LS-77 Reference Class Professional Monitor Loudspeakers Owner’s Manual
WARNINGS 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 may fall causing serious injury to a child or adult and serious damage to the unit. An appliance and cart combination should be moved with care.
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 anticipate the sonic performance of the LS-77 to settle only after it has been used for this approximate length of time.
Contents WARNINGS 3 Section 1 - Unpacking 7 Section 2 - Component Overview 9 4.4 Distance to back and side walls 4.5 Levelling/Speaker Support 4.6 Loudspeaker Toe-In 4.7 Room and furniture influence 17 18 19 19 Section 5 - Care & Maintainance 20 5.1 Care and maintenance 5.2 Running-in the loudspeakers 5.3 Power rating 20 20 21 Section 6 - LS- 77 Technical Features 22 Section 3 - Setup 11 3.1 Connecting the loudspeakers 3.2. Connecting the amplifier 3.3 Multi-channel set up 3.
Appendix A - Adjustment of tonal balance 25 Appendix B - Abbingdon Acoustic Setup Regime 28 Appendix C – Biamplifying 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 G.2 Good acoustics G.3 Reverberation time G.4 Diffusers G.4.1 Absorbtion or diffusion ? G.4.2 Absorbers G.5 Standing Waves G.
Section 1 - Unpacking Figure 1.1 - Front Panel of the LS-77 Figure 1.2 - Rear Panel of the LS-77 LS - 77 Professi onal Monitor Designed and Engineer ed in Great Britain 87dB 8Ohms 150W 600W 27Hz-40k Hz 100 90 High Freque ncy Level Adjustm ent Output ( dB ) Sensitiv ity: Impedan ce: Cont . Power Handing : Peak Prog .
Thank you for purchasing this AMR reference class component. We 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. Please check that all contents are present 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. Upon unpacking, please find in each package: i. ii. iii. iv. v. vi. vii. viii. ix. x.
Section 2 - Component Overview Figure 2.1 - LS-77 Front Fascia F1. HIGH FREQUENCY driver: to repoduce the high frequencies. F2. LOW FREQUENCY driver: to reproduce the low frequencies.
Figure 2.2 - LS-77 Rear Panel R1 LS - 77 Professi onal Monitor Designed and Engineer ed in Great Britain 87dB 8Ohms 150W 600W 27Hz-40k Hz 100 90 High Freque ncy Level Adjustm ent Warning: Output ( dB ) Sensitiv ity: Impedan ce: Cont . Power Handing : Peak Prog . Handing : Frequen cy Respons e: 80 70 60 50 100 1000 Frequency ( Hz ) 10000 R2 ensure no speaker connector is in contact with the chassis HF R3 LF R4 IN OUT R5 R6 10 R1.
Section 3 - Setup 3.1 Connecting the loudspeakers AMR recommends the sonically superior S p e a k o n connectors 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 existing system already fitted with cables prepared for such connections. AMR's preferred connection method is the professional Neutrik Speakon connector.
LS - 77 Speaker R LS - 77 Speaker L LS - 77 Professional Monitor Designed and Engineered in Great Britain LS - 77 Professional Monitor Designed and Engineered in Great Britain 100 100 Sensitivity: 87dB Impedance: 8Ohms Cont . Power Handing : 150W Peak Prog . Handing: 600W Frequency Response: 27Hz-40kHz Output ( dB ) 90 80 70 60 High Frequency 50 100 Level Adjustment IN 1000 90 Output ( dB ) Sensitivity: 87dB Impedance: 8Ohms Cont . Power Handing : 150W Peak Prog .
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.
LS - 77 Speaker R LS - 77 Speaker L LS - 77 Professional Monitor Designed and Engineered in Great Britain LS - 77 Professional Monitor Designed and Engineered in Great Britain 100 100 Sensitivity: Impedance: Cont . Power Handing : Peak Prog . Handing: Frequency Response: 90 80 70 60 High Frequency 50 100 Level Adjustment IN 1000 87dB 8Ohms 150W 600W 27Hz-40kHz 90 Output ( dB ) 87dB 8Ohms 150W 600W 27Hz-40kHz Output ( dB ) Sensitivity: Impedance: Cont . Power Handing : Peak Prog .
3.2. Connecting the amplifier Always switch your amplifier off when making or b r e a k i n g connections. 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.
Section 4 - Positioning The LS-77 Reference Class Professional Monitor is a Transmissionline 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 properties. Rooms are also shaped, decorated and furnished uniquely, and therefore remain quite independent regarding options for positioning loudspeakers.
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 experimentation and set-up.
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 or furniture.
4.6 Loudspeaker Toe-in Toe-in of the speakers often i m p r o v e s imaging! 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 matter of personal taste and room acoustics. 4.
Section 5 - Care & Maintainance 5.1 Care and maintenance To 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 the drivers but will have no effect on the Aluminum Enclosure.. Never use aggresive or abrasive cleaners! The cabinet and other plain parts should be cleaned with a soft dry or slightly damp cloth.
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. With 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 Professional Monitors have a reasonably high sensitivity, even high quality amps with a medium power rating can drive the speaker to yield excellent results.
Section 6 - LS- 77 Technical Features 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 distortion and thermal compression.
Section 7 - Troubleshooting Figure 7.
Section 8.1 - Specifications Figure 8.1 - Specifications Table Sensitivity (2.
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.
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.
Listening Distance around 5m (farfield listening or monitoring) HF Level +3 dB +1.5dB 0 dB - 1.5dB R1 15 R 15 R 15 R not Fitted R2 22 R 47 R not fitted 22 R Placement not recommended Placement of speaker on a bookshelf or very close to walls (factory fit.) Placement within around 1m of rear wall Placement of speaker 2m or more from rear wall If you feel that the tonal balance in the low frequencies of the LS-77 is not correct for you or your room, you may need to change the positioning of the LS-77.
Appendix B - Abbingdon Acoustic Setup Regime 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 correlates reliably with subjectively perceived "good sound".
With 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, mark the position on the floor when the artifact first appeared with tape. You now have the front and back borders of the ZOLI.
4 3 2 1 0 ~ 100″/ 254cm 2 1 0 1 2 2 ~ 115″/ 290cm 1 0 1 2 ~ 115″/ 290cm Figure B.
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 suitable piece of MDF or wood with smooth surfaces to making sliding the speakers around easier.
With 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 rough position.
Appendix C – Biamplifying 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 not have to deliver the large currents drawn by the woofer and hence will produce less distortion.
LS - 77 Speake r R LS - 77 Speaker L LS - 77 Professional Monitor Designed and Engineered in Great Britain LS - 77 Professional Monitor Designed and Engineered in Great Britain 100 100 Sensitivity: Impedance: Cont . Power Handing : Peak Prog . Handing: Frequency Response: 90 80 70 60 High Frequency 50 100 Level Adjustment IN 1000 87dB 8Ohms 150W 600W 27Hz-40kHz 90 Output ( dB ) 87dB 8Ohms 150W 600W 27Hz-40kHz Output ( dB ) Sensitivity: Impedance: Cont . Power Handing : Peak Prog .
LS - 77 Speake r R LS - 77 Speaker L 100 100 Sensitivity: Impedance: Cont . Power Handing : Peak Prog . Handing: Frequency Response: 90 HF Level Adjustment Resistor 80 70 60 50 100 1000 87dB 8Ohms 150W 600W ( see graph ) 90 HF Level Adjustment Resistor Output ( dB ) 87dB 8Ohms 150W 600W ( see graph ) Output ( dB ) Sensitivity: Impedance: Cont . Power Handing : Peak Prog .
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.
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. To remove Speakon connectors you need to pull the metal catch backwards and rotate the connector counter-clockwise to unlock the connector so it can be pulled out.
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 cables to the mains yet nor should the amplifiers be switched on.
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 connector marked “AM-77” Æ Left AM-77's Speakon socket Right speaker cable connector marked “AM-77” Æ Right AM-77's Speakon socket Now attach the input connections from your CD-Source ONLY to
D.3 - Testing and Troubleshooting the AMR Active System Please use the AMR Test & 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 low frequencies from the other. In this case please switch around the interconnects or speaker cables (one OR the other, not both) for the power amplifier.
D.4 - AMR Active System Configuration Diagram LS - 77 Speake r R AM - 77 Control Editon Pro HiFi Pro HiFi Mode M LS - 77 Professional Monitor Designed and Engineered in Great Britain L R LS - 77 Speaker L AM - 77 Monoblock Amplifier Mode M M M L R M M LS - 77 Professional Monitor Designed and Engineered in Great Britain 100 100 Sensitivity: Impedance: Cont . Power Handing : Peak Prog .
Appendix E – LS-77 in OptiArray configurations 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. i. The larger a room the louder must a speaker play for a given sound level at the listening position.
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. To 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 exhibit a significant increase in directivity at all frequencies over traditional systems attains an equal or greater improvement.
AMR recommends the following OptiArray Setups: Room Size ≤35m2 25m2–70m2 50m2-140m2 100m2-280m2 200m2-480m2 System Alpha Epsilon Iota Omicron Upsilon (passive) (passive) (passive) (passive) (passive) AM-77 LS-77 (pairs) Power SPL (3m) 1 1 360W 109dB 1 2* 360W 112dB 2 4* 720W 118dB 4 8* 1440W 124dB 8 16* 2880W 130dB System Beta Zeta Kappa Sigma Omega (active) (active) (active) (active) (active) 1 1 1 560W 113dB 1 1 2* 560W 116dB 1 2 4* 1120W 122dB 2 4 8* 2240W 128dB 4 8
Sensitivity: Impedance: Cont . Power Handing : Peak Prog . Handing: Frequency Response: 87dB 8Ohms 150W 600W 27Hz-40kHz High Frequency OUT Level Adjustment LF HF 1000 Frequency ( Hz ) 10000 Sensitivity: Impedance: Cont . Power Handing : Peak Prog . Handing: Frequency Response: 87dB 8Ohms 150W 600W 27Hz-40kHz Level Adjustment High Frequency - 100 Frequency ( Hz ) 1000 10000 77 PROFESSIONAL MONITOR 50 60 70 80 90 100 Sensitivity: Impedance: Cont . Power Handing : Peak Prog .
LS - 77 Professional Monitor Designed and Engineered in Great Britain High Frequency Level Adjustment IN High Frequency LF HF OUT Level Adjustment 100 1000 Frequency ( Hz ) 10000 In from Amplifier 50 60 70 80 90 100 Output ( dB ) 90 80 70 60 50 100 100 87dB 8Ohms 150W 600W 27Hz-40kHz 87dB 8Ohms 150W 600W 27Hz-40kHz LF HF OUT 1000 Frequency ( Hz ) 10000 Sensitivity: Impedance: Cont . Power Handing : Peak Prog . Handing: Frequency Response: Sensitivity: Impedance: Cont .
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.
Why do we have reverberation? The speed of the propagating sound wave is very slow - at least compared to light: approx. 1130ft. 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 reflected sound in one way or another, but there is still no reverberation. If the sound is generated in a room, there are a whole lot of reflections.
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.
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. To absorb a given frequency (and all frequencies above) the thickness of the absorber must be the quarter of the wavelength of that frequency.
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 between parallel walls are called axial modes. Other modes exist. For instance tangential and radial modes. Normally the axial modes are the strongest.
1 , 0 , 0 ( 25Hz ) 2 , 0 , 0 ( 50 Hz ) 3 , 0 , 0 ( 75Hz ) 4 , 0 , 0 ( 100Hz ) 1 , 0 , 0 ( 25Hz ) 2 , 0 , 0 ( 50 Hz ) 3 , 0 , 0 ( 75Hz ) 4 , 0 , 0 ( 100Hz ) 0 , 0 , 1 ( 62 Hz ) 0 , 0 , 1 ( 62 Hz ) 2 . 8m 2 . 8m 6 . 7m 6 . 7m Undesirable Listening Positions 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).
Abbingdon Music Research is a subsidiary of the Abbingdon Global Group 22 Notting Hill Gate; London; W11 3JE; United Kingdom; Tel: +44 (0) 870 420 5505; Fax: +44 (0) 700 596 1065 53
