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6.0 Technical Requirements for Studios to Obtain
Dolby Certification

6.1. The first essential requirement for the dubbing theatre is to monitor Dolby
mixes correctly, as well as play your own and other studios' printing masters
and optical soundtracks. To this end you will need to install a Dolby cinema
processor type CP650S1. The CP650S will provide analogue and digital
optical replay, Surround-EX decoding, matrix decoding, full equalisation2 for
loudspeaker calibration on all 7 channels, surround delay and master monitor
level control. The CP650S uses AES/EBU digital inputs and analogue, digital
or analogue cross-over outputs.

6.2. Optical replay of both the analogue and digital optical track is required for
foreign version and original feature mixing to allow the studio to match the
original recording, or to check the quality of an “Answer Print”. This will require
a solar cell and bracket assembly for analogue replay, as well as a Cat. No.
702 or an approved Dolby Digital reader to be added to the projector or sound
follower. The sound follower or projector must be able to run in synch with the
studio recorders.

6.3. The screen and surround speakers and amplifiers must be capable of
providing a frequency response to ISO2969 and, with the requirements of
Dolby Digital in mind, must be able to provide an SPL of 105dBC for peak
levels, after acoustic calibration, without distortion.
Theatre type speakers (pressure drivers with suitable horns) will be required in
medium to large rooms and these should have electronic crossovers.
Appendix A gives further guidance.
Bass management systems are not suitable.
The Dolby Studio Approval Calculator should be used to verify loudspeaker
and amplifier performance capabilities.
Suitable test material is available to check monitor headroom capability (“Jiffy”
test film tone sweep test and a pulsed short duration 0dBfs pink noise test).
Please note that Dolby level pink noise, 85dBC, equates to around -14dBfs.

6.4. The screen speakers must be at a height to give good coverage in the mixing
and listening area. When projecting a 2.35:1 picture the left and right speakers
will be inside the edge of the picture area and provide a 45° angle ± 5° with
the mixing position. If masking is used this must be of the acoustically
transparent type. We recommend that the mixing position be placed 2/3
back from the screen and require that the screen is at least 5 meters from
the mixer. The studio area will be greater than 45 meters square and room
volume will be greater than 150 cubic meters. We will allow some small
deviation to these requirements if, in our opinion, the proportions of the room
and equipment layout are spoilt in order to comply. Room ratios will be within
the shaded area shown in Figure 1 below and ideally close to the straight line.
Figure 1 Ideal Room Ratio
1 See Appendix B for selection chart
2 We strongly suggest that no external equalisation is used as headroom or S/N in some frequency bands may be
compromised.
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6.5. The acoustics of the mixing room must conform to the acoustic characteristics
shown in Figure 2. The reverberation time should ideally diminish and show no
reversals with increasing frequency.
Figure 2 Reverberation Time

6.6. Ambient noise levels must not exceed NC-25 as measured according to ISO
9568 Background acoustic noise levels in theatres, review rooms and dubbing
rooms.

6.7. Two track only “Printing Masters” must be supplied SR encoded for transfer to
optical sound negative on RDAT, Hi-8 (DTRS) or as .wav files. Dolby Digital
“Printing Masters” (6 track and 2 track) will be recorded on a Dolby Digital
Master MOD (Magneto Optical Disk) within the Dolby Digital Encoder for
transfer to optical negative. They must also be recorded to .wav files or Hi-8
(DTRS) tape. Some customers may still request them on 35mm magnetic film
with SR noise reduction.

6.8. Mixing consoles must have a minimum of 32 channels providing full
processing such as gain, EQ, dynamics and pan. The console must provide a
minimum of 24 professional grade faders at least two panoramic controls to
move sounds between at least four channels and preferably six. There must
be a minimum of 8 group outputs. If the studio intends to mix big budget
original productions the above will need to be significantly increased.

6.9. The monitor section of the console must provide PEC/DIR (direct/replay)
switching for 8 signal paths and a 16x8 summing monitor matrix to provide
correct monitor routing during pre-mixing. It must allow individual solos and
mutes of source and monitor channels. If the studio intends to mix big budget
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original productions, the number of PEC/DIR switches and matrix inputs will
need to be significantly increased. Virtual (internal) as well as external
solutions are acceptable as long as the user interface is dedicated to this
function.

6.10. The DMU and MME encoders have AES/EBU digital inputs. A Dolby or thirdparty
ADAC may be used for interfacing the encoder to analogue consoles, but
in order to enable full and correct functionality of the encoder, any third-party
ADAC must comprise:
• 8 channels of analogue to digital and digital to analogue conversion.
• A conversion from the studios analogue level to -20dBfs. Normally this
would be 0dBU or +4dBU equating to -20dBfs.
• Headroom of 20dB above the analogue reference level.
Converters not meeting the above specifications will not be accepted. If in
doubt please advise us the make and model number intended.
A suitable safety limiter on the input to prevent hard clipping at levels over
20dB above reference is not a requirement but is a valuable addition to the
specification.

6.11. Level standardisation at –20 dB below MSB or clip in the console main outputs
and recorders is essential. You may wish to check with the manufacturer that
digital and line levels conform to accepted standards i.e. +4dBu or 0dBu line
level for –20 dBFS internal console level and that the meters read –20 dB.

6.12. For synchronisation, the Dolby encoders require time code and video
reference signals. The DMU can also work with biphase (a 240 or 48 pulse per
frame bi-phase signal for a 24 frame per second rate). The studio must ensure
they can supply the appropriate synchronisation signals prior to digital
mastering.

6.13. Video projection must provide an image that when projecting a film made in an
aspect ratio of 1.85:1 (flat) or 2.35:1 (scope), covers the width of the screen to
at least the outer edge of the left and right screen speakers. Reflected light
from screen (measured at mixing position) must be at least 12fL, and the pixel
resolution of the projector must be a minimum of 1920 x 1080. Processing
delay must be known and compensated for by a suitable timecode offset to the
video replay device. If in doubt, please provide us with specifications and we
will determine suitability.