Avalon Acoustics Eclipse Owners manual

Eclipse

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

3.1 Wiring Options ....................................................... ..... ..... ..... ..... ..... ...................11

3.2 Connecting the Speaker to the Amplifier......................................................... ..... ....12

Standard Wiring........... ..... ..... ..... ..... ..... ..... ...................................................13

Bi-wiring ..... ..... ..... ..... ..... ............................................................................14

3.3 Multiple Amplifiers ................................................................................... ..... .....15

Bi-amplification............................................................................................15

4 Break-in Period. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . . . . . . . . . 16

5 Maximizing Performance. .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . . . . . . . . . 17

Break-in ...................................................................... ..... ..... ..... ..... ..... ..... ..17

Bi-wiring ..... ..... ..... ..... ..... ............................................................................17

Tweeter Screens........... ..... ..... ..... ..... ..... ..... ...................................................17

Grille Assemblies.................................................................................. ..... ...17

Speaker Placement and Symmetry........................................................ ..... ..... ..18

Toe-In........................ ..... ..... ..... ..... ..... ........................................................18

Apex‘ Couplers ..........................................................................................18

First Reflection Points................. ..... ..... ..... ..... ..... ..... .....................................19

Corner Treatment................... ..... ..... ..... ..... ..... ..... .........................................19

6 Care of Your Avalon Loudspeakers . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . 20

Cabinet (Hardwood Finish) ......................... ..... ..... ..... ..... ..... ...........................20

Cabinet (Black Textured Finish) .... ..... ..... ..... ..... ..............................................20

Grille Assembly........................................ ..... ..... ..... ..... ..... ...........................20

Drivers......................................................... ..... ..... ..... ..... ..... ......................20

7 Warranty . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . . . . . . . . . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. 21

In the Event of a Problem ........ ..... ..... ..... ..... ..... ..... .........................................21

Warranty Statement.......................................................................................22

8 Room Acoustics and Speaker Position . . . .. . . .. . . .. . . .. . . .. . . .. . . . . . . . . . . . . .. . . .. . . .. . . .. . . .. . . .. 24

Introduction .................................................................................................24

An Optical Analogy.......................................................................................25

Basic Room Acoustics ...................................................................................25

8.1 Standing Waves ..................................................................................................26

8.2 Flutter Echo ............... ..... ..... ..... ..... ..... ..... ..........................................................27

8.3 Early Reflections.............. ..... ..... ..... ..... ..... ..... .....................................................28

8.3 Avoiding Early Reflections .............................................. ..... ..... ..... ..... ..... ............29

8.4 Bass reinforcement ....................................................... ..... ..... ..... ..... ..... ..............31

8.5 Summary of Recommendations...................................................... ..... ..... ..... ..... ....34

Flutter Echo and Standing Waves.....................................................................34

Speaker Placement ...................... ..... ..... ..... ..... ..... ..... ....................................35

Early Reflections .............. ..... ..... ..... ..... ..... ..... ..............................................35

8.6 A Listening Room Example ............................................................... ..... ..... ..... ....36

9 Accuracy of Bass Reproduction. . . .. . . .. . . .. . . .. . . .. . . .. . . . . . . . . . . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. 37

Introduction .................................................................................................37

9.1 Sensitivity to Time-Related Information ................................ ..... ..... ..... ..... ..... .........38

"Fast Bass" ..... .............................................................................................38

9.2 Low Frequency Energy Storage .......................................................... ..... ..... ..... ....39

An Illustrative Analogy ............................................. ..... ..... ..... ..... ..... ............39

9.3 Sealed Enclosures ....... ..... ..... ..... ..... ..... ..... ..........................................................40

Another Definition of the Q Factor . ..................................................................42

Frequency Response Effects..... ..... ..... ..... ........................................................43

9.4 Vented Enclosures...............................................................................................44

The Helmholtz Resonator ................................................................... ..... ..... ..45

A Comparison of Vented and Sealed Enclosures ................................ ..... ..... ..... ..46

9.5 Passive Radiators .......................................... ..... ..... ..... ..... ..... .............................48

9.6 Dipole Radiators ...... ..... ..... ..... ..... .......................................................................49

9.7 Servo-Systems and Electronic Equalization..............................................................50

9.8 Rationale ................................................................................... ..... ..... ..... ..... ....51

Anechoic Frequency Response vs. In-Room Frequency Response ..........................51

9.9 Measurements of Audio Equipment ...... ..................................................................52

A Correlation with Amplifier Measurements .... ..... ..... ..... ...................................52

Loudspeaker Measurements .............................................. ..... ..... ..... ..... ..... .....53

Designing for Accurate Bass Reproduction ..... ...................................................54

9.10 Listening Qualities..... ..... ..... ..... ..... ..... ...............................................................55

Frequency Response Effects..... ..... ..... ..... ........................................................56

Listening for Size Distortions ..................................................... ..... ..... ..... ..... .56

Transient Response Effects .............................................................................57

9.11 Audibility of Resonances ....................................................... ..... ..... ..... ..... ..... ....58

Frequency Ranges of Musical Instruments ........................................................ .58

The Woofer As a Spurious Musical Instrument ................................................ ...59

Enlarging the Bass Drum.... ..... ..... ..... .............................................................60

Identifying Size Distortions..................................................................... ..... ...61

Visualizing the Sound Source.......................................... ..... ..... ..... ..... ..... .......61

9.12 Conclusion ............... ..... ..... ..... ..... ..... ..... ..........................................................62

10 Features . . . . . . . . . . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. 63

11 Specifications . . . . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. 64

12 Notes . .. . . . . . . . . . . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. 65

1 Introduction

Your new Avalon Acoustics Eclipse loudspeakers represent a true breakthrough in the
development of moving-coil loudspeakers intended for accurate music reproduction. Upon
initial listening, the immediacy and presence of a live performance becomes instantly
apparent. The intent is to closely reproduce the original musical event, as opposed to creating
a "spectacular" sonic character which can impress upon first listening, but fail to satisfy over a
long period of time.

The Eclipse accomplishes this goal by providing the transparency and clarity which is lacking
in many dynamic designs. Overall smoothness is achieved without depressing the
high-frequency response, a technique used in some products. Low frequencies are rendered
realistically and controlled, as opposed to a "larger than life" perspective, which can impress,
but compromises definition and harmonic integrity.

This high level of performance is retained in virtually any listening situation. The Eclipse has
been specifically designed to elicit the finest possible performance from any amplifier, tube or
solid-state, due to its easy-to-drive nature. Similarly, interaction with the room has been
minimized, allowing ease of placement in a wide variety of listening environments.

Your Eclipse loudspeaker was designed and built to the highest standards of workmanship
and performance. These standards are preserved through the test of time by careful attention
to component quality and meticulous testing of each unit before leaving the factory. As a new
owner of this Avalon Acoustics product, you can be assured that you possess one of the few
great loudspeakers the audio industry has to offer.

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 for Black Textured finished loudspeakers contains a set of replacement
grille pins. The accessory bag for Hardwood finished loudspeakers contains replacement
grille pins, a small bottle of furniture polish, and two lint-free polishing cloths.

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.

Figure 2.1 - To unpack the speakers.

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.

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 opening is
beveled on the side that faces the listener (away from the speaker).

1.

Remove screws
and panel from
top of crate.

3.

Push grille pins straight
into grille pin sockets.

2.

Pull grilles
straight out.

Figure 2.2 - To install the grille assemblies.

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.

3. Insert the new grille pin in the grille pin installation tool (see figure 2.5).

4. Carefully pull
the grille cloth away
from the frame
mounting hole. The
mounting hole must be
clear of all obstacles
during pin installation.

Figure 2.4 - Removal

of broken grille pin. Check for pin fragments in the mounting hole.

Figure 2.5 - Insertion of new grille pin into
installation tool.

5. Place the exposed end of the grille pin in the open mounting hole. The end of the pin

is notched at a 45 degree angle to match the contour of the grille frame; therefore it is
necessary to rotate the grille pin to align it with the angle on the frame. 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.

6.
Repositio

n the grille cloth
that was pulled
away from the
frame mounting
hole in step 4. The
cloth should lay
flat and wrinkle­free.

Figure 2.6 - Installing grille pin into Eclipse grille
frame. The grille pin is notched and must be oriented
to match the 45 degree contour of the frame. Note
that after installation, the grille pin flange is flush with
the surface of the grille.

3 Wiring Instructions

Introduction

The crossover is housed in a sealed chamber in the bottom of the speaker cabinet, to minimize
the effect of vibration on the components. The Eclipse 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.

Do NOT over-tighten the screws.

3.1 Wiring Options

Separate inputs are available for each crossover section, facilitating bi-wiring. Bi-wiring the
Eclipse separates the ground returns for the drivers. This reduces the possibility of inter-driver
modulation, and can result in a higher level of sound quality. Bi-wiring is highly
recommended as a cost-effective means to better sonics. All that is needed is one extra pair of
speaker cables. You should choose a wiring option before connecting the speakers.

3.2 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, as described below.

Do NOT over-tighten the screws.

3. Stand the speakers up.

Standard Wiring

(a single cable from the amplifier to each speaker)

Leave the factory-installed input jumper wires in place. Connect the wires from the amplifier
to the "Low" inputs. Please refer to Figure 3.1.

Figure 3.1 - Bottom view of the speaker showing the
connections from the amplifier for standard (single) wiring.

Bi-wiring

(two cables from the amplifier to each speaker, one for the woofer, the other for the
tweeter)

Remove the factory-installed input jumper wires. Then connect one set of cables from the
amplifier to the "LOW" inputs and the other set of cables to the "HIGH" inputs. Both sets of
cables are attached in parallel to the amplifier terminals. See Figure 3.2.

Figure 3.2 - Bottom view of the speaker showing the
connections from the amplifier for bi-wiring. The speaker
cables are connected in parallel at the amplifier terminals.
The input jumper wires have been removed.

3.3 Multiple Amplifiers

It is possible to use more than one amplifier to drive each speaker. Doing so may result in a
slight additional sonic benefit over bi-wiring, as the inter-driver modulation due to the
amplifier's finite output impedance is eliminated. All amplifiers are driven with a full-range
signal from the pre-amplifier, and the frequency division is performed by the passive
crossover.

It is important to use identical amplifiers when bi-amping. If this is not possible, then the
gains of the amplifiers must be adjustable and matched within 0.1 dB. Mismatched gain levels
can significantly alter the tonal balance of the Eclipse and lead to poor sound quality. It is also
important to be aware of the absolute polarity of the amplifiers. If any of the amplifiers invert
phase, be sure to compensate by reversing the polarity of the speaker leads at the amplifier's
output terminals.

Bi-amplification

Follow the instructions for bi-wiring (above), except connect the speaker cables to separate
amplifiers. The amplifiers are driven with the full-range signal from the pre-amplifier. If your
pre-amplifier only has one set of output jacks, use a "Y" connector to tie the inputs of the
amplifiers in parallel.

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 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.

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 16). 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.

Bi-wiring

Bi-wiring of the Eclipse is strongly recommended. The sonic benefits include increased bass
articulation, midrange definition, image solidity, and ambient information retrieval. Please
refer to page 14 (Tri-wiring) for further information.

Tweeter Screens

The tweeters are equipped with a screen to protect the fragile titanium dome. The screens
slightly reduce (1-2 dB) the tweeters' maximum diffusion characteristics above 10,000 Hz.
They are held in place by the magnet of the tweeter, and may be removed if your system
requires additional energy in the highest octave.

WARNING: The titanium domes are thinner than a human hair and are easily
damaged. Remove the screens at your own risk.

To remove the screens, firmly grasp their tapered sides with the thumb and forefinger, and
carefully pull the screen straight out. It is recommended that they be replaced if the speakers
are to be transported. When replacing the screens, be sure to hold them securely, as the
magnetic attraction from the tweeter will tend to pull them from your hand, which can
damage the dome.

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.

WARNING: Be extremely cautious positioning the felt in the tweeter area,
especially if you have removed the tweeter screens.

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 24):

•

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.

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.

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 28, 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.

6 Care of Your Avalon 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.

Cabinet (Black Textured Finish)

The Black Textured finish is an extremely durable high -tech coating. However, due to its
textured surface, it requires different care procedures than other finishes. For normal dusting,
a lint-free cloth or feather duster should be adequate.

Should the loudspeakers become soiled, moisten a lint-free cloth with lukewarm water, and
clean the surface with a circular rubbing motion. If this proves insufficient for an oily or
greasy stain, it may be necessary to use a dilute mild soap. This should be applied to a damp,
lint-free cloth using a circular rubbing motion to clean the stain.

IMPORTANT: Do NOT use cleaners that contain ammonia, strong solvents, or
abrasive materials. Use of these materials can degrade, scratch, or even
DESTROY the finish.

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 and tweeter) require no regular maintenance. Do not attempt to clean the
tweeter dome, as it is easily damaged. If desired, you may remove dust from the woofer cone
by using a small, soft dusting brush.

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.

Warranty Statement

1. Avalon Acoustics warrants the materials, workmanship, and proper functioning of this

product for a period 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
[phone]

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.

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.

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.

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.

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.

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.

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.

8.3 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 five feet to a wall or other surface, that surface should be covered with
sonically absorbent material.

Figure 8.1 - The reflected sound must travel further than the direct sound, and
therefore reaches the listener at a later time.

Since the floor is within five 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).

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.

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.

By selecting the distance from the speaker to the reflective surface, we can determine the
frequency at which the bass reinforcement takes effect. Please see Figures 8.3 and 8.4.
Furthermore, 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
additional bass reinforcement.

Figure 8.3 - Change in frequency response resulting from placement of speaker 3.3
from a reflective surface (relative to an anechoic environment).

Figure 8.4 - Same conditions as above, except speaker is 6.6 feet from the reflecting
surface. Note how the reinforcement now occurs at a lower frequency.

By properly selecting the distances to each surface, we can extend the in-room bass response
of the speaker much deeper than its anechoic response. Please see Figure 8.5. This is because
the bass reinforcement provides a boost which is complementary to the bass roll-off that
would be present in an anechoic chamber.

Conversely, improper placement of the loudspeakers can result in uneven frequency response.
This results in diminished bass quality. Please refer to Figure 8.6.

Figure 8.5 - Anechoic response of the Avalon Acoustics Eclipse, and in-room
response with the speaker placed 4.6 feet from the rear wall, and 3.0 feet from the
side wall. Note how the bass response is extended by the room reinforcement.

Figure 8.6 - Uneven frequency response caused by improper placement of the
speakers. In this case, the speaker is 2.0 feet from both the side and rear walls.

In order to take full advantage of the bass reinforcement to provide the most uniform and
extended bass response, the anechoic response of the speaker must be known. The Eclipse is
designed so that proper bass reinforcement occurs when the speaker is placed between two
and five feet from one of the walls (side or rear), and between four and ten feet from the other
wall.

The measurements are made from the wall to the center of woofer cone. The exact distances
are not overly critical, although the two distances should not be within about 33% of each
other. For example, if the distance to the side wall is three feet, then the distance to the rear
wall should be at least four feet. Some examples of typical placements are given in Figures

8.5, 8.7, and 8.8.

Figure 8.7 - In-room response of Avalon Acoustics Eclipse when the speaker is
placed 2.3 feet from the side wall, and 3.9 feet from the rear wall.

Figure 8.8 - In-room response of Avalon Acoustics Eclipse when the speaker is
placed 3.6 feet from the side wall, and 6.6 feet from the rear wall.

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.

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 Eclipse are two feet from one wall (side or rear),
and four 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.

The suggested maximum distances for the Eclipse are five feet from one wall (side or rear),
and ten feet from the other. As the distance from the speaker to the nearby walls increases,
early reflections become less of a problem, and the sound-stage becomes more spacious.
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.

8.6 A Listening Room Example

In order to make these points more clear, an example of a room layout is given in Figure 8.9,
illustrating the principles we have given.

Figure 8.9 - 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.

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.

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.

9.2 Low Frequency Energy Storage

Avalon Acoustics loudspeakers use the only practical bass loading system that results in the
complete absence of low frequency energy storage.2 This is a sealed enclosure with a Q
factor equal to 0.5.3 When this condition is met, there is no stored resonant energy in the
system. All other low -frequency loading systems (including sealed enclosures with a Q

factor greater than 0.5, vented enclosures, and planar speakers without enclosures)
deliberately add a low-frequency resonance to improve frequency response in an
anechoic chamber. However, a resonance is, by definition, due to energy storage. The

resulting time-related distortion is almost invariably audible.

An Illustrative Analogy

In order to more clearly understand the concept of stored resonant energy, consider the case of
an analog voltmeter. The meter might have a movement that moves freely, or it could have
some damping present, for example, in the form of silicone -damped bearings. The Q factor
refers to the amount of damping (mechanical resistance) present in the system.

Let us examine the behavior of the meter when it is connected to a battery. If the meter is
underdamped (Q factor greater than 0.5), the meter needle would swing past the correct
voltage of the battery and tend to fluctuate before settling down at the proper value. If the
meter is overdamped (Q factor less than 0.5), the meter would be slow to respond and take a
relatively long time to reach the final reading. If the meter is critically damped (Q factor equal
to 0.5), the needle would quickly reach the correct reading with essentially no overshoot.

2

A properly designed horn-loaded system can be free of energy storage effects, but will be
impractically large for extended bass response. Transmission-line designs can theoretically operate
as an infinite-baffle (infinitely large sealed enclosure), although no experimental analysis exists to
support this claim. All commercially available transmission-line designs are made to practical size
considerations and appear to operate as damped bass-reflex (vented) systems. In either instance,
the absence of low-frequency energy storage is not assured.

3

This refers to the condition when a damped resonant system has a damping coefficient exactly
equal to the square root of the quantity four times the moving mass times the suspension stiffness.
Due to a proprietary damping network in the Ascent crossover, this Q factor is maintained
regardless of the driving source impedance. This negates the effect of amplifier damping factor
and speaker cable resistance on the bass quality of the Ascent.

9.3 Sealed Enclosures

An analogous situation occurs with sealed-enclosure loudspeakers. Please refer to Figures 9.1
through 9.5. This shows the resultant sound pressure level versus time when various sealed
enclosure systems are subjected to a step (pulse) input. All of the systems display a similar
behavior in the initial phase of the pulse, but it is when the input signal has reached a steady
state that the differences may be seen. The system with Q = 0.5 undershoots the zero level
slightly, and then immediately returns to zero. As the Q factor is increased, the transient
response becomes worse, and the system exhibits increased oscillatory behavior (ringing).

Figure 9.1 - Transient response of a sealed enclosure loudspeaker with Q=0.5 when
subjected to a step pulse. After the signal undershoots the baseline, it returns to zero
with an exponential decay. This represents perfect transient performance.

Figure 9.2 - Transient response of a sealed enclosure loudspeaker with Q=0.7 when
subjected to a step-pulse. Note the greater amount of undershoot, caused by the cone
motion continuing after the input has become static. Although difficult to discern on
this plot, the pressure again rises above zero after the initial undershoot.

For a Q factor of 0.7, the system appears to have a well-behaved transient behavior. However,
the system now exhibits a damped oscillation at a defined frequency, which can be clearly

Figure 9.3 - Transient response of a sealed enclosure loudspeaker with Q=1.0 when
subjected to a step-pulse. The increasing Q factor indicates that there is insufficient
damping to control the cone's motion after the input signal has become static.

Figure 9.4 - Transient response of a sealed enclosure loudspeaker with Q=1.4 when
subjected to a step-pulse. A further decrease in damping results in greater amounts
of stored energy being released after the initial transient input.

Figure 9.5 - Transient response of a sealed enclosure loudspeaker with Q=2.0 when
subjected to a step-pulse. This small amount of damping allows the cone to oscillate
at the woofer's resonant frequency for many cycles.

seen when the vertical scale is magnified (Figures 9.6-9.8). This is one form of a time-related
distortion. In this instance, the woofer contains stored resonant energy and the cone continues
to oscillate after the input signal has become static. Almost all commercially available sealed
enclosure systems have a Q factor between 0.7 and 1.0.

Another Definition of the Q Factor

Figure 9.6 - Transient response of a sealed enclosure loudspeaker with Q=0.7 when
subjected to a step pulse.

Figure 9.7 - Same as above figure, except the vertical scale has been magnified 100
times (40 dB) to more clearly show the transient overshoot.

Figure 9.8 - Same as above figure, except the vertical scale has again been magnified
100 times (40 dB) to show continued ringing.

An alternate interpretation (not mathematically precise, but nonetheless helpful) of the Q
factor is to regard it as approximately the number of cycles that the system will ring after it
has been excited by a transient. For example, a dipole woofer with a Q = 4 will oscillate for
roughly four complete cycles before the speaker's damping stops the motion. A speaker with a
Q = 0.7 will oscillate for most of a cycle, giving the ear enough information to determine a
tone associated with the resonance. When the Q factor drops to 0.5 or less, there is no tone
identified with the speaker's resonance, as one-half of a cycle does not determine a frequency.

Frequency Response Effects

Figure 9.9 shows the anechoic frequency responses of sealed enclosures with different Q
factors. The system with a Q factor of 0.5 produces relatively less bass near the system
resonance than those systems with higher Q factors. Conversely, the situation is more clearly
seen from the opposite point of view. That is, if a Q factor of 0.5 represents perfect transient
response, then what is the magnitude of error created by a higher Q factor? One can examine
the graph and see that a system with a Q factor of 0.7 produces 3 dB of additional output at
resonance, while a Q factor of 1.0 produces 6 dB extra output. A resonant peak of 3 to 6 dB in
the midrange of a speaker would be justifiably criticized, but it is traditionally (and we believe
incorrectly) accepted in the bass response of most speakers. To sum up, increasing the Q
factor above 0.5 increases the magnitude of the bass response at the expense of decreased
transient performance.

Figure 9.9 - Frequency response characteristics of sealed enclosure systems with the
following Q factors (top to bottom): Q=2.0, Q=1.4, Q=1.0, Q=0.7, and Q=0.5. At
resonance, each curve is 3 dB from its neighbor.

9.4 Vented Enclosures

For comparison, the frequency response and the transient response of two popular
vented-system alignments are shown in Figures 9.10 through 9.12. The most commonly used
vented alignment is B4 (fourth order Butterworth). The QB3 (third order quasi-Butterworth)
alignment is often touted as possessing superior transient response. While better than the B4
alignment, its transient behavior is poorer than typical sealed enclosures, even those with
relatively high Q factors.

Figure 9.10 - Frequency response of vented enclosure loudspeakers.

Figure 9.11 - Transient response of a vented enclosure loudspeaker with B4 tuning
when subjected to a step-pulse. Although a Q factor cannot be assigned to vented
systems, the transient response is similar to a sealed system with Q=1.4.

Figure 9.12 - Transient response of a vented enclosure loudspeaker with a QB3
tuning when subjected to a step-pulse. This transient behavior is similar to a sealed
system with Q=1.1.

The Helmholtz Resonator

The source of this transient ringing is the vented enclosure acting as resonant cavity,
technically referred to as a Helmholtz resonator. Another example of a Helmholtz resonator is
an empty soda-pop bottle, which produces a tone when one blows across the opening. The
resonant frequency of the soda-pop bottle is determined by the mass of the air in the mouth of
the bottle and the compliance of the air "spring" in the body of the bottle.

In the case of the vented loudspeaker, the resonant frequency of the enclosure is determined
by the mass of the air in the vent (port), and the compliance of the air enclosed by the cabinet.
It is at this frequency that the vent contributes its maximum output.

A Comparison of Vented and Sealed Enclosures

In approximate terms, the vented enclosure is tuned so that it resonates (and increases the
system output) at the point where the output from the woofer would be falling off if the
enclosure were sealed. This is demonstrated in Figure 9.13, which compares the anechoic
frequency response of a woofer mounted in a vented enclosure to the same driver in a sealed
enclosure of the same volume. The vented enclosure is tuned to a fourth-order Butterworth
response. The sealed enclosure is identical except for the lack of the vent, which results in a Q
factor of 0.57.

4

4

It should be noted that closing the vent of a vented enclosure does not automatically result in a Q
factor of 0.57. This is only true for the case of the B4 tuning, which is achieved only with one
specific set of woofer and enclosure parameters.

Figure 9.13 - Frequency response characteristics of a vented enclosure loudspeaker
with a B4 tuning, and the same system except with the vent blocked, creating a
sealed system. Note that while the presence of the vent increases the system output
in the vicinity of the enclosure resonance, it decreases the system output at lower
frequencies.

The vented enclosure has greater output at the enclosure resonance, but below the enclosure
resonance, the vent output becomes out of phase to the woofer output, and reduces the total
output below that for the sealed enclosure.5 Furthermore, the presence of the vent severely
degrades the transient performance. This is shown in Figure 9.14. The designer of a vented
enclosure is clearly seen to be trading improved anechoic frequency response for inferior
transient response.

5

Sometimes speaker measurements of vented designs are given showing the contributions from the
woofer cone and the vent separately on the same graph. However, these fail to take into account
the phase difference between these two sources, and are therefore inaccurate and misleading.

Figure 9.14 - Transient response comparison between vented enclosure loudspeaker
with B4 tuning and same system with the vent blocked, thereby creating a sealed
system. The stored energy needed to create the resonance of the vented system is
released after the initial transient has passed.

9.5 Passive Radiators

The passive radiator (also known as a drone cone, auxiliary bass radiator, fluid-coupled
subwoofer, etc.) operates in very nearly the same manner as the vented enclosure. In this case,
the mass of the passive radiator replaces the mass of the air in the vent. The major difference
is a sharpening of the low-frequency corner of the frequency response curve, caused by the
additional element of the passive radiator's suspension compliance. This results in even
greater overshoot and ringing compared to the equivalent vented enclosure. However, there
are benefits to be gained relative to vented enclosures, especially the reduction of turbulent
wind noise which can exist in vents.

9.6 Dipole Radiators

Normally the low frequency response of a dipole radiator (panel or planar-type speaker) falls
off at 6 dB per octave, due to increasing cancellation from the anti-phase rear wave. The
frequency at which the cancellation begins to occur is dependent upon the physical
dimensions of the baffle, and is between 100 and 200 Hz for typical commercially available
systems. To compensate for this roll-off, virtually all manufacturers design the diaphragm to
have a low-frequency mechanical resonance, often using distributed or staggered multiple
resonances. The resonance of the diaphragm boosts the system output where it would
otherwise be reduced due to cancellation from the rear wave. A Q factor between 2 and 5 is
typically required to achieve the necessary correction and represents a significant amount of
energy storage and attendant transient inaccuracy.

9.7 Servo-Systems and Electronic Equalization

Although not achieving widespread acceptance, there always seems to be at least one
servo-controlled or electronically equalized woofer system available on the market. These
types of systems do not provide miracle cures for the maladies of bass reproduction; rather,
they are alternative design concepts, with their own set of advantages and disadvantages.

The main benefit of both techniques is that, for a given frequency response, a smaller
enclosure can be used than would otherwise be needed. This comes at the expense of
requiring greater amplifier power, that is, a lower effective efficiency of the woofer. This can
be a valid design choice in certain situations, although in many cases cone excursion or
thermal dissipation becomes the limiting factor in achieving extended bass response.

The servo-controlled system also has the capability to correct for non-linearities in the
low-frequency driver itself. At Avalon Acoustics, we believe that the superior approach is to
use a well designed driver that needs no correction, just as a well-designed amplifier can be
built with no negative feedback.

Concerning transient response, there is no advantage to using either of these systems
compared to a non-equalized system. This is because the transient response merely describes
an alternative view of the frequency response. In other words, by utilizing a servo-controller
adjusted to obtain the perfect transient response of a sealed enclosure with a Q factor of 0.5,
the frequency response will necessarily be the same for both systems, regardless of how that
response is attained. Although these electronic methods allow for easier adjustment of the
system parameters, most systems are designed for impressive anechoic frequency response at
the expense of accurate transient response.

9.8 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. Although this results in a slight sacrifice in
one traditionally measured area, we feel that the resulting gain in areas not traditionally
measured results in audibly superior overall performance.

Anechoic Frequency Response 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

24. 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.

9.9 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.

6

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.

6

The cynic will also note that a resistive test load produces the most impressive measurements for
use in advertisements.

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.7 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.8 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.

7

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.

8

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.

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.

9.10 Listening Qualities

We have seen how many speaker systems store resonant bass energy, resulting in ringing and
poor transient accuracy. We have also seen that a sealed enclosure with a Q factor of 0.5 can
yield complete freedom from energy storage effects, as well as provide more accurate in-room
frequency response. 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.9 Nevertheless, for the purposes of this discussion, we will treat
these two topics separately as much as is possible.

9

Below about 200 Hz, virtually every woofer operates as a minimum-phase device. This means that
the responses in the time-domain and the frequency-domain are inextricably linked, and that the
one generates the other. Thus, two woofers with the same frequency response will necessarily
exhibit the same time (phase) response. However, many crossover networks display non-minimum
phase response, and will thereby alter the phase response of the woofer in the speaker system.

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.

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.

10

10

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.

9.11 Audibility of Resonances

The other factor to bear in mind when performing listening tests is the frequency range of a
speaker's resonance. The audibility of the resonance is greatly influenced by the part of the
spectrum in which it lies.

Certainly the time-related distortions associated with a resonance will obscure detail in the
instruments that play in the range of that resonance, robbing the music of the richness of its
foundation. Just as damaging to the musical intention is another distortion mechanism which
can be quite subtle yet highly misleading at the same time. The reason that this other form of
distortion can be subtle is that the resonance of a large speaker system is often below the
range of most musical instruments.

Frequency Ranges of Musical Instruments

There are virtually no musical instruments that have significant output below 40 Hz. The
lowest E on a string (or electric) bass is at 41 Hz. The low A of a grand piano is 27 Hz, but it
is rarely played, and contains relatively little energy in the fundamental. Even large bass
drums rarely contain energy below 40 Hz. For example, the Cleveland Orchestra's infamous
bass drum featured on many Telarc recordings has a fundamental frequency of 38 Hz.
Similarly, the 40" bass drum used on the Wilson Audio recording entitled Center Stage has a
fundamental frequency of 35 Hz. Both of these drums are larger and more powerful than
those typically used in symphonic works, and are considered to fall in the "sonic blockbuster"
category. Most symphonic bass drums have fundamental tones in the 40 to 50 Hz range. This
leaves us with only two relatively common sources of truly deep bass: the pedals of a large
pipe organ, and a few rare synthesizer recordings.

The Woofer As a Spurious Musical Instrument

Just as each instrument plays in a certain frequency range, so do most speakers "play" at their
resonant frequency. In fact, the woofer cone (or diaphragm) may be likened to a drum head,
and a low-frequency transient corresponds to the mallet that strikes the drum. When "struck"
by a transient, this "drum" will ring out with its own tone at the woofer's resonant frequency.
This was illustrated earlier in this section with the graphs depicting the transient response of
various sealed and vented enclosures. How does this spurious "instrument" affect the
reproduced sound? Certainly the frequency and amplitude of a speaker's resonance must have
a bearing on the sound of that speaker.

As we listen to a loudspeaker system with a high-Q resonance in the range from 50 to 100 Hz,
which includes nearly all medium- and small-sized speakers, the effects are easily noticed.
Each time that a low-frequency transient is presented to the speaker, it plays along with its
own drum-like tone. Depending on the strength of the resonance (Q factor), the "drum" that
plays along will be of different relative strength, but in all cases it will interfere with the
proper reproduction of the music. Low-register instruments will acquire an unnatural
heaviness, and detailed information will be obscured.

However, when a speaker has a resonance below about 40 Hz, the audible effects become
more subtle. The only instruments with appreciable energy in the deepest bass (pipe -organ
pedals and some synthesizer settings) are not ones that easily provide audible clues as to a
speaker's accuracy. In the case of the synthesizer, there is no original acoustic signal that is to
be replicated, and no audible way of knowing if the speaker is performing accurately.
Pipe-organ pedals contain virtually no low-frequency transient information which are capable
of being blurred by a high-Q woofer resonance. Furthermore, few of us are familiar enough
with their original sound to reliably assess whether or not they are being reproduced correctly.

Enlarging the Bass Drum

But if this is true, is there any audible disadvantage to a speaker with stored resonant energy
at very low frequencies? The answer is a resounding "yes". Recall that low-frequency
transients will excite the woofer's resonance, which produces a spurious tone in virtually all
speakers. For instance, suppose you are auditioning a sealed-enclosure speaker with a
resonance of 30 Hz, and a Q factor of 0.8. If you are listening to an orchestral crescendo and a
large bass drum with a fundamental frequency of 40 Hz is struck, that low-frequency transient
will audibly excite the woofer resonance. The lower spurious note created by the woofer is
overlaid on the true sound of the bass drum to produce a deeper, louder tone than actually was
recorded, distorting the perceived size of the drum.

Since the bass drum is widely used in many types of music, it will be the primary sonic
casualty of a speaker with a high-Q resonance below 40 Hz. The reason this type of resonance
is so misleading is that one usually has no way of knowing the true size and sound of the
original drum with any degree of precision. Instead, one is presented with a larger-than-life
portrayal of the drum. At Avalon Acoustics, we believe that the goal of music reproduction is
to remain true to the composer's or artist's original intention. If a piece was scored for, and
performed on, a 36" bass drum, is it appropriate to transform that drum into a larger one? We
think not, yet that is what many loudspeakers effectively do.

Identifying Size Distortions

There are two methods which are useful in listening for the type of size distortions which
many speakers create. The first, and most direct, is to familiarize yourself as much as possible
with the original music that is to be reproduced. If you frequently attend live performances of
symphonic music, you will develop a mental image of the true sounds which are to be
re-created. Any distortions or exaggerations will then become readily apparent when listening
to a reproduction.

Visualizing the Sound Source

The other approach is to visualize the sound source. This is valuable when it is difficult to
ever listen to the original acoustic instruments, as is the case with most popular music using
amplified instruments. The visualization becomes easier as the resolution of the system
increases. When listening to a revealing system, one can notice minute details concerning the
performance. Is the drummer using Paiste or Zildjian cymbals? Is the violinist using a
Stradivarius or a Guarnerius? What brand of instrument is the guitarist using? How thick is
his pick? What gauge are his strings? All of these things can be discerned.

This same visualization can also be performed with the drums. For instance, almost all of
popular music uses a drum set with a pedal-operated bass drum. These drums range in size
from about 22" to 26", with thin plastic heads, and the hard felt beater on the pedal is about 2"
across. We all have developed a sense for the type of sounds that different objects will create.
For example, we know that a violin cannot create a bass note that can be felt in the pit of your
stomach. As you listen to popular music, ask yourself, "Is this a believable recreation of the
bass drum?" Does it sound as if an instrument that was about 2 feet across could create the
sound you are hearing, or does it sound more like an instrument that is perhaps 3 feet or even
4 feet across would make that sound? Does the beater sound like it is made of hard felt, or
does it sound like a large, soft, pillowy object? If these latter effects are true, then that speaker
is distorting the authentic sound.

Orchestral bass drums are usually somewhat larger than those used in popular music. These
drums do not have the damping material which is commonly applied to those used in popular
music. They are normally struck a glancing blow by a hand-held beater, which allows the
heads to ring out with a deep tone. A familiarity with their actual sound at a live concert will
enable one to tell when their sound is being exaggerated by the speaker during playback.

9.12 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 produce
transient-perfect bass response. 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.

10 Features

•

Advanced light weight driver diaphragm materials minimize energy storage and
time-domain distortion.

•

Each driver individually tested and matched for optimum performance.

•

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.

•

Multiple-stranded air-core coils provide ideal inductor properties.

•

Oversize screw terminals allow access to individual crossover section inputs,
allowing bi-wiring.

•

Careful crossover control of magnetic field interaction.

•

Polypropylene capacitors used exclusively to minimize energy storage.

•

Proprietary damping circuit controls the tweeter's electrical parameters, reducing
interaction with the amplifier.

•

Crossover circuitry housed in sealed chamber to provide isolation from vibrations.

•

Constrained-mode damping system absorbs cabinet vibrations.

•

Four and one-half 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.

11 Specifications

Driver Complement 1" titanium dome tweeter

8 1/2" Nomex-Kevlar composite cone woofer

Sensitivity 86 dB (2.83V, 1 meter)

Impedance 6 ohms (5.5 ohms minimum)

Frequency Response 45Hz to 24kHz (+/- 1.5 dB, anechoic)

(In room, typical -3 dB point is below 35Hz)

System Resonance Q=0.5

Recommended Amplifier Power 30 to 300 watts

Wiring Methods Four position terminal block

(providing bi-wiring option)

Dimensions 39" high

11" wide
15" deep

Weight 95 pounds (each)

12 Notes