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Regarding Sam Berkow's article Subtle Magic in the April 2002 issue, Cees Mulder writes, I'd like to express my gratitude for [discussing] this topic.

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Jun 1, 2002 12:00 PM

Regarding Sam Berkow’s article “Subtle Magic” in the April 2002 issue, Cees Mulder writes, “I’d like to express my gratitude for [discussing] this topic. I design and align [these systems, and] I have some comments.

“You mention that early systems ‘were unable to alter natural acoustics without significant tonal coloration or artificial-sounding tones.’ It depends which systems [you’re talking about]. You have to differentiate between enhancement systems (artificial reverberation systems like ACS, LARES, SIAP) and natural systems (reverberation amplification like AR and MCR). Artificial systems often introduce coloration; systems such as MCR do not, if they are well aligned. The analog systems installed by Philips work well without coloration.

“To get natural acoustics using electroacoustic means, you have to use reverberation amplification, because only this method complies with the formula p2=25ρcWT/V. Artificial systems don’t.

“When using artificial systems, the room has to have a low architectural reverberation time; otherwise, the reverberation amplification will dominate the artificial reverberation. This effect has to be understood before designing and installing a system. In my view you have to understand amplification reverberation before starting the next step of artificial reverberation.”

Mulder concludes with a request for more discussion about when to use reverberation amplification and when to use artificial reverberation: “I know rooms where you have to use reverberation amplification and artificial systems do not work, and I know rooms where the situation is the other way around.”

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