MartinLogan Sequel II User Manual
User's Manual
The Sequel II Speaker System
Important Contents
Your Sequel II
Limited 90 Day Warranty coverage.
You have the option, at no additional charge, to
receive Limited 3 Year Warranty coverage. To obtain
Limited 3 Year Warranty coverage you need only
complete and return the Certificate of Registration that
was included with your speakers to Martin-Logan,
within 30 days of purchase.
Martin-Logan may not honor warranty serviceMartin-Logan may not honor warranty service
Martin-Logan may not honor warranty service
Martin-Logan may not honor warranty serviceMartin-Logan may not honor warranty service
claims unless we have a completed Warrantyclaims unless we have a completed Warranty
claims unless we have a completed Warranty
claims unless we have a completed Warrantyclaims unless we have a completed Warranty
Registration card on file!Registration card on file!
Registration card on file!
Registration card on file!Registration card on file!
Should you be using your Martin-Logan product in a
country other than the one in which it was originally
purchased, we ask that you note the following:
1) The appointed Martin-Logan distributor for any given
country is responsible for warranty servicing only on
units distributed by or through it in that country in
accordance with its applicable warranty.
2) Should a Martin-Logan product require servicing in a
country other than the one in which it was originally
purchased, the end user may seek to have repairs
performed by the nearest Martin-Logan distributor,
subject to that distributor's local servicing policies,
but all cost of repairs (parts, labor, transportation)
must be born by the owner of the Martin-Logan
product.
If you did not receive a Certificate of Registration with
your Sequel II
having received new units. If this is the case, plea
speakers are provided with an automatic
speakers you cannot be assured of
Introduction 3
Installation in Brief 4
The Electrostatic Concept 5
History 6
Martin-Logan Exclusives 8
Operation 10
Room Acoustics 14
Placement 18
Questions 21
Troubleshooting 22
Recommended Music 23
Glossary 24
Specifications 26
Notes 27
Page 2 Sequel II User's Manual
Introduction
Congratulations, you have invested in one of the world’s
premier loudspeaker systems!
The Martin-Logan Sequel II represents the culmination of an
intensive, dedicated group research program directed
toward establishing a world class reference monitor
utilizing leading-edge technology, without compromising
durability, reliability, craftsmanship, or aesthetic design.
The Sequel II begins where the original Sequel was and
carries that level of performance several steps beyond. Bass
response now has better extension and improved definition,
high frequency response also has better extension and is
much more natural in character. Power handling and
system efficiency have been enhanced as well.
Like the original Sequel, all materials in your new Sequel II
speakers are of the highest quality to provide years of
enduring enjoyment and deepening respect. All trim
pieces are constructed from selected hardwoods. They are
then grain and color matched and finally hand finished.
The cabinetry is constructed from a special high-density
hardwood powderboard for structural integrity and is
finished with a durable and attractive suede paint.
Through rigorous testing, the curvilinear electrostatic panel
has proven itself to be one of the most durable and reliable
transducers available today. Fabricated from a custom
tooled, high-grade steel, the panel is then coated with a
special polymer that is applied via a proprietary electrostatic deposition process. This panel assembly houses a
membrane 0.0005 of an inch thick! Ruggedly constructed
and insulated, as much as 200 watts of continuous power
has driven the Sequel II’s energized diaphragm into
massive excursions with no deleterious effects.
We know you are anxious to listen to your new speakers. So,
to speed you along, we have provided an
BriefBrief
Brief
section ahead of the detailed descriptive information
BriefBrief
contained in this manual.
Please read and follow these instructions as you initially
connect your Sequel II
instructions are important and will prevent you from
experiencing any delay, frustration, or system damage
which might occur in a trial-and-error procedure.
The other sections of your
detail the operation of your Sequel II
philosophy applied to their design. A clear understanding
of your speakers will insure that you obtain maximum
performance and pleasure from this most exacting transducer. It has been designed and constructed to give you
years of trouble-free listening enjoyment.
Happy Listening!
speakers into your system. These
User’s ManualUser’s Manual
User’s Manual will explain in
User’s ManualUser’s Manual
speakers and the
Installation inInstallation in
Installation in
Installation inInstallation in
Page 3Sequel II User's Manual
Installation in Brief
We know you are eager to hear your
new Sequel II loudspeakers, so this
section is provided to allow fast and
easy set up. Once you have them
operational, please take the time to
read, in depth, the rest of the information in this manual. It will give you
perspective on how to attain the best
possible performance from this most
exacting transducer.
If you should experience any difficul-
ties in the set-up or operation of your
Sequel II speakers, please refer to the
Room Acoustics, PlacementRoom Acoustics, Placement
Room Acoustics, Placement or
Room Acoustics, PlacementRoom Acoustics, Placement
OperationOperation
Operation section of this manual.
OperationOperation
Should you encounter a persistent
problem that cannot be resolved,
please contact your Authorized
Martin-Logan dealer. He will provide
you with the appropriate technical
analysis to alleviate the situation.
Step 1: UnpackingStep 1: Unpacking
Step 1: Unpacking
Step 1: UnpackingStep 1: Unpacking
Remove your new Sequel II
Step 2: PlacementStep 2: Placement
Step 2: Placement
Step 2: PlacementStep 2: Placement
Place each SequeI Il at least two feet from any wall and angle them slightly
toward your listening area. This is a good place to start. Please see the
ment ment
ment section of this manual for more details.
ment ment
Step 3: PStep 3: P
Step 3: P
Step 3: PStep 3: P
Martin-Logan speakers require AC power to energize their electrostatic cells.
Using the AC power cords provided, plug them in, making sure that you have
made a firm connection, first to the AC power receptacle on the rear panel of the
speaker and then to the wall outlet. Extension cords may be used, if necessary,
since the power requirement of the Sequel II is extremely small.
Step 4: Signal ConnectionStep 4: Signal Connection
Step 4: Signal Connection
Step 4: Signal ConnectionStep 4: Signal Connection
connections! The chassis is earth grounded and can present a
ower Connection (Aower Connection (A
ower Connection (A
ower Connection (Aower Connection (A
Turn your amplifier off before making or breaking any signal
short circuit to your amplifier if contact is made!
speakers from their packing.
C)C)
C)
C)C)
WARNING !WARNING !
WARNING !
WARNING !WARNING !
Place-Place-
Place-
Place-Place-
Use the best speaker cables you can! Higher quality cables, available from your
specialty dealer, are recommended and will give you superior performance! Spade
or banana connectors are suggested for optimum contact and ease of installation.
Attach your speaker cables to the
consistent when connecting speaker leads to the terminals on the back of the
Sequel II: take great care to assign the same color to the (+) terminal on both the
left and right channels. If bass is nonexistent and you cannot discern a tight,
coherent image, you may need to reverse the (+) and (-) leads on one side to bring
the system into proper polarity. For Bi-wiring/Passive Bi-amping instructions, turn to
OperationsOperations
the
Operations section of this manual for proper set-up of the Sequel II system.
OperationsOperations
Step 5: Listen and EnjoyStep 5: Listen and Enjoy
Step 5: Listen and Enjoy
Step 5: Listen and EnjoyStep 5: Listen and Enjoy
Now, you may turn on your system and enjoy!
Page 4 Sequel II User's Manual
Signal Input Signal Input
Signal Input section on the rear panel. Be
Signal Input Signal Input
The Electrostatic Concept
How can sound be reproduced by something that you are
able to see through? Electrostatic energy makes this possible.
Where the world of traditional loudspeaker technology
deals with cones, domes, diaphrams and ribbons that are
moved with magnetism, the world of electrostatic loudspeakers deals with charged electrons attracting and
repelling each other.
To fully understand the electrostatic concept, some
background information will be helpful. Remember when
you learned, in a science or physics class, that like charges
repel each other and opposite charges attract each other?
Well, this principle is the
foundation of the electrostatic
concept.
An Electrostatic TransducerAn Electrostatic Transducer
An Electrostatic Transducer
An Electrostatic TransducerAn Electrostatic Transducer
An electrostatic transducer
consists of three pieces: the
stators, the diaphragm and the
Diaphragm
spacers (See Figure 1). The
diaphragm is what actually
Spacer
moves to excite the air and
create music. The stator's job is
to remain stationary, hence the
word stator, to provide a
reference point for the moving
diaphragm. The spacers
Figure 1Figure 1
Figure 1. Cut away view of an electrostatic transducer.
provide the diaphragm with a
fixed distance in which to move
Figure 1Figure 1
Notice the simplicity due to minimal parts usage.
between the stators.
As your amplifier sends music
signals to an electrostatic
An Electromagnetic TransducerAn Electromagnetic Transducer
An Electromagnetic Transducer
An Electromagnetic TransducerAn Electromagnetic Transducer
speaker, these signals are
changed into two high-voltage
Surround Cone
signals that are equal in
strength but opposite in
polarity. These high voltage
signals are then applied to the
stators. The resulting electrostatic field, created by the
opposing high voltage on the
stators, works simultaneously
with and against the diaphragm, consequently moving
it back and forth, producing
music. This technique is known
Basket Assembly
Magnet
Figure 2.Figure 2.
Figure 2. Cut away view of a typical moving coil driver.
Figure 2.Figure 2.
Notice the complexity due to the high number of parts.
as push-pull operation and is a
major contributor to the sonic purity of the electrostatic
concept due to its exceptional linearity and low distortion.
Since the diaphragm of an electrostatic speaker is
uniformly driven over its entire area, it can be extremely
light and flexible. This allows it to be very responsive to
transients, thus perfectly tracing the music signal. As a
result, great delicacy, nuance and clarity is possible.
When you look at the problems of traditional electromagnetic drivers, you can easily see why this is so beneficial.
The cones and domes which are used in traditional
electromagnetic drivers cannot be driven uniformly
because of their design. Cones are driven only at the apex.
Domes are driven at their
perimeter. As a result, the rest
of the cone or dome is just
"along for the ride". The very
concept of these drivers
require that the cone or dome
be perfectly rigid, damped
and massless. Unfortunately
these conditions are not
Stator
available in our world today.
To make these cones and
domes move, all electromagnetic drivers must use voice
coils wound on formers,
spider assemblies, and
surrounds to keep the cone or
dome in position (See Figure
2). These pieces, when
combined with the high mass
of the cone or dome materi-
Dust Cap
Voice Coil Former
als used, make it an extremely complex unit with
many weaknesses and
potential for failure. These
faults contribute to the high
Spider
distortion products found in
these drivers and is a
tremendous disadvantage
when you are trying to
Magnet Assembly
Magnetic GapVoice Coil
change motion as quickly
and as accurately as a
loudspeaker must (40,000
times per second!).
Page 5Sequel II User's Manual
History
In the late 1800’s, any loudspeaker was considered exotic.
Today, most of us take the wonders of sound reproduction
for granted.
It was 1880 before Thomas Edison had invented the first
phonograph. This was a horn-loaded diaphragm that was
excited by a playback stylus. In 1898, Sir Oliver Lodge
invented a cone loudspeaker, which he referred to as a
“bellowing telephone”, that was very similar to the conventional cone loudspeaker drivers that we know today.
However, Lodge had no intention for his device to reproduce music, because in 1898 there was no way to amplify
an electrical signal! As a result, his speaker had nothing to
offer over the acoustical gramophones of the period. It was
not until 1906 that Dr. Lee DeForrest invented the triode
vacuum tube. Before this , an electrical signal could not be
amplified. The loudspeaker, as we know it today, should
have ensued then, but it did not. Amazingly, it was almost
twenty years before this would occur.
In 1921, the electrically cut phonograph record became a
reality. This method of recording was far superior to the
mechanically cut record and possessed almost 30 dB of
dynamic range. The acoustical gramophone couldn't
begin to reproduce all of the information on this new disc.
As a result, further developments in loudspeakers were
needed to cope with this amazing new recording medium.
By 1923, Bell Telephone Laboratories made the decision to
develop a complete musical playback system consisting
of an electronic phonograph and loudspeaker to take
advantage of the new recording medium. Bell Labs
assigned the project to two young engineers, C.W. Rice
and E.W. Kellogg.
Rice and Kellogg had a well equipped laboratory at their
disposal. This lab possessed a vacuum tube amplifier with
an unheard of 200 watts, a large selection of the new
electrically cut phonograph records and a variety of
loudspeaker prototypes that Bell Labs had been collecting
over the past decade. Among these were Lodge’s cone, a
speaker that used compressed air, a corona discharge
(plasma) speaker, and an electrostatic speaker.
After a short time, Rice and Kellogg had narrowed the field
of “contestants” down to the cone and the electrostat. The
outcome would dictate the way that future generations
would refer to loudspeakers as being either “conventional”,
or “exotic”.
Bell Laboratory’s electrostat was something to behold. This
enormous bipolar speaker was as big as a door. The
diaphragm, which was beginning to rot, was made of the
membrane of a pigs intestine that was covered with fine
gold leaf to conduct the audio signal.
When Rice and Kellogg began playing the new electrically cut records through the electrostat, they were shocked
and impressed. The electrostat performed splendidly. They
had never heard instrumental timbres reproduced with
such realism. This system sounded like real music rather
than the honking, squawking rendition of the acoustic
gramophone. Immediately, they knew they were on to
something big. The acoustic gramophone was destined to
become obsolete.
Due to Rice and Kelloggs enthusiasm, they devoted a
considerable amount of time researching the electrostatic
design. However, they soon encountered the same difficulties that even present designers face; planar speakers
require a very large surface area to reproduce the lower
frequencies of the audio spectrum. Because the management at Bell Labs considered large speakers unacceptable, Rice and Kelloggs work on electrostatics would never
be put to use for a commercial product. Reluctantly, they
advised the Bell management to go with the cone. For the
next thirty years the electrostatic design lay dormant.
During the Great Depression of the 1930's, consumer audio
almost died. The new electrically amplified loudspeaker
never gained acceptance, as most people continued to
use their old Victrola-style acoustic gramophones. Prior to
the end of World War II, consumer audio saw little, if any,
progress. However, during the late 1940's, audio experienced a great rebirth. Suddenly there was tremendous
interest in audio products and with that, a great demand
for improved audio components. No sooner had the cone
become established than it was challenged by products
developed during this new rebirth.
Page 6 Sequel II User's Manual
In 1947, Arthur Janszen, a young Naval engineer, took part
in a research project for the Navy. The Navy was interested
in developing a better instrument for testing microphone
arrays. The test instrument needed an extremely accurate
speaker, but Janszen found that the cone speakers of the
period were too nonlinear in phase and amplitude
response to meet his criteria. Janszen believed that
electrostats were inherently more linear than cones, so he
built a model using a thin plastic diaphragm treated with a
conductive coating. This model confirmed Janszen's
beliefs, for it exhibited remarkable phase and amplitude
linearity.
Janszen was so excited with the results that he continued
research on the electrostatic speaker on his own time. He
soon thought of insulating the stators to prevent the destructive effects of arcing. By 1952 he had an electrostatic
tweeter element ready for commercial production. This new
tweeter soon created a sensation among American audio
hobbyists. Since Janszen's tweeter element was limited to
high frequency reproduction, it often found itself used in
conjunction with woofers, most notably, woofers from
Acoustic Research. These systems were highly regarded by
all audio enthusiasts.
load that some amplifiers did not like, its dispersion was
very directional, and its power handling was limited to
around 70 watts. As a result, many people continued to use
box speakers with cones.
In the early 1960's Arthur Janszen joined forces with the KLH
loudspeaker company and together they introduced the
KLH 9. Due to the large size of the KLH 9, it did not have as
many limitations as the Quad. The KLH 9 could play
markedly louder and lower in frequency than the Quad ESL.
Thus a rivalry was born.
Janszen continued to develop electrostatic designs. He
was instrumental in the design of the Koss Model One, the
Acoustech, and the Dennesen speakers. Roger West, the
chief designer of the JansZen Corporation became the
president of Sound Lab. When JansZen Corporation was
sold, the RTR loudspeaker company bought half of the
production tooling. This tooling was used to make the
electrostatic panels for the Servostatic, a hybrid electrostatic system that was Infinity's first speaker product. Other
companies soon followed; each with their own unique
applications of the technology. These include Acoustat,
Audiostatic, Beverage, Dayton Wright, Sound Lab, and Stax
to name a few.
As good as these systems were, they would soon be
surpassed by another electrostatic speaker.
In 1955, Peter Walker published three articles on electrostatic loudspeaker design in Wireless World, a British
electronics magazine. In these articles Walker demonstrated the benefits of the electrostatic loudspeaker. He
explained that electrostatics permit the use of diaphragms
that are low in mass, large in area, and uniformly driven
over their surfaces by electrostatic forces. Due to these
characteristics, electrostats have the inherent ability to
produce a wide bandwidth, flat frequency response with
distortion products being no greater than the electronics
driving them.
By 1956 Walker backed up his articles by introducing a
consumer product, the now famous Quad ESL. This speaker
immediately set a standard of performance for the audio
industry due to its incredible accuracy. However, in actual
use the Quad had a few problems. It could not play very
loud, it had poor bass performance, it presented a difficult
Electrostatic speakers have progressed and prospered
because they actually do what Peter Walker claimed they
would. The limitations and problems experienced in the
past were not inherent to the electrostatic concept. They
were related to the applications of these concepts.
Today, these limitations have been addressed. Advancements in materials due to the U.S. space program give
designers the ability to harness the superiority of the
electrostatic principle. Today's electrostats use advanced
insulation techniques or provide protection circuitry. The
poor dispersion properties of early models have been
addressed by using delay lines, acoustical lenses, multiple
panel arrays or, as in our own products, by curving the
diaphragm. Power handling and sensitivity have been
increased.
These developments allow the consumer the opportunity to
own the highest performance loudspeaker products ever
built. It's too bad Rice and Kellogg were never able to see
just how far the technology would be taken.
Page 7Sequel II User's Manual
Martin-Logan Exclusives
Full Range OperationFull Range Operation
Full Range Operation
Full Range OperationFull Range Operation
The most significant advantage of Martin-Logan's
exclusive transducer technology reveals itself when you
look at examples of other loudspeaker products on the
market today.
The Sequel II uses no crossover networks above 250 Hz
because they are not needed. The Sequel II consists of a
single, seamless electrostatic membrane reproducing all
frequencies above 250 Hz simultaneously. How is this
possible?
First we must understand that music is not composed of
separate high, mid and low
frequency pieces. In fact,
music is comprised of a single
complex waveform with all
frequencies interacting
simultaneously.
The electrostatic transducer of
the Sequel II essentially acts
as an exact opposite of the
microphones used to record
the original event. A microphone, which is a single
working element, transforms
acoustic energy into an
electrical signal that can be
amplified or preserved by
some type of storage media.
The Sequel II's electrostatic
transducer transforms electrical energy from your amplifier
into acoustical energy.
Due to the limitations of
electromagnetic drivers, no
single unit can reproduce the
full range of frequencies.
Figure 1. Figure 1.
Figure 1. Illustrates how a conventional speaker system
Figure 1. Figure 1.
must use a crossover network that has negative effects
on the musical performance unlike the Sequel II which
needs no crossover networks in the "critical zone".
Conventional Loudspeaker
TweeterTweeter
Tweeter
TweeterTweeter
MidrangeMidrange
Midrange
MidrangeMidrange
WooferWoofer
Woofer
WooferWoofer
Martin-Logan Sequel II Loudspeaker
Sequel IISequel II
Sequel II
Sequel IISequel II
ElectrostaticElectrostatic
Electrostatic
ElectrostaticElectrostatic
TransducerTransducer
Transducer
TransducerTransducer
WooferWoofer
Woofer
WooferWoofer
Instead, these drivers must be designed to operate
within narrow, fixed bandwidths of the frequency range
and then combined electrically so that the sum of the
parts equals the total signal. While nice in theory, we
must deal with real-world conditions.
In order to use multiple drivers, a crossover network is
enlisted to attempt a division of the complex musical
signal into the separate pieces (usually highs, mids,
and lows) that each specific driver was designed to
handle. Unfortunately, due to the phase relationships
that occur within all crossover networks and during the
acoustical recombination
process, nonlinearities and
severe degradation of the
music signal takes place in
the ear's most "critical zone"
(See Figure 1).
Critical ZoneCritical Zone
Critical Zone
Critical ZoneCritical Zone
250 - 20kHz250 - 20kHz
250 - 20kHz
250 - 20kHz250 - 20kHz
Critical ZoneCritical Zone
Critical Zone
Critical ZoneCritical Zone
250 - 20kHz250 - 20kHz
250 - 20kHz
250 - 20kHz250 - 20kHz
The Sequel II's electrostatic
transducer can singlehandedly reproduce all
frequencies above 250 Hz
simultaneously. So you have,
in one transducer, the ability
to handle, in elegant simplicity, the critical frequencies
above 250 Hz.
The crossover phase discontinuities that are associated
with traditional tweeter,
midrange, and woofer systems
are eliminated. This results in a
dramatic improvement in
imaging and staging performance due to the minutely
accurate phase relationship
of the full-range panel wave
launch.
Page 8 Sequel II User's Manual
Vapor Deposited FilmVapor Deposited Film
Vapor Deposited Film
Vapor Deposited FilmVapor Deposited Film
Curvilinear Line SourceCurvilinear Line Source
Curvilinear Line Source
Curvilinear Line SourceCurvilinear Line Source
The diaphragm material used in all Martin-Logan
speakers employs an extremely sophisticated conductive
surface that has been vapor deposited on the polymer
surface at an atomic level. A proprietary compound is
vaporized then electrostatically driven into the surface of
the polymer film in a vacuum chamber. This process
allows an optically transparent surface adding no mass
to the diaphragm that is extremely uniform in its surface
resistivity characteristics. This uniform surface resistivity
controls the electrostatic charge on the diaphragm
surface and regulates its migration. As a result, no
discharging or “arcing” can occur.
Transducer IntegrityTransducer Integrity
Transducer Integrity
Transducer IntegrityTransducer Integrity
All Martin-Logan transducers begin with two pieces of
high grade, cold rolled steel. These steel pieces are then
custom perforated and insulated with an exotic compos-
ite coating. This proprietary coating insulates the stator to
3 times its actual needed working voltage and gives the
Sequel II a wide margin of safe operation. In addition to
the electrical insulation properties, this coating also
provides the Sequel II with a durable, attractive finish that
dampens the steel to prevent ringing. These pieces are
then sandwiched with our exclusive vapor deposited
diaphragm and spacers into a curved geometry and
bonded together with aerospace adhesives whose
strength exceeds that of welding.
The result of these advanced technologies is a transducer that is attractive, durable, highly rigid, well
dampened, and neutral.
Since the beginning of Audio, achieving smooth dispersion has long been a problem for all loudspeaker
designers. Large panel transducers present even more of
a challenge because the larger the panel, the more
directional the dispersion pattern becomes.
Full range electrostats have long been one of the most
problematic transducers because they attain their full
range capabilities via a large surface area. It looked as
if they were in direct conflict to smooth dispersion and
almost every attempt to correct this resulted in either poor
dispersion or a serious compromise in sound quality.
After extensive research, Martin-Logan engineers discovered an elegantly simple solution to achieve a smooth
pattern of dispersion without degrading sound quality. By
curving the horizontal plane of the electrostatic trans-
ducer, a controlled horizontal dispersion pattern could
be achieved, yet the purity of the almost massless
electrostatic diaphragm remained uncompromised. After
creating this technology, Martin-Logan developed the
production capability to bring this technology out of the
laboratory and into the market place.
You will find this proprietary Martin-Logan technology
used in all of our products. It is one of the many reasons
behind our reputation for high quality sound with
practical usability. This is also why you see the unique
"see through" cylindrical shape of all Martin-Logan
products.
Page 9Sequel II User's Manual
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