MartinLogan Speaker CLS IIz User Manual

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M A R T I N L O G A N  
 
INSTALLATION IN BRIEF  
We know you are eager to hear your new CLS IIz 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 greatest  
possible performance from this most exacting transducer.  
washers. Please start the cap screws by hand to prevent  
stripping then tighten with the provided Allen head tool.  
Step 4: Install the Adjustable Feet  
Attach the enclosed feet to the bottom of the wooden  
transducer frame and electronics by threading into the  
metal inserts located in the bottom of each. These feet  
allow you to adjust the vertical ‘tilt’ of the speaker system.  
If you should experience any difficulties in the setup or  
operation of your CLS IIz speakers, please refer to the Room  
Acoustics, Placement or Operation sections of this manual.  
Step 5: Placement  
Place each CLS IIz 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 Placement section (pages 6–7)  
of this manual for more details.  
Should you encounter a persistent problem that cannot be  
resolved, please contact your authorized MartinLogan dealer.  
They will provide you with the appropriate technical analysis  
to alleviate the situation.  
Step 6: Power Connection (AC) (see warning)  
WARNING!  
•Hazardous voltages exist inside—do not  
remove cover  
•Refer servicing to a qualified technician  
To prevent fire or shock hazard, do not  
expose this module to moisture  
MartinLogan speakers require AC power to energize their  
electrostatic cells. Using the AC power cords provided, plug  
them in first to the AC power receptacle on the rear panel of  
the speaker, making sure that you have made a firm con-  
nection, and then to the wall outlet. Please see the Operation  
section (pages 4–5) of this manual for more details.  
Turn amplifier off and unplug speaker  
should any abnormal conditions occur  
•Do not operate if there is any visual  
damage to the electrostatic panel element  
•Do not over drive speaker beyond its rated power  
Step 7: Signal Connection  
Use the best speaker cables you can. Higher quality cables,  
available from your specialty dealer, are recommended  
and will give you superior performance. Spade connectors  
are suggested for optimum contact and ease of installation.  
Step 1: Unpacking  
Attach your speaker cables to the Signal Input section on  
the rear panel. Be consistent when connecting speaker  
leads to the terminals on the back of the CLS IIz: 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.  
Remove your new CLS IIz speakers from their packing.  
Carefully lean one transducer against a wall with the  
curved portion of the speaker resting against a wall.  
Step 2: Connection  
Do not connect the AC power cords to your electronics  
modules yet!  
Move the electronics module close to the transducer frame.  
Firmly insert the high voltage connector from the electro-  
static transducer into the matching socket near the front of  
the electronics module.  
Step 8: Listen and Enjoy  
Now, you may turn on your system and enjoy!  
Step 3: Attach Electronics Module  
Now attach the electronics module to the wooden trans-  
ducer frame using the Allen head cap screws and finish  
Installation in Brief  
3
 
INTRODUCTION & OPERATION  
Introduction  
AC Power Connection  
Congratulations! You have invested in one of the world’s  
premier loudspeaker systems.  
Because your MartinLogan CLS IIz’s use an internal power  
supply to energize their electrostatic cells with high-volt-  
age DC, they must be connected to an AC power source.  
For this reason they are provided with the proper IEC standard  
power cords. These cords should be firmly inserted into the  
AC power receptacles on the rear connection panel of the  
speakers, then to any convenient AC wall outlet. The CLS IIz’s  
integrate a signal-sensing power supply which will switch  
off after a few minutes of no music signal and requires less  
than two seconds to recharge the panels when a music signal  
is present.  
The MartinLogan CLS IIz 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 result of cumulative technology gleaned from previous  
research and development projects, the CLS IIz represents the  
latest developments in electrostatic loudspeaker technology.  
Your CLS IIz speakers are wired for the power service sup-  
plied in the country of original consumer sale. The AC  
power rating applicable to a particular unit is specified  
both on the packing carton and on the serial number plate  
attached to the speaker.  
The materials in your new CLS IIz speakers are of the highest  
quality and will provide years of enduring enjoyment and  
deepening respect. All wood pieces are constructed from  
selected hardwoods. They are grain and color matched and  
finally hand finished.  
If you remove your CLS IIz speakers from the country  
of original sale, be certain that AC power supplied in any  
subsequent location is suitable before connecting and  
operating the speakers. Substantially impaired performance  
or severe damage may occur to a CLS IIz speaker if opera-  
tion is attempted from an incorrect AC power source.  
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 tool  
punched high-grade steel, the patented panel is then coated  
with a special polymer that is applied via a proprietary  
electrostatic deposition process. This panel assembly houses  
a membrane just 0.0005 of an inch thick. Ruggedly con-  
structed and insulated, as much as 200 watts of continuous  
power has driven the CLS IIz’s energized diaphragm into  
massive excursions with no deleterious effects.  
WARNING! The power cord should not be installed,  
removed, or left detached from the speaker while  
the other end is connected to an AC power source.  
The other sections of your User’s Manual will explain  
in detail the operation of your CLS IIz speakers and the  
philosophy applied to their design. A clear understanding  
of your speakers will insure that you obtain maximum per-  
formance and pleasure from this most exacting transducer.  
It has been designed and constructed to give you years of  
trouble-free listening enjoyment.  
Signal Connection  
Use the best speaker cables you can. The length and type of  
speaker cable used in your system will have an audible  
effect. Under no circumstance should a wire of gauge higher  
(thinner) than #16 be used. In general, the longer the length  
used, the greater the necessity of a lower gauge, and the  
lower the gauge, the better the sound, with diminishing  
returns setting in around #8 to #12.  
4
Introduction & Operation  
 
OPERATION  
Break-In  
A variety of speaker cables are now available whose  
manufacturers claim better performance over standard  
heavy gauge wire. We have verified this in many cases, and  
the improvements available are often more noticeable  
than the differences between wires of different gauge. The  
effects of cables may be masked if the equipment is not of  
the highest quality.  
When you first begin to play your CLS IIz speakers allow  
90 hours of break-in at 90 dB (moderate listening levels)  
before any critical listening. The CLS will benefit from the  
initial break in process like any conventional driver. The  
membrane will flex and become more supple resulting in a  
richer, more detailed and accurate sound quality compared  
to the initial, out of the box, performance. Typically the bulk  
of the break-in will occur in the first 90 hours but subtle  
improvements will continue for quite some time.  
We also recommend, if possible, that short runs of speaker  
cable connect the power amplifier(s) and speakers and that  
high-quality long interconnect cables be used to connect  
the preamplifier and power amplifier. This results in the  
power amplifiers being close to the speakers, which may  
be practically or cosmetically difficult, but if the length of  
the speaker cables can be reduced to a few meters, sonic  
advantages may be obtained.  
High-Frequency Softening Switch  
On the rear panel of the CLS IIz electronics module, near  
the signal input, is a two position High Frequency Softening  
switch that allows you to select the type of high frequency  
response that you desire.  
Connections are made at the Signal Input section on the  
rear electronics panel of the CLS IIz. Use spade connectors  
for optimum contact and ease of installation. Make certain  
that all of your connections are tight.  
The ‘Flat’ position is considered the normal setting for  
most rooms. However, due to different listening environ-  
ments, different electronics characteristics and personal  
preferences, you may prefer the ‘Soft’ Position. We sug-  
gest that you listen to the speaker using both switch  
positions and decide which position is correct for you par-  
ticular situation.  
Be consistent when connecting the speaker cables to the  
Signal Input terminals. Take care to assign the same color  
cable lead to the (+) terminal on both the left and right  
channel speakers. If bass is nonexistent and you cannot  
discern a tight, coherent image, you may need to reverse  
the (+) and (–) leads on one speaker to bring the system  
into proper polarity.  
WARNING! Turn your amplifier off before making  
or breaking any signal connections!  
Operation  
5
 
PLACEMENT  
Listening Position  
By now your speakers should be placed approximately  
two to three feet from the front wall, the wall in front of  
the listening position, and at least one to two feet from the  
side walls. Your sitting distance should be farther than the  
distance between the speakers themselves. What you are  
trying to attain is the impression of good center imaging  
and stage width.  
sheet rock or textured wall is generally an adequate  
surface if the rest of the room is not too bright and hard.  
Sometimes walls can be too soft. If the entire front wall  
consists of only heavy drapery, your system can sound too  
soft or dull. You may hear dull, muted music with little  
ambience. Harder room surfaces will actually help in this case.  
The front surface should, optimally, be one long wall  
without any doors or openings. If you have openings, the  
reflection and bass characteristics from one channel to the  
other can be different.  
There is no exact distance between speakers and listener,  
but there is a relationship. In long rooms, naturally, that  
relationship changes. The distance between the speakers  
will be far less than the distance from you to the speaker  
system. However, in a wide room, you will still find that if  
the distance from the listener to the speakers becomes  
smaller than the distance between the speakers themselves,  
the image will no longer focus in the center.  
The Side Walls  
The same requirements exist for side walls. Additionally, a  
good rule of thumb is to have the side walls as far away  
from the speaker sides as possible, minimizing near-field  
side wall reflections. Sometimes, if the system is bright or  
the imaging is not to your liking, and the side walls are  
very near, try putting curtains or softening material directly  
to the edge of each speaker. An ideal side wall, however,  
is no side wall at all.  
Now that you have positioned your speaker system, spend  
some time listening. Wait to make any major changes in  
your initial setup for the next few days as the speaker  
system itself will change subtly in its sound. Over the first  
40 hours of play the actual tonal quality will change slightly  
with deeper bass and more spacious highs resulting.  
After a few days of listening you can begin to make refine-  
ments and hear the differences of those refinements.  
Experimentation  
Toe-in  
The Wall Behind the Listener  
Now you can begin to experiment. First begin by toeing your  
speakers in towards the listening area and then facing them  
straight into the room. You will notice that the tonal balance  
changes slightly. You will also notice the imaging changing.  
Generally it is found that the ideal listening position is with  
the speakers slightly toed-in so that you are listening to the  
inner third of the curved transducer section.  
Near-field reflections can occur from your back wall, the  
wall behind the listening position. If your listening position  
is close to the back wall, these reflections can cause problems  
and confuse the quality of imaging. Actually it is better for  
the wall behind you to be soft than to be bright. If you  
have a hard back wall and your listening position is close  
to it, experiment with devices that will soften and absorb  
information (i.e., wall hangings and possibly even sound  
absorbing panels).  
Experimenting with the toe-in will help in terms of tonal  
balance. You will notice that as the speakers are toed-out,  
the system becomes slightly brighter than when toed-in.  
This design gives you the flexibility to compensate for a  
soft or bright room.  
The Wall Behind the Speakers  
Tilting the Speakers Backwards and Forwards  
The front surface, the wall behind your speakers, should not  
be extremely hard or soft. For instance, a pane of glass  
will cause reflections, brightness and confused imaging.  
Curtains, drapery and objects such as bookshelves can  
be placed along the wall to soften a hard surface. A standard  
As can be seen from the diagrams in the Room Acoustics  
section of this manual (pages 10–11), the vertical dispersion  
is directional above and below the stator panel itself. In some  
instances, if you are sitting close to the floor, slight forward  
tilting of the speakers can enhance clarity and precision.  
6
Placement  
 
Imaging  
Your ideal listening position and speaker position will  
be determined by:  
•Tightness and extension of bass response  
•Width of the stage  
•Pinpoint focusing of imaging  
Once you have determined the best of all three of these  
considerations, you will have your best speaker location.  
In their final location, your CLS IIz’s should have a stage width  
somewhat wider than the speakers themselves. On well-  
recorded music, the instruments should extend beyond  
the edges of each speaker to the left and to the right, yet a  
vocalist should appear directly in the middle. The size of  
the instruments should be neither too large nor too  
small. Additionally, you should find good clues as to stage  
depth. Make sure that the vertical alignment, distance  
from the front wall, and toe-in, is exactly the same from  
one speaker to the other. This will greatly enhance the  
quality of your imaging.  
The Extra “Tweak”  
A major cable company developed the following procedure  
for speaker placement. As a final test of exact placement,  
use these measurements for your speakers placement, and  
see what can happen to the ultimate enhancement of  
your system’s performance. These two basic formulas will  
determine optimum placement of your speakers to minimize  
standing waves.  
Bass Response  
Your bass response should neither be one note nor too  
heavy. It should extend to even the deepest organ pas-  
sages, yet it should be tight and well defined. Kick-drums  
should be tight and percussive—string bass notes should  
be uniform and consistent throughout the entirety of the  
run without any booming or thudding.  
1. Distance from the front wall (the wall in front of the listening  
position) to the center of the curvilinear transducer. To  
determine distance from the front wall, measure the height  
of your ceiling (inches) and multiply the figure by 0.618  
(i.e., ceiling height in inches x 0.618 = the distance from  
the front wall to the center of the curvilinear transducer).  
Tonal Balance  
Voices should be natural and full, cymbals should be  
detailed and articulate yet not bright and piercing, pianos  
should have a nice transient characteristic and deep tonal  
registers as well. If you cannot attain these virtues, read the  
section on Room Acoustics (pages 1011). This will give  
you clues on how to get closer to those ideal virtues.  
2. Distance from the side-walls to the center of the curvilinear  
transducer. To determine distance from the side walls,  
measure the width of your room (inches) and divide by  
18. Next, multiply the quotient by 5 (i.e., room width in  
inches/18 x 5 = the distance from the side-walls to the  
center of the curvilinear transducer).  
Final Placement  
After obtaining good wall treatments and attaining proper  
angle, begin to experiment with the distance from the wall  
behind the speakers. Move your speaker slightly forward  
into the room. What happened to the bass response?  
What happened to the imaging? If the imaging is more  
open and spacious and the bass response is tightened, that  
is a superior position. Move the speakers back six inches  
from the initial setup position and again listen to the imaging  
and bass response. There will be a position where you will  
have pinpoint imaging and good bass response. That position  
is the point of the optimal placement from the front wall.  
Enjoy Yourself  
The CLS IIz is a very refined speaker and benefits from care  
in setup. With these tips in mind you will find, over your  
months of listening, that small changes can result in  
measurable differences. As you live with your speakers, do  
not be afraid to experiment with their positioning until  
you find the optimal relationship between your room and  
speaker system that gives to you the best results. Your efforts  
will be rewarded.  
Now experiment with placing the speakers farther apart.  
As the speakers are positioned farther apart, listen again,  
not so much for bass response but for stage width and  
good pinpoint focusing.  
You are now armed with the fundamental knowledge of  
room acoustics and the specific fundamentals of the CLS IIz  
loudspeaker. Happy listening!  
Placement  
7
 
ROOM ACOUSTICS  
Your Room  
This is one of those areas that requires both a little back-  
ground to understand and some time and experimentation  
to attain the best performance from your system.  
Resonant Surfaces and Objects  
All of the surfaces and objects in your room are subject to  
the frequencies generated by your system. Much like an  
instrument, they will vibrate and “carry on” in syncopation  
with the music, and contribute in a negative way to the  
music. Ringing, boominess, and even brightness can occur  
simply because they are “singing along” with your music.  
Your room is actually a component and an important part  
of your system. This component is a very large variable  
and can dramatically add to, or subtract from, a great  
musical experience.  
Resonant Cavities  
All sound is composed of waves. Each note has its own  
wave size, with the lower bass notes literally encompassing  
from 10 feet to as much as 40 feet. Your room participates  
in this wave experience like a three-dimensional pool with  
waves reflecting and becoming enhanced depending on  
the size of the room and the types of surfaces in the room.  
Small alcoves or closet type areas in your room can be  
chambers that create their own “standing waves” and can  
drum their own “one-note” sounds.  
Clap your hands. Can you hear an instant echo respond back?  
You have near-field reflections. Stomp your foot on the floor.  
Can you hear a “boom”? You have standing waves or large  
panel resonances such as a poorly supported wall. Put your  
head in a small cavity area and talk loudly. Can you hear a  
booming? You’ve just experienced a cavity resonance.  
Remember, your audio system can literally generate all of  
the information required to recreate a musical event in  
time, space and tonal balance. The purpose of your room,  
ideally, is to not contribute to that information. However,  
every room does contribute to the sound, and the better  
speaker manufacturers have designed their systems to  
accommodate this phenomenon.  
Rules of Thumb  
Hard vs. Soft Surfaces  
Let’s talk about a few important terms before we begin.  
If the front or back wall of your listening room is soft, it  
might benefit you to have a hard or reflective wall in  
opposition. The ceiling and floor should follow the same  
basic guideline as well. However, the side walls should be  
roughly the same in order to deliver a focused image.  
Terminology  
Standing Waves  
The parallel walls in your room will reinforce certain notes  
to the point that they will sound louder than the rest of the  
audio spectrum and cause “one-note bass, boomy bass”  
or “tubby bass. For instance, 100Hz represents a 10 feet  
wavelength. Your room will reinforce that specific fre-  
quency if one of the dominant dimensions is 10 feet. Large  
objects in the room such as cabinetry or furniture can help to  
minimize this potential problem. Some serious “audiophiles”  
will literally build a special room with no parallel walls just  
to help eliminate this phenomenon.  
This rule suggests that a little reflection is good. As a matter  
of fact, some rooms can be so “over damped” with carpeting,  
drapes and sound absorbers that the music system can  
sound dull and lifeless. On the other hand, rooms can be  
so hard that the system can sound like a gymnasium with  
too much reflection and brightness. The point is that balance  
is the optimum environment.  
Breakup Objects  
Objects with complex shapes, such as bookshelves, cabi-  
netry and multiple-shaped walls can help break up those  
sonic gremlins and diffuse any dominant frequencies.  
Reflective Surfaces (near-field reflections)  
The hard surfaces of your room, particularly if close to your  
speaker system, will reflect some waves back into the room  
over and over again, confusing the clarity and imaging of  
your system. The smaller sound waves are mostly affected  
here, and occur in the mid and high frequencies. This is  
where voice and frequencies as high as the cymbals occur.  
Solid Coupling  
Your loudspeaker system generates frequency vibrations  
or waves into the room. This is how it creates sound.  
Those vibrations will vary from 20 per second to 20,000  
per second. If your speaker system is not securely planted  
8
Room Acoustics  
 
Solid Footing  
on the floor or solid surface, it can shake as it produces  
sound and, consequently, the sound can be compromised.  
If your speaker is sitting on the carpet and only foot gliders  
are used, the bass can be ill defined and even boomy. The  
use of spikes is recommended to insure secured footing for  
your speakers. (See Solid Footing, this page, for spike infor-  
mation and installation instructions).  
After living and experimenting with your CLS IIz’s, you may  
want to use ETC (Energy Transfer Coupler) Spikes (See  
Figure 1), which are available from your local MartinLogan  
dealer or on our website at www.martinlogan.com. With  
the use of these spikes, the CLS IIz will become more firmly  
planted on the floor and, consequently, bass will tighten and  
imaging will become more coherent and detailed. It is  
best not to implement the spikes, however, until you are  
secure in the positioning, as the spikes can damage the floor  
if the speaker is moved. MartinLogan ETC spikes will fit  
Dipolar Speakers and Your Room  
1
any common /4 inch thread insert that may be found on  
MartinLogan electrostatic loudspeakers are known as dipolar  
radiators. This means that they produce sound from both  
their fronts and their backs. Consequently, musical infor-  
mation is reflected by the wall behind them and may arrive  
either in or out of step with the information produced by  
the front of the speaker.  
your other audio equipment (racks, speakers, etc.).  
Spike Installation Instructions:  
1. Carefully lay your speaker on its side to gain access to  
the bottom.  
2. Remove existing feet or spikes. Thread new spikes into  
holes and screw them in all of the way.  
The low frequencies can either be enhanced or nulled by  
the position from the front wall. Your CLS IIz’s have been  
designed to be placed two to three feet from the front wall  
(the wall in front of the listening position) to obtain the  
best results; however, your room may see things differently.  
So listening to the difference of the bass response as a  
result of the changes in distance from the front wall can  
allow you to get the best combination of depth of bass  
and tonal balance.  
3. Tighten jam nut snugly by hand. Do not over tighten  
the nut.  
4. Right the speaker.  
Caution: Make sure your hands and any cabling are clear  
of the spikes. Do not slide speaker as spikes are sharp and  
can damage your floor or carpet.  
Now that you know about reflective surfaces and resonant  
objects, you can see how the midrange and high frequencies  
can be affected. The timing of the initial wave as it radiates  
to your ears, and then the reflected information as it arrives  
at your ears later in time, can result in confusion of the pre-  
cious timing information that carries the clues to imaging.  
Consequently the result is blurred imaging and excessive  
brightness. Soft walls, curtains, wall hangings, or sound  
dampeners (your dealer can give you good information  
here) can be effective if these negative conditions occur.  
5. Adjust to level by rotating spikes. Tighten the jam nut  
securely when satisfied that speaker is level.  
Caution: Walking the speaker may result in a broken spike.  
Figure 1. The ETC Spike.  
Room Acoustics  
9
 
DISPERSION INTERACTIONS  
Controlled Horizontal Dispersion  
Three Major Types of Dispersion  
Your CLS IIz’s launch a 30-degree dispersion pattern when  
viewed from above. This horizontal dispersion field gives a  
choice of good seats for the performance while minimizing  
interactions with side walls (See Figure 2). Make sure both  
speakers stand exactly at the same vertical angle, otherwise  
the image can be skewed or poorly defined. The wave  
launch of both speakers is extremely accurate in both the  
time and spectral domain. Consequently, small refined  
adjustments can result in noticeable sonic improvements.  
In the field of loudspeaker design, it is a known fact that as  
the sound wave becomes progressively smaller than the  
transducer producing it, the dispersion of that wave  
becomes more and more narrow, or directional. This fact  
occurs as long as the transducer is a flat surface. Large flat-  
panel speakers exhibit venetian blind effects due to this  
phenomenon. This is why most manufacturers opt for  
small drivers (i.e., tweeters and midrange) to approximate  
what is known as a point source wave launch.  
Historically, most attempts to achieve smooth dispersion  
from large flat-panel transducers resulted in trade-offs.  
After exhaustive testing of these different solution attempts,  
we found an elegantly simple, yet very difficult to execute  
solution. By curving the radiating surface, we create the  
effect of a horizontal arc. This allows the engineers at  
MartinLogan to control the high frequency dispersion  
pattern of our transducers. That is why you see the gentle  
curve on our products.  
Controlled Vertical Dispersion  
As you can see from the illustrations, your CLS IIz speakers  
project a controlled dispersion pattern. Each CLS IIz is a 4-  
foot line source beginning a few inches above the floor  
level (See Figure 3). This vertical dispersion profile mini-  
mizes interactions with the floor and the ceiling.  
Figure 2. MartinLogan CLS IIz’s deliver a 30-degree wave launch dispersion  
Figure 3. Your CLS IIz speaker system is a 48 inch line source viewed vertically.  
pattern distributed horizontally.  
10 Dispersion Interactions  
 
Figure 45. As can be seen here, point source  
concepts invite a great deal of room interaction.  
While delivering good frequency response to a  
large listening audience, imaging is consequently  
confused and blurred.  
Figure 67. Even though they suffer from  
“venetian blind” effect, angled multiple panel  
speakers can deliver good imaging, but only  
to specific spots in the listening area.  
Figure 8–9. A controlled 30-degree cylindrical  
wave-front, which is a MartinLogan exclusive,  
offers optimal sound distribution with minimal  
room interaction. The result is solid imaging with  
a wide listening area.  
Dispersion Interactions 11  
 
ELECTROSTATIC ADVANTAGES  
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, diaphragms 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 back-  
ground 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.  
Figure 11. Cut-away view of an electrostatic transducer.  
Notice the simplicity due to minimal parts usage.  
An electrostatic transducer consists of three pieces: the  
stators, the diaphragm and the spacers (See Figure 11). The  
diaphragm is what actually moves to excite the air and  
create music. The stator’s job is to remain stationary, hence  
the word stator, and to provide a reference point for the  
moving diaphragm. The spacers provide the diaphragm  
with a fixed distance in which to move between the stators.  
As your amplifier sends music signals to an electrostatic  
speaker, these signals are changed into two high-voltage  
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 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.  
12 Electrostatic Advantages  
 
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 are 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 requires that the cone or dome be perfectly rigid,  
damped and massless. Unfortunately, these conditions are  
not available in our world today.  
Figure 12. Cut-away view of a typical moving coil driver.  
Notice the complexity due to the high number of parts.  
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 12). These pieces, when combined  
with the high mass of the cone or dome materials used,  
make it an extremely complex unit with many weaknesses  
and potential for failure. These faults contribute to the  
high distortion products found in these drivers and is a  
tremendous disadvantage when you are trying to change  
motion as quickly and as accurately as a loudspeaker  
must (40,000 times per second!).  
Electrostatic Advantages 13  
 
Full Range Operation  
The most significant advantage of MartinLogan’s exclusive  
transducer technology reveals itself when you look at  
examples of other loudspeaker products on the market today.  
a narrow, fixed bandwidth 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.  
The CLS IIz uses no crossover networks because they are  
not needed. The CLS IIz consists of a single, seamless elec-  
trostatic membrane reproducing all frequencies. How is  
this possible?  
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  
take place in the ear’s most critical zone (See Figure 13).  
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 CLS IIz 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 CLS IIz’s electrostatic transducer transforms  
electrical energy from your amplifier into acoustical energy.  
The CLS IIz’s electrostatic transducer can single-handedly  
reproduce all frequencies simultaneously. You have in one  
transducer the ability to handle in elegant simplicity the  
critical frequencies.  
The crossover phase aberrations that are associated with  
traditional tweeter, midrange, and woofer systems are  
eliminated. The result is a dramatic improvement in imaging  
and staging performance due to the minutely accurate phase  
relationship of the full-range panel wave launch.  
Due to the limitations of electromagnetic drivers, no  
single unit can reproduce the full range of frequencies.  
Instead, these drivers must be designed to operate within  
Conventional Loudspeaker  
CLS IIz  
Tweeter  
crossover point (2–5kHz)  
Critical Zone: 200Hz–20kHz  
Midrange  
ESL Panel  
crossover point (100–400Hz)  
Figure 13. This diagram illustrates how a conventional  
speaker system must use multiple crossover networks  
that have negative effects on the musical performance.  
Woofer  
14 Electrostatic Advantages  
 
MARTINLOGAN EXCLUSIVES  
Curvilinear Line Source (CLSTM)  
Vapor Deposited Film  
Since the beginning of audio, achieving smooth dispersion  
has 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.  
The diaphragm material used in all MartinLogan 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.  
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 disper-  
sion or a serious compromise in sound quality.  
After extensive research, MartinLogan 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 transducer, a con-  
trolled horizontal dispersion pattern could be achieved, yet  
the purity of the almost massless electrostatic diaphragm  
remained uncompromised. After creating this technology,  
MartinLogan developed the production capability to bring  
it out of the laboratory and into the market place.  
Transducer Integrity  
All MartinLogan transducers begin with two pieces of  
high-grade, cold rolled steel. These steel pieces are then  
custom perforated and insulated with a unique composite  
coating. This proprietary coating insulates the stator to  
three times its actual needed working voltage and gives  
the CLS IIz a wide margin of safe operation. In addition to  
the electrical insulation properties, this coating also provides  
the CLS IIz 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.  
You will find this proprietary MartinLogan 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” cylindri-  
cal shape of all MartinLogan products.  
The result of these advanced technologies is a transducer that  
is attractive, durable, highly rigid, well dampened and neutral.  
MartinLogan Exclusives 15  
 
ELECTROSTATIC LOUDSPEAKER HISTORY  
In the late 1800s, any loudspeaker was considered exotic.  
Today, most of us take the wonders of sound reproduction  
for granted.  
The outcome would dictate the way that future generations  
would refer to loudspeakers as being either “conventional”  
or “exotic.  
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.  
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  
a pig 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.  
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 gramo-  
Due to Rice and Kellogg’s 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  
phone couldn’t begin to reproduce all  
of the information on this new disc. As  
a result, further developments in loud-  
speakers were needed to cope with  
this amazing new recording medium.  
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  
Rice and Kellogg had  
narrowed the field of  
“contestants” down to the  
cone and the electrostat.  
Kellogg’s work on electrostatics would  
By 1923, Bell Telephone Laboratories made the decision  
to develop a complete musical playback system consisting  
of an electronic phonograph and a 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.  
never be put to use for a commercial product. Reluctantly, they  
advised the Bell management to go with the cone. For the  
next 30 years, the electrostatic design lay dormant.  
During the Great Depression of the 1930s, 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 1940s, 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.  
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.  
16 Electrostatic Loudspeaker History  
 
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  
around 70 watts. As a result, many people continued to  
use box speakers with cones.  
In the early 1960s 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.  
beliefs, for it exhibited remarkable phase  
and amplitude linearity.  
Janszen continued to develop electro-  
static 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,  
These developments allow  
the consumer to own the  
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  
highest performance loud-  
speaker products ever built.  
became the president of Sound Lab.  
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.  
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.  
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.  
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.  
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 also been increased.  
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 be played  
very loud, it had poor bass performance, it presented a  
difficult load that some amplifiers did not like, its dispersion  
was very directional and its power handling was limited to  
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.  
Electrostatic Loudspeaker History 17  
 
FREQUENTLY ASKED QUESTIONS  
How do I clean my speakers?  
Is there likely to be any interaction between my speakers  
and the television in my Audio/Video system?  
Actually, there is less interaction between a television and  
an electrostatic speaker than between a television and a  
conventional system. You will find the CLS IIz does not  
degrade your televisions picture, even if placed directly  
beside your television.  
Just use a dust free cloth or a soft brush to remove the  
dust from your speakers. We recommend a specialty cloth  
(available through the Xtatic shop at www.martinlogan.com)  
that cleans your speakers better than anything else we  
have ever tried. Do not spray any kind of cleaning  
agent on or in close proximity to the electrostatic  
element.  
Will my electric bill go ‘sky high’ by leaving my speak-  
ers plugged in all the time?  
What is the advantage of ESL?  
Since the polyester film diaphragm is uniformly driven  
over its entire surface—unlike a tweeter that is only driven  
at its edges—it is the only technology that can be made  
large enough to play bass, yet is still light enough for  
high frequencies. This unique property allows for the  
elimination of high frequency crossover points and  
their associated distortions.  
No. A pair of MartinLogans will draw about 5 watts  
maximum. There is some circuitry to turn off the static  
charge when not in use; however, the actual consumption  
will remain close to the same. The primary purpose of  
the sensing circuitry is to prevent dust collection on the  
electrostatic element.  
If the diaphragm is punctured with a pencil, stick, or  
similar item, how extensive would the damage to the  
speaker be?  
What size amplifier should I use?  
We recommend an amplifier with 100 to 200 watts per  
channel for most applications. Probably less would be  
adequate for our smaller hybrids or when used in home  
theater where a subwoofer is employed. Our hybrid  
designs will perform well with either a tube or transistorized  
amplifier, and will reveal the sonic character of either  
type. However, it is important that the amplifier be stable  
operating into varying impedance loads: a stable amplifier  
will be able to deliver twice its rated wattage into 4 Ohms  
and should again double into 2 Ohms.  
Our research department has literally punctured hundreds  
of holes in a diaphragm, neither affecting the quality of  
the sound nor causing the diaphragm to rip. However,  
you will be able to see the actual puncture and it can  
be a physical nuisance. If this is the case, replacing the  
electrostatic transducer will be the only solution.  
Will exposure to sunlight affect the life or performance  
of my speakers?  
We recommend that you not place any loudspeaker in  
direct sunlight, as the ultraviolet (UV) rays from the sun  
can cause deterioration of grill cloth, speaker cones,  
etc. Small exposures to UV will not cause a problem.  
In general, the filtering of UV rays through glass will  
greatly reduce the negative effects on the electrostatic  
membrane itself.  
Could you suggest a list of suitable electronics and  
cables that would be ideal for MartinLogan speakers?  
The area of electronics and cable choice is probably  
the most common type of question that we receive. It is  
also the most subjective. We have repeatedly found  
that brands that work well in one setup will drive someone  
else nuts in another. We use many brands with great  
success. Again, we have no favorites; we use electronics  
and cables quite interchangeably. We would suggest  
listening to a number of brands—and above all else,  
trust your ears. Dealers are always the best source for  
information when purchasing additional audio equipment.  
18 Frequently Asked Questions  
 
Will excessive smoke or dust cause any problems with  
my electrostatic speakers?  
Could my children, pets, or myself be shocked by the  
high-voltage present in the electrostatic panel?  
No. High voltage with low current is not dangerous. As a  
matter of fact, the voltage in our speakers is 10 times  
less than the static electricity that builds up on the surface  
of your television screen.  
Exposure to excessive contaminants such as smoke  
or dust may potentially affect the performance of the  
electrostatic membrane, and may cause discoloration  
of the diaphragm membrane. When not in use for  
extended periods, you should unplug the speakers and  
cover them with the plastic bags in which the speakers  
were originally packed.  
How do MartinLogan speakers hold up over a long term  
in the humidity of tropical climates?  
We should tell you that MartinLogan indeed has a very  
substantial number of customers in tropical regions of  
the world. Our speakers have been serving them nicely for  
many years. This concern may have come from our earlier  
design of speakers, which were charged continuously.  
Since 1993, all of our speakers have been designed so that  
they only charge the panel while music is being played.  
This improvement has made a tremendous difference  
in the consistent performance of our product. There may  
be a little more maintenance involved in humid regions  
when not in an air conditioned environment. Simply  
enough, the concern is to keep the electrostatic panels  
dust free. Humidity will combine with any dust on the  
panel to make it slightly conductive. This will result in a  
slight pathway for the charge to leave the membrane of  
the speaker. The solution is simple. They only require  
occasional vacuuming with a strong vacuum hose. You  
will have best results when the speakers have been  
unplugged for six hours or overnight. We are confident  
that they will serve you very well.  
It is a good idea to vacuum the electrostatic portion of  
each speaker once or twice a year. This will be most  
effective if the speaker has been unplugged for six  
hours or overnight. You need not worry about the vacuum  
pressure damaging the "delicate" membrane. It is  
extraordinarily durable.  
A problem has recently developed with my MartinLogan  
speakers. The right speaker seems to be hissing even  
when the amplifier and such are not connected. I was  
wondering if this sounds like any problem you have  
encountered previously and have a simple solution for  
or might it be something which will need to be looked  
into more carefully.  
Your speakers are dusty. The electrostatic charge on  
the element has attracted some airborne dust or pollen.  
First unplug the speakers for six hours or overnight.  
This will allow the charge to dissipate. Now vacuum  
the front of the panel with a very strong vacuum.  
Don’t worry about damaging the membrane. You won’t.  
This should take care of your problem.  
Should I unplug my speakers during a thunderstorm?  
Yes, or before. It’s a good idea to disconnect all of your  
audio/video components during stormy weather.  
By the way, since 1993, all of our speakers have been  
built with a charging circuit board that only charges the  
electrostatic element when music plays. At other times  
they are not charged, and cannot collect dust. You can get  
the same benefit by simply unplugging them whenever  
they are not in use. An easy way to do that is with a  
power strip that has a switch.  
Frequently Asked Questions 19  
 
TROUBLESHOOTING  
No Output  
Lack of Bass  
•Check your speaker wires. Is the polarity correct?  
•Check that all your system components are turned on.  
•Check your speaker wires and connections.  
•Check all interconnecting cables.  
Poor Imaging  
•Check placement. Are both speakers the same distance  
from the walls? Do they have the same amount of  
toe-in? Try moving the speakers away from the back  
and side walls.  
•Check the polarity of the speaker wires. Are they  
connected properly?  
Weak Output, Loss of Highs  
•Check the power cord. Is it properly connected to the speaker?  
Exaggerated Highs, Brightness  
•Check the toe-in of the speakers. Read Placement (pages 8–9)  
for more information.  
Popping and Ticking Sounds, Funny Noises  
Muddy Bass  
•These occasional noises are harmless and will not hurt your  
audio system or your speakers. All electrostatic speakers  
are guilty of making odd noises at one time or another.  
•These noises may be caused by dirt and dust particles  
collecting on the speaker, by high humidity, or by AC  
line fluctuations that may occur in your area.  
•Check placement. Try moving the speakers closer to the  
front and side walls.  
•Check the type of feet that are being used. Try attaching  
the coupling spikes.  
•Dirt and dust may be vacuumed off with a brush attachment  
connected to your vacuum cleaner, or you may blow  
them off with compressed air.  
20 Troubleshooting  
 
GENERAL INFORMATION  
Specifications  
Warranty and Registration  
The CLS IIz hybrid speaker system consists of a broad-  
range single-element electrostatic transducer integrated  
with a quick-response woofer. This approach takes advan-  
tage of the benefits that both technologies have to offer.  
Dispersion is a controlled 30 degrees. This was achieved  
by curving the electrostatic transducer element itself, an  
elegantly simple solution.  
Your CLS IIz speakers are provided with an automatic Limited  
90-Day Warranty coverage.  
You have the option, at no additional charge, to receive a  
Limited 5-Year Warranty coverage. To obtain the Limited  
5-Year Warranty coverage you need to complete and return  
the Certificate of Registration, included with your speakers,  
and provide a copy of your dealer receipt, to MartinLogan  
within 30 days of purchase.  
System Frequency Response  
35–20,000 Hz ± 3 dB  
MartinLogan may not honor warranty service claims unless  
we have a completed Warranty Registration card on file!  
Dispersion  
Horizontal: 30 Degrees  
Vertical: 48 inch (122 cm) Line Source  
If you did not receive a Certificate of Registration with  
your new CLS IIz speakers you cannot be assured of having  
received new units. If this is the case, please contact your  
authorized MartinLogan dealer.  
Sensitivity  
86 dB/2.83 volts/meter  
Impedance  
Nominal: 4 ohms  
Minimum: 1.5 ohms @ 20 kHz  
Service  
Should you be using your MartinLogan product in a country  
other than the one in which it was originally purchased,  
we ask that you note the following:  
Components  
Dual custom-wound audio transformer, polypropylene  
capacitors  
1. The appointed MartinLogan 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.  
Power Handling  
200 watts per channel  
Recommended Amplifier Power  
80200 watts per channel  
2. Should a MartinLogan 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 MartinLogan 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 MartinLogan product.  
Weight  
85 lbs. each (38.5 kg)  
Size  
28 inches W × 14.5 inches D × 57.5 inches H  
(71.1 cm W × 36.8 cm D × 146 cm H)  
3. If, after owning your speakers for six months, you  
relocate to a country other than the one in which  
you purchased your speakers, your warranty may be  
transferable. Contact MartinLogan for details.  
General Information 21  
 
GLOSSARY OF AUDIO TERMS  
AC. Abbreviation for alternating current.  
DC. Abbreviation for direct current.  
Active crossover. Uses active devices (transistors, ICs, tubes)  
and some form of power supply to operate.  
Diffraction. The breaking up of a sound wave caused by  
some type of mechanical interference such as a cabinet  
edge, grill frame or other similar object.  
Amplitude. The extreme range of a signal. Usually measured  
from the average to the extreme.  
Diaphragm. A thin flexible membrane or cone that vibrates  
in response to electrical signals to produce sound waves.  
Arc. The visible sparks generated by an electrical discharge.  
Distortion. Usually referred to in terms of total harmonic  
distortion (THD) which is the percentage of unwanted  
harmonics of the drive signal present with the wanted signal.  
Generally used to mean any unwanted change introduced  
by the device under question.  
Bass. The lowest frequencies of sound.  
Bi-Amplification. Uses an electronic crossover, or line-level  
passive crossover, and separate power amplifiers for the  
high and low frequency loudspeaker drivers.  
Driver. See transducer.  
Capacitance. That property of a capacitor which determines  
how much charge can be stored in it for a given potential  
difference between its terminals, measured in farads, by  
the ratio of the charge stored to the potential difference.  
Dynamic Range. The range between the quietest and the  
loudest sounds a device can handle (often quoted in dB).  
Efficiency. The acoustic power delivered for a given electrical  
input. Often expressed as decibels/watt/meter (dB/w/m).  
Capacitor. A device consisting of two or more conducting  
plates separated from one another by an insulating material  
and used for storing an electrical charge. Sometimes called  
a condenser.  
ESL. Abbreviation for electrostatic loudspeaker.  
Headroom. The difference, in decibels, between the peak  
and RMS levels in program material.  
Clipping. Distortion of a signal by its being chopped off.  
An overload problem caused by pushing an amplifier beyond  
its capabilities. The flat-topped signal has high levels of  
harmonic distortion which creates heat in a loudspeaker  
and is the major cause of loudspeaker component failure.  
Hybrid. A product created by the marriage of two different  
technologies. Meant here as the combination of a dynamic  
woofer with an electrostatic transducer.  
Crossover. An electrical circuit that divides a full bandwidth  
signal into the desired frequency bands for the loudspeaker  
components.  
Hz (Hertz). Unit of frequency equivalent to the number of  
cycles per second.  
Imaging. To make a representation or imitation of the original  
dB (decibel). A numerical expression of the relative loudness  
of a sound. The difference in decibels between two  
sounds is ten times the Base 10 logarithm of the ratio of  
their power levels.  
sonic event.  
Impedance. The total opposition offered by an electric circuit  
to the flow of an alternating current of a single frequency.  
It is a combination of resistance and reactance and is  
measured in ohms. Remember that a speaker’s impedance  
changes with frequency, it is not a constant value.  
22 Glossary of Audio Terms  
 
Inductance. The property of an electrical circuit by which  
a varying current in it produces a varying magnetic field  
that introduces voltages in the same circuit or in a nearby  
circuit. It is measured in henrys.  
Resistor. A device that is used in a circuit primarily to  
provide resistance.  
Resonance. The effect produced when the natural vibration  
frequency of a body is greatly amplified by reinforcing  
vibrations at the same or nearly the same frequency from  
another body.  
Inductor. A device designed primarily to introduce inductance  
into an electrical circuit. Sometimes called a choke or coil.  
Linearity. The extent to which any signal handling process  
is accomplished without amplitude distortion.  
Sensitivity. The volume of sound delivered for a given  
electrical input.  
Midrange. The middle frequencies where the ear is the  
most sensitive.  
Stator. The fixed part forming the reference for the moving  
diaphragm in a planar speaker.  
Passive crossover. Uses no active components (transistors,  
ICs, tubes) and needs no power supply (AC, DC, battery)  
to operate. The crossover in a typical loudspeaker is of the  
passive variety. Passive crossovers consist of capacitors,  
inductors and resistors.  
THD. The abbreviation for total harmonic distortion.  
(See Distortion.)  
TIM. The abbreviation for transient intermodulation distortion.  
Transducer. Any of various devices that transmit energy  
from one system to another, sometimes one that converts  
the energy in form. Loudspeaker transducers convert electrical  
energy into mechanical motion.  
Phase. The amount by which one sine wave leads or lags a  
second wave of the same frequency. The difference is  
described by the term phase angle. Sine waves in phase  
reinforce each other; those out of phase cancel.  
Transient. Applies to that which lasts or stays but a short  
time. A change from one steady-state condition to another.  
Pink noise. A random noise used in measurements, as it has  
the same amount of energy in each octave.  
Tweeter. A small drive unit designed to produce only  
Polarity. The condition of being positive or negative with  
high frequencies.  
respect to some reference point or object.  
Wavelength. The distance measured in the direction of  
progression of a wave, from any given point characterized  
by the same phase.  
RMS. Abbreviation for root mean square. The effective  
value of a given waveform is its RMS value. Acoustic  
power is proportional to the square of the RMS sound  
pressure.  
White noise. A random noise used in measurements, as it  
has the same amount of energy at each frequency.  
Resistance. That property of a conductor by which it opposes  
the flow of electric current, resulting in the generation of  
heat in the conducting material, usually expressed in ohms.  
Woofer. A drive unit operating in the bass frequencies only.  
Drive units in two-way systems are not true woofers but  
are more accurately described as being mid/bass drivers.  
Glossary of Audio Terms 23  
 
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M A R T I N L O G A N  
2101 Delaware Street, Lawrence, Kansas 66046, USA tel 785.749.0133 fax 785.749.5320 www.martinlogan.com  
©2002 MartinLogan, All rights reserved  
Rev. #052902  
 

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