Loudspeaker-Types, designs, Application & Crossover

A loudspeaker is an electro acoustic transducer; a device which converts an electrical audio signal into a corresponding sound. (Electrical energy to acoustical energy)

1. AUDIOGRAPHY
UNIT –2 -Loudsperkers
PREPARED BY
SANKARANARAYANAN K. B
ASST. PROFESSOR
DEPARTMENT OF VISUAL COMMUNICATION
NEHRU ARTS AND SCIENCE COLLEGE(Autonomous)
COIMBATORE

2. Expected outcomes
Studentswillbeabletounderstandaboutthe
variousloudspeakers,itstypeanddesign.
Studentswillbeabletoremembertheworking
patternsandprinciplesofdifferentloudspeaker
types.
Studentswillbeabletochoosetherightspeakers
accordingtotheirpurpose.
Studentswillknowaboutthecharacteristicsofeach
loudspeakers.

3. Introduction
A loudspeakerisan electro
acoustictransducer;adevicewhichconvertsan
electricalaudiosignalintoa
correspondingsound.(Electricalenergyto
acousticalenergy)
Themostwidelyusedtypeofspeaker
isinventedin1924byEdwardW.
KelloggandChesterW.Rice.

4. Operating Principle
Thedynamicspeakeroperatesonthesamebasic
principleasadynamicmicrophone,butinreverse,to
producesoundfromanelectricalsignal.
Whenanalternatingcurrent(AC)electricalaudio
signalisappliedtoitsvoicecoil,acoilofwire
suspendedinacirculargapbetweenthepolesof
apermanentmagnet,thecoilisforcedtomoverapidly
backandforthduetoFaraday'slawofinduction,
whichcausesadiaphragm(usuallyconicallyshaped)
attachedtothecoiltomovebackandforth,pushingon
theairtocreatesoundwaves.

5. Driver design: dynamic loudspeakers
Cutaway view of a dynamic loudspeaker
1.Magnet
2.Voice coil
3.Suspension
4.Diaphragm

6. Image Source: https://www.ht-audio.com/images/Basics15.gif

7. Diaphragm
Thediaphragmisusuallymanufacturedwitha
cone-ordome-shapedprofile.Avarietyof
differentmaterialsmaybeused,butthemost
commonarepaper,plastic,andmetal.Theideal
materialwould
1)berigid,topreventuncontrolledcone
motions;
2)havelowmass,tominimizestartingforce
requirementsandenergystorageissues;
3)bewelldamped,toreducevibrations
continuingafterthesignalhasstoppedwithlittle
ornoaudibleringingdueto
itsresonancefrequencyasdeterminedbyits
usage.

8. Working
Dynamicloudspeaker,usesalightweightdiaphragm,orcone,
connectedtoarigidbasket,orframe,viaaflexible
suspension,commonlycalledaspider,thatconstrainsavoice
coiltomoveaxiallythroughacylindricalmagneticgap.A
protectivecapgluedinthecone'scenterpreventsdust,
especiallyironfilings,fromenteringthegap.Whenan
electricalsignalisappliedtothevoicecoil,amagneticfieldis
createdbytheelectriccurrentinthevoicecoil,makingita
variableelectromagnet.

9. Other Parts
Basket
Thechassis,frame,orbasket,isdesignedtobe
rigid,preventingdeformationthatcouldchange
criticalalignmentswiththemagnetgap,perhaps
allowingthevoicecoiltorubagainstthemagnet
aroundthegap.Chassisaretypicallycastfrom
aluminumalloy,inheaviermagnet-structure
speakers;orstampedfromthinsheetsteelin
lighter-structuredrivers.
Conematerials
Theconesurroundcanberubberor
polyesterfoam,treatedpaperoraringof
corrugated,resincoatedfabric;itisattachedto
boththeouterconecircumferenceandtothe
upperframe.

10. Driver types
Individualelectrodynamicdriversprovidetheirbest
performancewithinalimitedfrequencyrange.
Multipledrivers(e.g.,subwoofers,woofers,mid-
rangedrivers,andtweeters)aregenerally
combinedintoacompleteloudspeakersystemto
provideperformancebeyondthatconstraint.The
threemostcommonlyusedsoundradiationsystems
arethecone,domeandhorntypedrivers.

11. Speaker drivers
Loudspeaker for home use with three types
1.Mid-range driver(Squawker)
2.Tweeter
3.Woofers
The hole below the lowest woofer is a port
for abass reflexsystem.

12. Full-range drivers
Afull-rangedriverisaspeakerdesignedtobe
usedalonetoreproduceanaudiochannel
withoutthehelpofotherdrivers,andtherefore
mustcovertheentireaudiofrequencyrange.
Full-range(ormoreaccurately,wide-range)
driversaremostcommonlyheardinpublic
addresssystems,intelevisions(althoughsome
modelsaresuitableforhi-filistening),small
radios,intercoms,somecomputerspeakers,etc.
Inhi-fispeakersystems,theuseofwide-range
driveunitscanavoidundesirableinteractions
betweenmultipledriverscausedbynon-
coincidentdriverlocationorcrossovernetwork
issues.

13. Subwoofer
Asubwooferisawooferdriverused
onlyforthelowest-pitchedpartofthe
audiospectrum:typicallybelow
200Hzforconsumersystemsbelow
100Hzforprofessionallivesound.
Sincesoundinthisfrequencyrange
caneasilybendaroundcorners
bydiffraction,thespeakeraperture
doesnothavetofacetheaudience,
andsubwooferscanbemountedin
thebottomoftheenclosure,facing
thefloor.
Image Source : https://www.canalsoundlight.com/wp-content/uploads/2013/08/p-24746-SUB-
8006-AS-RIGHT-NO-GRILL.jpg

14. Woofer
Awooferisadriverthatreproduceslowfrequencies.
Thedriverworkswiththecharacteristicsofthe
enclosuretoproducesuitablelowfrequencies.Some
loudspeakersystemsuseawooferforthelowest
frequencies,sometimeswellenoughthatasubwoofer
isnotneeded.Additionally,someloudspeakersuse
thewoofertohandlemiddlefrequencies,eliminating
themid-rangedriver.Thiscanbeaccomplishedwith
theselectionofatweeterthatcanworklowenough
that,combinedwithawooferthatrespondshigh
enough,thetwodriversaddcoherentlyinthemiddle
frequencies.

15. Mid-range driver
Amid-rangespeakerisaloudspeakerdriverthat
reproducesabandoffrequenciesgenerallybetween
1–6kHz,otherwiseknownasthe'mid'frequencies
(betweenthewooferandtweeter).
Mid-rangedriverdiaphragmscanbemadeofpaper
orcompositematerials,andcanbedirectradiation
drivers(ratherlikesmallerwoofers)ortheycan
becompressiondrivers(ratherlikesometweeter
designs).

16. Tweeter
Atweeterisahigh-frequencydriverthat
reproducesthehighestfrequenciesinaspeaker
system.Amajorproblemintweeterdesignis
achievingwideangularsoundcoverage(off-axis
response),sincehighfrequencysoundtendstoleave
thespeakerinnarrowbeams.Soft-dometweeters
arewidelyfoundinhomestereosystems,andhorn-
loadedcompressiondriversarecommonin
professionalsoundreinforcement.

17. Coaxial drivers
Acoaxialdriverisaloudspeakerdriverwithtwoor
severalcombinedconcentricdrivers.
Image Source: https://www.madisoundspeakerstore.com/images/products/integra-624.jpg Image Source: https://cdn.shopify.com/s/files/1/1577/7605/products/new_coax-
15_pair_a0e3f47e-6daf-4bdd-9e16-05f96e66cccd_1024x1024.jpg?v=1510262356

18. Active(Powered) and Passive speakers
Passivespeakerdoesn’thaveaamplifierthatisBuilt-
in.Anamplifierisneededtopowerthespeaker
throughnormalspeakerwire.Thisspeakersignal
levelwillbeamplifiedtodrivethespeakers
sufficiently.
Activespeakers,haveabuilt-inamplifierandare
suppliedbyalow-level(line-level)signalfromthe
mixerorinterface.Sincetheamplifierisinsidethe
speakersitneedspower,andyouhavetopowerthem
externally.
More Info: https://www.youtube.com/watch?v=kApwnPm3RNU

19. Image Source: https://www.astounded.com/wp-content/uploads/Passive-Active-Speakers-.png

20. System design
Crossover
Enclosures
Wiringconnections
Wirelessspeakers

21. Crossover
Usedinmulti-driverspeakersystems,thecrossover
isanassemblyoffiltersthatseparatetheinput
signalintodifferentfrequencyranges(i.e.
"bands"),accordingtotherequirementsofeach
driver.Crossoverscanbepassiveoractive.
Apassivecrossoverisanelectroniccircuitthatuses
acombinationofoneormoreresistors,inductors,or
non-polarcapacitors.Thesecomponentsare
combinedtoformafilternetworkandaremost
oftenplacedbetweenthefullfrequency-range
poweramplifierandtheloudspeakerdriversto
dividetheamplifier'ssignalintothenecessary
frequencybandsbeforebeingdeliveredtothe
individualdrivers.
Anactivecrossoverisanelectronicfiltercircuitthat
dividesthesignalintoindividualfrequency
bandsbeforepoweramplification,thusrequiringat
leastonepoweramplifierforeachbandpass.

22. Enclosures
Mostloudspeakersystemsconsistofdrivers
mountedinanenclosure,orcabinet.Theroleofthe
enclosureistopreventsoundwavesemanatingfrom
thebackofadriverfrominterferingdestructively
withthosefromthefront.mostenclosuresfunction
bycontainingtherearradiationfromthemoving
diaphragm.
Asealedenclosurepreventstransmissionofthe
soundemittedfromtherearoftheloudspeakerby
confiningthesoundinarigidandairtightbox.
Techniquesusedtoreducetransmissionofsound
throughthewallsofthecabinetincludethicker
cabinetwalls,lossywallmaterial,internalbracing,
curvedcabinetwalls—ormorerarely,visco-
elasticmaterials(e.g.,mineral-loadedbitumen)
orthinleadsheetingappliedtotheinterior
enclosurewalls.

23. Wiring connections
Mosthomehi-filoudspeakersuse
twowiringpointstoconnectto
thesourceofthesignal(for
example,totheaudioamplifier
orreceiver).
Withsoundreinforcement
system,PAsystemandinstrument
amplifierspeakerenclosures,
cablesandsometypeofjackor
connectoraretypicallyused.
Speakon connectorsare
consideredtobesaferforhigh
wattageamplifiers,becausethe
connectorisdesignedsothat
humanuserscannottouchthe
connectors.

24. Specifications
Speaker or driver type(individual units only)–Full-range, woofer, tweeter, ormid-range.
Sizeof individual drivers.(Voice-coil diameter may also be specified.)
Rated Power -Nominal (or even continuous)power, and peak (or maximum short-term) power
a loudspeaker can handle.
Impedance–typically 4Ω(ohms), 8Ω, etc
Baffle or enclosure type(enclosed systems only)–Sealed, bass reflex, etc.
Number of drivers(complete speaker systems only)–two-way, three-way, etc.
Classof loudspeaker: Class 1, 2, 3, 4.
Frequency response : measured, or specified, output over a specified range of frequencies
for a constant input level varied across those frequencies.
Sensitivity : sound pressure level produced by a loudspeaker in a non-reverberant
environment, often specified in dB and measured at 1 meter with an input of 1 watt
Maximum sound pressure level: highest output the loudspeaker can manage

25. Other speaker designs
Moving-iron loudspeakers
Piezoelectric speakers
For More Info: https://en.wikipedia.org/wiki/Loudspeaker#Other_speaker_designs

26. MCQs / Assessment
Multiple Choice Questions Link will be shared in
Quizziz.com
Model Question :
What is the operating principle of a transducer in Moving Coil
loudspeaker?
a) Electromagnetic Induction b) Electrostatic Principle
c) None of the Above d) Both a & b

27. Summary
Aloudspeakerisanelectroacoustictransducer,a
devicewhichconvertsanelectricalaudiosignalinto
acorrespondingsound.
MainlytherearethreetypeofSpeakerdrivers:Full
range,Mid-rangeandwoofers.
Speakersareoftwotypes:ActiveandPassive
Speakerscanbeclassifiedaccordingtoitsbaffle
design,poweroutput,enclosure,and
sensitivty/frequencyresponse.
Theplacementanddirectivityofspeakersare
essentialforhearinggoodqualitysound.

28. Points to Remember
Loaudspeakersworkoppositetotheworking
patternofmicrophone.
Electricalenergyisconvertedintoacousticalenergy.
MajorDrivertypesare:Full-rangedrivers,
Subwoofer,Woofer,Mid-rangedriver,Tweeter,
Coaxialdrivers.
Thesystemdesignofspeakersareclassifiedinto
crossovertypesused,enclosure,wiringand
transmissionofloudspeakers.

29. Source for Reference
1.https://youtu.be/mD6P39t8obo
2.https://www.youtube.com/watch?v=048tBZMt3eY
3.https://www.crunchreviews.com/blog/different-
types-of-speakers/
4.https://blog.landr.com/how-do-speakers-work/
5.https://www.youtube.com/watch?v=fpGlz_HpnmY

30. Introduction of Next Session
Amplifiers
Types and designs
Uses and applications
Audio chain

31. Thank You
SANKARANARAYANAN K. B
ASST. PROFESSOR
DEPARTMENT OF VISUAL COMMUNICATION
NEHRU ARTS AND SCIENCE COLLEGE(Autonomous)
COIMBATORE
Mail Id: [email protected]