Abbingdon Music Research LS-77 Appendix D The AMR Active System, AM-77 Control Center Edition CCE

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Appendix D – The AMR Active System

For maximum performance AMR's active system allows AMR's LS-77 speakers to be driven in active mode by AMR's amplifiers. Separating the frequency ranges before the amplifiers avoids the destructive intermodulation between the low and high frequency signals being passed through the same amplifier and increases the available power and SPL.

AMR uses custom designed high quality passive filters instead of large numbers of Op-Amp's and other active components, as a result avoiding many shortfalls (e.g. signal distortion) commonly associated with other active systems. Hence, AMR's active system combines all the benefits of fully active operation with a much simplified handling and physical setup.

D.1 - The AM-77 Control Center Edition (CCE)

The corner stone of AMR's active system is the AM-77 CCE Amplifier. The AM-77 CCE acts as a (i) preamplifier, (ii) active crossover and (iii) high frequency amplifier. Thus it combines three separate devices into one without loss of performance but with the added benefit of eliminating several interconnects.

The amplifier boards are optimised for high frequency reproduction including the use of non-magnetic Silver Foil

&Mica dielectric coupling capacitors, which have been found most ideal for detailed, resolved and non-fatiguing high frequency reproduction. Hence the high frequency outputs from the active crossover are routed directly to the internal power amplifier. The low frequency outputs of the active crossover are sent to additional AM-77s configured as power amplifiers via the "Option" connector.

All control functions such as Input selection, volume control etc. are performed ONLY by the AM-77 CCE, in effect the AM-77 CCE acts as the preamplifier with additional active crossover function and high frequency amplification built-in.

Two or even four AM-77 CCE can in turn be operated as monoblock amplifiers with control functions to allow very large systems to be assembled around AMR's core components. Any AM-77 can be converted into a CCE Amplifier and visa versa by your AMR retailer at notional cost.

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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 Appendix G Acoustics Background In formation AcousticsGood acoustics Reverberation timePage Diffusers Absorption or Diffusion ?Absorbers Membrane absorbersStanding Waves Porous absorbersRoom modes
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