alma- high performance crossovers

8/13/2019 Alma- High Performance Crossovers

1/76

HighP

erformancesCross

oversfor

Profess

ionalLou

dspeaker

Systems

andth

eirRealW

orldapplications

B

yMarioDiCola,

AudioLabsSystems,

Milano,Italia

SeniorLoudspea

kerSystemEngineer

[email protected]

A

LMAEuropeanSymposium,Frankfurt,April2009

DerivedbytheAESPaperPresentedbyM.DiCola,M.Hadelich,D.PonteggiaandD.Saronniat121stAESCo

nvention,October2006,SanFrancisc

o,USA

HighPerformancesCrossoverforProfess

ionalLoudspeakers,ALMAS

ymposium,Frankfurt2009-

MarioDiCola,AudioLabsS

ystems,Milano,Italy


2/76

Multiwa

ysystem

s

Alm

ostthetotalityo

fSoundReinfo

rcement

LoudspeakerSystem

saremultiway

systems

Forsev

eralreasonson

esingletransd

ucercannot

re

producetheen

tireAudioBand

width

Theway

thecrossoverismadeisdeep

lyinfluencing

thefinalperformancesoftheLoudspea

kerSystem

HighPerform

ancesCrossoverforProfess




ystems,Milano,Italy


3/76

W

hyasystemneedtobemulti-

way?

Howthecross-ove

rshouldbedesigned?

HighPerform





ystems,Milano,Italy


4/76

Subwoofer

Low-MidCone

HighFrequen

cyDriver

Subwoofer

Low

-MidCone

HighFrequencyDriver

W

hyasystemneedtobemulti-way?

Howthecross-ove

rshouldbedes

igned?

HighPerform





ystems,Milano,Italy


5/76

Onesim

plequestion

:

Whath

appenstoth

esignalpassingthrough

aCros

soverFilter?

HighPerform





ystems,Milano,Italy


6/76

Input

Outp

ut

LinearSystem

TransferFunction

time

S

inewavethrou

ghaLinearSystem

HighPerform





ystems,Milano,Italy


7/76

Input

Output

LinearSys

tem

TransferFunction

S

inewavethrou

ghaLinearSystem

HighPerform





ystems,Milano,Italy


8/76

Input

Output

LinearSystem

SinewavethroughaLinearSystem:

effectof

PhaseShiftinFilters

Example1:

Frequencyinside

the

Pass-Band

HighPerform





ystems,Milano,Italy


9/76

Input

Output

LinearSystem


effectof

PhaseShiftinFilters

Example2:

Frequencycloseto

thecut

frequency

HighPerform





ystems,Milano,Italy


10/76

Input

Output

LinearSystem


effectof

PhaseShiftinFilters

Example2:

Frequencyoutsid

ethe

Pass-Band

HighPerform





ystems,Milano,Italy


11/76

Sinewavethrougha

LinearSystem:

effectofPhaseS

hiftinFilters

HighPerform





ystems,Milano,Italy


12/76

Desired

TargetResponseatanycrossoverpoint:

asimpleexam

pleofaoptima

lsummationbe

tween2perfec

tly

symmetricalre

sponsesof4th

Order(24dB/O

ct),Linkwitz-Riley

HighPerform





ystems,Milano,Italy


13/76

Howthe

CrossoverApproachcanaffectthe

Loudspeak

erTimeAlignment?

HF

Arrival

Cros

soverPoint

LFEnergy

Arrival

Time

Frequ

ency

WaveletAn

alysisDiagram

HighPerform





ystems,Milano,Italy


14/76

Low

PassFilter

Asim

plesymm

etricCrossover:

2ndOrde

r,L-RType

HighPerform





ystems,Milano,Italy


15/76

HighPassFilter

Asim

plesymm

etricCrossover:

2ndOrde

r,L-RType

HighPerform





ystems,Milano,Italy


16/76

4thOrd

erL-RSy

mmetricC

rossover

2ndOrder

2n

dOrder

2ndOrder

2n

dOrder

HighPerform





ystems,Milano,Italy


17/76

4thOrderL-RSymmetricCro

ssover

Low

PassFilter

H

ighPassFilter

-180deg

+180deg

HighPerform





ystems,Milano,Italy


18/76

4thOrderL-RSymmetricCro

ssover

Low

PassFilter

H

ighPassFilter

OverallPhaseRelationshipb

etweenthe

twooutpu

tscouldbemorec

learusinga

+3

60-360

phasediagram

-360deg

+360deg

HighPerform





ystems,Milano,Italy


19/76

Driv

ersTimea

lignmentin

differentC

rossoverD

esign

strategies

appliedtoasample2

waysystem

A

ll-PassNetworkCros

sover

(O

nlygeometricIssuesaretakenincountwhile

TimeAligningthedrivers

an

dthenPhaseA

lignmentisusu

allyobtained

delayingthewoofer)

Desired

TimeOrigin

ActualPosition:

effectofLow

PassGroupDelay

Addedtothed

riverdelay

Delayingthe

C

loserSpeaker

HighPerform





ystems,Milano,Italy


20/76

Driv

ersTimea

lignmentin

differentC

rossoverD

esign

strategies

appliedtoasample2

waysystem

D

elayCompen

satedCrossover:

(LPFilterGroupDelayis

takenincountinDriv

ersTimeAlignment)

Type1

Typicallysmallerdelay,butHFPolarity

reversed

Desired

TimeOrigin

Effectof

Filt

erGroupDelay

HighPerform





ystems,Milano,Italy


21/76

Driv

ersTimea

lignmentin

differentC

rossoverD

esign

strategies

appliedtoasample2

waysystem

D

elayCompen

satedCrossover:

(LPFilterGroupDelayis

takenincountinDriv

ersTimeAlignment)

Type2

Typicallylargerdelay,withHFinstraight

Polarity

Desired

TimeOrigin

Effectof

Filt

erGroupDelay

HighPerform





ystems,Milano,Italy


22/76

Driv

ersTimea

lignmentin

differentC

rossoverD

esign

strategies

appliedtoasample2

waysystem

Lin

earPhaseF

iltersCrosso

ver

(O

nlygeometricIssuesneedtobetakenincountwhileTimeAligningthe

driverssinceGroupDelayremainsconstantatanyfrequency)

Desired

TimeOrigin

Delayingthe

C

loserSpeaker

HighPerform





ystems,Milano,Italy


23/76

Crossov

erTechn

iquesco

mpariso

n

Aquickreviewon

relationsh

ipbetwee

n

TimeRes

ponseandTransf

erFuncti

on

Analysisofpracticalapplicationofdifferentcrossover

strategiestothesample

2-waylouds

peakersyste

m

HighPerform





ystems,Milano,Italy


24/76

IdealSystem

StepResponse

andRelativeT

ransferFunctio

n:

AMinimum

PhaseSystem

HighPerform





ystems,Milano,Italy


25/76

4thOrderButterworthHighPass(24dB/O

ct)Response.

StepR

esponseandR

elativeTransferFunction:

StillaMinimu

mPhaseSyste

m

TypicalResponsefor

aB

assReflexaligne

dloudspeaker

HighPerform





ystems,Milano,Italy


26/76


ct)Response.

StepR

esponseandR


StillaMinimu

mPhaseSyste

m

TypicalResponsefor

aHighPassFiltered

BassReflexlou

dspeaker

HighPerform





ystems,Milano,Italy


27/76

Loudspeak

erSystemUsedfortheSetup

Asimp

le2-way

ProfessionalLoudspeakerSystem

HighPerform





ystems,Milano,Italy


28/76

StepResponse

SquareWaveRespons

e

Example1:

All-PassNetworkCross

over

HighPerform





ystems,Milano,Italy


29/76

StepResponse

Example1:

All-PassNetworkCross

over

WaveletAnalysis

HighPerform





ystems,Milano,Italy


30/76

0 -5

-10

-15

-20

-25

Frequency

[Hz]

500

1k

2k

5k

10k

0-15

-30

-45

-60

-75

-90

15

30

45

60

75

90

[deg]Angle

[dB]

Level

LevelMark

er:

z=-6d

Ex

ample1

:AllPassNetworkCrossover

VerticalPola

rDirectivityMap

HighPerform





ystems,Milano,Italy


31/76


ct)Response.

StepR

esponseandR


NOTaMinimu

mPhaseSyste

m

HighPerform





ystems,Milano,Italy


32/76

IdealSystem

S

tepResponse

4thOrderHP

M

inimumPhase

System

6thOrderHP

MinimumPhase

System

6thOrderHP

AllPassNetworkSys

tem:

NonMinimum

Phas

e

St

epResponseofdifferentorderCo

mparison

HighPerform





ystems,Milano,Italy


33/76

Example2:

DelayC

ompens

atedTy

pe1

StepResponse

SquareWaveRespons

e

HighPerform





ystems,Milano,Italy


34/76

Example2:

DelayC

ompens

atedTy

pe1

StepResponse

WaveletAnalysis

HighPerform





ystems,Milano,Italy


35/76

0 -5

-10

-15

-20

-25

Frequency

[Hz]

500

1k

2k

5k

10k

0-15

-30

-45

-60

-75

-90

15

30

45

60

75

90

[deg]Angle

[dB]

Level

LevelMarke

r:

z=-6d

Example2:

DelayC

ompens

atedTy

pe1

VerticalPola

rDirectivityMap

HighPerform





ystems,Milano,Italy


36/76

Example3:

DelayC

ompens

atedTy

pe2

StepResponse

SquareWaveRespons

e

HighPerform





ystems,Milano,Italy


37/76

Example3:

DelayC

ompens

atedTy

pe2

StepResponse

WaveletAnalysis

HighPerform





ystems,Milano,Italy


38/76

0 -5

-10

-15

-20

-25

Frequency

[Hz]

500

1k

2k

5k

10k

0-15

-30

-45

-60

-75

-90

15

30

45

60

75

90

[deg]Angle

[dB]

Level

LevelMarker:

z=-6d

VerticalPola

rDirectivityMap

Example3:

DelayC

ompens

atedTy

pe2

HighPerform





ystems,Milano,Italy


39/76

Examp

le4:LinearPhas

eFilters

StepResponse

SquareWaveRespons

e

HighPerform





ystems,Milano,Italy


40/76

Examp

le4:LinearPhas

eFilters

StepResponse

Wa

veletAnalysis

HighPerform





ystems,Milano,Italy


41/76

0 -5

-10

-15

-20

-25

Frequency

[Hz]

500

1k

2k

5k

10k

0-15

-30

-45

-60

-75

-90

15

30

45

60

75

90

[deg]A

ngle

[dB]

Level

LevelMarke

r:

z=-6d

Examp

le4:LinearPhas

eFilters

VerticalPola

rDirectivityMap

HighPerform





ystems,Milano,Italy


42/76

TransferFunctionsCom

parison

AllPassNetwork

DelayCompensated

Type1

DelayCompensated

Type2

LinearPhaseFilters

24dB/Oct

approx.

HighPerform





ystems,Milano,Italy


43/76

0 -5

-10

-15

-20

-25

Frequency

[Hz]

500

1k

2k

5k

10k

0

-15

-30

-45

-60

-75

-90

15

30

45

60

75

90

[deg]

Angle

[dB]

Level

LevelMarker:

z=-6dB

0 -5

-10

-15

-20

-25

Frequency

[Hz]

500

1k

2k

5k

10k

0

-15

-30

-45

-60

-75

-90

15

30

45

60

75

90

[deg]

Angle

[dB]

Leve

LevelMarker:

z=-6d

0 -5

-10

-15

-20

-25

Frequency

[Hz]

500

1k

2k

5k

10k

0

-15

-30

-45

-60

-75

-90

15

30

45

60

75

90

[deg]

Angle

[dB]

Leve

LevelMarker:

z=-6d

0 -5

-10

-15

-20

-25

Frequency

[Hz]

500

1k

2k

5k

10k

0

-15

-30

-45

-60

-75

-90

15

30

45

60

75

90

[deg]

Angle

[dB]

Leve

LevelMarker:

z=-6d

ALL

PASS

DLY

Type1

LIN

PHASE

DLY

Type2

Cr

ossover

Comparison

HighPerform





ystems,Milano,Italy


44/76

FurtherIm

proveme

nts

Performaces

oftheLinearPhaseFilterprocessed

versioncanb

efurtherimp

rovedinterm

sofvertical

directivitycon

trol

Steeperfilter

functions,in

fact,canbeintroducedw

ithout

additionalphasedistortion

Additionalad

vantagesintermsofPow

erhandlinga

nd

reducedDistortioncanbe

introducedb

ysteeper

crossoverfilters

HighPerform





ystems,Milano,Italy


45/76

0 -5

-10

-15

-20

-25

Frequency

[Hz]

500

1k

2k

5k

10k

0

-15

-30

-45

-60

-75

-90

15

30

45

60

75

90

[deg]

Angle

[dB]

Level

LevelMarker:

z=-6d

SquareWaveResponse

WaveletAnaly

sis

VerticalPolarDirecivity

Map

Linea

rPhase

Filters24dB/Oct

HighPerform





ystems,Milano,Italy


46/76

0 -5

-10

-15

-20

-25

Frequency

[Hz]

500

1k

2k

5k

10k

0

-15

-30

-45

-60

-75

-90

15

30

45

60

75

90

[deg]

Angle

[dB]

Level

LevelMarker:

z=-6d

Linea

rPhase

Filters74dB/Oct

SquareWaveRe

sponse

WaveletAnalysis

VerticalPolarDirecivity

Map

HighPerform





ystems,Milano,Italy


47/76

Exampleofpractical

measurement

s

Practical,realwo

rldtransfer

function

measurementsusingadedicatedDual

Channel,F

FTAnalyzer

HighPerform





ystems,Milano,Italy


48/76

Comp

arisonbetwe

enAll-Pass

NetworkandLinearPhaseFilters

settings:Magnitude

andPhaseResponse

All-Pass

Network

LinearPhase

Netwo

rk

HighPerform





ystems,Milano,Italy


49/76

All-PassNetworkCrossover

settings:MagnitudeandPhase

R

esponseshowingeachin

dividualspeakercontribu

tion

HighFreq.

Contribution

LowFr

eq.

Contribu

tion

HighPerform





ystems,Milano,Italy


50/76

LinearPhaseFiltersCrossove

rsettings:M

agnitudeand

Phase

R

esponseshowingeachin

dividualspeakercontribu

tion

HighFreq.

Contribution

LowFr

eq.

Contribu

tion

HighPerform





ystems,Milano,Italy


51/76

MagnitudeandPhaseres

ponsecomparisonBetwe

en:

DelayCompensatedType1,Type2andLinearPh

ase

Filters

LinearPhase

Filters

Delay

Compensated

Type1

Delay

Compensated

Type2

HighPerform





ystems,Milano,Italy


52/76

An

exampleofh

owDelayCo

mpensatedTechniquesc

anbe

ado

ptedinordertomatchaL

owFrequencyextending

unitto

aLinearPhaseFiltersprocesse

dsystem

UpperBand

Res

ponse

Subwoofer

Response

HighPerform





ystems,Milano,Italy


53/76

An

exampleofh

owDelayCo

mpensatedTechniquesc

anbe

ado

ptedinordertomatchaL

owFrequencyextending

unitto

aLinearPhaseFiltersprocesse

dsystem

Reduced

Phase

ShiftSub

woofer

Plusupp

ersystem

Crossoverpoint

HighPerform





ystems,Milano,Italy


54/76

Asim

pledire

ctadvan

tageof

minimizingoverallphaseshift

HighPerform





ystems,Milano,Italy


55/76

An

All-PassCrossover2wayspeaker

HighPerform





ystems,Milano,Italy

ImagestakenfromtheAESPaper

WrittenbyJustinBairdandDavidMcGrathabout

LinearPhaseFiltersadvantages


56/76

An

All-PassCrossover3wayspeaker

HighPerform





ystems,Milano,Italy





57/76

Effectofsumm

ationofthetwospeakerinthe

overlappingarea

HighPerform





ystems,Milano,Italy





58/76

Ex

ampleofapplicationo

fLinear

Phasefilte

rstoanexisting

s

ystem.

HighPerform





ystems,Milano,Italy


59/76

LF

LF

MF

MF

HF

Sche

maticviewofth

eexisting3wa

ysystem

usedforthepracticalapplication

Exampleo

fapplica

tionofLinearPhase

filterstoanexistings

ystem

HighPerform





ystems,Milano,Italy


60/76

LinearPhaseFilters

Processing

OriginalPreset

Processing

3WaySystemPr

ocessing

Comparison

HighPerform





ystems,Milano,Italy


61/76

LinearPhaseFiltersProcessing

OriginalPresetProcessing

3WaySystemPr

ocessing

Comparison

HighPerform





ystems,Milano,Italy


62/76

Ad

ditionalTestRes

ults

HorizontalPolarDirecivityMap

HorizontalPolarDirecivity

Map

StepResponse

StepResponse

Line

arPhaseFilters

Processing

OriginalPreset

Processing

HighPerform





ystems,Milano,Italy


63/76

Results

Someadvantage

scanbeachievedwhileprocessingloudspeaker

sy

stemswithLinearPhaseFilters

Reducingtheove

rallphaseshift

ofaloudspeak

ersystemresponse

ca

nresultinbettersoundquality

duetoimprove

dtimecoheren

ce

It

wasfoundthat

goodandencouragingresults

canbeobtained

applyingthistech

niquetoConce

rtSoundReinforcementSyste

ms:

betterarray-abilit

ypropertiesanddirectivitycon

trolcanbeachieved

besideimproved

soundquality

LinearPhaseCro

ssoverisprese

ntlysomething

readilyavailablefor

anybody.Bythewaytransformin

gClassicFilter

sbasedCrosso

verinto

a

LinearPhaseC

rossoverrequiressomeaccuratemeasureme

ntand

so

mecarefulatte

ntion,inordertobeproperlydone

HighPerform





ystems,Milano,Italy


64/76

AnExampleo

n

Phas

eRespo

nseLine

arization

ofan

AllPassNetworkSystem

HighPerform





ystems,Milano,Italy


65/76

Mag

nitudeandP

hase

responseofa

n

All-PassCrossover

Lou

dspeakerSy

stem

HighPerform





ystems,Milano,Italy


66/76

Mag

nitudeandP

hase

responseofa

n

All-PassCrossover

Lou

dspeakerSy

stem

Com

paredtoam

odel

ofa

MinimumPhase

System

MinimumPhaseResponse

HighPerform





ystems,Milano,Italy


67/76

Modelofthe1.4kHzAll-Pas

sComponent

Modelofthe1.4kHz

All-PassComponent

Th

ePhaseShiftat

1

.4kHzcould

be

approximatedw

itha

modelofanAll-Pass

Filter

HighPerform





ystems,Milano,Italy


68/76

Modelofthe1.4kHzInverted

All-PassComponent

The

1.4kHzAll-

Pass

Filte

rcouldbeinverted

viaanFIRInve

rse

Filter

HighPerform





ystems,Milano,Italy


69/76

All-PassCompensated

PhaseRespo

nse

T

heresultofthe

applicationofthe

inversefilterto

approximate

a

M

inimumPha

se

Response

HighPerform





ystems,Milano,Italy


70/76

NonMinimu

m

Phase-Shifta

tLF

Fur

therimprovement

ofth

eMinimumP

hase

Response

a

pproximation

is

po

ssibleimproving

TheLFpartof

the

inversefilter

HighPerform





ystems,Milano,Italy


71/76

AddedLFPhaseShift

Compensation

FinalResultof

the

ImprovedPha

se

Response

Compensatio

n

withtheinverse

filter

HighPerform





ystems,Milano,Italy


72/76

Impleme

ntationo

fa

DelayCompensatedCrossoverType

viaPassiveFilt

er

HighPerform





ystems,Milano,Italy


73/76

Pa

ssiveFilterDela

yCompensatedS

ystem

TotalMagnitud

e,SingleContributionsMagnitudeandPhaseResponse

PassiveFilter+InputEQCombinat

ion

PhaseM

atcharound

CrossoverRegion

HighPerform





ystems,Milano,Italy


74/76

PassiveFilterDela

yCompensated

System

STEPRESPONSE

HighPerform





ystems,Milano,Italy


75/76

Pass

iveFilterDela

yCompensated

System

Beamwid

th,DirectivityIndexandPolarMapsofBothPlanes

HighPerform





ystems,Milano,Italy


76/76

Than

kYou

forProfess




ystems,Milano,Italy

alma- high performance crossovers

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