Abbingdon Music Research LS-77 owner manual Appendix a Adjustment of tonal balan ce

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Appendix A - Adjustment of tonal balance

If you feel that the tonal balance in the upper midrange and lower treble frequencies of the LS-77 is not correct for you, you may wish to change the resistor combination fitted under the cover labelled “High Frequency Level Adjustment”. Some of the required adjustment may be due to the differences in listening distance while others may be a result of differences in taste and furnishings.

		LS-77 Professional Monitor
		Designed and Engineered in Great Britain
Sensitivity:	87dB
Impedance:	8Ohms	(dB)
Peak Prog. Handing:	600W	Output
Cont. Power Handing:	150W
Frequency Response:	27Hz-40kHz	High Frequency
		High Frequency
		Level Adjustment	Frequency (Hz)
		Level Adjustment

HF

Remove this cover after removing the machine screws that hold the cover in place using the 2mm metric hex key (Allen Key) which is provided with your speakers (or equivalent replacement if lost). Under the cover you will in stock condition find two resistors one marked 15Ù and one marked 47R. You will also find a pair of optional resistors included per speaker, one marked 100

15Ω	47Ω	and the other marked 220.
		Respectively the resistor marked 100 will be
		referred to below as 10R, the 15Ù as 15R and
		the one marked 220 as 22R. Using different
		combinations allows an adjustment of the upper
		midrange and lower treble frequencies by +/-3dB
		in steps of around 1.5dB.

LF

INOUT

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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