Dolby CP100 Cinema Processor
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The 70mm Newsletter
Written by: Dolby Laboratories CP100 brochure plus addition color
pictures and captions by Robin Dakin. Brochure text prepared for
in70mm.com by Anders M. Olsson, Lund, Sweden
it is possible to enjoy good quality stereo sound in most homes. It is thus
reasonable that the moviegoer should be able to hear the same high quality
of sound in the theatre, adding realism, immediacy and impact to the superb
high definition picture on the screen.
During the last eighteen months, tests carried out by Dolby Laboratories on
monaural optical sound-tracks have led to the development of new techniques
which for the first time make possible optical sound-tracks in stereo high
fidelity. These tracks are made with conventional black-and-white sound
processing techniques, utilizing two tracks side by side on the film, in the
same location as a conventional monaural track. To play back this track in
stereo high fidelity requires Dolby noise reduction decoding of the two
signal elements, circuitry to derive centre-channel information for
three-loudspeaker systems, and third-octave equalization for accurate
matching of the loudspeaker characteristics to the existing theatre
acoustics. These facilities form the basis of the new Dolby CP100 Cinema
In addition to stereo optical playback capability, the CP100 also employs
its equalization circuitry when other film formats are being played. The
unit contains comprehensive provision for the playback of conventional
optical tracks and, when required, magnetic stripe.
Additionally, the unit contains a non-sync capability, so that tapes and
records can be played back in the auditorium in high fidelity while using
the existing theatre loudspeaker units.
The unit represents a simple one-time cost if the theatre already has three
suitable power amplifiers and loudspeakers.
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DP70s of the Empire
Presented in 70mm
Presentations in London, England 1958 - 2012
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The CP100 Cinema Processor consists of a 19-inch main frame, into which the
modules listed below are plugged in two levels.
(1) Stereo optical playback module, incorporating amplifiers and changeover
functions for two projectors.
(2) Standby stereo optical playback module, identical to (1), selected by
the changeover module in the case of failure of the main module.
(3) Changeover module, which incorporates the projector changeover logic.
(4)-(8) Meter modules, to check and calibrate internal signal levels.
(9) Non-sync module, with inputs for two stereo sources and also for a p.a.
(10) Six-channel ganged fader, electronically controlled and remotable.
(11) Local control module for setting volume levels in the auditorium,
selecting film format, and also providing a monitoring control for booth
Lower level (beneath a swing panel)
(12) Noise reduction modules. These are the standard Dolby A-Type noise
reduction modules (Cat. 22) of which over 20,000 are currently in service
(13) Equalization modules which have been specifically designed for theatre
reproduction and consist of 27 filter bands together with upper and lower
frequency tone controls.
(14) Mono/Stereo optical format module with logic circuit to ensure stable
(15) Space for two further format modules, allowing the acceptance of
magnetic inputs, or for processing of any other cinema format.
(16) Facilities module, allowing for local or remote control of projector
changeover, fader control, and format selection. This module incorporates a
bypass key to remove the complete unit from the signal path in case of
failure, giving immediate restoration of sound to the auditorium.
Dolby CP100 Specifications
to see enlargement
Unitary chassis, containing all necessary modules for playback of stereo
optical tracks, including pre-amplifiers, noise reduction modules and cinema
equalization modules. Also contains non-sync inputs module and control and
facilities modules, providing full signal selection and processing from
projector to the input of existing power amplifiers. Extra (optional)
modules plug into pre-wired frame allowing full replay of 4 or 6 channel
magnetic tracks, or for other cinema sound-track formats.
Standard screw-type terminal blocks for signal channels and remote
facilities. Solder-tag fanning strip supplied for each terminal block.
a) Optical pre-amplifier designed for stereo solar cell (current source)
b) Magnetic tracks. 10 K ohm input impedance, requiring 300 mV for Dolby
c) Non-sync sources. Two switchable stereo channels provided, input
impedance 10 K ohm, 5OO mV max sensitivity. Also input for public address
microphone, input impedance 2 K ohms.
Six output channels, 30 ohm output impedance. Will drive any load impedance
from 200 ohms upwards. Maximum output level +23 dB into bridging load, +22
dBm into 600 ohms. Typical operating level 1.23 V, +4 dB for Dolby Level,
giving 18 dB overload margin.
Dolby A-Type professional characteristics providing 10dB of noise reduction
from 30 Hz to 5 kHz, rising to 15 dB at 15 kHz. Two Dolby Cat. 22 modules
supplied for stereo optical, with provision for third plug-in module for
used to own the very first CP100 used for "Tommy" at the Odeon West End,
although not the Quintaphonic decoder. It was only used for "Tommy" then
removed. After that, its history seems unclear. I spoke to many people about
it and got nowhere. I got it from a dealer of equipment for spares in 1995
and swapped it for a television picture tube and when I got it home, I soon
realized it was different and stored it on a display shelf for several years
until 2003, when Dolby suddenly asked me if I want to sell it or have
With local fader control set at 7 (10dB from maximum), output level of +4 dB
(1.23 V), and NR switched off, noise on outputs in optical mode is typically
-65 dB (20 Hz - 20 kHz), or -70 dB CCIR/ARM weighted, referenced to Dolby
Level (Test Tone).
Better than 40 dB between channels at 10 kHz.
Facilities provided for remote operation of
b) Projector change-over
c) Full remote control of a) and b) and mode/format selection by remote
control units, one per projector. Automation facilties built-in (some
programmers may require simple relay interface); functions switched by
applying an earth (ground) to appropriate function terminal on rear of unit.
gave it to them in return for a DA20 and cat701 head so I could modify my
existing CP100 (something I had always wanted to do). I took the photos on
slide film and sent the originals prints to Dolby. These are copies I made
off the slides. The 2 photos of the rear show the messy wiring were a CP100
is loomed neatly and the back plate which shows its a noise reduction unit,
not a cinema processor and its been relabelled with masking tape.
System is highly stable and does not require alignment after installation.
Ambient operating temperature
Up to 40°C.
Plug-in modules throughout, accessible through front panel. Fibreglass
printed circuits, solid state devices throughout. Precision cast aluminium
frame with steel panels, black stoved textured finish. Front panel stove
enamelled red with white characters.
267 x 493 mm rack mounting (10½ in x 19 in). Maximum projection behind
mounting surface: 280 mm (11 in). Maximum projection in front of mounting
surface: 25 mm (1 in) excluding handles, which project 50 mm (2 in).
16.5 kg (36 lbs).
module pictures is the optical pre amp and the label shows for prototype
CP100. The front originally came with the outer meter modules missing I
fitted blanks as it looked better on display. The CP100 now sits on a glass
shelf in Dolby's San Francisco head quarters. There is a picture of it on
the Film-tech web site under photos for Dolby Labs Screening Room. One
retired Odeon engineer gave me a original brochure which I enclose.
Units are designed for operation from centrally switched power source (power
cable provided). Unit requires 105-130 V or 210-260 V, 50-60 Hz single
phase, 50 VA.
20 mm standard size, 1 A slow blow for 115V, 0.5 A slow blow for 230 V
'Dolby' and the double-D symbol are trademarks of Dolby Laboratories Inc
Dolby Laboratories Inc
731 Sansome Street
San Francisco CA 94111
Telephone (415) 392-0300
346 Clapham Road
Telephone 01-720 1111
Cables Dolbylabs London
75/207 Printed in England
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