Avalon Sentinel User manual

Serial Numbers ____________________
Handcrafted by:
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This product is certified to meet the requirements of the European
Union (EU) Electromagnetic Compatibility (EMC) Directive
(89/336/EEC). Because the permanent magnets attached to the
loudspeaker drivers produce magnetic fields, it is recommended
that the product not be positioned in very close proximity to
computer monitors or television sets.
Musical Masterpieces

Table of Contents
1 Introduction ......................................................................................................................... 5
Overview .............................................................................................................5
1.1 Low Noise Floor.........................................................................................................6
1.2 Coherent Energy Transfer .......................................................................................7
1.3 The Active Reference System ................................................................................8
2 Unpacking Instructions.......................................................................................................9
Introduction ........................................................................................................9
Contents..............................................................................................................9
2.1 Room Preparation and Verification......................................................................10
2.2 Crate and Box Placement for Unpacking ...........................................................11
2.3 Opening the Crates.................................................................................................12
2.3 Opening the Sub Amplifier Crates ........................................................................14
3 System Set-up...................................................................................................................... 15
Preparation .........................................................................................................15
Removing ApexCouplers from Set-up Blocks ...........................................15
Left / Right Channel Matching ........................................................................16
3.1 Lower Speaker Cabinet Set-up .............................................................................17
3.2 Upper Speaker Cabinet Set-up .............................................................................18
3.3 Crossover Cabinet Set-up ......................................................................................21
3.4 The Felt Anti-Diffraction Mask.................................................................................22
Orientation of the upper Felt Mask.................................................................22
3.5 Sub Amplifier Set-up ................................................................................................23
4 Wiring Instructions ............................................................................................................... 24
Introduction ........................................................................................................24
4.1 Wiring and Field Interactions..................................................................................25
Inductive field effects .......................................................................................25
4.2 Connecting Upper Speaker Cabinet to Crossover ............................................26
4.3 Connecting Speaker Cable to the Crossover ....................................................27
4.4 Connect Speaker Cable to your Amplifier ..........................................................28
4.4 Connecting Subwoofer to the Sub Amplifier ......................................................29
4.5 Connecting Preamplifier to the Amplifiers...........................................................30
1. Interconnect Y-cable at the preamplifier ................................................30
2. Two outputs at the preamplifier .................................................................30
3. Loop-Out from the Subwoofer Amplifier...................................................30
5 Break-in Period.................................................................................................................... 31
6 Subwoofer Amplifier .......................................................................................................... 32
Design Principle…………………………………………………………………………32
7Maximizing Performance
Break-in ................................................................................................................34
Separate Left / Right Amplifiers .......................................................................34
Felt Anti-diffraction Masks.................................................................................34
Room Treatment and System / Listener Position...........................................35
Toe-In ...................................................................................................................35
ApexCouplers ................................................................................................35
First Reflection Points .........................................................................................36
Corner Treatment ..............................................................................................36
8 Care of Your Avalon Loudspeakers .................................................................................. 37
Cabinet ...............................................................................................................37
Crossover Cabinet.............................................................................................37
Felt Anti-diffraction Masks.................................................................................37
Drivers...................................................................................................................37
9 Warranty ............................................................................................................................... 38
In the Event of a Problem .................................................................................38
Warranty Statement ..........................................................................................39

10 Room Acoustics and Speaker Position ...........................................................................41
Introduction ........................................................................................................41
An Optical Analogy ..........................................................................................42
Basic Room Acoustics .......................................................................................42
10.1 Standing Waves .....................................................................................................43
10.2 Flutter Echo .............................................................................................................44
10.3 Early Reflections .....................................................................................................45
Avoiding Early Reflections ................................................................................46
Low Frequency Reflections ..............................................................................48
10.4 Bass reinforcement ................................................................................................49
10.5 Summary of Recommendations..........................................................................52
Flutter Echo and Standing Waves...................................................................52
Early Reflections .................................................................................................53
Speaker Placement...........................................................................................53
10.6 A Listening Room Example ...................................................................................54
11 Listening Position ...............................................................................................................55
Path Length Symmetry......................................................................................55
Time Alignment ..................................................................................................55
Summary .............................................................................................................56
12 Accuracy of Bass Reproduction......................................................................................57
Introduction ........................................................................................................57
12.1 Sensitivity to Time-Related Information ..............................................................58
"Fast Bass" ............................................................................................................58
12.2 Measurements of Audio Equipment...................................................................59
A Correlation with Amplifier Measurements..................................................59
Loudspeaker Measurements ...........................................................................60
Designing for Accurate Bass Reproduction ..................................................61
12.3 Listening Qualities ..................................................................................................62
Frequency Response Effects ............................................................................62
Listening for Size Distortions...............................................................................62
Transient Response Effects ...............................................................................63
12.4 Active Subwoofer System.....................................................................................64
Anechoic Frequency Response vs. In-Room Frequency
Response .............................................................................................................64
Active Control of Bass Energy..........................................................................64
13 Features..............................................................................................................................65
14 Specifications .....................................................................................................................66
Loudspeaker.......................................................................................................66
Subwoofer Amplifier ..........................................................................................66
15 Notes ..................................................................................................................................67

5
1 Introduction
Overview
The Avalon Acoustics Sentinel Active Reference System represents the
application of edge-of-the-art loudspeaker technology in every area of high
accuracy transducer development. New research in diaphragm materials,
magnetics, low-noise circuitry, resonance control, and temporal coherence,
never before employed in high energy transducers, redefines the boundaries
of music reproduction. The intent has been to create a full range transducer
capable of high-energy transfer that behaves like a small array with point-
source accuracy.
The Sentinel accomplishes this goal by lowering the noise floor and
eliminating stray energy, thereby preserving timing detail, transient accuracy,
natural instrumental timbre, and stage presentation while providing
transparency, clarity, and detailed focus up and down the frequency
spectrum. Powered by a dedicated high-energy subwoofer amplifier,
Sentinel actively controls and realistically renders low frequencies, down to 16
Hz, while maintaining transient accuracy and harmonic integrity. Truly an
Active Reference System, the Sentinel re-creates musical events in a manner
that is uncompromised and sonically neutral.
Your Sentinel is designed and built to the highest standards of workmanship
and performance. These standards are preserved through the test of time by
careful attention to component quality and meticulous testing of each unit
before leaving the factory. As a new owner of this Avalon Acoustics product,
you can be assured that you possess one of the few great loudspeakers the
audio industry has to offer.

6
1.1 Low Noise Floor
A key element in achieving the sonic goals mentioned in the previous section
is significantly reducing the noise floor. The term "noise floor," in this discussion,
refers to the stray uncorrelated energy that is produced as an artifact by the
loudspeaker. This manifests itself in latent energy below the musical signal
and in deleterious phase noise. Both must be reduced to an absolute
minimum.
Through new proprietary technologies in the elements of the crossover
circuitry, the noise floor has been lowered by more than 25 dB over any
existing design. The low noise principle has also been applied to cabinet
design and construction, where new techniques in resonance control and
careful attention to diffraction and driver coupling effects further reduce
stray acoustic energy.
The overall sonic result is a three dimensional spatial presentation of the
instruments recorded within the context of their original environment. The
background seems black and devoid of contaminating energy, while each
individual instrument breathes into the space in which it was recorded. Truly
low level details, such as wall reflections from the original recording site, are
clearly and concretely apparent. The entire recording environment, whether
natural or artificial, can now be transposed in toto to your listening room.

7
1.2 Coherent Energy Transfer
Coherent energy is both an aspect of the absolute quantity of energy, and
also the speed with which that energy begins and ends. Entirely new
technologies in current transfer and in magnetic field energy storage within
the crossover maximizes the transient speed of the transducer, while
eliminating the ringing that can give recorded music a fatiguing and etched
quality.
Dynamic measurement techniques provide prediction of circuit behavior
under actual musical conditions. Through these techniques, current
saturation effects throughout the system are greatly reduced. Proper phasing
of elements within the crossover circuitry is now achievable. With these new
technical developments, the level of inter-driver jitter (mis-timing between
drivers) can be virtually eliminated.
The sonic results of this technology are stable, tightly focused images that
retain their position and harmonic structure, regardless of input intensity
(provided, of course, that the chain of amplification is able to deliver the
quantity of energy required with great speed). The most apparent benefit of
coherent energy transfer is in the rendering of bass information. Low
frequencies are delivered with a clarity that reveals the subtle harmonic
structure of pipe organ and bass guitar passages, while precise timing
provides a coherent temporal structure throughout the frequency spectrum.

8
1.3 The Active Reference System
A definitive transducer project of this magnitude demands the holistic
integration of diverse design goals, including perfect phase response, critical
damping, and point source accuracy. In addition, horizontal dispersion must
be uniform across the frequency spectrum in order to generate a coherently
focused wavefront and minimize room interaction artifacts. The difficulty of
integrating all of these elements increases exponentially as the size of the
array grows larger. It is only through complex computer modeling, meticulous
physical and electrical alignment, and scores of hours of dedicated listening
that correct phase response, without restricting the frequency response, has
been achieved. The result is a transducer that is extremely revealing of
microphone placement and phasing techniques from the recording site. The
most subtle ambient information is clearly apparent. There is no exaggeration
of details over fundamental elements of the recording; context is always
clearly maintained.
These qualities are most apparent when using the Sentinel Active Reference
System as an evaluation tool. Amplifiers, for example, that were previously
thought to have similar sonic characteristics are now definitively separated by
their individual signatures. The system's smooth non-reactive impedance
response insures that the sound of an amplifier is not due to an interactive
effect, but is a true representation of its sonic fingerprint. By ameliorating
many of the technical shortcomings of all previous transducers, the music
lover moves closer to the performance and the intent of the artist. Similarly,
the critical evaluator now has a transparent window through which the
differences between the elements under test (e.g. amplifiers, cartridges, etc.)
can be clearly discerned.

9
2 Unpacking Instructions
Introduction
Your Avalon Acoustics loudspeakers and sub amplifiers were shipped in seven
heavy-duty crates to ensure their safe arrival. It is recommended to save
these crates and boxes for possible future use. Due to the weight of the
system, the listening room floor structure must be extremely robust and
reliable.
WARNING: The Sentinel Active Reference System weighs over 1,100 pounds
(approximately 520 kg). You MUST evaluate and verify the integrity of the
intended listening room floor structure before bringing the crates into the
home.
In addition, it will require three persons to un-crate them and position them for
listening. Please arrange for your dealer and/or other friends to assist in this
project.
CAUTION: Three people are required for unpacking and set-up. To avoid
injury, do NOT attempt to unpack or set-up by oneself.
Contents
There are six Sentinel loudspeaker cabinets and two subwoofer amplifiers
packaged as follows:
Two upper loudspeaker cabinets in two crates
Two lower loudspeaker cabinets two crates
Two crossover cabinets in one crate
One subwoofer amplifiers in two crates
One of the crates also contains twenty threaded ApexCouplers, two set-up
blocks, one 7/16" - 1/2" open end wrench, one 5/32" hex wrench, and this
owner's manual.

10
2.1 Room Preparation and Verification
The Sentinel Active Reference System weighs over 1,100 pounds (about 520
kg). It is therefore crucial to verify the soundness of the intended listening
room floor structure and to insure that the structure can safely support the
device. If the listening room is not located on the ground floor, and/or if the
floor structure is suspended, it is recommended that you consult a structural
engineer for assistance.
WARNING: The Sentinel Active Reference System weighs over 1,100 pounds
(approximately 520 kg). You MUST evaluate and verify the integrity of the
intended listening room floor structure before bringing the crates into the
home.
The Sentinel is a full-range frequency device capable of accurately
reproducing the deep bass of a pipe organ or large bass drum. Any loose
items within the listening room (such as picture frames, light fixtures, drapery
controls, etc.) can easily become excited and resonate when the transducer
reproduces these very low frequencies. In order to avoid these vibration
effects, care should be taken to secure loose items or remove them from the
listening environment.