3Com CP-1 owner manual Surround Programs, Mono Logic

Page 48

Theory and Design

Lexicon

The Surround Programs

sides to the front, while leaving the side outputs on.)

The Surround programs: Mono Logic, Stereo Logic and Pro Logic, are specifically designed for film sound or for systems set up primarily for

Mono Logic

enhanced film viewing.

Mono Logic is a stereo conversion program for monaural film sound tracks. A quick look through any video rental selection will prove the usefulness of such a program; the vast majority of titles are mono.

The problem of mono-to-stereo conversion is an old one. One time-honored solution is to break the incoming signal into frequency bands, sending some to one channel and the rest to the other. When the filters are complementary (when the sum of the two output channels equals the original input channel) this solution can give stereo spread without ruining the tonal balance. When the filters are non-complementary, they can produce an unpleasant fake stereo effect.

Some effort has been made to design filter pairs for film sound which leave voice frequencies unchanged while spreading out the music. More recent designs have gone in another direction, using digital or analog delay lines to produce a comb filter effect. So far, these attempts have not been very successful.

The principal element of film sound is dialog and the principal rule in reproducing it is to assure that it appears exclusively in the center channel. Broadcasters, who have an interest in converting mixtures of dialog and music to synthesized stereo, have built circuits designed to turn off the stereo synthesizer when voice appears. Unfortunately, the switch from mono to stereo is often abrupt and the chances of dropping into mono by mistake during music are high. One basic problem with films, especially modern ones, is that music or background effects which should be spread out into the side speakers frequently appear at a low level beneath the dialog.

The Mono Logic program electronically identifies certain properties of film speech and removes it from the stereo synthesis. This allows music and effects in the dialog to be spread out while leaving the dialog centered. The remaining music and effects are directed to the input of a room simulation program that creates a space the size of a large room or small theater. The

Page 44

Page 47 Page 49
Image 48
Page 47 Page 49
Contents CP-1 Digital Audio Environment Processor Owners ManualPanorama Ambience Reverb SurroundPrecautions Unpacking and InspectionAcknowledgements Safety Suggestions Table of Contents Controls IntroductionControls Indicators Front PanelSource Monitor Rear Panel InputsRemote Control ProgramsPanorama Volume BankParameter EffectControls Indicators Installation PrecautionsConnection Calibration Connections to Other EquipmentConnecting the CP-1 in a Tape Monitor Loop Connection and CalibrationAudio Inputs Setting Main Input Output Levels Front Panel AdjustmentsConnection Calibration Input LevelsOutput Levels Balancing Additional ChannelsCalibration of the Panorama Program Silence Noise Speaker Set-Up Configuration ConfigurationSpeaker Configurations Speaker Set-Up Configuration For FilmSpeaker Set-Up Configuration For Music Speaker Set-Up Configuration Speaker Set-Up Configuration Using the 4 Programs Test ModeTo Load, Modify and Store Programs Panorama Program ParametersRear Level Rear Delay Effect LevelInput Balance Listener PositionAmbience Room Shape LivenessPrograms Ambience Reverb Pre-Delay Mid RTBass RT TrebleSurround Program Parameters Mono LogicStereo Logic Pro LogicProgram Parameters contd Auto Azimuth BalanceBass Blend Rear EffectUsing Programs Restoring Original SettingsTo Rename and Store a Register Naming a RegisterUsing Programs Troubleshooting TroubleshootingProblem Troubleshooting Restoring defaults Troubleshooting Theory Design Lateral SoundConcert Hall Acoustics Theory and Design Lateral Sound in your Listening EnvironmentTheory DesignAmbience Extraction Ambience GenerationPanorama Program Theory Design Theory and Design Ambience Program Be the sound that comes from the sides Reverb Program Surround Programs Mono LogicPro Logic Dolby Surround Decoding Pro Logic DecodingCP-1 Decoder Stereo Logic Speaker Set-Ups for Pro Logic Theory and Design References Theory and Design Specifications Frequency ResponseOptional Equipment 06/00 Lexicon 070-06619 Rev
Top Page Image Contents