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Avalon Sentinel Manual

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Musical Masterpieces
Serial Numbers ____________________
_________________________________
_________________________________
_________________________________
_________________________________
This product is certified to meet the requirements of the European
Union
(EU)
Electromagnetic
(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.
Handcrafted by:
Compatibility
(EMC)
Directive

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  • Page 1 Musical Masterpieces Serial Numbers ____________________ Handcrafted by: _________________________________ _________________________________ _________________________________ _________________________________ 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.

  • Page 3: Table Of Contents

    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...
  • Page 4 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...

  • Page 5: Introduction

    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.

  • Page 6: Low Noise Floor

    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.

  • Page 7: Coherent Energy Transfer

    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.

  • Page 8: The Active Reference System

    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.

  • Page 9: Unpacking Instructions

    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.

  • Page 10: Room Preparation And Verification

    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.

  • Page 11: Crate And Box Placement For Unpacking

    2.2 Crate and Box Placement for Unpacking Because of the weight and size of the Sentinel Active Reference System, it is important to plan the layout of your room and carefully place the crated devices within the listening environment BEFORE unpacking.

  • Page 12: Opening The Crates

    2.3 Opening the Crates All of the crates features a one-piece top assembly which is fastened to the crate bottom with screws around the lower perimeter. To unpack the crossovers, remove the screws and lift the upper portion of the crate straight up (this will require two people).
  • Page 13 To unpack the upper speaker cabinets, remove the screws and lift the upper portion of the crate straight up (this will require two people). Carefully lift the cabinets by the small overhang at the base. See Figure 2.3. CAUTION: Three people are required for unpacking. To avoid injury, do NOT attempt to unpack by oneself.

  • Page 14: Opening The Sub Amplifier Crates

    2.3 Opening the Sub Amplifier Crates The Subwoofer Amplifiers are also packed in heavy-duty crates. To unpack, remove the screws and lift the upper portion of the crate straight up (this will require two people). Carefully lift the amplifiers off of the crate base. Take them out of the plastic bag and check to ensure the following has also been included: •...

  • Page 15: System Set-Up

    3 System Set-up WARNING: Failure to follow the set-up and wiring instructions explicitly may cause damage to your loudspeakers and void your warranty. Preparation In order to begin system set-up, it is important that all materials are unpacked and all cabinets are removed from the crates in accordance with Chapter 2, Unpacking Instructions, beginning on page 9.

  • Page 16: Left / Right Channel Matching

    Left / Right Channel Matching The two system channels (left and right) are consecutively serialized at the factory. The elements of each channel are matched as a set for both their electrical and aesthetic characteristics. Therefore, it is important to keep the three cabinets of one channel (upper speaker, lower speaker, crossover) which are labeled with the same serial number together on one side of the room, separate from the three cabinets of the other channel.

  • Page 17: Lower Speaker Cabinet Set-Up

    3.1 Lower Speaker Cabinet Set-up CAUTION: Three people are required for the set-up procedure. To avoid injury, do NOT attempt to set-up by oneself. 1. Carefully lift and place each lower speaker cabinet in its measured final location, as it becomes more difficult to move once the Apex couplers are attached.

  • Page 18: Upper Speaker Cabinet Set-Up

    3.2 Upper Speaker Cabinet Set-up CAUTION: Three people are required for the set-up procedure. To avoid injury, do NOT attempt to set-up by oneself. 1. Lay the upper speaker on one side, using a blanket or other soft material to avoid scratching the finish. 2.
  • Page 19 5. Carefully lift each upper speaker cabinet by the small overhang at the base, and place it directly on top of the lower speaker cabinet, with the set- up blocks between them. Then gently slide the upper cabinet slightly forward to expose the wiring tubes in the lower cabinet (See Figure 3.4).
  • Page 20 Once the wiring is routed through the wiring tubes, slide the upper speakers cabinets back, so that the couplers on the upper speaker cabinet are directly above the sockets on the lower speaker cabinet (see Figure 3.5). If necessary, gently adjust the upper speaker cabinet on the set-up blocks. 7.

  • Page 21: Crossover Cabinet Set-Up

    3.3 Crossover Cabinet Set-up CAUTION: Three people are required for the set-up procedure. To avoid injury, do NOT attempt to set-up by oneself. 1. Lay the crossover cabinet on one side, just behind the speaker cabinet, using a blanket or other soft material to avoid scratching the finish. The cabinet should be oriented so that output terminals are adjacent to the back surface of the speaker cabinets (see Figure 3.6).

  • Page 22: The Felt Anti-Diffraction Mask

    3.4 The Felt Anti-Diffraction Mask The anti-diffraction masks are installed at the factory, and fit within the recesses on the cabinet face. It is very important that the felt mask make physical contact with the face of the loudspeaker, as air space between the felt and the speaker face will adversely affect sound quality.

  • Page 23: Sub Amplifier Set-Up

    3.5 Sub Amplifier Set-up Place the Sub Amplifiers in their final set-up positions, allowing 8 inches at the rear for tightening the speaker output connectors. The power transformer in the Sub Amplifier is located at the front-center of the unit. Ideally, a few feet should separate this area from components which potentially could pick up hum.

  • Page 24: Wiring Instructions

    Do NOT connect the subwoofer amplifier (or your own amplifier) directly to the upper speaker cabinet drivers. Because of the weight and size of the Sentinel Active Reference System, it is important to complete the set-up procedure before making wiring connections (see Chapter 3, System Set-up, beginning on page 15).

  • Page 25: Wiring And Field Interactions

    4.1 Wiring and Field Interactions The Sentinel Active Reference System is an extremely revealing, high-energy device. Therefore, it is important to carefully plan the placement and routing of wires when setting up your music reproduction system. Wiring is a task that is often performed in a quick and haphazard manner, driven by the excitement and anticipation of listening to one's brand new system.

  • Page 26: Connecting Upper Speaker Cabinet To Crossover

    4.2 Connecting Upper Speaker Cabinet to Crossover Locate the upper speaker cabinet wiring harnesses: a four-conductor wiring harness with labels "HIGH" and "MID" for the tweeter and midrange, and a two-conductor wiring harness with labels "LOW" for the woofer. These harnesses are hard-wired directly to the upper loudspeaker cabinet drivers (routed through the wiring tubes in the lower speaker cabinet), in order to provide the most unobstructed signal path.

  • Page 27: Connecting Speaker Cable To The Crossover

    4.3 Connecting Speaker Cable to the Crossover 1. Locate the input terminal block on the bottom of the crossover cabinets. Route your own SINGLE-WIRED speaker cables to these INPUT terminals. 2. Connect your own speaker wires (for the upper speaker cabinet drivers) to the INPUT terminal block on the bottom of the crossover cabinet, as shown in Figure 4.2.

  • Page 28: Connect Speaker Cable To Your Amplifier

    4.4 Connect Speaker Cable to your Amplifier Although it is possible to power the Sentinel Active Reference System with a single stereo amplifier, it is recommended to separate the amplification into left and right channels. This is accomplished by using two mono amplifiers.

  • Page 29: Connecting Subwoofer To The Sub Amplifier

    4.4 Connecting Subwoofer to the Sub Amplifier 1. Locate the lower speaker cabinet wiring harnesses: two single-conductor wiring cables with the label "SUB". These harnesses are hard-wired directly to the lower loudspeaker cabinet sub drivers, in order to provide the most unobstructed signal path.

  • Page 30: Connecting Preamplifier To The Amplifiers

    4.5 Connecting Preamplifier to the Amplifiers The Sentinel subwoofer section is actively powered by its own subwoofer amplifier, whereas the upper speaker section is powered by your own amplifier that is directly connected to the Sentinel crossover cabinet. Therefore, you will need to make two separate output connections from your preamplifier.

  • Page 31: Break-In Period

    5 Break-in Period Your new Avalon Acoustics Sentinel Active Reference System has an initial break-in period. It will not perform to its full sonic potential when first installed in your system. This is due to a residual polarization of the dielectric materials used in the crossover capacitors and internal wiring.

  • Page 32: Subwoofer Amplifier

    As a fundamental component of the Sentinel Reference System, the subwoofer amplifier has been specifically designed to match the superlative speed and coherence of the Sentinel's upper frequency response. The 450 watt subwoofer amplifier is a push-pull with fully balanced circuitry.
  • Page 33 Microsoft Powerpoint tutorial included with this manual. (See disc in back of this manual.) Your new Sentinel Sub Amplifier will allow you to work with any room size, and can help address particular room frequency anomolies with a notch filter designed to navigate around said frequencies.

  • Page 34: Maximizing Performance

    7 Maximizing Performance These details are imperative to obtaining optimum results from your Avalon Acoustics loudspeakers. Break-in The break-in period is critical to maximizing sonic performance and should take place before other adjustments (see the discussion on page 29). The break-in should begin with three to six hours of quiet music, followed by 200 to 300 hours of loud and dynamic source material.

  • Page 35: Room Treatment And System / Listener Position

    A comfortable, centered listening position at a minimum distance of three meters from the system allows proper wave front convergence. Toe-In The exemplary horizontal polar response of the Sentinel Active Reference System makes large amounts of toe-in unnecessary. The optimum toe-in position is between two and three degrees.

  • Page 36: First Reflection Points

    First Reflection Points Since the ear/brain system tends to integrate the sounds arriving within a 10 millisecond time window, it is important to control the early reflections arriving from the side walls to the listening position. A hard-surfaced wall can produce a strong frequency-dependent reflection that can interfere with the reproduced sound-stage, as well as change the perceived tonal balance of the system.

  • Page 37: Care Of Your Avalon Loudspeakers

    2. Wipe off the excess polish until the desired luster is achieved. Crossover Cabinet Your Sentinel crossover cabinets are manufactured with high-density solid surface material. This beautiful finish also requires minimal attention. cabinets should be dusted with a soft, non-abrasive cloth, moistened with water.

  • Page 38: Warranty

    In the Event of a Problem In the unlikely event of a problem with your Avalon Acoustics loudspeakers, the component most susceptible to failure is one of the driver units. If driver replacement is required, have your dealer contact Avalon Acoustics. The performance curves of the drivers in each pair of loudspeakers are kept on file at the factory.

  • Page 39: Warranty Statement

    If the registration card is not returned to the factory within the seven day period, this warranty is null and void. If any defects are found in the materials or workmanship of this Avalon Acoustics product, or if the product ceases to properly function within the appropriate warranty...
  • Page 40 6. The above warranty is the sole warranty given by Avalon Acoustics, and is in lieu of all other warranties. All implied warranties, including warranties of merchantability or fitness for any particular purpose shall be strictly limited in duration to five years from the date of original purchase, and upon the...

  • Page 41: Room Acoustics And Speaker Position

    10 Room Acoustics / Speaker Position Introduction The listening room forms the final link of the playback system, as important as any other component in the chain. Just as an otherwise superb system is handicapped by an inferior pre-amplifier (for example), so can a well-matched system be hindered by poor room acoustics.

  • Page 42: An Optical Analogy

    An Optical Analogy Let us use a visual analogy to aid our understanding of acoustics. Imagine that you are in a room that is lit only by a candle in its center. There is (approximately) a uniform amount of light cast in all directions. If a large mirror is held closely to candle, one half of the room becomes darkened, while the other half receives twice as much light.

  • Page 43: Standing Waves

    10.1 Standing Waves The parallel surfaces of most listening rooms can lead to a potential problem at any frequency. A sound wave can be repeatedly reflected from opposing surfaces, back and forth. If the distance between the surfaces is an integral multiple of one-half the sound wavelength, a standing wave will be set up.

  • Page 44: Flutter Echo

    10.2 Flutter Echo These parallel, reflective surfaces can also produce a different audible problem. If there is little absorption at higher frequencies, a musical transient containing high frequencies, such as a hand clap or the strike of a percussion instrument, can be heard bouncing repeatedly between the surfaces. Called flutter echo (or slap echo), these multiple reflections can obscure musical detail.

  • Page 45: Early Reflections

    10.3 Early Reflections Another situation that can reduce the subjective quality of reproduced sound is the presence of early reflections. By early reflections, we are referring to reflected sound waves that reach the listener within 10 to 20 milliseconds of the direct signal from the loudspeaker.

  • Page 46: Avoiding Early Reflections

    Avoiding Early Reflections The speed of sound is approximately one foot (30 cm) per millisecond. Therefore, to preserve the natural sound stage on your recordings, there should be no reflected sounds arriving at the listening position with a path length less than ten feet (3 meters) longer than the direct path from speaker to listener (see Figure 9.1).
  • Page 47 It is not necessary to acoustically treat the entire room to achieve good results. Strategic treatment of specific locations can realize considerable benefits. Remember that when sound waves reflect from a flat surface, the angle of reflection is equal to the angle of incidence, just as a mirror reflects light waves.

  • Page 48: Low Frequency Reflections

    Low Frequency Reflections The first significant reflection of low frequency sound waves comes from two corners behind the loudspeakers. Another important reflection occurs on the wall behind the speakers, midway between them. Similarly, low frequency corner and wall reflections take place at the opposite wall, behind the listener.

  • Page 49: Bass Reinforcement

    10.4 Bass reinforcement By bass reinforcement, we mean the effect of the room boundaries on the propagation of sound. It is widely known that speaker placement relative to the floor and walls can affect the relative amount of bass that the system produces.
  • Page 50 As frequency increases and wavelength becomes more similar to the distance to the boundary, the phase difference between original and reflected waves increases, and the air coupling effect is diminished. particular, when the wavelength equals about four times the distance to the boundary, the reflected wave is antiphase to the original wave, resulting in a cancellation (dip) in the output.
  • Page 51 33% of each other. A good rule of thumb in establishing the lateral position of the Sentinel Active Reference System is to apply the ratio 4 : 10 : 4. In other words, the distance to the side wall is 4/18 (or about 22.2%) of the room width, and the distance...

  • Page 52: Summary Of Recommendations

    10.5 Summary of Recommendations Now that we have looked at some of the common problems of listening rooms, as well as their cures, let us summarize our findings and recommendations. Flutter Echo and Standing Waves These situations are the result of the room having parallel, reflective surfaces. The potential problems are independent of the audio system, and need to be addressed at the source.

  • Page 53: Early Reflections

    Speaker Placement Although the Sentinel Active Reference System may be placed in a variety of positions relative to the walls of the room, it is still wise to apply the basic guidelines described in this chapter to achieve optimal results.

  • Page 54: A Listening Room Example

    10.6 A Listening Room Example In order to make these points more clear, an example of a room layout is given in Figure 9.6, illustrating the principles we have given. DRAPERIES SHELVES SHELVES CHAIR DESK Listening Position TABLE TABLE SOFA TAPESTRY Figure 9.6 - Example listening room.

  • Page 55: Listening Position

    Time Alignment The front planes of the Sentinel Active Reference System have been carefully sculpted to establish accurate driver time alignment. In Figure 10.1, notice that the acoustic centers of the drivers are situated so that the wave front converges precisely at the listener's ear.

  • Page 56: Summary

    3 meters (118 inches) from the system. Summary When the listener and system are situated properly within a carefully planned and set-up listening environment, the Sentinel multi-way system can deliver high-energy output with point-source accuracy. It is crucial to begin with a...

  • Page 57: Accuracy Of Bass Reproduction

    In any case, these type of distortions are distracting and can keep us from enjoying the full measure of the performer's intent. When it comes to the reproduction of low frequencies, Avalon Acoustics pursues a different design goal than most other manufacturers. Specifically, we believe that the complete absence of stored resonant energy is of paramount sonic importance.

  • Page 58: Sensitivity To Time-Related Information

    12.1 Sensitivity to Time-Related Information It is widely known that the human ear/brain system is extremely sensitive to time-related distortions. This can be understood when one realizes that directional and spatial information is provided by inter-aural time (and phase) differences. During the period of man's evolution, the ability to accurately determine the direction and distance of sound sources conferred a decided survival advantage, hence our present day aural sensitivity to time-related information.

  • Page 59: Measurements Of Audio Equipment

    12.2 Measurements of Audio Equipment It should be recognized that measurements are not the final arbiter of sound quality of audio components. Often times a measurement standard has evolved because it is easily performed, or because it is easily repeatable, or it has shown some link to certain audible characteristics.

  • Page 60: Loudspeaker Measurements

    Loudspeaker Measurements Returning to loudspeakers, a similar situation has developed. Although nobody listens to music in an anechoic chamber, loudspeaker measurements are commonly performed in them. Although various proposals have been made for performing low frequency measurements in a more realistic setting, there has been no agreement as to what that setting should be.

  • Page 61: Designing For Accurate Bass Reproduction

    Designing for Accurate Bass Reproduction How, then, does one arrive at the goal of a loudspeaker that provides tonal accuracy in the listening room? The answer, in large part, comes in the form of the digital computer. It is possible to create a mathematical model of a listening room, and predict the response of a given speaker in that room.

  • Page 62: Listening Qualities

    12.3 Listening Qualities Now we will turn our attention to the listening experience, and describe how these measurable properties correlate with our subjective impressions. There are two main factors which affect subjective low-frequency accuracy, frequency response and transient response. At low frequencies, these two descriptions are different aspects of the same event.

  • Page 63: Transient Response Effects

    Transient Response Effects A speaker with poor transient response will store energy, releasing it after the initial musical transient has passed. This causes a loss of detail and obscures important musical information. Also associated with poor transient response is a narrow-band resonance, which can emphasize specific notes. When listening for the low-frequency transient accuracy of a speaker, it will be useful to utilize a broad variety of recordings.

  • Page 64: Active Subwoofer System

    Active Control of Bass Energy In order to properly control the bass energy and achieve a flat frequency response in-room, the Sentinel Active Reference system employs an active, powered subwoofer system. The subwoofer amplifier is specifically designed to handle the high-power demands of low-frequency signal, via the amplifier's massive toroidal transformer, exceptional storage capacity, and unmatched high voltage/current regulation.

  • Page 65: Features

    13 Features • Application of new cabinet research features nineteen separate aperiodically damped internal chambers in three distinct speaker cabinets for superior resonance control. • Advanced light weight driver diaphragm materials minimize energy storage and time-domain distortion. • High-definition diamond membrane tweeter. Midrange driver has ultra-light concave ceramic dome diaphragm.

  • Page 66: Specifications

    14 Specifications Loudspeaker Driver Complement 1" concave diamond dome tweeter 3 ½" concave ceramic dome midrange 9" Nomex-Kevlar composite cone woofer Two 13" Nomex-Kevlar composite cone subwoofers Sensitivity 88 dB (2.83V, 1 meter) Impedance 4 ohms nominal (3.6 ohms minimum) Frequency Response 16Hz to 100kHz (+/- 1 dB, anechoic) Recommended Amplifier Power...

  • Page 67: Notes

    15 Notes Sub Amplifier settings for future reference. Band Pass settings________________ Amplitude setting_________________...

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