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Avalon Acoustics Sentinel Reference

Avalon sentinel reference system
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Musical Masterpieces
Serial Numbers ____________________
_________________________________
_________________________________
_________________________________
_________________________________
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.
Handcrafted by:

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Summary of Contents for Avalon Acoustics Sentinel

  • Page 1 Musical Masterpieces Serial Numbers ____________________ _________________________________ _________________________________ _________________________________ _________________________________ 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

    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.
  • Page 4 9 Room Acoustics and Speaker Position ...41 Introduction ...41 An Optical Analogy...42 Basic Room Acoustics...42 9.1 Standing Waves ...43 9.2 Flutter Echo ...44 9.3 Early Reflections ...45 Avoiding Early Reflections ...46 Low Frequency Reflections...48 9.4 Bass reinforcement...49 9.5 Summary of Recommendations ...52 Flutter Echo and Standing Waves ...52...

  • Page 5: Introduction

    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.

  • 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. Should you...

  • 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 lower speaker cabinets, first remove the top of the crate. Then slide the speaker part way off of the crate base so that the plastic bag can be unfastened from the enclosure bottom. Stand the speaker up and the bag can be slid off the top.

  • 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 it out of the plastic bag and check to ensure the following has also been included: One (1) detachable AC linecord...

  • Page 15: System Set-Up

    Removing Apex‘ Couplers from Set-up Blocks Figure 2.4 – To unpack the lower speaker cabinets.. Remove all twenty Apex‘ couplers from the two set-up blocks (see Figure 3.1). Three couplers will get installed in each of the six cabinets. Use the 1/2"...

  • Page 16: Left / Right Channel Matching

    The serial number on the crossover cabinet is printed on the nameplate on the bottom of the cabinet. The lower speaker cabinet has a serial number label located on the top, near the back of the cabinet, and the upper speaker cabinet has a serial number label located on the bottom, near the back of the cabinet.

  • Page 17: Lower Speaker Cabinet Set-Up

    WARNING: The wiring harnesses are fragile and can be easily damaged by pinching them beneath the cabinet base. 2. Lay the speaker on its side, using a blanket or other soft material to avoid scratching the finish. 3. Install three Apex‘ couplers on the bottom of the cabinet by fastening the threaded ends of the couplers into the cabinet inserts (see Figure 3.2).

  • Page 18: 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. Install three Apex‘ couplers on the bottom of the cabinet by fastening the threaded ends of the couplers into the cabinet inserts (see Figure 3.2).
  • 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 Apex ‘ Coupler into its receiving socket. Figure 3.5 – Removal of the set-up blocks between upper and lower speaker cabinets.

  • Page 21: 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

    The driver openings are beveled on the side that faces the listener (away from the speaker). Figure 3.7 displays the proper installation. Apply gentle pressure to the felt where it touches the adhesive tape strips, while taking care not to damage the transducer diaphragms.

  • 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

    2. Connect the upper speaker cabinet wiring harnesses (routed through the wiring tubes in the lower speaker cabinet) to the OUTPUT terminal block on the bottom of the crossover cabinet, as shown in Figure 4.1.

  • Page 27: 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

    2. Connect the lower speaker cabinet wiring to the OUTPUT connectors on the back of the sub amplifier. 3. Check to insure the correct polarity: The spade with the RED label connects to the positive (+) terminal, and the spade with the WHITE label connects to the negative (-) terminal.

  • 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 2400 watt subwoofer amplifier is a push-pull bridged design with fully balanced circuitry.
  • Page 33 1. Set the Master Gain on the subwoofer amplifier (see Figure 6.1) to match the output level of your main amplifier. This adjustment is both equipment and room dependent and should be tuned by ear while performing careful listening tests. Consult your dealer should you need assistance. ROOM COMPENSATION FREQUENCY 42 Hz...

  • Page 34: Maximizing Performance

    Felt Anti-diffraction Masks The felt anti-diffraction masks are integral elements of the reference system design. Unlike many other products, Avalon Acoustics loudspeakers are designed to be used with the felts in place while listening, and removing them will degrade the system's performance. It is very important that the felt...

  • Page 35: Room Treatment And System / Listener Position

    • 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. reflections from the side walls are a problem, pointing the speakers inward up to a maximum of five degrees can be helpful.

  • 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. 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. The 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

    Since the floor is within 5 feet of the speaker, it is best to have a carpeted floor to absorb floor reflections. A thick, dense carpet and pad will absorb lower frequencies more effectively than a thin one.
  • 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 Figure 9.4 - Change in frequency response resulting from placement of speaker 3.3 feet from a reflective surface (relative to an anechoic environment). Figure 9.5 - Same conditions as above, except speaker is 6.6 feet from the reflecting surface. Note how the cancellation and reinforcement occur at lower frequencies.
  • 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. Figure 9.6 - Example listening room. The area around the speakers is free of any object that would produce early reflections..

  • 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

    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. relatively large room that is acoustically treated reasonably and to follow the set-up guidelines detailed in Chapter 9, Room Acoustics and Speaker Position.

  • 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

    "fast bass" to the use of a light diaphragm or the use of a powerful energizing system. diaphragm can be set into motion that imparts a speaker with "fast" bass. Rather, it is how fast that motion can be stopped, how quickly the stored energy can be dissipated, that results in the sensation of "fast"...

  • Page 59: Measurements Of Audio Equipment

    It is widely acknowledged that this standard is far removed from the actual conditions in which the amplifier will be used. One doesn't listen to resistors, one listens to loudspeakers, and the load that the speaker presents to the amplifier is nearly always highly reactive (varies with frequency). The...

  • Page 60: Loudspeaker Measurements

    Briefly, the interaction of the dispersion pattern of the speaker with the reflective surfaces in the room (and the variation of both with frequency) creates an in-room frequency response that may vary markedly from the anechoic response.

  • Page 61: Designing For Accurate Bass Reproduction

    With the computer model, it is quite easy to change the position of the speaker in the room, or other parameters of the model. In this way, a composite picture can be created of a wide variety of rooms and speaker locations.

  • Page 62: Listening Qualities

    A speaker with excessive in-room bass response can create these effects. On the other hand, a speaker system with rolled-off bass can shrink the size of instruments, turning the same stand-up bass into a cello-sized instrument.

  • 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.

  • 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 tweeter and midrange have ultra-light concave •...

  • Page 66: Specifications

    14 Specifications Loudspeaker Driver Complement Sensitivity Impedance Frequency Response Recommended Amplifier Power Wiring Methods Dimensions Weight Subwoofer Amplifier Frequency response: Sensitivity: Input Impedance: Gain: S/N Ratio: THD+N: Rated Output: Dimensions: Weight: 1" concave ceramic dome tweeter 3 _" concave ceramic dome midrange 9"...

  • Page 67: Notes

    15 Notes...

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