Abbingdon Music Research Reference Class Proffessional Monitor LS-77 manual

LS-77 Reference Class Professional Monitor Loudspeakers Owner’s Manual[...]

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3 The exclamation point within an equilateral triangle is intended to alert the user to the presence of important operating and maintenance (servicing) instructions in the literature accompanying this component. This component weighs over 30 kilograms. Do not place this component on an unstable cart, stand, tripod, bracket or table as the component[...]

4 Precautions This component has been tested and found to comply with the limits set out in the EMC Directive using a connection cable shorter than 3 metres. Running-In AMR estimates that the LS-77 may take between 300-500 operating hoursat fairly high sound pressure levels for all of the internal components to be fully-broken in. Hence, please ant[...]

5 W ARNINGS 3 Section 1 - Unpacking 7 Section 2 - Component Overview 9 Section 3 - Setup 1 1 3.1 Connecting the loudspeakers 1 1 3.2. Connecting the amplifier 15 3.3 Multi-channel set up 15 3.4 Choice of loudspeaker cable 15 Section 4 - Positioning 16 4.1 Symmetry and room modes 16 4.2 Distance between the loudspeakers 16 4.3 Distance to the loudsp[...]

6 Appendix A - Adjusting tonal balance 25 Appendix B - Abbingdon Acoustic Setup Regime 28 Appendix C – Biamping the LS-77 33 Appendix D – The AMR Active System 36 Appendix E – LS-77 in OptiArray configurations 42 Appendix F - Acoustics Background Information 47 G.1 Acoustics 4 7 G.2 Good acoustics 47 G.3 Reverberation time 47 G.4 Diffusers 49[...]

7 Figure 1.1 - Front Panel of the LS-77 Figure 1.2 - Rear Panel of the LS-77 Section 1 - Unpacking L S 7 7 P R O F E S S I O N A L M O N I T O R - H F L F D e s ig n e d a n d E n g in e e r e d in G r e a t B r it a in LS 77 P rofessio nal M on itor - S e nsitivity : F requ en cy R e sp o n se : P e a k P r o g H a n d in g : . C on tP ow er H a n[...]

8 Thank you for purchasing this AMR reference class component. W e hope you derive as much pleasure from using your new AMR LS-77 Reference Class Professional Monitors as we have enjoyed making them for you. This section refers to the unpacking of the LS-77 and its subsequent setup. Due to the weight the LS-77 Pair is shipped individually packaged.[...]

9 Figure 2.1 - LS-77 Front Fascia Section 2 - Component Overview F1. HIGH FREQUENCY driver: to r epoduce the high fr equencies. F2. LOW FREQUENCY driver: to r epr oduce the low fr equencies. LS 77 PROFESSIONAL MONITOR - 15 F1 F2[...]

10 Figure 2.2 - LS-77 Rear Panel R1. TRANSMISSIONLINE PORT : to r epr oduce the lowest fr equencies. R2. HIGH FREQUENCY LEVEL ADJUSTMENT cover: to cover the r eplaceable resistors in the high fr equency level adjustment circuit. R3. SP ADE/BANANA high fr equency inputs: for connection of standar d termination speaker cables. R4. SP ADE/BANANA low f[...]

11 Section 3 - Setup AMR recommends the sonically superior Speakon connectors 3.1 Connecting the loudspeakers The LS-77 is fitted with shrouded binding posts prepared for bi-wiring that are standard in high end audio. However , we do not normally recommended their use. They are provided to allow users to easily integrate our speakers into an existi[...]

12 Speaker Cable Speaker Cable Interconnect Cable Interconnect Cable Speaker L Speaker R Pre-amplifier Analog Outputs R Analog Outputs L Pre-amplifier LS 77 - LS 77 - LS 77 - LS 77 - HF LF Designed and Engineered in Great Britain LS 77 Professional Monitor - Sensitivity : Frequency Response : Peak Prog Handing : . Cont Power Handing . : Impedance :[...]

13 3.1.2 Using Binding Posts When not using AMR's or another manufacturer’s Speakon® equipped loudspeaker cables, you need to use a conventional two or four pole speaker cable. Please consult your authorised AMR retailer for recommendations. Connect a suitable loudspeaker cable to the speaker binding posts, located at rear of the LS-77. Whe[...]

14 Speaker Cable Speaker Cable Interconnect Cable Interconnect Cable Speaker L Speaker R Pre-amplifier Analog Outputs R Analog Outputs L Pre-amplifier LS 77 - LS 77 - LS 77 - LS 77 - HF LF Designed and Engineered in Great Britain LS 77 Professional Monitor - Sensitivity : Frequency Response : Peak Prog Handing : . Cont Power Handing . : Impedance :[...]

15 3.2. Connecting the amplifier Connect the other cable ends to the loudspeaker outputs of your switched-off power amplifier . When using Speakon® equipped speaker cables you only need to identify the correct channel and connect the cable. If using two or four pole speaker cables of conventional design, please make sure that the red marked posts [...]

16 Section 4 - Positioning The LS-77 Reference Class Professional Monitor is a T ransmissionline port loaded loudspeaker design with no unusual or extraordinary positioning demands, neither in stereo nor in multichannel applications. Despite this, every room will typically have its own particular sound characteristics as shaped by its own acoustic [...]

17 If the speakers are positioned too close to each other , the stereo image will not seem realistic; if that distance is too wide, the image may leave an acoustic hole in the middle. Paying attention to the image during listening tests and using the adjustment/diagnostic tracks on AMR's test CD will help dictate optimum placement during exper[...]

18 4.5 Levelling/Speaker Support The best surface for any compact speaker is a dedicated stand construction, providing a solid foundation and allowing the proper listening height (high frequency driver at ear height). Dedicated high quality stands are available at your AMR retailer . As an alternative, the LS-77 may also be placed on shelves, bases[...]

19 4.6 Loudspeaker T oe-in Depending on your personal listening environment and room dimensions, the LS-77 Reference Class Professional Monitors may be angled in towards the listening area to help focus the sound radiation. This positioning will typically improve imaging, and is recommended by AMR. The ultimate positioning, however , is also a matt[...]

20 Never use aggresive or abrasive cleaners! Section 5 - Care & Maintainance 5.1 Care and maintenance T o maintain the aesthetic quality of the LS-77 Reference Class Professional Monitors for the long term, placing them into a very warm, very cold, or very humid environment should be avoided. Direct sunlight or excessive brightness can affect t[...]

21 5.3 Power rating Due to the construction and the driver technology , the LS-77 Reference Class Professional Monitors can be driven with very high power levels. W ith a high quality amplifier , delivering undistorted signals, the LS-77 can achieve high volumes without any compromise in sound quality . Also, as the LS-77 Reference Class Profession[...]

22 The following section provides a brief explanation of the most salient technical features of the LS-77. 10” High Performance Low Frequency Driver - a unique design provides unparalleled low frequency extension in a compact speaker , combined with the midrange performance only available from large dome midrange drivers while minimising distorti[...]

23 Section 7 - T roubleshooting Figure 7.1 Troubleshooting Guide Symptom Possible cause Solution No sound • incorrect audio cable connections • connect the cables correctly • incorrect amplifier operation • make sure that the input selector on the amplifier is set to the desired source Sound with no bass • check speaker connectors are not[...]

24 Figure 8.1 - Specifications T able Sensitivity (2.83V/1m in room): 87dB Long T erm Power Handling (AES/RMS): 150W Peak Program Power Handling : 600W Impedance, nominal: 8Ohm Impedance, minimal: 6Ohm Frequency Response (in IEC Standard Room): 26Hz - 40kHz (+/-3dB) Directivity Index (DI) 500-10KHz: 6dB (+/-3dB) Low Frequency Driver: 243mm/10"[...]

25 Appendix A - Adjusting 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 lis[...]

26 Below and overleaf are listed our recommendations for different listening distances and placements. However , there is not per se any specific value that is right or wrong. Please use your own preference, discernment and hearing as guide. It is right when it sounds right. T o increase the upper midrange and lower treble frequencies compared to w[...]

27 Listening Distance around 5m (farfield listening or monitoring) HF Level R 1 R 2 Placement +3 dB 15 R 22 R not recommended +1.5dB 15 R 47 R Placement of speaker on a bookshelf or very close to walls (factory fit.) 0 d B 1 5 R not fitted Placement within around 1m of rear wall - 1.5dB not Fitted 2 2 R Placement of speaker 2m or more from rear wal[...]

28 Appendix B - AASR The Abbingdon Acoustic Setup Regime (AASR) is a process of optimising the Speaker/room/listener placement interactively , repeatable and is rooted in decades worth of practice. AASR takes account of the simple fact that no rigid mathematical principle, no simulation software and no measurement system currently available correla[...]

29 W ith the person speaking and continuing to walk toward the listening position while talking at the same level, listen for the next change in the voice's tonal quality . This will be the first interaction of the opposite wall and should sound like a loss of focus that seems to resonate because of the side and rear wall reflections. Again, m[...]

30 ~″ / 100 254cm ~″ / 100 254cm ~″ / 1 15 290cm ~″ / 1 15 290cm ~″ / 1 15 290cm ~″ / 1 15 290cm 0 1 1 2 2 0 1 1 2 2 0 1 2 3 4 Figure B.1 - AASR illustrated[...]

31 If your floor is not carpeted (which is a bad idea acoustically) you may want to put something between the speaker stand and floor that will allow you to slide the speakers more easily , like a cloth or mat with a smooth underside. If your stands’ lower surface is not smooth and you have a carpeted floor you may wish to place the stand on a su[...]

32 W ith the most important of the rough adjustment being the front-to-back distance, mark the speakers' positions on the floor where the front edge of the speaker would be with tape, so you can always return to this position. The tape should extend beyond the ends of the baffle, because you will be moving the speaker relative to the main roug[...]

33 Appendix C – Biamping the LS-77 AMR’s LS-77 speakers are designed from the inception with the option to be bi-ampliffied. This means that dedicated amplifiers are used to drive the low frequency driver and high frequency driver separately . This provides improved clarity and resolution, as the amplifier driving the high frequency driver does[...]

34 Speaker Cable Interconnect Cable Interconnect Cable Speaker Cable Analog Outputs Pre-amplifier Analog Outputs R L Pre-amplifier Speake rR Speake rR LS 77 - LS 77 - Speaker L Speaker L LS 77 - LS 77 - HF LF Designed and Engineered in Great Britain LS 77 Professional Monitor - Sensitivity : Frequency Response : Peak Prog Handing : . Cont Power Han[...]

35 Figure C.2 - System connection using banana plug/spade connector equipped speaker cables i. Connect the respective spade/banana connector or bar e wir e of the speaker cables to the LS-77, use one cable pair for the pair of binding posts labelled “HF” and the other for the binding posts labelled “LF”. Observe polarity/marked colours of b[...]

36 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 amplifie[...]

37 D.2 - Setting up the AMR Active System Loosely place the speakers and connect the bi-amplification speaker cable supplied to each speaker , using the connector marked "LS-77". Speakon connectors are first inserted and then rotated clockwise until they lock in place. T o remove Speakon connectors you need to pull the metal catch backwar[...]

38 Scenario 2: AM-77 CCE x 1 AM-77 x 2 (each AM-77 must be in Monoblock Power Amplifier Mode) (see page 46 of AM-77 Manual). Option cable Left channel RCA (Blue) Æ Left AM-77 Input 1 Left Channel Option cable Right channel RCA (Red) Æ Right AM-77 Input 1 Left Channel Attach the power cables to the amplifiers, however do not connect the power cabl[...]

39 Scenario 2: AM-77 CCE x 2 (each AM-77 CCE must be in Monoblock mode) AM-77 x 2 (each AM-77 must be in Monoblock Mode) Left speaker cable connector marked "CCE" Æ AM-77 CCE 's Left Channel Speakon socket Right speaker cable connector marked "CCE" Æ AM-77 CCE 's Right Channel Speakon socket Left speaker cable connec[...]

40 D.3 - T esting and T roubleshooting the AMR Active System Please use the AMR T est & Burn In CD's channel identification track to verify that your system’s channel assignment is correct. If the low frequency channels have been mixed up the channel identification sequence will have the high frequencies coming from one channel with the [...]

41 D.4 - AMR Active System Configuration Diagram Figure D.1 - System connection using Speakon connector equipped speaker cables i. Connect the respective Speakon connectors of the speaker cables to the LS-77 (left & right). ii. Connect the respective dual headed end of the speaker with its Speakon connectors of the speaker cables to your amplif[...]

42 Appendix E – LS-77 OptiArray 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.[...]

43 While one can (and should) add acoustical treatment to large spaces, these are only effective to a certain degree and not at really low frequencies. T o effectively damp the reflection of a 350Hz tone the layer of damping material applied to the wall would have to be at least 25cm thick! Instead of damping the reverbrations, using speakers that [...]

44 AMR recommends the following OptiArray Setups: Room Size ≤ ≤ ≤ ≤ ≤ 35m 2 25m 2 –70m 2 50m 2 -140m 2 100m 2 -280m 2 200m 2 -480m 2 System Alpha Epsilon Iota Omicron Upsilon (passive) (passive) (passive) (passive) (passive) AM-77 11248 LS-77 (pairs) 1 2 *4 *8 *1 6 * Power 360W 360W 720W 1440W 2880W SPL (3m) 109dB 1 12dB 1 18dB 124dB 13[...]

45 AMR offers preconfigured wiring harnesses and where neccesary mounting and safety hardware for all larger OptiArray® systems. However , due to the complexity of setting up the larger OptiArray® systems we recommend to arrange the installation with your AMR retailer . The following pages show the wiring diagrams and setup options for some of th[...]

46 LS 77 PROFESSIONAL MONITOR - LS 77 PROFESSIONAL MONITOR - Speaker Cable HF LF D e sig ne d an dE n g in eered in G rea tB rita in LS 77 Professional Monitor - Sensitivity : Frequency Response : Peak Prog Handing : . Cont Power Handing . : Impedance : 87dB 8Ohms 150W 600W 27Hz-40kHz IN OUT 100 100 1000 1000 10000 10000 Frequency Hz () Frequency H[...]

47 Appendix G - Acoustics Background 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. T oday we know a lot about the parameters [...]

48 Why do we have reverberation? The speed of the propagating sound wave is very slow - at least compared to light: approx. 1 130ft. or 340m per sec. If there are no reflecting surfaces between the sound source and our ears, only the direct sound is heard and there is no reverberation. If there is a single reflecting surface we may hear the reflect[...]

49 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"[...]

50 G.4.2.2 Porous absorbers These absorbers include mineral wool, foam, carpets, curtains, and so on. They can be very effective, but the thickness of the material has to be taken into account. Thin layers will only absorb the highest frequencies. T o absorb a given frequency (and all frequencies above) the thickness of the absorber must be the qua[...]

51 wave. Or one whole wavelength - or 1½, 2, 2½ and so on. This phenomenon is called standing waves. Actually the sound wave is not standing. But it is experienced like that because the sound pressure maxima and minima are positioned in fixed places in the room. G 6 Room modes These special frequencies are also called room modes. Standing waves b[...]

52 How does the standing waves influence the sound field? - The curve expresses the area of the room where the actual frequency is audible. At the minima the frequency is represented at a much lower level (sometimes -40 dB compared to the maximum). If the room has the same dimensions as length, width, and even height it is very problematic to obtai[...]

53 Abbingdon Music Research is a subsidiary of the Abbingdon Global Group 22 Notting Hill Gate; London; W11 3JE; United Kingdom; T el: +44 (0) 870 420 5505; Fax: +44 (0) 700 596 1065[...]