Avalon Acoustics Sentinel manuel d'utilisation

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 ma[...]

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Table of Contents 1 I nt ro du ct io n ................................................................................................................... 5 Ov e rv ie w ..................................................................................................5 1. 1 Lo w N oi se F l oo r .....................................................[...]

9 R oo m Ac ou st ic s an d Sp ea ke r Po si ti on ......................................................................... 41 In t ro du ct i on ..............................................................................................4 1 An Op ti ca l A na lo g y ...............................................................................[...]

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 ener[...]

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 signa[...]

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 ca[...]

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 wavefr[...]

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. WARN[...]

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 [...]

11 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 d[...]

12 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. Se[...]

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. To unpack the lower spea[...]

14 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 in[...]

15 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, begi[...]

16 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 lab[...]

17 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 int[...]

18 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 [...]

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). 6. Route the upper speaker cabinet wiring through t[...]

20 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.[...]

21 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 a[...]

22 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 upp[...]

23 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. Th[...]

24 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 dir[...]

25 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 an[...]

26 4 . 2 C o n n e c t i n g U p p e r S p e a k e r C a b i n e t t o C r o s s o v e r 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 a[...]

27 4 .3 Co n n ec t i ng S pe a k er C ab l e t o th e Cr o s so v e r 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 c[...]

28 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[...]

29 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 wi[...]

30 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. [...]

31 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 th[...]

32 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 [...]

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. FREQUENC Y A MPLI TUD E R O O M C O M PE N SAT I O N 4 2 H z[...]

34 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 maxi mizing 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, fol[...]

35 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 (b[...]

36 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 so[...]

37 8 C a r e o f Y o u r A v al o n L o u d s p e ak e r s 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 [...]

38 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 vo[...]

39 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[...]

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 expiration of the warranty period [...]

41 1 0 R o o m A c o u s t i c s / S p e a k e r P o s i t i o n 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 hinder ed by poor room acoustics[...]

42 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 receiv[...]

43 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 inc[...]

44 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[...]

45 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 [...]

46 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 Figur[...]

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. Therefore, the most importan[...]

48 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 reflecti[...]

49 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. Si[...]

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. In particular, when the wavelength equals about four times the distance to the boundary, the reflected wave is antiphase to the original wave, [...]

51 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 placemen[...]

52 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[...]

53 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 a[...]

54 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.. A tapestry is hung opposite the draperies to absorb t[...]

55 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. In order to fully benefit f[...]

56 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 relatively large room that is acoustically treated reasonably and to follow the set-up guidelines detailed i[...]

57 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 inten[...]

58 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[...]

59 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 l[...]

60 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 [...]

61 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. Wit[...]

62 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[...]

63 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[...]

64 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, significan[...]

65 13 Features • Application of new cabinet research featu res 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-lig[...]

66 14 Specifications Loudspeaker Driver Complement 1" concave ceramic dome tweeter 3 _" concave ceramic dome midrange 9" Nomex-Kevlar composite cone woofer T wo 1 3 " Nom e x- Ke v l ar c o m po site c o n e su bw o o fe rs Sensitivity 88 dB (2.83V, 1 meter) Impedance 4 ohms nominal (3.6 ohms minimum) Frequency Response 16Hz to [...]

67 15 Notes[...]