Abbingdon Music Research owner manual Appendix E LS-77 in OptiArray configurations

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AppendixE – LS-77 in OptiArray configurations

E.1 Introducing AMR's OptiArray® scalable acoustic system

Above and beyond the role of an exceptional quality midfield monitor, the AMR LS-77 is designed to form the main element of the AMR OptiArray® scalable, modular loudspeaker system. The OptiArray® system takes account of several basic acoustic facts.

i. The larger a room the louder must a speaker play for a given sound level at the listening position.

iiThe larger a room the more and to lower frequencies must the speaker directionality increase to maintain the same ratio between direct sound (that of the recording - wanted) and indirect sound (reverbrations in the room, - unwanted).

Large listening spaces invariably require more acoustic power applied to the air volume in the room to excite the same amount of pressure change (a bottle of beer will nearly fill a pint glass, however in a large bucket it will barely moisten the bottom), this much is quite obvious, so the need for more output from the speaker as rooms get larger is simple and intuitive.

However, large listening spaces are invariably also less well damped, in an acoustical sense, than small ones. This and the much longer dimensions with the thus increased delay between reflections lead to much longer reverb times in the room. The room reverbrant field (that is sound radiated and re-radiated by the walls, floor and ceiling) will interfere most crucially with the percieved space of the recording and will secondarily often change the tonality of the sound as well.

For a striking example compare the sound of a portable radio in an equal size empty room and one well furnished. In the empty room the sound will be clattery, echoy, phasey and indistinct as well as subjectively too bright. In a normally furnished room with carpeted floor the sound will be much more natural. Ideally we wish to keep the unavoidable contribution of the room sound over the direct sound below the threshold where the room influenced sound overwhelms the direct sound.

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Contents LS-77 Reference Class Professional Monitor Loudspeakers Page Page Precautions Running-InContents Page Unpacking Front Panel of the LS-77Please check that all contents are present Component Overview LS-77 Front FasciaContact with the chassis Setup Connecting the loudspeakersUsing AMRs OptiLink Speakon Cable Speaker R Speaker L Using Binding Posts Speaker Cable Stereo Amplifier Interconnect Cable Connecting the amplifier Multi-channel set upChoice of loudspeaker cable Positioning Symmetry and room modesDistance between the loudspeakers Distance to the loudspeakers Distance to back and side wallsLevelling/Speaker Support Loudspeaker Toe-in Room and furniture influenceCare and maintenance Care & MaintainanceRunning-in the loudspeakers Power rating LS- 77 Technical Features Troubleshooting Troubleshooting GuideSpecifications Specifications TableAppendix a Adjustment of tonal balan ce HF Level Placement Suggestions HF Level R1 Placement Appendix B Abbingdon Acoustic Setup Regime Page ~100″/254cm ~115 ″/290cm Page Page Appendix C Biamplifying the LS-77 LS-77 Speaker R Speaker L Speaker Cable Appendix D The AMR Active System AM-77 Control Center Edition CCESetting up the AMR Active System Line Level ConnectionSpeaker Connection Scenario Testing and Troubleshooting the AMR Active System AMR Active System Configuration Diagram LS-77 Speaker LAppendix E LS-77 in OptiArray configurations Introducing AMRs OptiArray scalable acoustic systemPage AMR recommends the following OptiArray Setups Epsilon/Zeta Iota/Zappa Omicron/Sigma Epsilon/Zeta System wiring Good acoustics Appendix G Acoustics Background In formationAcoustics Reverberation timePage Absorbers DiffusersAbsorption or Diffusion ? Membrane absorbersStanding Waves Porous absorbersRoom modes
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