Dolby Laboratories CP650 Installation Manual download pdf (Page 52)

Dolby

Model CP650 Installation Manual Front-Panel and Alignment Overview

3-10

The final factor is masking of the screen. The masking curtains must be drawn back

sufficiently to clear the left and right screen speakers before any adjustments or

measurements are made. The high-frequency horns should clear the screen frame and

be mounted as close as possible to the screen. Conventional black felt side-masking

can severely restrict high-frequency response. Consequently, there would be severe

losses if the left and right loudspeakers were equalized with the masking set for a

2.35:1 film, and then the masking were brought in for a 1.85:1 film, thus obscuring

the outer speakers. To avoid this problem, some theatres have installed acoustically

transparent masking cloth, and others leave the masking open whenever they are

showing a 1.85:1 film with a stereo soundtrack. Moving the speakers towards the

center of the screen to clear heavy masking is not a good solution, since the stereo

separation would be degraded.

Repainted screens cannot be used for quality sound playback, because the

perforations, which allow the high frequencies through the screen, can become

clogged with paint.

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Dolby Laboratories CP650 Installation Manual Page 52