Abbingdon Music Research Reference Class Proffessional Monitor LS-77 User manual

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

2

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 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. Quick stops, excessive force and uneven
surfaces may cause the component and cart combination to overturn.
Any mounting of the device on a wall or ceiling should follow the manufacturer's instructions and should use a
mounting accessory recommended by the manufacturer.
Read and follow all the safety and operating instructions before connecting or using this component.
All warnings on the component and in its operating instructions should be adhered to.
Retain this Owner's Manual for future reference.
Do not use this unit near water; for example, near a bath tub, washbowl, kitchen sink, laundry tub, in a wet
basement or near a swimming pool.
Unplug the component before cleaning. Never use benzine, thinner or other solvents for cleaning; use only a soft
damp cloth.
WARNINGS
!

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 anticipate the sonic performance of the
LS-77 to settle only after it has been used for this approximate length of time.
We recommend the following procedure to speed upthe "burn in" for the LS-77:
Place the speakers face to face with faceplates almost touching and connect normally to the Amplifier. In
conjunction with an out of phase mono signal this will cancel most noise.Aheavy blanket may be thrown over
the speakers to cancel more noise.
Play the “Pink Noise Out Of Phase” track (Track 4) fromAMR’s SystemTest CD (included with the speakers)
on repeat. Raise the volume as high as sensible (but quite high), the out of phase nature will cancel a lot of noise,
so be careful when raising levels not to overload theAmplifier.
UsingAMR’sAM-77& CD-77the maximumlevelrecommended forburn inis-10db, theminimumlevel -16db.
When using -16db a minimum of 120 Hours burn in should be applied, with -12…-10db level setting on theAM-
77 this can be shortened to 72 Hours. This will take the LS-77’s through the phase where the performance
changes quite dramatically.

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WARNINGS 3
Section 1 - Unpacking 7
Section 2 - Component Overview 9
Section 3 - Setup 11
3.1 Connecting the loudspeakers 11
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 loudspeakers 17
4.4 Distance to back and side walls 17
4.5 Levelling/Speaker Support 18
4.6 Loudspeaker Toe-In 19
4.7 Room and furniture influence 19
Section 5 - Care & Maintainance 20
5.1 Care and maintenance 20
5.2 Running-in the loudspeakers 20
5.3 Power rating 21
Section 6 - LS- 77 Technical Features 22
Section 7 - Troubleshooting 23
Section 8 - Specifications 24
Contents

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AppendixA -Adjusting tonal balance 25
Appendix B -AbbingdonAcoustic Setup Regime 28
Appendix C – Biamping the LS-77 33
Appendix D – TheAMRActive System 36
Appendix E – LS-77 in OptiArray configurations 42
Appendix F -Acoustics Background Information 47
G.1Acoustics 47
G.2 Good acoustics 47
G.3 Reverberation time 47
G.4Diffusers 49
G.4.1Absorbtion or diffusion ? 49
G.4.2Absorbers 49
G.5 Standing Waves 50
G.6 Room modes 51

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Figure 1.1 - Front Panel of the LS-77 Figure 1.2 - Rear Panel of the LS-77
Section 1 - Unpacking
LS77PROFESSIONALMONITOR
-
HF
LF
DesignedandEngineeredin GreatBritain
LS 77 Professional Monitor
-
Sensitivity:
Frequency Response:
PeakProgHanding:.
ContP
ower Handing
.:
Impedance:
87dB
8Ohms
150W
600W
27Hz-40kHz
IN OUT
100
100 1000
1000 10000
10000
FrequencyHz
()Frequency Hz()
50 50
60 60
70 70
80 80
90 90
100
100
Output dB()Output dB()
HF
LF
LevelA
djustment
HighFrequency

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Thank you for purchasing this AMR reference class component.
We hope you derive as much pleasure from using your newAMR 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
shippedindividually packaged.
Upon unpacking, please find in each package:
i. LS-77 Reference Class Professional Monitor
ii. Set of two TO-220 Power Resistors (10R & 22R).
iii. Set of two Foam Port Plugs
iv. Set of two OptiLink® Bi-Wire Jumpers (installed)
v. Quick-Start Card
vi. AMR Warranty Card
vii. Aluminium professional flightcase
viii. LS-77 Owner's Manual
ix. AMR Test Disk
x. 2mm Allen Key
Please ensure that all items are present. Should an item be missing, please contact yourAMR distributor/retailer.
Please check that
all contents are
present

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Figure 2.1 - LS-77 Front Fascia
Section 2 - Component Overview
F1. HIGH FREQUENCY driver: to repoduce the high
frequencies.
F2. LOW FREQUENCY driver: to reproduce the low
frequencies.
LS 77 PROFESSIONAL MONITOR
-
15
F1
F2

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Figure 2.2 - LS-77 Rear Panel
R1. TRANSMISSIONLINE PORT: to reproduce the lowest
frequencies.
R2. HIGH FREQUENCY LEVEL ADJUSTMENT cover: to
cover the replaceable resistors in the high frequency level
adjustment circuit.
R3. SPADE/BANANA high frequency inputs: for connection
of standard termination speaker cables.
R4. SPADE/BANANA low frequency inputs: for connection
of standard termination speaker cables.
R5. SPEAKON® low & high frequency outputs: for
connection of Speakon terminated speaker cables.
R6. SPEAKON® low & high frequency inputs: for
connection of Speakon terminated speaker cables.
Warning:
ensure no
speaker con-
nector is in
contact with
the chassis
HF
LF
Designed and Engineered in Great Britain
LS 77 Professional Monitor
-
Sensitivity:
Frequency Response:
Peak Prog Handing:.
Cont Power Handing.:
Impedance:
87dB
8Ohms
150W
600W
27Hz-40kHz
IN OUT
100 1000 10000
Frequency Hz()
Frequency Hz()
50
60
70
80
90
100
Output dB()
Output dB()
HF
LF
Level Adjustment
High Frequency
R6
R5
R3
R2
R1
R4

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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 existing system already fitted with cables prepared for such connections.
AMR's preferred connection method is the professional Neutrik Speakon connector. This provides a sonically
vastlysuperior andmore reliablemethodof connection,due totheconnector’s goldcontacts, gastightconstruction
and special locking, high-pressure contact arrangement.
AMR's own speaker cables are equipped with Speakon connectors, as areAMR's amplifiers thus guaranteeing
the highest performance and most reliable method of speaker connection available.
3.1.1 Using AMR's OptiLink Speakon® Cable
When usingAMR's Speakon® equipped OptiLink loudspeaker cables, you simply plug the Speakon® connector
into the Speakon® socket marked “IN” and then twist the whole connector clockwise to lock the connector.
Thisestablishes afull bi-wiredconnection withthe correctpolarity andensures theconnection ismaximally tight
and corrosion free all in one go.
To disconnect the Speakon® cable you need to pull back the latch and twist the connector counterclockwise.
Then you can simply pull out the plug.

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Speaker CableSpeaker Cable
Interconnect Cable Interconnect Cable
Speaker LSpeaker 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:
87dB
8Ohms
150W
600W
27Hz-40kHz
IN OUT
100 1000 10000
Frequency Hz()
Frequency Hz()
50
60
70
80
90
100
Output dB()
Output dB()
HF
LF
Level Adjustment
HighFrequency
HF
LF
Designed and Engineered in Great Britain
LS 77 Professional Monitor -
Sensitivity:
Frequency Response:
Peak Prog Handing:.
Cont Power Handing.:
Impedance:
87dB
8Ohms
150W
600W
27Hz-40kHz
IN OUT
100 1000 10000
Frequency Hz()
Frequency Hz()
50
60
70
80
90
100
Output dB()
Output dB()
HF
LF
Level Adjustment
HighFrequency
Stereo Amplifier
Figure 3.1 - 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 Speakon® connectors of the speaker cables to your amplifier.

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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 authorisedAMR retailer for recommendations.
Connect a suitable loudspeaker cable to the speaker binding posts, located at rear of the LS-77.
When using two-pole speaker cables, the cable should be connected to the upper pair of binding posts and the
included short Bi-Wire Jumper Cables must be connected between the upper and lower binding post of the same
colour marking. When using four-pole speaker cables usually two of these poles will be dedicated to carrying the
high frequency signal, connect these to the upper pair of binding posts. The low frequency poles are connected
to the lower binding posts. In all cases observe the polarity, usually marked by black and red markers on the
cable and match these markers with the colour coding of the binding posts.
The LS-77 high quality binding posts can accommodate different connection systems:
6 mm pins: The pins can be placed directly into the binding post without any screwing necessary.
Cable spades: Un-tighten the binding posts, insert the spades into the openings, and secure the spades into the
posts by tightening the posts. Tighten the posts, and check the contacts after a few days to make sure that they
have not loosened.
Barewires: Un-tighten the binding posts and place the cable into the binding posts.Tighten the posts. With bare
wire terminations, make sure that no thin metal strand of wire is in contact with another strand of wire. Tighten
the posts, and check the contacts after a few days to make sure that they have not loosened.
With every connection system, it is important to ensure that the contact is tight and has a proper contact area.
Connectors with similar gold plating as the LS-77 Reference Class Professional Monitor binding posts will
typically offer the best results while also remaining corrosion-free.
Warning: ensure
no speaker
connector is in
contact with the
speaker enclosure
to cause a short-
circuit!

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Speaker CableSpeaker Cable
Interconnect Cable Interconnect Cable
Speaker LSpeaker 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:
87dB
8Ohms
150W
600W
27Hz-40kHz
IN OUT
100 1000 10000
Frequency Hz()
Frequency Hz()
50
60
70
80
90
100
Output dB()
Output dB()
HF
LF
Level Adjustment
HighFrequency
HF
LF
Designed and Engineered in Great Britain
LS 77 Professional Monitor -
Sensitivity:
Frequency Response:
Peak Prog Handing:.
Cont Power Handing.:
Impedance:
87dB
8Ohms
150W
600W
27Hz-40kHz
IN OUT
100 1000 10000
Frequency Hz()
Frequency Hz()
50
60
70
80
90
100
Output dB()
Output dB()
HF
LF
Level Adjustment
HighFrequency
Stereo Amplifier
Figure 3.2 - System connection using banana plug/spade connector equipped speaker cables
i. Connect the respective bi-wire jumper cables as shown.
ii. Connect the respective spade/banana connector or bare wire of the speaker cables to the LS-77.
iii. Connect the respective spade/banana connector or bare wire of the speaker cables to your amplifier.

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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 of the
speaker are connected to the red marked output of your amp, and the white or black marked posts to the white
or black marked output accordingly.
AMR loudspeakers feature a carefully matched and fine-tuned crossover, to achieve a truly balanced and
smooth frequency response. However, optimising the frequency bands through bi-wiring or bi-amplification can
offer significant benefits. Please consult your authorisedAMR retailer for recommendations and demonstrations
and see theAppendix C - Biamplifying the LS-77 for options usingAMR equipment.
3.3 Multi-channel set up
TheAMR LS-77 Reference Class Professional Monitor is designed to offer the most advanced performance in
both stereo and multi-channel applications, effectively enabling the maximum performance from either of these
formats. When connecting a loudspeaker to a multi-channel system, in general the same guidelines as previously
mentioned in the text above will apply. Because there are many different set up options - from 5.1 to 10.2
channelapplications -and dueto thefact thatloudspeaker positioningwill alsodepend uponthe room'sparticular
shape, please consult your authorisedAMR retailer for special applications and placement options.
3.4 Choice of loudspeaker cable
The loudspeaker cable may may have a dramatic effect on sound quality, though in general, quality cable
products will yield a quality result. The LS-77’s are designed to be very neutral, and as such are not extremely
reliant on any one particular type of cable. The choice of cable is as much a factor of matching the cable to the
entire audio system, while also a matter of personal taste and preference. In an all AMR System AMR's
OptiLink Speakon® connector equipped cables are highly recommended.
Always switch
your amplifier off
when making or
breaking
connections.

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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.AMR suggests that you consult your experiencedAMR retailer for further
assistance if needed. The following steps are general suggestions that will optimise the speaker placement.
4.1 Symmetry and room modes
It is preferred to establish a loudspeaker layout that provides an adequate and equal left/right image. The basis
for this symmetry, meaning that the distance from the listening position to the left and the right speakers should
be identical; and if not listening in the near field (1m or less), then additionally identical distance to the side-walls
should be maintained.
In all normal rooms certain low frequencies will be boosted or reduced by standing waves developing between
parallel walls. If the speakers are placed directly at walls or at half way or quarter way between walls these
standing waves will influence the speakers’ performance to the largest extent, hence such placement is best
avoided. Equally, it is preferable to locate the listener not at any half way or quarter way point between parallel
walls. You may also wish to review the material in Appendix F - Acoustics Background Information for more
details.
4.2 Distance between the loudspeakers
AMR recommends a distance between the speakers from slightly less (closer together) to slightly wider (further
apart) than the distance from the point centered in-between the pair of speakers and the listening position.
The closer the listening position is in relation to the loudspeakers, the closer the speakers need to be positioned
to each other, though as a starting point it is recommended that the speakers be about 2.0 - 3.0 meters apart from
each other.
Always try to
place the speakers
symmetricalinthe
listening room.

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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.Adistance between the loudspeakers that is approximately the same as the distance
to the listening position is a good starting point for such experimentation during set-up.
4.3 Distance to the loudspeakers
Because of the excellent integration of frequencies, the LS-77 Reference Class Professional Monitors will
deliverexcellent imagingevenin near-fieldapplicationswith smalllisteningdistances. Thedistanceto thespeakers
ultimately depends upon the room's shape, size and your personal listening taste. Please note that when listening
to the speakers from a long distance, the room must allow the speakers to be positioned with a wider distance
between each other as well.
To maintain a balanced sound integration from the driver arrangement, a 2.0 meter distance is a good starting
pointduring experimentation.Thelistening distancetoeach speakerfrom thelisteningposition shouldbeidentical.
4.4 Distance to back and side walls
Whenloudspeakers arepositioned tooclose towalls, thesound qualitycanbe restricted.Time-delayed reflections
occur and add colorations, distorting the original music signal. The LS-77 Reference Class Professional Monitor
was developed to be primarily placed free-standing, and therefore reaches its optimum performance when
positioned as clear of any walls as possible. The rear bass port was tuned to integrate perfectly with the drivers,
thus if possible, this port should not be covered by any surfaces or objects. However, the loudspeakers may
effectively be placed into cabinets or enclosures as long as there is a minimal (one-inch) clearance above and
behind the speakers. When placing the Speaker very close to walls it may be necessary to adjust both the high
frequency and low frequency balance of the speakers (see Appendix A - Adjustment of tonal balance).

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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.
This will often restrict the sound quality, though with careful use of some basic techniques and due to the wide
ranging adjustability ofAMR's speakers it is possible to materially minimise any negative influence.
a) Set the speaker on a solid, rigid level surface using compliant supports (available from your
AMR retailer). The surface should be free from resonances. There must me no protrusions or other
obstructions in front of the speakers.
b) Place the speakers so that the high frequency drivers are at ear-height and oriented vertically.
c) If necessary the speakers can be placed with the woofer above the tweeter to make this easier to
achieve.
d) If necessary the high frequency drivers can be rotated by 90 Degrees. This will be carried by
your authorised AMR retailer as it requires disassembly of your speakers.
e) If the speakers cannot be placed with the high frequency drivers at ear-height use placement that
elevates the high frequency drivers as close as possible to ear-height. Then use suitable means to
elevate either the rear or front edge of the speaker to aim the high frequency drivers main axis at
approximately ear height at the listening position.
f) If necessary, adjust both the high frequency and low frequency balance of the speakers (see
Appendix A - Adjustment of tonal balance).
Always place the
speakersonarigid
and level surface!

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4.6 Loudspeaker Toe-in
Dependingon yourpersonal listeningenvironment androomdimensions, theLS-77 ReferenceClassProfessional
Monitors may be angled in towards the listening area to help focus the sound radiation. This positioning will
typically improve imaging, and is recommended byAMR. The ultimate positioning, however, is also a matter of
personal taste and room acoustics.
4.7 Room and furniture influence
The furniture, wall materials and other objects found in the listening room may influence the sound quality of any
loudspeaker. Therefore it may be necessary to adjust both the high frequency and low frequency balance of the
speakers (seeAppendixA -Adjustment of tonal balance) to suit your listening environment.
For example, a large room without much furniture that has many clean, hard wall surfaces may yield a bright and
diffuse sound with diverse reverberating frequencies. In such a case, due to the "Controlled Dispersion" design
of the LS-77, a placement with as much toe-in as is practical can reduce the reverb significantly. By adjusting
thehigh frequencytonalbalance toproduceless highfrequencyoutput thebrighttonal balancemaybe ameliorated.
Nevertheless, it may also be desirable to fit some acoustic treatment or at least some carpets and maybe some
heavy wall-hanging rugs or whatever means are suitable to domestic harmony.
A room with thick carpet, curtains and many soft furniture surfaces might yield a slightly warmer, darker and
less lively sound. In such a case using very little toe-in and adjusting the high frequency tonal balance to produce
more high frequency output can produce a more lively and open sound.
Please consult your authorised AMR retailer for recommendations and help. In order to maximise the sonic
quality of the reproduction from your LS-77 speakers you may also wish to employ the Abbingdon Acoustic
Setup Regime (AASR) described in the Appendix B.
Toe-in of the
speakers often
improves
imaging!
Furniture and
general room
design strongly
influence the
sonic result!

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Never use
aggresive or
abrasive cleaners!
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..
The cabinet and other plain parts should be cleaned with a soft dry or slightly damp cloth. Please avoid any
aggressive cleaning fluids or abrasive cleaners. Dust on the woofer diaphragms or the tweeters waveguide may
be removed with a fine furniture brush.
For safety reasons, please switch off all the components of your system when cleaning any of these components.
As any form of cloth or foam cover or metal grille interferes significantly with sound reproduction, no grill is
included.
Allmaterials usedbyAMRare integratedinto theLS-77 ReferenceClass ProfessionalMonitors withexceptional
care. By taking care of your LS-77 Reference Class Professional Monitors, you will preserve the finish and
build quality for a very long time.
5.2 Running-in the loudspeakers
The moving parts of a newly manufactured LS-77 Reference Class Professional Monitors have been acoustically
checked after production, but nevertheless are not as flexible as they need to be for optimum performance
results to be realised. The higher the quality of any driver system, the more demanding the loudspeaker will be
regarding time for running-in the system. A newly unpacked pair of AMR speakers therefore requires several
weeks of running in or playing to reach its optimum performance capability. After that period, a couple of
minutes before every listening session will be helpful to ‘warm up’ the loudspeakers.