Harman Kardon AVP-1A Owners Manual - Page 20

Set-up

&

Calibration

TESTING

FOR

PROPER

SPEAKER

POLARITY

Proper

polarity

throughout

the

system

is

required

before

level

calibration

can

be

established.

Wiring

the

loudspeak-

ers

in

proper

polarity

is

essential

for

precise

localization

of

images

and

bass

response

-

both

important

goals

of

the

Home

THX

Audio

system.

Achieving

proper

polarity

is

made

more

complicated

if

amplifiers

of

different

types

are

used

in

the

system.

Some

ampl

ifier

designs

invert

the

polarity

of

their

output

relative

to

the

input

signal.

Speakers

attached

to

these

amplifiers

must

have

their

polarity

invert-

ed

again

to

get

it

back

where

it

belongs.

Some

speaker

models,

such

as

certain

JBL

models,

use

inverted

polarity

inputs

(the

Red

terminal

is

negative

while

the

Black

terminal

is

positive).

The

best

way

to

ensure

proper

polarity

in

any

home

audio

system

is

to

compare

each

speaker

to

a

single

speaker

which

is

used

as

the

reference

for

the

system.

We

will

use

the

Left

front

speaker

as

the

reference

in

our

example.

Check

the

wiring

color

code

on

both

the

ampl

ifier

and

speaker

jacks

to

verify

correct

polarity.

L

-R

POLARITY:

Check

Left

-Right

polarity

by

listening

to

both

speakers

in

the

stereo

bypass

or

center

speaker

off

mode.

Listen

for

a

solid

center

image.

If

in

doubt,

reverse

the

leads

on

the

Right

speaker

only

and

compare

the

results.

Speakers

with

mis-matched

polarity

wil

l

have

a

poorly

-defined

image

smeared

al

l

over

their

end

of

the

room.

Some

listeners

will

even

feel

strange

pressure

sensa-

tions

in

their

ears!

If

you

have

any

doubt,

try

using

the

pink

noise

on

Chapter

6

of

WOW!

-

this

should

make

the

differ-

ence

extremely

clear.

1.

L

-C

POLARITY:

Check

Left

-Center

polarity

in

the

Home

THX

Cinema

mode

by

feeding

mono

program

material

(dia-

log,

or

Chapter

6

of

WOW!)

and

setting

the

input

balance

to

the

left

so

as

to

get

equal

sound

pressure

levels

out

of

both

the

left

and

center

speakers.

Again,

listen

for

a

solid

image

between

the

left

and

center

speakers

RELATIVE

SUBWOOFER

POLARITY-

If

multiple

sub

-

woofers

are

used,

it

is

important

to

have

their

polarity

with

regard

to

each

other

correct.

Reverse

the

polarity

of

one

of

the

two

subwoofers

while

program

material

with

deep

bass

is

playing

(being

careful

not

to

momentarily

short

the

two

speakers

leads

to

one

another).

The

pink

noise

on

Chapter

6

of

WOW!

can

be

used

as

a

constant

source

of

bass

energy

by

shutting

off

all

speakers

except

the

subwoofers.

You

will'

immediately

notice

either

a

loss

or

an

increase

in

bass.

The

correct

polarity

is

the

one

which

exhibits

the

most

bass.

ABSOLUTE

SUBWOOFER

POLARITY:

It

is

also

impor-

tant

for

both

subwoofers

to

have

the

correct

polarity

with

regard

to

the

rest

of

the

system.

Now

that

the

LCR

speakers

are

all

matched,

play

some

program

material

(or

Chapter

6

of

WOW!)

with

significant

energy

around

80

Hz.

Reverse

the

polarity

of

al

l

subwoofers

in

the

system

and

l

isten

again.The

polarity

with

the

greatest

bass

output

in

this

vital

region

is

correct.

(A

third

-octave

warble

tone

centered

on

80

Hz

is

ideal

for

this

test

and

is

available

on

some

test

compact

discs.)

SURROUND

POLARITY:

Using

tne

Pro

Logic

mode

(not

the

THX

mode),

stand

by

the

screen

and

face

the

surround

speakers.

With

strong

surround

program

materials

(such

as

Chapter

11

on

WOW!),

you

should

hear

a

solid

center

image

between

the

surround

speakers

and

your

standing

position.

Harman Kardon AVP-1A Owners Manual - Page 20

Set-up, Calibration

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