Mike Atkinson, senior project manager at The National Theatre, said: "We had tried triac dimmers before, but the noise was completely unacceptable. The Cottesloe is equipped with 600 ways of low-noise IGBT dimmers from IES and although there was some attenuation, the buzzing could clearly be heard." For the last year Mike had also been testing and evaluating IES’s iSine - a new high-frequency sine wave dimmer, so he decided to try them out in a live production. "The effect was amazing. You could put your ear next to the batten while it was fading up and down and it was silent. The single battens were no problem either. We simply set the maximum output voltage we needed, knowing that the dimmer would produce a perfect 108V sine wave which was also very kind to the lamp filaments."
IES’s iSine sinewave silent dimmers have been in regular use throughout Europe for the past 12 months and are now in volume production. In addition to the silence due to the pure sinewave output, the underlying technology also eliminates the effects of high peak currents and reactive power, which would otherwise require over-sized mains cables, over-rated generators and transformers. The National Theatre is set to be the first theatre in the UK with a complete sine wave installation when the electrical refurbishment of the Lyttelton Theatre is completed.
(Ruth Rossington)
