3Com CP-1 owner manual Be the sound that comes from the sides

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Theory and Design

Lexicon

be the sound that comes from the sides.

The best way to generate spatial im- pression (SI) is with appropriate sig- nals from loudspeakers at the side. Reverb, Ambience and the Surround programs can all be used to generate these signals.

A

B

Placement of side loudspeakers is critical! Placement B sounds much better than A, especially when the room is well damped.

Early research with quadraphonics involved extensive experimentation with speaker placement, and confirmed that additional speakers beside the listener sounded better than the conventional approach of putting pairs of speakers in front and behind. Our research into speaker placement with Ambience confirmed the previous results of others: The side speakers should be directly to the side of the main listening position, plus or minus about 20 degrees. Beyond this critical angle the spatial impression is greatly reduced.

The sides are the most important additional speakers, much more so than the rears. Keep in mind that, although you can use the left and right main speakers to simulate a phantom center speaker, you cannot produce SI with one speaker in the front and one at the rear . (You can perform this experiment for yourself with the CP-1 using the Ambience program: Try the side speakers both in their usual positions and in the front corners. If your listening room has enough absorption to damp its side-wall reflections, the side location will provide much more spatial impression, and will sound substantially better.) Speakers in the front are useful - if you want the best possible sound from Ambience you may want to try an additional pair in the front corners, wired in parallel with the rear. This additional pair, as well as the rear speakers, may sound best if placed above the listener.

The effectiveness of the CP-1’s Ambience simulation is heavily dependent on the source material and the playback room. If the playback room is large and reverberant, its reflections may dominate those generated by the program. Carpet, drapes and furniture can all be used to break up or absorb undesirable reflections, making it easier to hear the processor’s output. The balance between the side, rear and front speakers is also very important. If the channels are set up properly, no single speaker will be audible by itself.

There are two basic hall shapes in Ambience: Rectangular and Fan. In a listening room with sufficient acoustical absorption, using source material without too much reverberation of its own, the two shapes are clearly distinguishable. For most classical recordings the rectangular hall sounds somewhat better because of its stronger side reflections. In our fan-shaped hall (unlike actual physical designs) you can increase the proportion of side to rear sounds, by increasing the Effect Level and shifting the F/B Balance controls toward the front. When this is done, another different but also pleasant sound results.

Although the Ambience program can provide some recirculation (adjust- able with the Liveness parameter), for long decay times it is better to use Reverb. The Large Hall ambiences are not intended to be used on material which is more appropriate to a smaller ambience, such as a small hall or a club. Highly percussive material is almost always better in the Small program which is quite successful in livening and expanding popular

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Contents Panorama Ambience CP-1 Digital Audio Environment ProcessorOwners Manual Reverb SurroundUnpacking and Inspection PrecautionsAcknowledgements Safety Suggestions Table of Contents Controls IntroductionFront Panel Controls IndicatorsSource Monitor Rear Panel InputsPrograms Remote ControlPanorama Parameter VolumeBank EffectControls Indicators Connection Calibration InstallationPrecautions Connections to Other EquipmentConnection and Calibration Connecting the CP-1 in a Tape Monitor LoopAudio Inputs Connection Calibration Setting Main Input Output LevelsFront Panel Adjustments Input LevelsOutput Levels Balancing Additional ChannelsCalibration of the Panorama Program Silence Noise Configuration Speaker Set-Up ConfigurationSpeaker Configurations Speaker Set-Up Configuration For FilmSpeaker Set-Up Configuration For Music Speaker Set-Up Configuration Speaker Set-Up Configuration Test Mode Using the 4 ProgramsTo Load, Modify and Store Programs Panorama Program ParametersInput Balance Rear Level Rear DelayEffect Level Listener PositionAmbience Room Shape LivenessPrograms Ambience Reverb Bass RT Pre-DelayMid RT TrebleSurround Program Parameters Mono LogicStereo Logic Pro LogicBass Blend Program Parameters contd Auto AzimuthBalance Rear EffectTo Rename and Store a Register Using ProgramsRestoring Original Settings Naming a RegisterUsing Programs Troubleshooting TroubleshootingProblem Troubleshooting Restoring defaults Troubleshooting Lateral Sound Theory DesignConcert Hall Acoustics Theory and Design Lateral Sound in your Listening EnvironmentAmbience Extraction TheoryDesign 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 Frequency Response SpecificationsOptional Equipment 06/00 Lexicon 070-06619 Rev
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