[postprosound]

I copied this from gearslutz. Perhaps this should be a sticky?


Theatrical Sound Production Facility Requirements

1. Introduction

Dolby Production Services contracts services and encoding equipment to content owners and
distributors wishing to release their theatrical program in a Dolby format. To ensure the highest
quality and reliability, Dolby requires that these services take place in an audio production facility that
meets the minimum requirements outlined below.

Facilities wishing to be considered for Dolby approval should contact Dolby Production Services.

2. Room Design

2.1. The room must be large enough to accommodate at least “Mid Field” monitoring. The minimum
acceptable room dimensions are 20’ long (Screen to Rear Wall) by 13’ wide with a 9’ ceiling
height. The optimum mix position is located 2/3 the length of the room away from the screen. In
the minimum sized 20’x13’ room, this position is 13’-4” from the screen.

Refer to chart below for acceptable room dimensioning ratios. The shaded area represents
acceptable conditions, whereas the straight line represents the optimum ratio.

3. Speakers

3.1. The screen speakers (Left, Center, and Right) must be the same make and model and must be
behind a perforated projection screen. The screen speakers should be able to reproduce
frequencies +/-3dB from 40 Hz to 16 kHz without assistance (satellite systems utilizing a
subwoofer to achieve full range are not acceptable for use as the screen speakers). The screen
speakers must be able to produce “clean” sound pressure levels (peaking) up to 105dBC SPL.
The location of the Left and Right speakers should not subtend an angle greater than 45
degrees from the mix position. The speaker cabinets should also be mounted at the same
vertical height, which should be mid-screen, for all screen channels.

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3.2. There must be at least (2) pairs of surround speakers mounted along the sidewalls to create an
effective surround “array”. Larger mixing rooms will have several surround pairs that cover
listening areas in front of and behind the mix position. In smaller rooms, the first pair of
surrounds must be slightly in front of the mix position. The second surround pair should be
slightly behind the mix position.

Mix stages that are to be equipped for Dolby Digital Surround EX must also have at least (1)
pair of surround speakers mounted on the rear wall. A separate two-channel amplifier must also
power the rear surround speakers to allow proper Surround EX monitoring.

For smaller mix rooms, surround speakers should never be directly “on axis” with the mix
position. The surround speaker array must be able to produce “clean” sound pressure levels
(peaking) up to 105dB SPL.

3.3. There must be a separate subwoofer capable of producing an equalized response of 25Hz-
120Hz +/- 3dB. The subwoofer must also be able to produce “clean” sound pressure levels
(peaking) up to 115dBC SPL.

4. Equalization & Delay

4.1. The speaker system must be equalized to the ISO 2969 “X” curve. There must be 1/3 octave or
parametric equalization inserted before the screen channel amplification to accomplish this
equalization. For the surround channels, single octave EQ is acceptable but not recommended.

4.2. If the distance from the mixer to the screen is more than 1.5 times the distance from the mixer to
the surrounds, a suitable delay line should be inserted (Pre-EQ) into each surround channel
monitoring path. It is recommended that the delay line is patchable so that it can be inserted in
the recording chain should a separate picture and track screening master be required.

4.3. A parametric EQ of at least one but preferably more bands and a 120 Hz low pass filter (Pre-EQ)
should be inserted in the LFE (subwoofer) monitor path. The LFE filter should be a 3rd order
Butterworth filter set with a crossover point at 120 Hz. Higher order filters are acceptable, but
lower order filters can cause incorrect perception of the LFE channel. Also, it is recommended
that the 120 Hz low pass filter is patchable so that it can be inserted in the recording chain
should a separate picture and track screening master be required.

5. Level

5.1. After proper equalization, the monitor levels need to be calibrated to 85 dBC SPL for each
screen channel (L,C,R), 82 dBC for each surround channel, and +10 dB in-band gain (RTA
method) referenced from the center channel for the subwoofer. A compliance check of EQ and
levels by a Dolby engineer must be performed prior to commencement of each contracted mix.

5.2. The sound system must be designed to provide a minimum headroom specification of +20dB
above normal reference level for each channel.

5.3. The console monitor section must have a multi-channel assignable fader with at least six inputs
and outputs. The monitor section must also provide a ‘fixed reference level’ mode for proper
listening levels when mixing and print mastering.

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6. Equipment

6.1. Dolby will supply a Digital Mastering Unit (DMU) to approved 5.1 mixing studios IF the length of
the film is 40 minutes or more. For short subjects or trailers, the film must be mastered to a
digital multitrack format and transferred at an approved Dolby Digital transfer facility..

6.2. Studios that are approved to use the Dolby DMU mastering system must also meet certain
business requirements (films per year) to be considered for a permanent installation. For studios
not meeting these business requirements, Dolby supplies a traveling DMU on a “per-mix” basis.

6.3. The “Dolby Surround Tools” plug-in for ProTools can not be used to create an Lt/Rt during the
final film print master. This plug-in does not facilitate the proper metering and processing needed
during mastering. Although the plug-in cannot be used for print mastering, it can be used for pre-
mixing. Also, any analog tape machines being used for the mix should be equipped with Dolby
SR noise reduction

Note: Dolby Laboratories, Inc. Model CP650 is a recommended cinema processor for decoding many
formats such as: Dolby Digital Film Soundtrack, SR/A Optical Film Soundtrack, and Digital 5.1 and
Lt/Rt Studio Masters.



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