Abbingdon Music Research LS-77 owner manual Diffusers, Absorption or Diffusion ?, Absorbers

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G.4 Diffusers

A diffuser provides diffuse reflection of the sound radiated against it. It can be a very useful solution in cases where reflections are disturbing the sound image and it is not advisory to add further absorption. So in order to reduce flutter echoes, comb filtering etc., special elements can be placed on the "disturbing" surface. These elements must have dimensions comparable to the frequencies at which diffusion is wanted.

Often bookshelves stocked with books of irregular sizes and/or music collections (LP's or CD's) can act as non-ideal diffuser, if dedicated diffuser devices cannot be used.

G.4.1 Absorption or Diffusion ?

A special technique developed by Manfred Schroeder is very capable in making a smooth and controlled diffusion. These diffusers normally referred to as "Schroeder Diffusers" can be found as readily made modules.

Schroeder type Diffusor

G.4.2 Absorbers

All materials in the room act acoustically even if they are not specially designed acoustical materials. In domestic situations we have generally two types of absorbers.

G.4.2.1 Membrane absorbers

This kind of absorber includes wooden floors, windows, doors, etc. This absorber provides absorption in the low end of the frequency range. The efficiency is normally not very high, but under normal conditions large areas are included in the basic room construction. Special designed membrane absorbers can be very effective. Placing a wood laminate floor on suitable acoustic backing can provide one such absorber.

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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 Connecting the loudspeakers SetupUsing AMRs OptiLink Speakon Cable Speaker R Speaker L Using Binding Posts Speaker Cable Stereo Amplifier Interconnect Cable Multi-channel set up Connecting the amplifierChoice of loudspeaker cable Symmetry and room modes PositioningDistance between the loudspeakers Distance to back and side walls Distance to the loudspeakersLevelling/Speaker Support Room and furniture influence Loudspeaker Toe-inCare & Maintainance Care and maintenanceRunning-in the loudspeakers 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 Acoustics Appendix G Acoustics Background In formationGood acoustics Reverberation timePage Absorption or Diffusion ? DiffusersAbsorbers Membrane absorbersPorous absorbers Standing WavesRoom modes
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