Steve House |
March 21st, 2007 10:20 AM |
The 0VU = -20dBFS model is the one generally used today for high dynamic range delivery systems such as DVD and theatrical cinema. The 0VU=-14dBFS or -12dBFS models are generally used for lower headroom media such as VHS video. Very high dynamic range media like DVD and other strictly digital delivery may go with reference levels even lower than -20.
Meters will only correspond roughly to the subject sensation of loudness. As such, IMHO meters should be used to monitor technical characteristics of the signal while your ears and calibrated monitor speakers should be used to judge subjectve qualities such as loudness. In a surround sound setup you should be metering each channel individually, watching for clipping etc. The procedure is to set the gain of each channel in the system so that reference level pink noise hits a specific sound pressure level. depending on delivery destination, at the mastering engineer's ears. T. Holman suggests for high headroom destinations like theatrical release and DVD to align each channel with 1kHz, 0VU reference tone to read -20dBFS on the meters. Then without readjusting the system's levels, switch to a -20dBFS pink noise signal and while muting all but one channel at a time, go from one channel to the next in turn and set each monitor speaker's volume control with a sound pressure meter at the listening position. His recommended levels are 79dB SPL on all channels for video release, 81dB SPL on the L,C, and R channels and 78dB on the LS and RS channels for theatrical masters.
You might want to check out Thomlinson Holman's (he's the 'TH' in "THX Sound") book "Sound for Digital Video" where he devotes an entire chapter to mastering and monitoring and how to go about setting up the system. It includes a CD with the necessary sine and pink noise alignment tones recorded at the right level.
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