (safer), longer lasting, and they added to fuel efficiency. But, existing cars with older suspensions couldn’t use them… Putting radial tires on an unmodified ‘65 Buick was disastrous. The same type of thing occurs when putting household or commercial LED lamps on an older, phase-controlled dimming system. Dimmable LED lamps are not plug and play on theatrical systems.

Typically, older house lighting systems are coupled with older stage lighting power and control systems with DMX routed only to the dimmer processors, not to the fixtures directly. You know, when they renovated the space in the early 1990s…? LEDs and performance lighting control technology have evolved exponentially since then.

So, for venue operators considering “changing the light bulb”, more research is needed. To get it right, they should be considering replacing all the performance lighting technology.

By Peter A. Scheu, ASTC