Avalon Acoustics | OPUS Ceramique Loudspeaker | Specifications | Avalon Acoustics OPUS Ceramique Loudspeaker Specifications

Avalon Acoustics OPUS Ceramique Loudspeaker Specifications
M us ic al M as t er piec es
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.
Table of Contents
1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Unpacking Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Introduction .................................................................................................6
Contents......................................................................................................6
2.1 Opening the Crate ...............................................................................................7
2.2 Installing the Grilles ............................................................................................8
Orientation of the Felt Anti-Diffraction Mask .....................................................8
2.3 Replacing Grille Pins ............................................................................................9
3 Wiring Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Introduction .................................................................................................11
Connecting the Speaker to the Amplifier............................................................11
4 Break-in Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5 Maximizing Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Break-in ......................................................................................................14
Grille Assemblies..........................................................................................14
Speaker Placement and Symmetry....................................................................14
Toe-In.........................................................................................................15
Apex™ Couplers ..........................................................................................15
First Reflection Points....................................................................................16
Corner Treatment..........................................................................................16
6 Care of Your Loudspeakers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Cabinet (Hardwood Finish) .............................................................................17
Grille Assembly............................................................................................17
Drivers........................................................................................................17
7 Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
In the Event of a Problem ...............................................................................18
Warranty Statement.......................................................................................19
8 Room Acoustics and Speaker Position. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Introduction .................................................................................................21
An Optical Analogy.......................................................................................22
Basic Room Acoustics ...................................................................................22
8.1 Standing Waves ..................................................................................................23
8.2 Flutter Echo .......................................................................................................24
8.3 Early Reflections.................................................................................................25
Avoiding Early Reflections .............................................................................26
8.4 Bass reinforcement ..............................................................................................28
8.5 Summary of Recommendations..............................................................................31
Flutter Echo and Standing Waves.....................................................................31
Speaker Placement ........................................................................................32
Early Reflections ..........................................................................................32
8.6 A Listening Room Example ..................................................................................33
9 Accuracy of Bass Reproduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Introduction .................................................................................................34
9.1 Sensitivity to Time-Related Information ..................................................................35
"Fast Bass" ..................................................................................................35
9.2 Rationale ...........................................................................................................36
Anechoic vs. In-Room Frequency Response.......................................................36
9.3 Measurements of Audio Equipment ........................................................................37
A Correlation with Amplifier Measurements ......................................................37
Loudspeaker Measurements ............................................................................38
Designing for Accurate Bass Reproduction ........................................................39
Frequency Response Effects............................................................................40
Listening for Size Distortions ..........................................................................40
Transient Response Effects .............................................................................41
9.4 Conclusion.........................................................................................................42
10 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
11 Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
12 Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
1 Introduction
The Opus Ceramique was conceived as an alternative to our award winning original
Opus. Designed specifically for moderate sized listening rooms, the Ceramique presents
a taught and coherent soundfield, free of stored energy. Staging of exceptional clarity and
harmonic structure is achieved through innovations in crossover technology and the use of
low mass drivers, all utilizing the same ceramic diaphragm material.
“Purity of musical communication”, was the touchstone phrase that we kept foremost in our
minds while designing the Ceramique ; to bring the listener closer to the intent of the
musicians while preserving the sonic illusion of the performance. The recovery of ambient
spatial information within an extremely quiet background transports the listeners into the
acoustic space in which the recording was made. Dynamic contrasts blossom from a “black”
background, filling the performance with a visceral realism. All of these virtues from a
transducer of modest size, able to project a palpable soundstage well beyond the boundaries of
the listening room.
Meticulous engineering employing proprietary electronic and acoustic measurements with the
extensive use of CAD modeling has provided us with the ability to predict and manipulate the
most ubiquitous of variables. Dynamic testing has yielded unsurpassed octave-to-octave
energy balance, without compression, under the most demanding program conditions.
Proprietary construction methods utilizing precision components have led to our defining
achievement of low noise ambiance retrieval and soundstage focus, revealing the most subtle
detail of the recording site and the artists performance.
Built entirely by hand, our craftsmanship demands comparison not with the audio industry,
but with the finest cabinet makers of the 18th and 19th centuries. Modern materials,
assembled to the most stringent tolerances, have created a “classic” that will endure the test of
time. Individually crafted, we treat each pair of loudspeakers as a unique work of art unto
itself.
5
2 Unpacking Instructions
Introduction
Your Avalon Acoustics loudspeakers were shipped in a heavy-duty crate to ensure their safe
arrival. It is recommended to save this crate for possible future use. Due to the weight of the
speakers, it will require two persons to un-crate them and position them for listening. Please
arrange for your dealer or other friend to assist in this project.
Contents
The shipping crate contains the following items:
•
two loudspeaker cabinets
•
two grille assemblies
•
the owner’s manual
•
one set of six Apex‘ Couplers
•
an accessory bag
The grille assemblies and owner’s manual are contained in an outer compartment on the top
of the shipping crate. The Apex‘ Couplers and accessory bag are packed together on the
bottom of one of the loudspeaker cabinets.
The accessory bag contains replacement grille pins, a small bottle of furniture polish, and two
lint-free polishing cloths.
IMPORTANT: It is imperative that the Apex™ Couplers are utilized, in order to insure
that the bottoms of the loudspeakers are not blocked. This is especially important on
thick carpeting.
6
2.1 Opening the Crate
The crate features a one-piece top assembly which is fastened to the crate bottom with screws
around the lower perimeter. To unpack, remove the screws and lift the upper portion of the
crate straight up (this will require two people).
Next, slide each 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. Please refer to Figure 2.1.
1. Remove screws.
`
2. Lift case.
`
3. Slide speaker,
then undo bag.
4. Stand speaker up,
then remove bag.
Figure 2.1 - To unpack the loudspeakers.
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2.2 Installing the Grilles
The grille assemblies are behind a panel on the outside of the speaker crate. Remove the
screws securing the panel, and then carefully pull the grilles straight out. The grilles are
installed with friction fasteners and press into place on the speaker cabinets. Please see Figure
2.2.
1. Remove screwsand panel fromtop of crate.2. Pull grillesstraight out.3. Push grille pins s
Figure 2.2 - To install the grille assemblies.
Orientation of the Felt Anti-Diffraction Mask
The grille assembly includes a felt anti-diffraction mask. Should the felt mask be removed, be
sure to note the correct inside-outside orientation when re-installing it. The tweeter and
midrange openings are beveled on the side that faces the listener (away from the speaker).
8
2.3 Replacing Grille Pins
The grille pins installed on the grille assemblies are fragile and can be easily damaged.
Should any of the pins break, you may replace them using the following procedure.
1. Place the grille assembly face-down on a padded surface (a towel or carpeting).
2. Remove the damaged grille pin by pulling it straight out with a small pliers or similar tool.
Please refer to figure 2.4. Make sure that the complete pin is removed and that there are no
pin fragments left in the mounting hole.
Figure 2.4 - Removal of broken grille pin. Check for pin fragments in the mounting
hole.
3. Insert the new grille pin in the grille pin installation tool (see figure 2.5).
Figure 2.5 - Insertion of new grille pin into installation tool.
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4. Carefully pull the grille cloth away from the frame mounting hole. The mounting hole
must be clear of all obstacles during pin installation.
5. Place the exposed end of the grille pin in the open mounting hole. Check to insure that the
grille cloth is not trapped between the pin and frame. Use a small hammer and gently tap the
new grille pin in place. Then, pull the insertion tool off the new pin and verify that the pin
flange is flush with the surface of the grille. Please refer to Figure 2.6.
WARNING: Grille pin breakage may result if the grille cloth becomes trapped between
the pin and frame during installation.
Figure 2.6 - Installing grille pin into Opus Ceramic grille frame. Note that after
installation, the grille pin flange is flush with the surface of the grille.
6. Reposition the grille cloth that was pulled away from the frame mounting hole in step 4.
The cloth should lay flat and wrinkle-free.
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3 Wiring Instructions
Introduction
The crossover is housed in a sealed, non-accessible chamber in the bottom of the speaker
cabinet, to minimize the effect of vibration on the components. The Opus Ceramic is
equipped with high-quality barrier terminals for connecting the speaker cables. Ring terminals
or spade lugs designed for #10 screws are recommended for cable termination.
Connecting the Speaker to the Amplifier
1. Place the speaker in its approximate location, then lay the speaker on its side, using a soft
surface to avoid scratching the finish.
2. Connect the speaker wires to the terminal block on the speaker bottom (see Figure 3.1).
Check to insure the correct polarity (positive lead connected to the (+) terminal and negative
lead connected to the (-) terminal.
Do NOT over-tighten the screws.
3. Stand the speakers up.
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INPUTS
From Amplifier
Figure 3.1 - Bottom view of the speakers showing the connections from the amplifier
to the loudspeaker. Check to insure the correct polarity (positive lead connected to
the (+) terminal and negative lead connected to the (-) terminal.
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4 Break-in Period
Your new Avalon Acoustics loudspeakers have an initial break-in period. They will not
perform to their full sonic potential when first installed in your system. This is partially 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. Similarly, the suspensions of the drivers will reach their optimal
mechanical properties as the speakers are played. Only after the break-in period will the full
performance of your Avalon Acoustics loudspeakers be realized.
The break-in process will occur naturally as music is played through the system. To reduce
the time required, it is recommended that the system be played continuously, using either a
digital source in the repeat mode or an FM broadcast signal. The recommended break-in
procedure is as follows:
•
Initial warm-up: three to six hours of quiet music.
•
Extended break-in: 200 to 300 hours of loud and dynamic source material (e.g.
Tangerine Dream, Optical Race, RCA 2042-2-P).
During the break-in period, the sonic properties of your loudspeakers may undergo several
gradual shifts as the various components break-in at different rates. It is therefore suggested
that the fine-tuning of the system be delayed until after the break-in period is completed.
However, during the final phases of the break-in period, the sonic image will open up, the
sound-stage will gain specificity, the bass control and impact will increase, and the overall
sound will have a more relaxed, involving presentation.
1
A high-voltage test is applied to wiring and capacitors during their manufacture. This results in a
residual polarization of the dielectric materials.
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5 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 13). 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.
Grille Assemblies
The grille assemblies, with their felt anti-diffraction masks, are integral elements of the
loudspeakers' design. Unlike many other products, Avalon Acoustics loudspeakers are
designed to be used with the grilles in place while listening, and removing them will degrade
the system's performance. It is extremely important that the felt anti-diffraction masks make
physical contact with the face of the loudspeakers, as air space between the felt and the
speaker face will adversely affect sound quality.
Speaker Placement and Symmetry
Selecting the proper room position for your Avalon Acoustics loudspeakers can dramatically
improve their performance. The following points highlight the fundamental concepts in
loudspeaker positioning from the in-depth discussion in Chapter 8, Room Acoustics and
Speaker Position (beginning on page 21):
•
Left to right room symmetry aids in producing a balanced sound stage.
•
Image depth is enhanced when the distance to the rear wall is increased.
•
The most even bass response will be attained when the distances to the side and rear
walls are not overly similar.
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Toe-In
Adjusting the toe-in angle of the speakers is useful in tailoring the sound to best match the
characteristics of your system and listening room.
When the speakers are facing straight forward, they tend to create a large, expansive
sound-stage, painted with broad brush strokes. As they are rotated toward the listening
position, the image becomes more compact, with increased focus, creating a greater sense of
intimacy. Pointing the speakers inward is also helpful in situations where strong reflections
from the side walls are a problem.
Start with the loudspeakers facing straight forward, and play either a mono source, or a stereo
source with a distinct center image, through both channels. Carefully rotate the loudspeakers
inward in small increments to bring the image in precise center focus (small adjustments can
be made with the speaker on Apex™ couplers). Toe-in adjustment is rather delicate, and
experimentation is necessary to achieve the proper angle for your listening situation. The
optimum angle is usually between three and ten degrees inward.
Apex™ Couplers
Supplied with your Avalon Acoustics loudspeakers are six Apex™ couplers, used to couple
the speakers to the floor, thereby minimizing time-smearing resonance effects. The result is
an increase in focus and solidity of the sonic images.
On hardwood floors, you may protect the floor from the pointed spike using a large coin, such
as a quarter. However, the coupling effect of the Apex™ couplers will be reduced.
Once you have located the proper position and toe-in angle for your Avalon Acoustics
loudspeakers, place the couplers under the speaker bases. It is easiest to install the couplers
with the assistance of a friend. Lean the speaker forward first, and position two couplers
pointing downward, one under each rear corner. Then lean the speaker backward and place
one Apex™ coupler under the front center of the base.
IMPORTANT: It is imperative that the Apex™ Couplers are utilized, in order to insure
that the bottoms of the loudspeakers are not blocked. This is especially important on
thick carpeting.
15
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 sidewalls 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. Please refer to Section 8.3, Early Reflections, beginning on page 25, for
further information.
Corner Treatment
It is important to control the first reflections of low frequency sound, which normally occur at
the corners behind the loudspeakers. These reflections can cause significant distortions in
phase and amplitude, resulting in muddy bass definition and smeared bass transients. Placing
Tube-Traps (available from Acoustic Sciences Corporation) at the room corners can
significantly control these bass colorations and restore the quickness of bass transients.
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6 Care of Your Loudspeakers
Cabinet (Hardwood Finish)
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. Apply the supplied polish to one of the clean, lint-free polishing cloths (or use cotton cloth
that is clean and lint-free), and carefully wipe it on the cabinet. Be careful NOT to apply the
polish to the loudspeaker drivers.
WARNING: Do NOT apply polish to the loudspeaker drivers.
2. Wipe off the excess polish until the desired luster is achieved.
Grille Assembly
The grille assembly may be removed from the cabinet and gently vacuumed to remove dust. If
the felt insert is removed, please note the inside-outside orientation when re-installing it. The
hole for the tweeter is beveled on the side toward the listener, to provide optimal dispersion
characteristics.
Drivers
The drivers (woofer, midrange, and tweeter) require no regular maintenance. Do not attempt
to clean the woofer, midrange or tweeter dome, as they are easily damaged.
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7 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. In the unlikely event that you did not receive the
registration card with your loudspeakers, please contact the factory immediately so that
we may send you a replacement card. This warranty is transferable to subsequent
purchasers within the original five year period. A complete statement of warranty is given
below. Please take the time to fill out and return the enclosed warranty registration card.
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. This enables Avalon Acoustics to supply an exact
replacement unit, ensuring continued operation at the highest level of performance. The
defective driver must then be returned to the factory for inspection to determine the status of
the warranty claim. This on-site replacement of the driver units eliminates the time and
expense of shipping the entire speaker to the factory for repair. All warranty claims must be
made through an authorized Avalon Acoustics dealer or distributor.
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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. 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 period from the date of first purchase, the unit will be repaired or replaced by
Avalon Acoustics or its authorized agent after receiving authorization from the factory or
dealer.
2. Purchaser must return the product, packaged in the original shipping carton, freight prepaid
to:
Avalon Acoustics
2800 Wilderness Place
Boulder, Colorado 80301
(303) 440-0422
3. Avalon Acoustics reserves the right to inspect any products which are the subject of
any warranty claim prior to repairing or replacing. Final determination of warranty
coverage lies solely with Avalon Acoustics. Any products which do not conform to this
warranty shall be repaired or replaced by Avalon Acoustics as soon as possible following
receipt of the product and claim, but in no event later than 30 days after receipt of the
product. Out-of-warranty claims will be billed for labor, materials, return freight, and
insurance as required. Any product for which a warranty claim is accepted will be
returned to the purchaser and cost of shipping and insurance will be factory prepaid
within the boundaries of the USA. Units to be shipped outside of the USA will be
shipped freight collect only. This warranty gives specific legal rights. The purchaser also
has implied warranty rights, and may also have other rights which vary from state to
state.
4. This warranty is extended to the purchaser and any purchaser from him for value.
5. Avalon Acoustics strives to manufacture the very finest possible equipment, and therefore
reserves the right to make changes in design and improvements upon its products, without
necessarily assuming an obligation to retrofit such changes upon its previously manufactured
models.
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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. Further, Avalon Acoustics shall in no event be obligated
for any incidental or consequential damages as a result of any defect or any warranty claim,
whether express or implied. Some states do not allow exclusion or limitation of incidental or
consequential damages or limitations on how long implied warranties last, so the above
limitations and exclusions may not apply to you.
7. Avalon Acoustics does not authorize any third party, including any dealer or sales
representative to assume any liability for Avalon Acoustics, or make any warranty for Avalon
Acoustics. The unit must not have been altered or improperly serviced or repaired. The serial
number on the unit must not have been altered or removed.
8. Warranty registration cards must be completed and mailed to Avalon Acoustics within
seven days of date of purchase; otherwise, this warranty is null and void. Avalon Acoustics
may, at its option, require from the purchaser valid proof of purchase (dated copy or
photocopy of dealer's original invoice).
9. If this product is used in a commercial or industrial application, then special warranty
exclusions may apply. Contact your dealer or Avalon Acoustics for commercial warranty
policies.
20
8 Room Acoustics and 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. In fact, a dedicated listening room usually requires additional sound
treatment, due to a lack of other items in the room that can help provide good acoustics.
However, a degree of attention to set-up can greatly increase your listening satisfaction, no
matter what your listening situation.
Listening in a properly set-up room can be a startling experience. Due to the limitations of the
two-channel format and the listening environment, the illusion of actually being transported to
the recording site cannot usually be achieved. However, an uncanny sense of realism can be
created. Perhaps it is best described as if the front half of your listening room has been
removed, so that it now opens out into the recording site.
To optimize your equipment set-up and the listening-room acoustics requires a basic
understanding of the principles which affect the propagation of sound in the room. Also, we
will discuss the way in which our brain interprets spatial cues, and how the room acoustics
can affect our sonic perceptions.
21
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. This is because there are
effectively two candles now illuminating that half of the room, the real candle, and the virtual
(or reflected) candle. The energy that had been sent to both sides of the room has now been
concentrated in one side only.
If we repeat the same experiment using a large piece of black cloth instead of a mirror, the
results will be somewhat different. The side of the room behind the cloth is darkened, just as
before, but the level of light on the side of the candle remains unchanged. This is because the
light is absorbed by the cloth, rather than being reflected back into the room.
Thus we can see that the energy can either be absorbed or reflected. A similar situation occurs
with sound waves, although we must account for the much greater wavelengths of audible
frequencies. Of course no material is a perfect absorber or an absolute reflector. Furthermore,
the sonic absorption coefficient of a given material usually varies with frequency.
Basic Room Acoustics
The great majority of all listening rooms are rectangular, with parallel surfaces. The walls and
ceiling are typically hard surfaces, which are acoustically reflective. These large areas are the
predominating factors in the overall room acoustics, although the other items in the room
(furnishings, carpeting, wall hangings, doorways, etc.) will also play a role. Without going
into excessive detail, there are four primary areas of potential concern:
•
1. Standing waves.
•
2. Flutter echo.
•
3. Early reflections.
•
4. Bass reinforcement.
The first three items are problems which should be reduced or eliminated. The last item, bass
reinforcement, needs to be matched to the entire system for proper tonal balance.
22
8.1 Standing Waves
The parallel surfaces of most listening rooms can lead to a potential problem in the low
frequencies. 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. This irregular distribution of sound level is caused by cancellation
and reinforcement between the reflected and direct sound waves.
At high frequencies, this pattern of high and low sound pressure levels within the room
becomes too finely spaced to be discerned. However, when the dimensions of the room are
comparable to the wavelengths of the musical notes, there will be obvious changes in the
intensity of certain bass notes in different locations within the room. Additionally, the
existence of the standing wave implies a resonant condition where acoustic energy is stored in
the room. This energy storage can result in "heavy", "muddy", or "slow" bass.
Since the presence of standing waves is caused by parallel reflective surfaces, practically
every listening room suffers from this problem to some degree. However, several factors are
working in our favor here. First, as the room size increases, the affected frequencies become
lower and thereby less audibly apparent. Second, the presence of shelving or furniture against
the walls will break up the large surfaces, reducing the magnitude of the problem. Third,
upholstered furniture can absorb a significant amount of bass, diminishing the build-up of
resonant energy. Fourth, typical wall construction is not completely reflective at low
frequencies.
However, in some cases audibly objectionable standing waves will still be present in the
listening room. This can be noted by large variations of the intensity of certain bass notes in
different areas of the room. Another indicator is an unevenness of loudness of different bass
notes. (This is sometimes what is actually on the recording, so be sure that this is consistently
a problem on a variety of recordings.)
If you wish to reduce or eliminate standing waves that may exist in your room, it will be
necessary to reduce the low-frequency reflectiveness of at least one of the parallel surfaces of
opposing surfaces. The most effective method is to use Tube-Traps, available from Acoustic
Sciences Corporation. This is the only commercially available sound treatment that absorbs
significant amounts of energy below 400 Hz. Experimentation will be needed to determine the
optimal locations.
23
8.2 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. The situation is analogous to standing between two parallel mirrors, when the
outline of your reflection becomes more difficult to discern, due to the additional reflected
images present.
Again, it is only necessary to reduce the reflectiveness of one of the surfaces in each pair of
surfaces to eliminate flutter echo. Since we are concerned with the high frequencies, any soft
material is appropriate. Drapery or fabric wall hangings are quite effective on the walls.
Bookshelves also work well by breaking up the flat surfaces. Carpeting should eliminate
potential problems between the floor and ceiling.
24
8.3 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. However, if the reflected sound arrives within
around 20 milliseconds of the direct sound, the ear/brain system integrates the two sounds so
that only one sound is heard. This integration is done in such a way that spatial information is
preserved, providing an acoustical "picture" of the physical space that created the reflections.
However, the source recording also contains ambient information that portrays the original
recording site. Early reflections in the listening room will tend to obscure the ambient
information in the recording, leading to a loss of dimensionality or spaciousness. Secondary
arrivals within the first 10 milliseconds are especially problematic, becoming less
troublesome as the arrival time lengthens to 20 milliseconds or so.
25
Avoiding Early Reflections
The speed of sound is approximately one foot (30 cm) per millisecond. Therefore, to preserve
the natural soundstage 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 8.1). This means that if the speaker or listener is placed
closer than about 5 feet to a wall or other surface, that surface should be covered with
sonically absorbent material.
Direct Sound
Reflected Sound
Figure 8.1 - The reflected sound must travel further than the direct sound, and
therefore reaches the listener at a later time.
26
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. Due to their complex structure, carpets and pads of natural materials, such as wool
and jute, will exhibit a more uniform absorption over the frequency spectrum than synthetic
materials will.
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 8.2).
Angle X
Angle Y
Reflected Sound
Direct Sound
Figure 8.2 The sound is reflected at the same angle that it struck the surface; i.e.,
Angle X = Angle Y. Since light waves obey this same rule, a mirror can be used to
find the point which can be acoustically damped to avoid early reflections.
27
8.4 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. However, when the path
length difference of the reflected wave is short relative to the wavelength of the sound, the
reflected wave is substantially in-phase with the original wave. When this condition is met,
the coupling coefficient between the speaker diaphragm and the air increases, and the
speaker efficiency increases. This changes the actual frequency response of the speaker,
and is not attributable to standing waves or other room resonances.
28
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. At frequencies above this level, the effect becomes less
significant and creates similar but smaller variations in output. Figures 8.3 and 8.4 illustrate
these concepts.
6
3
0
dB
-3
-6
10
20
50
100
200
500
Hz
Figure 8.3 - Change in frequency response resulting from placement of speaker 3.3
feet from a reflective surface (relative to an anechoic environment).
6
3
0
dB
-3
-6
10
20
50
100
200
500
Hz
Figure 8.4 - Same conditions as above, except speaker is 6.6 feet from the reflecting
surface. Note how the cancellation and reinforcement occur at lower frequencies.
29
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.
In order to take full advantage of bass reinforcement and to provide the most uniform and
extended bass response, it is recommended that the loudspeaker be placed between three and
seven feet from one of the walls (side or rear), and between five and fifteen feet from the
other wall. The measurements are made from the wall to the center of the 9" woofer cone.
The exact distances are not overly critical, although the two distances should not be within
about 33% of each other.
A good rule of thumb in establishing the lateral position of Opus Ceramic 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 from speaker to speaker is 10/18 (or about 55.5%) of room width.
30
8.5 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. This
means that at least one surface in an opposing pair of surfaces needs to be made less reflective
and/or non-parallel.
•
Low Frequency Absorption
If a problem exists with standing waves, it is the low frequencies that will need to be
addressed. Remember that the absorption spectrum of different materials and objects is not
uniform. That is, some items will absorb only high frequencies, and some objects may only
absorb the middle frequencies. At low frequencies, about the only common item that can
absorb a meaningful amount of energy is heavily upholstered furniture. Another effective
means of absorption is the use of Tube-Traps, from Acoustic Sciences Corporation.
•
High Frequency Absorption and Room Symmetry
Since flutter echo is a high-frequency effect, it becomes much easier to manage potential
problems in this area. Almost any item attached to the walls will be less reflective at high
frequencies than the bare walls themselves. Draperies, wall hangings, paintings, bookshelves
and other items will normally be present in the room, and will usually eliminate any possible
problems. If flutter echo is still audible, a fabric wall hanging provides an effective and
attractive cure.
Additionally, it is desirable to maintain a degree of left/right symmetry in the room to
preserve a balanced acoustic "space". For example, if your listening room has full length
draperies along the right wall, and the left wall is bare, slap echo will not be a problem.
Nonetheless, the sound-stage may be somewhat distorted, and it could be beneficial to place a
fabric hanging or tapestry on the wall opposite the draperies.
•
Parallel Surfaces
Although it is not generally possible to make the walls non-parallel, the same effect is
achieved by breaking up the large, flat surfaces with furniture and shelving.
31
Speaker Placement
Although your Avalon Acoustics loudspeakers may be placed in a wide variety of positions
relative to the walls of the room, it is still wise to experiment a bit to achieve optimal results.
The suggested minimum distances for the Opus Ceramic are 3 feet from one wall (side or
rear), and 5 feet from the other (all distances are measured to the center of the woofer cone).
This will provide the proper degree of bass reinforcement, as well as minimize early
reflections.
There is no suggested upper limit for the distances to the walls. Even a distance of 10 feet to
one wall and 15 feet to the other wall will provide suitable bass reinforcement, and problems
due to early reflections will be non-existent. However, regardless of the absolute numbers
used, the most even bass response will be attained if the distances from the side wall and the
rear wall are not overly similar.
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. In this way,
the area behind the listener will contain items that will reduce problems with standing waves
and/or flutter echo, while the zone around the speakers remains relatively free from reflective
objects.
If you wish to achieve an even more spacious sound-stage, it may be useful to place a
sonically absorbent material on the side and rear walls near the speakers. This can be
particularly effective at the points where the sound wave is directly reflected to the listening
position (a mirror can be used to determine these points, as illustrated in Fig. 8.2). As the
distance to the wall becomes smaller, the suppression of these reflections becomes more
important.
Early reflections will tend to diminish the soundstage in the direction of the reflections, i.e.
early reflections from the side walls tend to reduce sound-stage width, while early reflections
from the back wall will reduce image depth. We have found that a strong sense of depth
enhances the feeling of involvement when listening, due to the three-dimensional solidity of
images. Therefore, it is more important to have a greater distance from the speakers to the rear
wall than to the sides walls. Typically, this is easier to achieve if the speakers are placed along
the short wall of the listening room.
32
8.6 A Listening Room Example
In order to make these points more clear, an example of a room layout is given in Figure 8.5,
illustrating the principles we have given.
DRAPERIES
SHELVES
SPEAKER
EQUIPMENT
SHELVES
CHAIR
DESK
AMP
TABLE
AMP
SOFA
TABLE
SPEAKER
SOFA
TAPESTRY
Figure 8.5 - Example listening room. The area around the speakers is free of objects
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.
The area behind the listening position contains items which help break-up standing
waves and flutter echoes. Heavily upholstered sofas will help avoid low-frequency
standing waves, while a carpet absorbs early reflections from the floor.
33
9 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 speaker manufacturers. Specifically, we believe that the complete
absence of stored resonant energy is of paramount sonic importance. First, we will discuss
some of the technical aspects of bass reproduction and perception, and then explain how this
relates to the listening experience.
34
9.1 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.
This sensitivity to time-related information can be observed when listening to audiophiles
discussing the quality of a system's bass reproduction. Many of the terms refer to temporal
properties. A system with poor transient bass response is described as "boomy", "heavy",
"sluggish", or "slow". When the transient response is accurate, the bass is characterized as
"tight", "clean", "quick", or "fast".
"Fast Bass"
The term "fast bass" would seem to be an oxymoron on the surface. After all, it is the
"slowness" of a note that makes it a low frequency. Nonetheless, the term provides an
accurate description of our subjective impression. Many people have erroneously ascribed
"fast bass" to the use of a light diaphragm or the use of a powerful energizing system.1 In
fact, it is not how fast the 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" bass.
1
The acceleration of an object is equal to the force exerted upon it, divided by the mass of the
object. Since a loudspeaker is used above its fundamental resonance, it operates in what is known
as the mass-controlled region. In this region, high acceleration (large driving force and/or small
driven mass) does not imply extended high frequency response or fast transient response. Instead,
high acceleration confers high efficiency.
35
9.2 Rationale
There is an old saying, "There's no such thing as a free lunch." There are many trade-offs in
speaker design, as in almost any area one can think of. In this case, the trade off is between
transient response and anechoic frequency response (the speaker's frequency response in an
anechoic chamber). Almost all manufacturers have chosen to sacrifice transient response for
improved anechoic frequency response.
At Avalon Acoustics, we have chosen to pursue a goal of complete freedom from resonances
and stored energy to ensure transient accuracy. We feel that the resulting gain in areas not
traditionally measured results in audibly superior overall performance.
Anechoic vs. In-Room Frequency Response
It must be remembered that very little listening actually takes place in anechoic chambers.
Placement of the speakers in a real-world listening room will boost the bass response of the
speaker, as explained in Section 8, Room Acoustics and Speaker Position, beginning on page
21. Since a loudspeaker with perfectly flat anechoic frequency response will exhibit a
low-frequency boost in a normal listening environment, a loudspeaker with a gradual bass
roll-off (in an anechoic chamber) can exhibit more accurate in-room frequency response.
Avalon loudspeakers are carefully designed taking these factors into account. When placed in
a variety of representative positions in the room, Avalon loudspeakers will produce deep,
accurate, and unexaggerated bass response, with complete freedom from stored resonant
energy.
36
9.3 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. After all, the listener
is not concerned with how a piece of audio equipment measures, he is only concerned with
the faithful recreation of the original musical event.
On the other hand, measurement techniques that correspond to audible effects are an
invaluable tool to the designer. However, it is the degree of correlation with the subjective
experience which is important, and anechoic bass response does not have a high correlation
with musical accuracy in the listening room. In-room frequency response and transient
accuracy are both significant factors in determining subjective quality. Nevertheless, anechoic
frequency response is by far the most prevalent measurement used to characterize speakers.
A Correlation with Amplifier Measurements
A striking parallel exists in the measurement of audio amplifiers. The power output and
distortion of an amplifier is invariably measured into an eight-ohm resistor. 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 eight-ohm resistive load has developed as a standard because it somewhat
approximates a speaker load, is easily reproducible by different testing facilities, and it
represents something of a lowest common denominator. That is, while everybody recognizes
that a different load should be used for amplifier testing, nobody can agree as to what that
alternative should be.2
In the last decade, there has been a growing awareness of the importance of an amplifier's
capability to drive a real-world loudspeaker. This is the reason we have seen the emergence of
amplifiers with high current output capabilities, and a lack of current-limiting or similar
protection circuitry. The ability to drive reactive loads has been accepted as having a higher
correlation with audible qualities than the traditional measurement into a load resistor.
2
The cynic will also note that a resistive test load produces the most impressive measurements for
use in advertisements.
37
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.
There is a developing appreciation that this traditionally performed measurement is not an
accurate predictor of the performance actually attained in the listener's room. Certainly,
in-room frequency response is more important than anechoic response in determining a
speaker's tonal accuracy. Placement of the speaker within a room will cause changes in the
frequency response compared to the anechoic condition.4 At lower frequencies, the speaker's
output is modified by the acoustic loading presented by the walls and floor. However, when
making measurements, it is difficult to separate the effects of a room's bass reinforcement
from standing waves and other resonances associated with that room.
3
Since an anechoic chamber which performs accurately to low frequencies is extremely large and
expensive, other measurement methods are also commonly used. These include near-field
measurements, when the microphone is extremely close to the driver, and half-space
measurements, when the speaker under test is buried with its front baffle flush with the ground,
facing upwards. Both of these methods are equivalent to anechoic measurements below the
frequency at which the speaker baffle appreciably changes the acoustic load to the woofer,
typically between 100 and 200 Hz. Note that these conditions are also non-representative of an
actual listening situation.
4
Since this discussion is concerned with the reproduction of low frequencies, we will not delve
deeply into the high-frequency variations between the anechoic response and the in-room response
of a loudspeaker. 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.
38
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. In this way, a composite picture
can be created of a wide variety of rooms and speaker locations. This enables one to design
the speaker so that it interfaces properly with the listening environment and provides correct
bass response in real-world environments.
The accuracy of the computer model must also be tested in the physical world, using pink
noise, warble tones, and time-delay spectrometry for verification. The final, and most
important check, is the listening test. Theory and measurements become useless if they do not
agree with what our ears tell us. Even the best measurement methods provide little more than
a simplified, one-dimensional translation of what is, in reality, an extremely complex,
multi-dimensional experience. Again, the goal is the recreation of a musical event, and the
faithfulness of that recreation can only be determined through listening.
39
Frequency Response Effects
As you listen to music, images of the instruments that created the sounds are elicited. For
instance, one can tell the approximate size of a drum from the sound it produces. On a
high-resolution playback system, finer details can be heard; i.e., is the head made of plastic or
calfskin? Is the player using light sticks or heavy ones?
A relatively broad-band emphasis (or de-emphasis) of a given frequency range can tend to
exaggerate (or diminish) the relative size of the instruments playing in that range. A useful
tool for evaluating these distortions of size is a recording of a small group of unamplified
acoustic instruments made with a simple microphone set-up.
Listening for Size Distortions
Play a recording of this type, with the volume adjusted to achieve a natural playback level. As
you listen, create a mental image of the players based on sounds being recreated. Then ask
yourself, "Does this sonic image correspond to the musical instruments that generated these
sounds?"
Is the portrait a natural one, or are certain elements distorted? Does a stand-up bass sound like
the correct size, or is it exaggerated, sounding like it is ten feet tall, or as if the strings are the
size of ropes? 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.
40
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. Try playing a rock or jazz group, and listen to the
interplay between the drummer and the bassist. Is it easy to distinguish the kick drum from the
bass, or is there a blurring of low-frequency detail caused by the speaker's time-smear?
To listen for narrow-band low frequency resonances, use a recording with the bass line played
by a synthesizer. As you listen to the bass line, are the individual notes of equal level, or are
some of them more prominent than others? Electronic instruments can be more useful for this
test since acoustic instruments have resonances of their own which can hide flaws in the
speaker, unless you are intimately familiar with the instrument and the recording. Similarly,
an electric bass that has been recorded by miking its speaker/amplifier will exhibit the
resonances of its speakers, which are inevitably considerable, masking defects in the
loudspeaker under evaluation.5
5
There is a technique known as "direct injection" where the signal from an electric instrument is
connected directly from the amplifier to the recording console, bypassing the speakers. In this
instance, an electric bass will prove to be a consistent low-frequency source. The difference
between direct injection and miking of the speaker/amplifier is easily audible with high-quality
speakers.
41
9.4 Conclusion
Most loudspeakers have been designed to perform well in the frequency domain when
measured in an anechoic test chamber. We have seen how this design paradigm produces
audible bass distortion and exaggeration. While these exaggerations may sometimes seem
impressive in the short term, they quickly prove to be distracting from the musical intentions
of the composer. At Avalon Acoustics, we design all of our speakers to minimize resonance
and stored energy, thereby ensuring transient accuracy. As you listen to music on Avalon
Acoustics loudspeakers, your enjoyment of the music will grow as you hear the full measure
of low-frequency detail, without exaggeration, and come close to the heart of the artist's
intent.
42
10 Features
•
Advanced ultra-light weight ceramic driver diaphragm materials minimize energy
storage and time-domain distortion.
•
Each driver individually tested and matched for optimum performance.
•
Smooth, wide polar response for superlative imaging capabilities.
•
Moderate impedance characteristic allows for ideal interface with any amplifier.
•
Star-grounding techniques eliminate signal modulation.
•
Crossover circuitry is hard-wired with surface-only conductors, eliminating
deleterious sonic effects of printed-circuit boards.
•
Oversize screw terminals.
•
Careful crossover control of all magnetic field interaction.
•
Polypropylene capacitors used exclusively to minimize energy storage.
•
Proprietary damping circuits control each driver's electrical parameters, reducing
interaction with the amplifier.
•
Constrained-mode damping system absorbs cabinet vibrations.
•
Four inch thick front panel supplies acoustically inert wave-launch platform.
•
Acoustically-engineered grille assembly decreases edge diffraction effects.
•
Distinctive faceted cabinet design provides optimal polar characteristics.
43
11 Specifications
Driver Complement
1" concave ceramic dome tweeter
3 1/2" concave ceramic dome midrange
9" concave ceramic dome woofer
Sensitivity
87 dB (2.83V, 1 meter)
Impedance
5 ohms nominal (4.5 ohms minimum)
Frequency Response
28Hz to 24kHz (+/- 1.5 dB, anechoic)
Recommended Amplifier Power
30 to 300 watts
Wiring Methods
Two position terminal block, designed to
accept spade lugs for #10 screws
Dimensions
41" high (104 cm)
10" wide (26 cm)
16" deep (41 cm)
Weight
95 pounds each (43 kg each)
44
12 Notes
45
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