T H E A T E R TM iu s e r ’ s m a n u a l

c l s e l e c t r o s t a t i c

MA R T I N L O G A N ®

2 Contents

CONTENTS & INTRODUCTION

Contents & Introduction . . . . . . . . . . . . . . . . . . . . . . . . .2ContentsIntroduction

Installation in Brief . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Low Voltage Power ConnectionSignal ConnectionUsing Only One Power Supply . . . . . . . . . . . . . . . . . . .5Break-In

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Using the Adjustable MountInstallation OptionsRubber Bumper Feet

Stand Removal and Installation . . . . . . . . . . . . . . . . . . .7Removing the StandInstalling the Stand

Mounting the Theater i On A Wall . . . . . . . . . . . . . . . . .8Warnings and NotesAbout the Wall AnchorsMounting the Theater i

Dispersion Interactions . . . . . . . . . . . . . . . . . . . . . . . . .11Controlled Horizontal DispersionControlled Vertical DispersionThree Major Types of Dispersion

Home Theater i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Electrostatic Advantages . . . . . . . . . . . . . . . . . . . . . . . .14MartinLogan Exclusives . . . . . . . . . . . . . . . . . . . . . . . . .15

Curvilinear Line SourceTransducer IntegrityLow Voltage PowerPlasma Deposited DiaphragmControlled Dispersion ArrayMicroPerf Stator

Electrostatic Loudspeaker History . . . . . . . . . . . . . . . .16Frequently Asked Questions . . . . . . . . . . . . . . . . . . . . .18Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20General Information . . . . . . . . . . . . . . . . . . . . . . . . . . .21

SpecificationsWarranty and RegistrationService

Glossary of Audio Terms . . . . . . . . . . . . . . . . . . . . . . . .22

Congratulations! You have invested in a new world ofhome theater!

The MartinLogan Theater i represents the culmination ofan intensive, dedicated group research program directedtoward establishing a world class reference monitor utilizingleading-edge technology, without compromising durability,reliability, craftsmanship or aesthetic design.

The advantages of MartinLogan hybrid technology willpresent themselves to you from the moment the moviebegins. The box effect (a phenomenon similar to cuppingyour hand around your mouth when speaking) producedby dynamic midrange drivers is absent and the naturalopenness of the human voice comes through. Never beforein home theatre has the midrange been so clear. Sounds floataround the screen clearly defining the area from wherethey were created, not the area of the speaker that createdthem. This superior performance is made possible throughthe use of our proprietary curved electrostatic transducer.This is the same design technology that is used in state-of-the-art MartinLogan loudspeaker systems.

The materials in your new Theater i speaker are of the high-est quality and will provide years of enduring enjoymentand deepening respect. The cabinetry is constructed fromthe highest quality composite material for acoustical integrityand is finished with our attractive custom finish.

Through rigorous testing, the curvilinear electrostatic panelhas proven itself to be one of the most durable and reli-able transducers available today. Fabricated from a customtool punched high-grade steel, the patented panel is coat-ed with a special polymer that is applied via a proprietaryelectrostatic bonding process. This panel assembly housesa membrane just 0.0005 of an inch thick. Ruggedly con-structed and insulated, as much as 200 watts of continuouspower has driven the Theater i’s energized diaphragm intomassive excursions with no deleterious effects.

The other sections of your User’s Manual will explain indetail the operation of your Theater i speaker and the philoso-phy applied to their design. A clear understanding ofyour speakers will insure that you obtain maximum perfor-mance and pleasure from this most exacting transducer. It hasbeen designed and constructed to give you years of trouble-free listening enjoyment.

Contents Introduction

Installation in Brief 3

INSTALLATION IN BRIEF

We know you are eager to hear your new Theater i centerchannel, so this section is provided to allow fast and easyset up. Once you have it operational, please take the time toread, in depth, the rest of the information in this manual. Itwill give you perspective on how to attain the greatestpossible performance from this most exacting transducer.

If you should experience any difficulties in the setup oroperation of your Theater i speaker, please refer to theOperation or Installation sections of this manual.

Should you encounter a persistent problem that cannot beresolved, please contact your authorized MartinLogandealer. They will provide you with the appropriate technicalanalysis to alleviate the situation.

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.•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 drive speaker beyond its rated power.

Step 1: UnpackingRemove your new Theater i speaker from the packaging.

Step 2: PlacementPlace the Theater i directly between your front left andright speakers and point it directly at the listening position.Please see the Installation section (page 6) of this manualfor more details.

Step 3: Power Connection (see warning)The Theater i requires power to energize its electrostaticpanel. Plug the provided power supply first into the Power Inpower receptacle on the rear panel of the speaker, makingsure that you have made a firm connection, and then to aconvenient wall outlet. Please see the Operation section(pages 4–5) of this manual for more details.

Step 4: Signal ConnectionUse the best speaker cables you can. Higher quality cables,available from your specialty dealer, are recommendedand will give you superior performance. Spade connectorsare suggested for optimum contact.

Attach your speaker cables to the signal input section onthe rear panel. Be consistent when connecting speaker leadsto the terminals on the back of the Theater i. Take greatcare to assign the same color to the (+) terminal on boththe speaker and the amplifier. Please see the Operationsection (pages 4–5) of this manual for more details.

Step 5: Listen and EnjoyNow, you may turn on your system and enjoy!

The lightning bolt flash with arrowhead symbol, withinan equilateral triangle, is intended to alert the user tothe presence of uninsulated “dangerous voltage” withinthe product’s enclosure that may be of sufficient mag-nitude to constitute a risk of electric shock.

The exclamation point within an equilateral triangle isintended to alert the user to the presence of importantoperating and maintenance (servicing) instructions inthe literature accompanying the appliance.

Installation in Brief

Your Theater i uses an external low-voltage power supplyto energize its electrostatic panel. For this reason the properlow-voltage power supply is provided. The power supplyshould be firmly inserted into the ‘Power In’ receptacle onthe rear connection panel of the speaker, then to any con-venient AC wall outlet (see figure 1). Your Theater i integratesa signal sensing circuit which will switch the Theater i off aftera few minutes of no music signal, and requires less than twoseconds to recharge the panel when a music signal is present.

Your Theater i speaker is provided with a power supply forthe power service supplied in the country of original con-sumer sale. The AC power rating applicable to a particularunit is specified both on the packing carton and on thepower supply.

If you remove your Theater i speakers from the country oforiginal sale, be certain that the AC power supplied in anysubsequent location is suitable before connecting the low-voltage power supply. Substantially impaired performance orsevere damage may occur to a Theater i speaker if opera-tion is attempted from an incorrect AC power source.

WARNING! The power supply should not beinstalled, removed, or left detached from thespeaker while connected to an AC power source.

Signal Connection

Use the best speaker cables you can. The length and typeof speaker cable used in your system will have an audibleeffect. Under no circumstance should a wire of gaugehigher (thinner) than #16 be used. In general, the longerthe length used, the greater the necessity of a lower gauge,and the lower the gauge, the better the sound, withdiminishing returns setting in around #8 to #12.

A variety of speaker cables are now available whose manufacturers claim better performance than standardheavy gauge wire. We have verified this in many cases,and the improvements available are often more notice-able than the differences between wires of differentgauge. The effects of cables may be masked if the equip-ment is not of the highest quality.

We also recommend, if possible, that short runs of speakercable connect the power amplifier and speaker and that

Low-Voltage Power Connection

OPERATION

Figure 2. Single wire connection. One channel shown.

4 Operation

Figure 1. Power connection. One channel shown.

high quality long interconnect cables be used to connectthe preamplifier and power amplifier. This results in thepower amplifiers being close to the speakers, which maybe practically or cosmetically difficult, but if the length ofthe speaker cables can be reduced to a few meters, sonicadvantages may be obtained.

Connections are done at the signal input section on therear electronics panel of the Theater i (see figure 2). Usespade connectors for optimum contact. Make certain thatall of your connections are tight.

Be consistent when connecting speaker leads to the terminalson the back of the Theater i. Take great care to assign thesame color to the (+) terminal on both the speaker andthe amplifier.

WARNING! Turn your amplifier off before makingor breaking any signal connections!

Using Only One Power Supply

You may have noticed a connection on the back of yourTheater i’s labeled ‘Power Out’. The use of this connec-tion will allow you to daisy-chain up to five low-voltageMartinLogan products and eliminate the need for multiplelow-voltage power supplies.

A variety of low voltage interconnect cables may be pur-chased at your local MartinLogan dealer. Please ask themabout options to fit your specific needs.

To use this connection option choose a primary speaker(whichever speaker is most conveinent) and connect it asinstructed in the ‘Low-Voltage Power Connection’ sectionon the previous page. To attach additional speakers, run alow-voltage interconnect cable from the ‘Power Out’ tothe next speakers ‘Power In’ (see figure 3).

Break-In

When you first begin to play your Theater i speaker, it willsound a bit bass shy. This is due to the high-quality, long-lifecomponents used in our woofer. Our custom made, butylsurround woofer requires at least 30 hours of break-in at90 dB (moderate listening levels) before any critical listening.The break-in requirements of the crossover components(and, to a lesser degree, the electrostatic transducer) are equal.

Figure 3. Connecting power to multiple speakers using one power supply.

Operation 5

6 Installation

For optimum performance the Theater i must be tilted onits stand towards the main listening position and directedtowards the audiences ears (see figure 5). After you haveplaced your Theater i in its final location, loosen the 2 knobslocated on the stand arm, pivot the Theater i towards themain listening position, and then re-tighten the knobs.

The stand shipped with the Theater i loudspeakeris designed for use only with the Theater i. Usewith other appliances may result in instabilitycausing possible injury.

Installation Options

On the TelevisionIf your television provides a wide, level and stable platform,the shielded Theater i can be placed directly on top of thetelevision (see figure 5). For this option we recommendinstallation of the rubber bumper feet.

On the WallThe adjustable mount (stand) allows you to mount theTheater i on the wall (see figures 5 and “Mounting theTheater i On A Wall,” pages 8–10). If hanging the Theater ion the wall is the best placement for your system, theadjustable mount (stand) will allow you to tilt the Theater itowards the listening position.

On the FloorPlacing the Theater i on the floor will position it too low toblend with the front speakers. (see figure 5). If placing theTheater i on the floor is the best placement for your sys-tem, the adjustable mount (stand) will allow you to tilt theTheater i towards the listening position. For this option werecommend installation of the rubber bumper feet.

WARNING! Installation other than thatdescribed in the body of this document requiresspecific documentation from MartinLogan.

If you are using the Theater i on top of your television, orsetting it on any type of surface, we recommend installingthe 5 rubber bumper feet included with the Theater i.

Rubber Bumper Feet Installation Instructions:1. Prepare a surface to work on by laying down a towel or

large soft cloth on top of a large flat surface.

2. Securely tighten the 2 knobs on the theater i stand arm,making sure the Theater i cabinet is level with the stand.

3. Turn the Theater i upside down so that the bottom ofthe stand is pointing up.

4. Insert the 5 rubber bumper feet in the 5 outer holes (seefigure 4).

Using the Adjustable Mount Rubber Bumper Feet

Figure 5. Theater i installation on the floor, on a television and on a wall.

Figure 4. The Theater i stand, shown from the bottom, with bumperinsertion locations shown.

INSTALLATION

Stand Removal and Installation 7

Required Tools (not included):1/8” Allen tool

NOTE: The Theater i is intended to be used with its standattached in almost all installation options. Stand Removal andInstallation instructions are provided in case you are using acustom installation that does not require the use of the stand.

Removing the Stand

1 Support the Theater i body by placing the shipping foamon both ends of the speaker, or setting a stack of booksbeneath both ends of the speaker cabinet. The mountshould hang down from the Theater i and contact thesurface of your table or floor (see figure 6, step A).

2 Before beginning to remove the mount screws, pleasenote that the mount is held in place with 8 screws con-nected to 4 brackets. These 4 brackets are attached tothe Theater i cabinet. Do not remove these bracketsfrom the Theater i cabinet. To detach the mount, use a

1/8” Allen tool to remove 2 screws from each of the 4brackets (see figure 6, step B).

3 To remove the stand, simply pull it back, away from theTheater i cabinet (see figure 6, step C).

Installing the Stand

1 Support the Theater i body by placing the shippingfoam on both ends of the speaker, or setting a stack ofbooks beneath both ends of the speaker cabinet. Thespeaker cabinet should be raised high enough thatwhen the stand is moved into place, it can rest on thesurface of the table or floor (see figure 6, step A).

2 Carefully slide the stand into place so that it aligns withthe 4 brackets already attached to the Theater i cabinet(see figure 6, step C).

3 Using a 1/8” Allen tool insert and tighten 2 screws intoeach of the 4 brackets (see figure 6, step B).

STAND REMOVAL AND INSTALLATION

Figure 6. Stand removal and installation.

8 Mounting the Theater i On A Wall

MOUNTING THE THEATER i ON A WALL

WARNING! Installing the Theater i on the wallrequires 2 people. Do not try this alone.

Mounting the Theater i on a wall requires a mini-mum use of 1 lag bolt sunk directly into a studand 2 wall anchors. If you are able to engagemore than 1 stud with a lag bolt when mountingthe Theater i on a wall we highly recommenddoing so (see figure 10).

NOTE: To assure that your Theater i is safely wall mounted,these instructions must be carefully followed. Study themthoroughly before beginning to install your Theater i.

NOTE: The following instructions assume the mountingsurface is of standard wood frame and standard sheet rockconstruction. If you wish to mount the Theater i to anothertype of material, you should consult a bonded contractor.

About the Wall Anchors

When using the special wall anchors provided with theTheater i, it is recommended that they are sunk into thewall by hand and not by using an electric screwdriver (seefigure 7, step 1). Once the special self-drilling wall anchors(provided with the Theater i) have been set into the wall,they work as follows: after the screw has been insertedapproximately 1/2 inch into the wall anchor, the screw willhit a seal that requires slight pressure to break. Once theseal has broken, the screw will continue to slide into thewall anchor another 11/2 inch. At this point the screw willhave rotated the anchor out and into position inside ofyour wall (see figure 7, step 2 and 3). The screw will nowrequire slight pressure to engage the anchor. When theanchor has been engaged, the screw will continue to slideinto the wall anchor until it is flush (see figure 7, step 4).You will notice however that the screw continues to freelyturn at this point. The screw is now pulling the anchor upagainst the back of the drywall. The screw will tighten andstop turning when it has securely engaged the anchor withthe back of the drywall (see figure 7, step 5).

Required Tools (not included):24 inch (60 cm) or longer ruler, level, pencil, electric drill,1/8 inch (3 mm) drill bit, Phillips head bit, 7/16 inch (11 mm)socket wrench, #2 Phillips head screw driver

Required Hardware (included, see figure 9):(2) wall anchors, (2) Z-brackets, (2) 21/8 inches (5.4 cm) sheetmetal Phillips head screws, (2) lag bolts, (4) washers

1. Locate and mark the center point (point A, see figure 11)where you would like to position the top of the Theater i.Measure 24 inches (61 cm) horizontally in each direc-tion from the center point. This area should be clear ofany obstructions in order to mount the Theater i. Alsomake certain that there will be at least 12 inches (30.5cm) of clearance above or below in order to access theknobs and tilt the speaker up and down.

2. Using a level, vertically measure down 23/8 inches (6 cm)from point A and mark this point (point B, see figure 11).Next, measure horizontally to the left of point B a minimumof 23/4 inches (7 cm) and mark the nearest stud or put amark at 13 inches (33 cm), whichever comes first (point C,see figure 11). Repeat the same to the right of point B(point D, see figure 11). Pre-drill holes at points C andD with a 1/8 inch (3 mm) size drill bit.

3. If point(s) C and/or D are on a stud:Using a 7/16 inch (11 mm) socket, attach a Z-bracket topoint(s) C and/or D with a lag bolt, making sure that thebolt engages the stud. Make sure that the Z-bracket issnug to the wall, but not overly tightened (see figure 8).

If point(s) C and/or D are not on a stud:Using a #2 Phillips screwdriver, drive a wall anchor intopoint(s) C and/or D. Next, attach a Z-bracket by sinkinga 21/8 inch (5.4 cm) sheet metal Phillips head screw andwasher into the wall anchor (see "About the Wall Anchors"and figure 7). Make sure that the Z-bracket is snug tothe wall, but not overly tightened.

NOTE: When the Z-bracket is properly installed on a wall,its thickest half should hang down, and its thinner halfshould point up. The bend at the top of the Z-bracketshould point away from the wall.

Mounting the Theater iWarnings and Notes

Mounting the Theater i On A Wall 9

Figure 9. Hardware included with the Theater i.

Figure 10. The Theater i mounted in various stud configurations. Front View.Please note, to simplify this illustration, the stand is shown without theTheater i attached. When mounting the Theater i, the stand should not beremoved. The Lag Bolts, Walls Anchors, and Z-Brackets are also exagger-ated in size to make this illustration easier to read.

Figure 7. Using wall anchors for points C and/or D. Side view.

Figure 8. Using lag bolts for points C and/or D. Side view.

10 Mounting the Theater i On A Wall

4. Using a level, vertically measure down from point B41/16 inches (10.3 cm) and mark this point (point E, seefigure 11).

5. If point E is on, or horizontally within 21/2 inches(6.3 cm) of a stud:Using a level, mark a point (point F, see figure 11) hori-zontal to Point E on the stud that is within 21/2 inches(6.3 cm) of point E. Next, pre-drill a hole at point F witha 1/8 inch (3mm) size drill bit.

If point E is not within 21/2 inches (5 cm) of a stud:Using a #2 Phillips screwdriver, drive a wall anchor intothe wall at point E (see figure 7, step 1).

6. With the Theater i mount sitting on a flat surface, loosenthe knobs on the stand arm and pivot the Theater i onthe stand so that the front of the speaker is facing up.Re-tighten the knobs. With the help of a second person,lift the speaker up, and rotate it (mount and all) so that themount is parallel to the wall. Hang the Theater i on theZ-brackets and position the speaker so that point E (or F)lines up with the long hole in the stand, above the cut-out MartinLogan zig logo. The second person shouldcontinue to support the speaker once it is in place. At thispoint the Theater i and mount can be carefully slid tothe left or right to fine tune its position.

7. For this step you may need to loosen the knobs on thestand arm, pivot the speaker enough that you can accessthe lower center point, and re-tighten the knobs.

If point E is on, or horizontally within 21/2 inches(6.3 cm) of a stud:Using a 7/16 inch (11 mm) socket, sink a lag bolt and awasher into point F, making sure that the bolt engagesthe stud (see figure 8).

If point E is not within 21/2 inches (6.3 cm) of a stud:Using a short handled Phillips screwdriver or electricdrill, sink a 21/8 inch (5.4 cm) sheet metal Phillips headscrew and washer into the wall anchor at point E (see fig-ure 7 and "About the Wall Anchors" on page 8).

8. Securely tighten all of the lag bolts and screws. The secondperson may now release the Theater i.

9. To direct the speaker to the desired listening position,support the Theater i with one hand, slightly loosen theknobs on either side of the stand arm, and rotate theTheater i to its desired listening position. Securely re-tight-en both knobs.

Figure 11. Measurements and point locations required to mount the Theater i. Please note, to simplify this illustration, the stand is shown without the Theater iattached. When mounting the Theater i, the stand should not be removed.

Dispersion Interactions 11

The convex electrostatic panel launches a 30 degree dis-persion pattern when viewed from above. This horizontaldispersion field gives you a choice of good seats for theperformance while minimizing interaction with side walls(see figure 12).

As you can see below (see figure 13), your Theater i speakerprojects a controlled dispersion pattern. This vertical dis-persion profile minimizes interactions with the floor andthe ceiling. The controlled dispersion triple dipole arrayextends the frequency range over which this happens.

Controlled Horizontal Dispersion Controlled Vertical Dispersion

Figure 12. The MartinLogan Theater i delivers a 30 degree wave launchdispersion pattern distributed horizontally.

Figure 13. The MartinLogan Theater i vertical dispersion profile mini-mizes interactions with the floor and ceiling.

DISPERSION INTERACTIONS

12 Dispersion Interactions

Figure 14–15. As can be seen here, point sourceconcepts invite a great deal of room interaction.While delivering good frequency response to alarge listening audience, imaging is consequentlyconfused and blurred.

Figure 16–17. Even though they suffer from“venetian blind” effect, angled multiple panelspeakers can deliver good imaging, but onlyto specific spots in the listening area.

Figure 18–19. A controlled 30-degree cylindricalwave-front, which is a MartinLogan exclusive,offers optimal sound distribution with minimalroom interaction. The result is solid imaging witha wide listening area.

In the field of loudspeaker design, it is a known fact that asthe sound wave becomes progressively smaller than thetransducer producing it, the dispersion of that wavebecomes more and more narrow, or directional. This factoccurs as long as the transducer is a flat surface. Large flatpanel speakers exhibit venetian blind effects due to thisphenomenon. This is why most manufacturers opt forsmall drivers (i.e. tweeters and midrange) to approximatewhat is known as a point source wave launch.

Historically, most attempts to achieve smooth dispersionfrom large flat panel transducers resulted in trade-offs.After exhaustive testing of these different solution attempts,we found an elegantly simple, yet difficult to execute solu-tion. By curving the radiating surface, we create the effect ofa horizontal arc. This allows the engineers at MartinLogan tocontrol the high frequency dispersion pattern of our trans-ducers. That is why you see the gentle curve on our products.

Three Major Types of Dispersion

HOME THEATER

Home Theater 13

It had long been the practice of stereo buffs to connect theirtelevision to a stereo system. The advantage was the use ofthe larger speakers and more powerful amplifier of thestereo system. Even though the sound was greatly improved, itwas still mono and limited by the broadcast signal.

In the late 1970’s and early ‘80’s two new home movieformats became widely available to the public: VCR andlaser disc.

By 1985, both formats had developed into very high qualityaudio/video sources. In fact, the sonic performance of somevideo formats exceeded audio-only formats. Now, withtheater quality sound available at home, the only elementmissing was the "surround sound" presentation found inmovie houses.

Fortunately, "Dolby” and “DTS" encoded movies (whichinclude almost all movies) have the same surround soundinformation encoded on home releases as the theater films.All that is required to retrieve this information is a decoderand additional speakers and amps to reproduce it.

Home Theater is a complex purchase and we recommendthat you consult your local MartinLogan dealer as they arewell versed in this subject.

Each piece of a surround system can be purchasedseparately. Take your time and buy quality. No one hasever complained that the movie was too real. The followinglist and descriptions will only give you a brief outline of theresponsibilities and demands placed on each speaker.

Front Left and Front RightIf these speakers will also be the same two used for yourstereo playback then they should be of very high qualityand able to play loud (over 102 dB) and reproduce bassbelow 80 Hz.

Center Channel.This is the most important speaker in a video system, asalmost all of the dialogue and a large portion of the frontspeaker information is reproduced by the center channel.It is important that the center speaker be designed bythe same manufacturer as the front speakers, and that it isrecommended for use as a center speaker. This is not theplace to cut corners.

Surround Speakers.We recommend that the surround speakers play downto 80 Hz or below. The surround speakers contain theinformation that makes it appear that planes are flying overyour head. Some may suggest that this is the place to savemoney and purchase a small inexpensive speaker. If youchoose to do so, be prepared to upgrade in the future asdiscrete six channel digital encoding becomes availableand the demands on the surround speakers increase.

Subwoofer.With any good surround system you will need a high-qualitysubwoofer (the .1 in a 5.1 channel surround system). Mostmovie soundtracks contain large amounts of bass informa-tion as part of the special effects. Good subwoofers willprovide a foundation for the rest of the system.

Figure 20. Ascent i speakers as front channels, Theater i as the center channel,Script i speakers as side surround (effects) channels, and Depth subwoofersas 0.1 (effects) channel.

Home Theater

How can sound be reproduced by something that you areable to see through? Electrostatic energy makes this possible.

Where the world of traditional loudspeaker technologydeals with cones, domes, diaphragms and ribbons thatare moved with magnetism, the world of electrostaticloudspeakers deals with charged electrons attracting andrepelling each other.

To fully understand the electrostatic concept, some backgroundinformation will be helpful. Remember when you learnedin a science or physics class that like charges repel eachother and opposite charges attract each other? Well, thisprinciple is the foundation of the electrostatic concept.

An electrostatic transducer consists of three pieces: the stators,the diaphragm and the spacers (see figure 21). The diaphragmis 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 inwhich to move between the stators.

As your amplifier sends music signals to an electrostaticspeaker, these signals are changed into two high-voltagesignals 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 opposinghigh voltage on the stators, works simultaneously withand against the diaphragm, consequently moving it backand forth, producing music. This technique is known as

push-pull operation and is a major contributor to the sonicpurity of the electrostatic concept due to its exceptionallinearity and low distortion.

Since the diaphragm of an electrostatic speaker is uniformlydriven over its entire area, it can be extremely light andflexible. This allows it to be very responsive to transients,thus perfectly tracing the music signal. As a result, greatdelicacy, nuance and clarity is possible. When you look atthe problems of traditional electromagnetic drivers, youcan easily see why this is so beneficial. The cones anddomes which are used in traditional electromagneticdrivers cannot be driven uniformly because of their design.Cones are driven only at the apex. Domes are driven attheir perimeter. As a result, the rest of the cone or domeis just “along for the ride”. The very concept of thesedrivers requires that the cone or dome be perfectly rigid,damped and massless. Unfortunately, these conditions arenot available in our world today.

To make these cones and domes move, all electromagneticdrivers must use voice coils wound on formers, spiderassemblies, and surrounds to keep the cone or dome inposition (see figure 22). These pieces, when combinedwith the high mass of the cone or dome materials used,make it an extremely complex unit with many weaknessesand potential for failure. These faults contribute to thehigh distortion products found in these drivers and is atremendous disadvantage when you are trying to changemotion as quickly and as accurately as a loudspeakermust (40,000 times per second!).

Figure 21. Cut away view of an electrostatic transducer. Notice the sim-plicity due to minimal parts usage.

Figure 22. Cut away view of a typical moving coil driver. Notice the com-plexity due to the high number of parts.

ELECTROSTATIC ADVANTAGES

14 Electrostatic Advantages

Electrostatic Advantages

Since audio began, achieving smooth dispersion has been aproblem for loudspeaker designers. Full range electrostatshave long been one of the most problematic transducersbecause they attain their full range capabilities via a largesurface area. It looked as if they were in direct conflict tosmooth dispersion and almost every attempt to correct thisresulted in either poor dispersion or a serious compromisein sound quality.

After extensive research, MartinLogan engineers discoveredan elegantly simple solution to achieve a smooth patternof dispersion without degrading sound quality. By curvingthe horizontal plane of the electrostatic transducer, a con-trolled horizontal dispersion pattern could be achieved, yetthe purity of the almost massless electrostatic diaphragmremained uncompromised. After creating this technology,MartinLogan developed the production capability to bringit out of the laboratory and into the market place.

You will find this proprietary MartinLogan technology used inall of our products. It is one of the many reasons behind ourreputation for high quality sound with practical usability.This is also why you see the unique “see through” cylindricalshape of all MartinLogan products.

Transducer Integrity

All MartinLogan transducers begin with two pieces of high-grade, cold rolled steel. These steel pieces are then customperforated and insulated with a unique composite coating.This proprietary coating insulates the stator to three timesits actual needed working voltage and gives the Theater i awide margin of safe operation. In addition to the electricalinsulation properties, this coating also provides the Theater iwith a durable, attractive finish that dampens the steel toprevent ringing. These pieces then sandwich a proprietarydiaphragm and spacers into a curved geometry, and bondtogether with aerospace adhesives whose strength exceedsthat of welding.The result of these advanced technologiesis a transducer that is attractive, durable, highly rigid, welldampened, and neutral.

Low Voltage Power

To eliminate the need for a traditional IEC power cord andbroaden ease of installation, especially for custom installers,the Theater i features a low-voltage power supply.

The diaphragm in the Theater i employs an extremely sophis-ticated conductive surface that has been applied to thepolymer surface at an atomic level using a plasma bondingprocess. A proprietary compound is driven into the surfaceof the polymer film in an oxygen free argon chamber. Thisprocess allows extremely uniform surface resistivity character-istics, an optically transparent surface and adds no mass tothe diaphragm. This uniform surface resistivity controls theelectrostatic charge on the diaphragm surface and regulatesits migration. As a result, no discharging or “arcing” can occur.

Controlled Dispersion Array

The Theater i matches the dispersion and detail characteris-tics of our other CLS electrostatic speaker systems whilelimiting floor and ceiling reflections. The result is a seamlesssoundstage and perfect clarity throughout your home theater.In order to provide a high frequency dispersion pattern thatmatches other MartinLogan speakers, we've added a highfrequency controlled dispersion array to the Theater i. TheTheater i dispersion array consists of three proprietary highfrequency drivers and specially engineered electronics whichmaintain an expanded yet exact vertical dispersion patternthroughout the high frequency spectrum.

Theater i's Dispersion Array also eliminates lobbing, a non-uniform pattern resulting from closely spaced wide-dispersiontransducers firing a signal in the same direction. This isaddressed by configuring the center driver to play only atfrequencies above 8000Hz. Above 3000Hz output of theupper and lower drivers is limited. Above 10,000Hz, thecentral driver begins to narrow it's dispersion.

MicroPerfTM Stator

The MicroPerf stator design reduces the size of individualholes in a stator, allowing more openings per square inch thana standard MartinLogan stator. This maximizes efficiencyand dispersion of small stat panels and also increases opticalclarity. In addition, the tighter grid of holes permits the MicroPerf stator to drive the diaphragm extremely uniformly.

Curvilinear Line Source (CLSTM) Plasma Deposited Diaphragm

MartinLogan Exclusives 15

MARTINLOGAN EXCLUSIVES

16 Electrostatic Loudspeaker History

ELECTROSTATIC LOUDSPEAKER HISTORY

In the late 1800s, any loudspeaker was considered exotic.Today, most of us take the wonders of sound reproductionfor granted.

It was 1880 before Thomas Edison had invented the firstphonograph. This was a horn-loaded diaphragm that wasexcited by a playback stylus. In 1898, Sir Oliver Lodgeinvented a cone loudspeaker, which he referred to as a “bellowing telephone”, that was very similar to theconventional cone loudspeaker drivers that we knowtoday. However, Lodge had no intention for his device toreproduce music because in 1898 there was no way toamplify an electrical signal! As a result, his speaker hadnothing to offer over the acoustical gramophones of theperiod. It was not until 1906 that Dr. Lee DeForrest invent-ed the triode vacuum tube. Before this, an electrical signalcould not be amplified. The loudspeaker, as we know ittoday, 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 areality. This method of recording was far superior to themechanically cut record and possessed almost 30 dB ofdynamic range. The acoustical gramo-phone couldn’t begin to reproduce allof the information on this new disc. Asa result, further developments in loud-speakers were needed to cope withthis amazing new recording medium.

By 1923, Bell Telephone Laboratories made the decision todevelop a complete musical playback system consisting of anelectronic phonograph and a loudspeaker to take advantageof the new recording medium. Bell Labs assigned the pro-ject to two young engineers, C.W. Rice and E.W. Kellogg.

Rice and Kellogg had a well equipped laboratory at theirdisposal. This lab possessed a vacuum tube amplifier withan unheard of 200 watts, a large selection of the newelectrically cut phonograph records and a variety ofloudspeaker prototypes that Bell Labs had been collectingover the past decade. Among these were Lodge’s cone, aspeaker that used compressed air, a corona discharge(plasma) speaker, and an electrostatic speaker.

After a short time, Rice and Kellogg had narrowed the fieldof “contestants” down to the cone and the electrostat. Theoutcome 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. Thediaphragm, which was beginning to rot, was made of apig intestine that was covered with fine gold leaf to con-duct the audio signal.

When Rice and Kellogg began playing the new electricallycut records through the electrostat, they were shockedand impressed. The electrostat performed splendidly.They had never heard instrumental timbres reproducedwith such realism. This system sounded like real musicrather than the honking, squawking rendition of theacoustic gramophone. Immediately, they knew they wereon to something big. The acoustic gramophone was des-tined to become obsolete.

Due to Rice and Kellogg’s enthusiasm, they devoted aconsiderable amount of time researching the electrostaticdesign. However, they soon encountered the same diffi-culties that even present designers face; planar speakers

require a very large surface area toreproduce the lower frequencies ofthe audio spectrum. Because themanagement at Bell Labs consideredlarge speakers unacceptable, Riceand Kellogg’s work on electrostaticswould never be put to use for a com-

mercial product. Reluctantly, they advised the Bellmanagement to go with the cone. For the next 30 years,the electrostatic design lay dormant.

During the Great Depression of the 1930s, consumer audioalmost died. The new electrically amplified loudspeakernever gained acceptance, as most people continued to usetheir old Victrola-style acoustic gramophones. Prior to theend of World War II, consumer audio saw little, if any,progress. However, during the late 1940s, audio experi-enced a great rebirth. Suddenly there was tremendousinterest in audio products, and with that, a great demandfor improved audio components. No sooner had the conebecome established than it was challenged by productsdeveloped during this new rebirth.

In 1947, Arthur Janszen, a young Naval engineer, took part ina research project for the Navy. The Navy was interested in

Rice and Kellogg hadnarrowed the field of

“contestants” down to thecone and the electrostat.

ESL History

Electrostatic Loudspeaker History 17

developing a better instrument for testing microphonearrays. The test instrument needed an extremely accuratespeaker, but Janszen found that the cone speakers of theperiod were too nonlinear in phase and amplitude responseto meet his criteria. Janszen believed that electrostats wereinherently more linear than cones, so he built a model usinga thin plastic diaphragm treated with a conductive coating.This model confirmed Janszen’s beliefs, for it exhibitedremarkable phase and amplitude linearity.

Janszen was so excited with the resultsthat he continued research on the elec-trostatic speaker on his own time. Hesoon thought of insulating the stators toprevent the destructive effects of arcing.By 1952, he had an electrostatic tweeterelement ready for commercial produc-tion. This new tweeter soon created a sensation amongAmerican audio hobbyists. Since Janszen’s tweeter elementwas limited to high frequency reproduction, it often founditself used in conjunction with woofers—most notably,those from Acoustic Research. These systems were highlyregarded by all audio enthusiasts.

As good as these systems were, they would soon be sur-passed by another electrostatic speaker.

In 1955, Peter Walker published three articles regardingelectrostatic loudspeaker design in Wireless World, aBritish magazine. In these articles, Walker demonstratedthe benefits of the electrostatic loudspeaker. He explainedthat electrostatics permit the use of diaphragms that arelow in mass, large in area and uniformly driven over theirsurfaces by electrostatic forces. Due to these characteristics,electrostats have the inherent ability to produce a widebandwidth, flat frequency response with distortion productsbeing no greater than the electronics driving them.

By 1956, Walker backed up his articles by introducing a con-sumer product, the now famous Quad ESL. This speakerimmediately set a standard of performance for the audioindustry due to its incredible accuracy. However, in actualuse, the Quad had a few problems. It could not be playedvery loud, it had poor bass performance, it presented adifficult load that some amplifiers did not like, its dispersionwas very directional and its power handling was limited toaround 70 watts. As a result, many people continued touse box speakers with cones.

In the early 1960s Arthur Janszen joined forces with theKLH loudspeaker company, and together they introducedthe KLH 9. Due to the large size of the KLH 9, it did nothave as many limitations as the Quad. The KLH 9 couldplay markedly louder and lower in frequency than theQuad ESL. Thus a rivalry was born.

Janszen continued to develop electrostatic designs. Hewas instrumental in the design of the Koss Model One, the

Acoustech and the Dennesen speak-ers. Roger West, the chief designerof the Janszen Corporation, becamethe president of Sound Lab. WhenJanszen Corporation was sold, theRTR loudspeaker company boughthalf of the production tooling. Thistooling was used to make the elec-

trostatic panels for the Servostatic, a hybrid electrostaticsystem that was Infinity’s first speaker product. Othercompanies soon followed; each with their own uniqueapplications of the technology. These include Acoustat,Audiostatic, Beverage, Dayton Wright, Sound Lab and Stax,to name a few.

Electrostatic speakers have progressed and prosperedbecause they actually do what Peter Walker claimed theywould. The limitations and problems experienced in thepast were not inherent to the electrostatic concept. Theywere related to the applications of these concepts.

Today, these limitations have been resolved. Advancementsin materials due to the U.S. space program give designersthe ability to harness the superiority of the electrostaticprinciple. Today’s electrostats use advanced insulationtechniques or provide protection circuitry. The poor disper-sion properties of early models have been addressed byusing delay lines, acoustical lenses, multiple panel arraysor, as in our own products, by curving the diaphragm.Power handling and sensitivity have also been increased.

These developments allow the consumer the opportunityto own the highest performance loudspeaker products everbuilt. It’s too bad Rice and Kellogg were never able to seejust how far the technology would be taken.

These developments allowthe consumer to own the

highest performance loud-speaker products ever built.

18 Frequently Asked Questions

FREQUENTLY ASKED QUESTIONS

How do I clean my speakers?Just use a dust free cloth or a soft brush to remove the dustfrom your speakers. We recommend a specialty cloth(available at the Xtatic shop at www.martinlogan.com)that cleans your speakers better than anything else wehave tried. Do not spray any kind of cleaning agenton or in close proximity to the electrostatic element.

What is the advantage of ESL? Since the diaphragm is uniformly driven over its entiresurface—unlike a tweeter that is only driven at its edges—it is the only technology that can be made large enough toplay bass, yet is still light enough for high frequencies. Thisunique property allows for the elimination of high fre-quency crossover points and their associated distortions.

What size amplifier should I use? We recommend an amplifier with 100 to 200 watts perchannel for most applications. Probably less would beadequate for our smaller hybrids or when used in hometheater where a subwoofer is employed. Our hybriddesigns will perform well with either a tube or transis-torized amplifier, and will reveal the sonic character ofeither type. However, it is important that the amplifier bestable operating into varying impedance loads: a stableamplifier will be able to deliver twice its rated wattageinto 4 Ohms and should again double into 2 Ohms.

Could you suggest a list of suitable electronics andcables that would be ideal for MartinLogan speakers?

The area of electronics and cable choice is probably themost common type of question that we receive. It isalso the most subjective. We have repeatedly foundthat brands that work well in one setup will drive some-one else nuts in another. We use many brands withgreat success. Again, we have no favorites; we use elec-tronics and cables quite interchangeably. We wouldsuggest listening to a number of brands—and above allelse—trust your ears. Dealers are always the bestsource for information when purchasing additionalaudio equipment.

Is there likely to be any interaction between my speakersand the television in my Audio/Video system?

Actually, there is less interaction between a televisionand an electrostatic speaker than between a televisionand a conventional system. However, we do recom-mend that you keep your speakers at least one footaway from the television because of the dynamic wooferthey employ. In the case of our center channel speakers,however, they are fully shielded and can go anywhere.

Will my electric bill go ‘sky high’ by leaving my speakersplugged in all the time?

No. A pair of MartinLogans will draw about 5 watts max-imum. There is circuitry to turn off the static charge whennot in use; however, actual consumption will remain closeto the same. The primary purpose of the sensing circuitryis to prevent dust collection on the electrostatic element.

If the diaphragm is punctured with a pencil or similaritem, how extensive would the damage to the speaker be?

Our research department has literally punctured hundredsof holes in a diaphragm, neither affecting the quality ofthe sound nor causing the diaphragm to rip. However,you will be able to see the actual puncture and it canbe a physical nuisance. If this is the case, replacing theelectrostatic transducer will be the only solution.

Will exposure to sunlight affect the life or performanceof my speakers?

We recommend that you not place any loudspeaker indirect sunlight. The ultraviolet (UV) rays from the sun cancause deterioration of grill cloth, speaker cones, etc. Smallexposures to UV will not cause a problem. In general,the filtering of UV rays through glass will greatly reducethe negative effects on the electrostatic membrane itself.

Frequently Asked Questions

Frequently Asked Questions 19

Will excessive smoke or dust cause any problems withmy electrostatic speakers?

Exposure to excessive contaminants such as smokeor dust may potentially affect the performance of theelectrostatic membrane, and may cause discolorationof the diaphragm membrane. When not in use forextended periods, you should unplug the speakers andcover them with the plastic bags in which the speakerswere originally packed. It is a good idea to vacuum theelectrostatic portion of each speaker once or twice ayear. See the vacuuming FAQ.

A problem has recently developed with my MartinLoganspeakers. The right speaker seems to be hissing evenwhen the amplifier and such are not connected. I waswondering if this sounds like any problem you haveencountered previously and have a simple solution foror might it be something which will need to be lookedinto more carefully.

Your speakers are dusty. See the vacuuming FAQ. Theelectrostatic charge on the element has attracted airbornedust or pollen. Since 1993, all of our speakers have beenbuilt with a charging circuit board that only charges theelectrostatic element when music plays. At other timesthey are not charged and cannot collect dust. You can getthe same benefit by simply unplugging them wheneverthey are not in use. A power strip is an easy way to do that.

Could my children, pets, or myself be shocked by thehigh-voltage present in the electrostatic panel?

No. High voltage with low current is not dangerous. As amatter of fact, the voltage in our speakers is 10 timesless than the static electricity that builds up on the surfaceof your television screen.

How do MartinLogan speakers hold up over a long termin the humidity of tropical climates?

We should tell you that MartinLogan indeed has a verysubstantial number of customers in tropical regions ofthe world. Our speakers have been serving them nicely formany years. This concern may have come from our earlierdesign of speakers, which were charged continuously.Since 1993, all of our speakers have been designed so thatthey only charge the panel while music is being played.This improvement has made a tremendous differencein the consistent performance of our product. There maybe a little more maintenance involved in humid regionswhen not in an air conditioned environment. Simplyenough, the concern is to keep the electrostatic panelsdust free. Humidity will combine with any dust on thepanel to make it slightly conductive. This will result in aslight pathway for the charge to leave the membrane ofthe speaker. The solution is simple. They only requireoccasional vacuuming with a strong vacuum hose.

How do I vacuum my MartinLogan speakers?Vacuuming will be most effective if the speakers havebeen unplugged for six hours or overnight. You neednot worry about the vacuum pressure damaging the"delicate" membrane. It is extraordinarily durableDirt and dust may be vacuumed off with a brush attach-ment connected to your vacuum cleaner, or you mayblow them off with compressed air.

Should I unplug my speakers during a thunderstorm? Yes, or before. It’s a good idea to disconnect all of youraudio/video components during stormy weather.

20 Troubleshooting

TROUBLESHOOTING

No Output• Check that all your system components are turned on.• Check your speaker wires and connections.• Check all interconnecting cables.

Weak Output from Electrostatic Panel, Loss of Highs• Check the power cord. Is it properly connected to the

speaker and to the wall?• Is the power cord connected to a switched outlet?• Dirt and dust may need to be vacuumed off. Please see

the FAQ regarding vacuuming.

Popping and Ticking Sounds, Funny Noises• These occasional noises are harmless and will not hurt

your audio system or your speakers. All electrostaticspeakers are guilty of making odd noises at one time oranother. It is the result of airborne contaminates (mostnotably dust). Vacuuming is recommended.

• These noises may be caused by dirt and dust particlescollecting on the speaker, by high humidity.

• Dirt and dust may need to be vacuumed off. Please seethe FAQ regarding vacuuming.

Troubleshooting

The Theater i hybrid speaker system consists of a broad-range single element electrostatic transducer integrated witha quick-response woofer. This approach takes advantage ofthe benefits that both technologies have to offer. Dispersionis a controlled 30 degrees. This was achieved by curvingthe electrostatic transducer element itself, an elegantlysimple solution.

System Frequency Response70–22,000 Hz ± 3 dB

Dispersion30 degrees

Sensitivity90 dB/2.83 volts/meter

ImpedanceNominal: 4 ohms, Minimum: 3.1 ohms @ 140 Hz

Crossover Frequencies300, 3000 Hz

Woofer TypeTwo 6.5” (16.5cm) magnetically shielded. Non-resonanceasymmetrical chamber format.

CLSTM Mid-RangePatented CLSTM (curvilinear line source) electrostatic transducer

High Frequency DriversThree 1” (2.7cm) soft dome, controlled dispersion array

Power Handling250 watts rms

Weight (With Mount/Stand)57 lbs. (26kg)

Size (Without Mount/Stand)43 inches W × 11.5 inches D × 10.5 inches H(109.2cm W × 29.2cm D × 26.7cm H)

Size (With Mount/Stand)43 inches W × 11.5 inches D × 13 inches H(109.2cm W × 29.2cm D × 33cm H)

Your Theater i speaker is provided with an automatic Limited90 Day Warranty coverage.

You have the option, at no additional charge, to receive aLimited 5 Year Warranty coverage. To obtain the Limited5 Year Warranty coverage you need to complete and returnthe Certificate of Registration, included with your speakers,and provide a copy of your dealer receipt, to MartinLoganwithin 30 days of purchase.

For your convenience MartinLogan also offers online warrantyregistration at www.martinlogan.com.

MartinLogan may not honor warranty service claims unlesswe have a completed Warranty Registration card on file!

If you did not receive a Certificate of Registration withyour new Theater i speaker, you cannot be assured of hav-ing received new units. If this is the case, please contactyour authorized MartinLogan dealer.

Service

Should you be using your MartinLogan product in a countryother than the one in which it was originally purchased,we ask that you note the following:

1 The appointed MartinLogan distributor for any givencountry is responsible for warranty servicing only onunits distributed by or through it in that country inaccordance with its applicable warranty.

2 Should a MartinLogan product require servicing in acountry other than the one in which it was originallypurchased, the end user may seek to have repairs per-formed by the nearest MartinLogan distributor, subjectto that distributor’s local servicing policies, but all costof repairs (parts, labor, transportation) must be born bythe owner of the MartinLogan product.

3 If, after owning your speakers for six months, yourelocate to a country other than the one in whichyou purchased your speakers, your warranty may betransferable. Contact MartinLogan for details.

General Information 21

GENERAL INFORMATION

Warranty and RegistrationSpecifications

AC. Abbreviation for alternating current.

Active crossover. Uses active devices (transistors, ICs, tubes)and some form of power supply to operate.

Amplitude. The extreme range of a signal. Usually measuredfrom the average to the extreme.

Arc. The visible sparks generated by an electrical discharge.

Bass. The lowest frequencies of sound.

Bi-Amplification. Uses an electronic crossover, or line-levelpassive crossover, and separate power amplifiers for thehigh and low frequency loudspeaker drivers.

Capacitance. That property of a capacitor which determineshow much charge can be stored in it for a given potentialdifference between its terminals, measured in farads, bythe ratio of the charge stored to the potential difference.

Capacitor. A device consisting of two or more conductingplates separated from one another by an insulating materialand used for storing an electrical charge. Sometimes calleda condenser.

Clipping. Distortion of a signal by its being chopped off. Anoverload problem caused by pushing an amplifier beyond itscapabilities. The flat-topped signal has high levels of harmon-ic distortion which creates heat in a loudspeaker and is themajor cause of loudspeaker component failure.

CLS. The abbreviation for curvilinear linesource.

Crossover. An electrical circuit that divides a full bandwidthsignal into the desired frequency bands for the loudspeakercomponents.

dB (decibel). A numerical expression of the relative loud-ness of a sound. The difference in decibels between twosounds is ten times the Base 10 logarithm of the ratio oftheir power levels.

DC. Abbreviation for direct current.

Diffraction. The breaking up of a sound wave caused bysome type of mechanical interference such as a cabinetedge, grill frame or other similar object.

Diaphragm. A thin flexible membrane or cone that vibratesin response to electrical signals to produce sound waves.

Distortion. Usually referred to in terms of total harmonicdistortion (THD) which is the percentage of unwantedharmonics of the drive signal present with the wanted signal.Generally used to mean any unwanted change introducedby the device under question.

Driver. See transducer.

Dynamic Range. The range between the quietest and theloudest sounds a device can handle (often quoted in dB).

Efficiency. The acoustic power delivered for a given electricalinput. Often expressed as decibels/watt/meter (dB/w/m).

ESL. The abbreviation for electrostatic loudspeaker.

Headroom. The difference, in decibels, between the peakand RMS levels in program material.

Hybrid. A product created by the marriage of two differenttechnologies. Meant here as the combination of a dynamicwoofer with an electrostatic transducer.

Hz (Hertz). Unit of frequency equivalent to the number ofcycles per second.

Imaging. To make a representation or imitation of the originalsonic event.

Impedance. The total opposition offered by an electric circuitto the flow of an alternating current of a single frequency. Itis a combination of resistance and reactance and is measuredin ohms. Remember that a speaker’s impedance changeswith frequency, it is not a constant value.

22 Glossary of Audio Terms

GLOSSARY OF AUDIO TERMS

Glossary of Audio Terms

Inductance. The property of an electrical circuit by which avarying current in it produces a varying magnetic field thatintroduces voltages in the same circuit or in a nearby circuit.It is measured in henrys.

Inductor. A device designed primarily to introduce inductanceinto an electrical circuit. Sometimes called a choke or coil.

Linearity. The extent to which any signal handling processis accomplished without amplitude distortion.

Midrange. The middle frequencies where the ear is themost sensitive.

NAC. The abbreviation for natural ambience compensation.

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 thepassive variety. Passive crossovers consist of capacitors,inductors and resistors.

Phase. The amount by which one sine wave leads or lags asecond wave of the same frequency. The difference isdescribed by the term phase angle. Sine waves in phasereinforce each other; those out of phase cancel.

Pink noise. A random noise used in measurements, as ithas the same amount of energy in each octave.

Polarity. The condition of being positive or negative withrespect to some reference point or object.

RMS. Abbreviation for root mean square. The effective valueof a given waveform is its RMS value. Acoustic power isproportional to the square of the RMS sound pressure.

Resistance. That property of a conductor by which it opposesthe flow of electric current, resulting in the generation ofheat in the conducting material, usually expressed in ohms.

Resistor. A device used in a circuit to provide resistance.

Resonance. The effect produced when the natural vibra-tion frequency of a body is greatly amplified by reinforcingvibrations at the same or nearly the same frequency fromanother body.

Sensitivity. The volume of sound delivered for a given elec-trical input.

Stator. The fixed part forming the reference for the movingdiaphragm in a planar speaker.

THD. The abbreviation for total harmonic distortion. (SeeDistortion)

TIM. The abbreviation for transient intermodulation distortion.

Transducer. Any of various devices that transmit energy fromone system to another, sometimes one that converts theenergy in form. Loudspeaker transducers convert electricalenergy into mechanical motion.

Transient. Applies to that which lasts or stays but a shorttime. A change from one steady-state condition to another.

Tweeter. A small drive unit designed to reproduce onlyhigh frequencies.

Wavelength. The distance measured in the direction ofprogression of a wave, from any given point characterizedby the same phase.

White noise. A random noise used in measurements, as ithas the same amount of energy at each frequency.

Woofer. A drive unit operating in the bass frequencies only.Drive units in two-way systems are not true woofers butare more accurately described as being mid/bass drivers.

Glossary of Audio Terms 23

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