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).
Table of Contents 1 Introduction...................................................................................................................5 Overview ..................................................................................................5 1.1 Low Noise Floor ..............................................................................................6 1.2 Coherent Energy Transfer...............................................................................7 1.
9 Room Acoustics and Speaker Position .........................................................................41 Introduction ..............................................................................................41 An Optical Analogy..................................................................................42 Basic Room Acoustics...............................................................................42 9.1 Standing Waves ................................................................
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.
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.
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.
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.
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).
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.
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 require assistance with planning your listening room, please refer to the in-depth discussion in Chapter 9, Room Acoustics and Speaker Position (beginning on page 41). If you require additional assistance, contact your dealer or phone the factory.
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). Carefully lift the cabinets by the small overhang at the base. See Figure 2.2. CAUTION: Three people are required for unpacking. To avoid injury, do NOT attempt to unpack by oneself. Figure 2.2 – To unpack the crossover cabinets..
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. 1. Remove screws. 2. Lift case. Figure 2.3 – To unpack the upper speaker cabinets.. To unpack the lower speaker cabinets, first remove the top of the crate.
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.
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. Then remove all the empty crates from the listening room to provide for additional assembly space.
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.
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. Carefully route the sub's integral wiring between the legs of the cabinet base, thereby protecting the wiring harnesses from becoming pinched.
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. 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). Lightly tighten the couplers and insure that the base of the coupler contacts the bottom of the recess.
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 setup blocks between them. Then gently slide the upper cabinet slightly forward to expose the wiring tubes in the lower cabinet (See Figure 3.4). 6. Route the upper speaker cabinet wiring through the wiring tubes and out the bottom rear of the lower speaker cabinets, as shown in Figure 3.4. Figure 3.
cabinet slightly, remove the front set-up block, and lower the single front Apex ‘ Coupler into its receiving socket. Figure 3.5 – Removal of the set-up blocks between upper and lower speaker cabinets.
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). OUTPUTS INPUTS Figure 3.6 – Proper placement of crossover cabinet behind speaker. 2.
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. Orientation of the upper Felt Mask Should the felts come loose from the cabinets during shipping, remember to reinsert them, as they are critical to loudspeaker performance.
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. These include preamplifiers, turntables, and interconnect cables.
4 Wiring Instructions WARNING: Failure to follow the set-up and wiring instructions explicitly may cause damage to your loudspeakers and void your warranty. Introduction The Sentinel crossover is designed specifically for use with the drivers in the upper speaker cabinet. The crossover is housed in a separate enclosure, designed to be placed directly behind the speaker.
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.
4.2 Connecting Upper Speaker Cabinet to Crossover 1. 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. 2.
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. Figure 4.2 – Connecting your speaker cables to the crossover. Make sure to check the polarity of the connections. Do NOT over-tighten the binding posts.
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. Separating the left and right channel amplification eliminates amplifier inter-channel modulation due to the amplifier's finite output impedance and aids in preserving the Sentinel's pristine phase relationships.
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. 2. Connect the lower speaker cabinet wiring to the OUTPUT connectors on the back of the sub amplifier. 3.
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. This is accomplished in one of the following three methods: 1.
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.1 As music is played through the loudspeakers, the electrical signal will gradually anneal these materials.
6 Subwoofer Amplifier Design Principle The Sentinel subwoofer amplifier provides essential support for the lowest octaves of the musical spectrum. 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.
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. MASTER GA IN ROOM COMPENSATION FREQUENCY AMPLITUDE 42 Hz Flat 30 Hz 65 Hz -6 dB 28dB/ 34dB + 6dB 22dB/ 28dB 34dB/ 40dB Figure 6.1– Room Compensation and Master Gain controls for the Subwoofer Amplifier. 2.
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.
Room Treatment and System / Listener Position Selecting the proper room and listener positions within your listening environment can dramatically improve system performance. The following points highlight the fundamental concepts in room treatment and positioning from the in-depth discussions in Chapter 9, Room Acoustics and Speaker Position (beginning on page 41) and in Chapter 10, Listener Position (page 55): • Left to right room symmetry aids in producing a balanced sound stage.
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. Therefore, damping these first reflection points is strongly recommended.
8 Care of Your Avalon Loudspeakers Cabinet Avalon Acoustics’ hardwood finished loudspeakers are supplied with a special polish and two lint-free polishing cloths, in order to properly care for the high quality furniture lacquer. The following polishing instructions should be observed: IMPORTANT: Use the supplied furniture polish ONLY. Do NOT use cleaners that contain ammonia, strong solvents, or abrasive materials. Use of these materials can degrade, scratch, or even DESTROY the finish. 1.
9 Warranty Your Avalon Acoustics loudspeakers are warranted against defects in workmanship and materials for a period of five years,!provided that the enclosed registration card is returned to the factory!within seven days of the purchase date. If the registration card is not returned within the seven day period, this warranty is null and void, and you will not be notified of future updates.
Warranty Statement 1. Avalon Acoustics warrants the materials, workmanship, and proper functioning of this product for a period of five years, provided that the completed registration card is returned to Avalon Acoustics within seven days of the date of purchase. If the registration card is not returned to the factory within the seven day period, this warranty is null and void.
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 expiration of the warranty period (five years), Avalon Acoustics shall have no further obligation of any kind whether express or implied, including but not limited to merchantability.
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. It is not necessary to listen to your system in a specially-designed sound chamber in order to enjoy it.
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.
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. This means that the incident and reflected waves combine with each other so that a stationary pattern of high and low sound pressures is established in the room.
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.
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. When a reflected sound reaches the listener more than 40 milliseconds later than the direct sound, the reflection is heard as a discrete echo.
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).
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. Therefore, the most important location for sound absorbing material is the point where the sound waves reflect to the listener (see Figure 9.2).
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. These reflections can cause significant distortions in phase and amplitude, resulting in muddy bass definition, smeared bass transients, and compressed image definition.
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. To make this interaction more clear, let us refer to the optical analogy of the candle. Similar to the way that the mirror reflected the light of the candle, so can the surfaces near the loudspeaker reflect the sound waves back into the listening room.
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. In 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.
There are typically three reflective surfaces near each speaker: the floor, the rear wall, and the side wall. Each of these surfaces produces its own reflection, and hence its own cancellation and reinforcement. By properly selecting the distances to each surface, we can provide a uniform and extended bass response. Conversely, improper placement of the loudspeakers can result in uneven frequency response, resulting in diminished bass quality.
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.
Early Reflections When arranging the furnishings in your listening room, remember that reflective objects should not be within a five foot radius of either the speaker or listener to avoid early reflections. This suggests the possibility of a dual-purpose room, with one end devoted to music reproduction, and the other end for another use, such as a study or office.
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. The area around the speakers is free of any object that would produce early reflections.. A tapestry is hung opposite the draperies to absorb the reflection from the side-wall and to help maintain left-right symmetry.
11 Listening Position Just as loudspeaker positioning and room treatment can address the issues of standing waves, flutter echo, reflections, and bass reinforcement, careful attention to listening position is crucial to achieving accurate sound stage placement, tonal balance, harmonic structure, focus, and image size.
3 meter path length 110 cm Figure 10.1 - Convergence of the wave front occurs with the listener ear situated approximately 110cm (43 1/2") from the floor and a preferred minimum of 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.
12 Accuracy of Bass Reproduction Introduction We have all had the experience of listening to speakers with poor bass quality. Perhaps the bass was muddy, or ill-defined. Possibly the bass was exaggerated or bloated. 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.
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.
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. Unquestionably, it is the latter criterion which is the most important one.
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.3 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. Loudspeakers continue to be measured in a test chamber that is equivalent to the absence of any room at all.
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. With the computer model, it is quite easy to change the position of the speaker in the room, or other parameters of the model.
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.5 Nevertheless, for the purposes of this discussion, we will treat these two topics separately as much as is possible.
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.
12.4 Active Subwoofer System Designing a loudspeaker system for accurate low-frequency reproduction is a challenging proposition. Given a reasonable listening environment, there is very good correlation between the anechoic and in-room responses at frequencies above 350 Hz. However, at low frequencies, boundary effects come into play, significantly altering the in-room response. Anechoic Frequency Response vs.
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 ceramic dome diaphragms.
14 Specifications Loudspeaker Driver Complement 1" concave ceramic dome tweeter 3 _" 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 34kHz (+/- 1 dB, anechoic) Recommended Amplifier Power 100 to 1000 watts Wiring Methods Two position terminal block, designed to accept spade lugs for #10 screws.
15 Notes 67
