Abbingdon Music Research LS-77 Appendix G Acoustics Background In formation, Good acoustics

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Appendix G - Acoustics Background Information

G.1 Acoustics

When we talk about making a room "sound right", we are probably dealing with room acoustics. As a science acoustics has been around for about a hundred years. Until then good acoustics happened by experiment, by experience, or simply by accident.

Today we know a lot about the parameters that influence the "sound" of a room. Talking about the listening room we know that basically this room should act as neutral as possible. But this is not always the case. Lets just take a short look on some of the issues that one must be aware of.

G.2 Good acoustics

Here is a list of important parameters concerning good acoustics.

yProper reverberation time

yGood sound distribution

yAdequate sound pressure level

yLow background noise level

yNo echo (flutter echo)

Now lets have a look on these headlines that will be adequate for the most purposes concerning sound production.

G.3 Reverberation time

The reverberation time is defined by the time it takes a sound to attenuate 60 dB after the source is stopped. In real life we can experience reverb times from approximately 0sec. (outdoors or in anechoic chambers) to something like 10-12 sec. In special reverb chambers the time may exceed 20 sec. Listening rooms normally should have a reverb time around 0.2 - 0.3 sec.

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Contents LS-77 Reference Class Professional Monitor Loudspeakers Page Page Running-In PrecautionsContents Page Front Panel of the LS-77 UnpackingPlease check that all contents are present LS-77 Front Fascia Component OverviewContact with the chassis Using AMRs OptiLink Speakon Cable SetupConnecting the loudspeakers Speaker R Speaker L Using Binding Posts Speaker Cable Stereo Amplifier Interconnect Cable Choice of loudspeaker cable Connecting the amplifierMulti-channel set up Distance between the loudspeakers PositioningSymmetry and room modes Distance to back and side walls Distance to the loudspeakersLevelling/Speaker Support Room and furniture influence Loudspeaker Toe-inRunning-in the loudspeakers Care and maintenanceCare & Maintainance Power rating LS- 77 Technical Features Troubleshooting Guide TroubleshootingSpecifications Table SpecificationsAppendix 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 AM-77 Control Center Edition CCE Appendix D The AMR Active SystemLine Level Connection Setting up the AMR Active SystemSpeaker Connection Scenario Testing and Troubleshooting the AMR Active System LS-77 Speaker L AMR Active System Configuration DiagramIntroducing AMRs OptiArray scalable acoustic system Appendix E LS-77 in OptiArray configurationsPage AMR recommends the following OptiArray Setups Epsilon/Zeta Iota/Zappa Omicron/Sigma Epsilon/Zeta System wiring Reverberation time Appendix G Acoustics Background In formationAcoustics Good acousticsPage Membrane absorbers DiffusersAbsorption or Diffusion ? AbsorbersPorous absorbers Standing WavesRoom modes