Adcom Gfa-7000 User manual

/DCOM

details

you

can

hear

G

FA-7000

High

Current

THX®

5-Channel

Power

Amplifier

IUCASFILM

I

HX

OWNER’S

MANUAL

THE

FOLLOWING

PRECAUTIONS

AND

SAFETY

INSTRUCTIONS

ARE

REQUIREMENTS

OF

UL

AND

CSA

SAFETY

REGULATIONS

Warning:

To

reduce

the

risk

of

fire

or

electric

shock,

do

not

expose

this

unit

to

rain

or

moisture.

CAUTION

RISK

OF

ELECTRIC

SHOCK

DO

NOT

OPEN

AVIS*.

RISQUE

DE

CHOC

ELECTRIQUE-NE

PAS

OUVRIR

The

graphic

symbol

of

a

lightning

flash

with

an

arrow

point

within

a

triangle

signifies

that

there

is

dangerous

voltage

within

the

unit

and

it

poses

a

hazard

to

anyone

removing

the

cover

to

gam

access

to

the

interior

of

the

unit

Only

qualified

service

personnel

should

make

any

such

attempt.

The

graphic

symbol

of

an

exclamation

point

within

an

equilateral

triangle

warns

a

user

of

the

device

that

it

is

necessary

to

refer

to

the

instruction

manual

and

its

warnings

for

proper

operation

of

the

unit

Do

not

place

this

unit

on

an

unstable

cart,

stand,

tripod,

bracket,

or

table

The

unit

may

fall,

causing

serious

injury

to

a

child

or

adult,

and

serious

damage

to

the

unit

Use

only

with

a

cart,

stand,

tripod,

bracket,

or

table

recommended

by

the

manufacturer,

or

sold

with

the

unit

Any

mounting

of

the

device

should

follow

the

man¬

ufacturer’s

instructions,

and

should

use

a

mounting

ac¬

cessory

recommended

by

the

manufacturer

Read

all

the

safety

and

operating

instructions

before

connecting

or

using

this

unit

Retain

this

notice

and

the

owner’s

manual

for

future

reference

All

warnings

on

the

unit

and

in

its

operating

instructions

should

be

adhered

to

All

operating

and

use

instructions

should

be

followed

Do

not

use

this

unit

near

water,

for

example,

near

a

bathtub,

washbowl,

kitchen

sink,

laundry

tub,

in

a

wet

basement,

or

near

a

swimming

pool

The

unit

should

be

installed

so

that

its

location

or

position

does

not

interfere

with

its

proper

ventilation

For

example,

it

should

not

be

situated

on

a

bed,

sofa,

rug,

or

similar

surface

that

may

block

the

ventilation

openings,

or

placed

in

a

built-in

installation,

such

as

bookcase

or

cabinet,

that

may

impede

the

flow

of

air

through

its

ventilation

openings

The

unit

should

be

situated

away

from

heat

sources

such

as

radiators,

heat

registers,

stoves,

or

other

devices

(including

amplifiers)

that

produce

heat

The

unit

should

be

connected

to

a

power-supply

outlet

only

of

the

voltage

and

frequency

marked

on

its

rear

panel

The

power-supply

cord

should

be

routed

so

that

it

is

not

likely

to

be

walked

on

or

pinched,

especially

near

the

plug,

convenience

receptacles,

or

where

the

cord

exits

from

the

unit

Clean

unit

only

as

recommended

in

its

instruction

manual

The

power-supply

cord

of

the

unit

should

be

unplugged

from

the

wall

outlet

when

it

is

to

be

unused

for

a

long

period

of

time

Care

should

be

taken

so

that

objects

do

not

fall,

and

liquids

are

not

spilled,

into

the

enclosure

through

any

openings

This

unit

should

be

serviced

by

qualified

service

personnel

when

A

The

power

cord

or

the

plug

has

been

damaged,

or

B

Objects

have

fallen,

or

liquid

has

been

spilled,

into

the

unit,

or

C

The

unit

has

been

exposed

to

rain,

or

liquids

of

any

kind,

or

D

The

unit

does

not

appear

to

operate

normally,

or

exhibits

a

marked

change

in

performance,

or

E

The

device

has

been

dropped,

or

the

enclosure

damaged

DO

NOT

ATTEMPT

SERVICING

OF

THIS

UNIT

YOURSELF.

REFER

SERVICING

TO

QUALIFIED

SERVICE

PERSONNEL.

ATTENTION

POUR

PREVENIR

LES

CHOCS

ELECTRIQUES

NE

PAS

UTILISER

CETTE

FICHE

POLARISEE

AVEC

UN

PROLONGATEUR,

UNE

PRISE

DE

COURANT

OU

UNE

AUTRE

SORTIE

DE

COURANT,

SAUF

SI

LES

LAMES

PEUVENT

ETRE

INSEREES

A

FOND

SANS

EN

LAISSER

AU-

CUNE

PARTIE

A

DECOUVERT

CAUTION

TO

PREVENT

ELECTRIC

SHOCK

DO

NOT

USE

THIS

POLARIZED

PLUG

WITH

AN

EXTENSION

CORD,

RECEPTACLE

OR

OTHER

OUTLET

UN¬

LESS

THE

BLADES

CAN

BE

FULLY

INSERTED

TO

PREVENT

BLADE

EXPOSURE

CAUTION

POWER

LINES

Any

outdoor

antenna

must

be

located

away

from

all

power

lines.

OUTDOOR

ANTENNA

GROUNDING

If

an

outside

antenna

is

connected

to

your

tuner

or

tuner-preamplifier,

be

sure

the

antenna

system

is

grounded

so

as

to

provide

some

protection

against

voltage

surges

and

built-up

static

charges.

Section

810

of

the

National

Electrical

Code,

ANSI/NFPA

No.

70-1984,

provides

information

with

respect

to

proper

grounding

of

the

mast

and

supporting

structure,

grounding

of

the

lead-in

wire

to

an

antenna

discharge

unit,

size

of

grounding

conductors,

location

of

antenna

discharge

unit,

connection

to

grounding

electrodes,

and

requirements

for

the

grounding

electrode.

a.

Use

No.10

AWG

(5.3

mm

2

)

copper,

No.8

AWG

(8

4

mm

2

)

aluminum,

No.17

AWG

(1

0

mm

2

)

copper-clad

steel

or

bronze

wire,

or

larger,

as

a

ground

wire.

b

Secure

antenna

lead-in

and

ground

wires

to

house

with

stand-off

insulators

spaced

from

4-6

feet

(1.22-1.83

m)

apart.

c

Mount

antenna

discharge

unit

as

close

as

possible

to

where

lead-in

enters

house

d.

Use

jumper

wire

not

smaller

than

No.6

AWG

(13.3

mm

2

)

copper,

or

the

equivalent,

when

a

separate

antenna-grounding

electrode

is

used.

See

NEC

Section

810-21

(j)-

EXAMPLE

OF

ANTENNA

GROUNDING

AS

PER

NATIONAL

ELECTRICAL

CODE

INSTRUCTIONS

CONTAINED

IN

ARTICLE

810

-

RADIO

AND

TELEVISION

EQUIPMENT

NOTE

TO

CATV

SYSTEM

INSTALLER

This

reminder

is

provided

to

call

the

CATV

system

installer’s

attention

to

Article

820-22

of

the

National

Electrical

Code

that

provides

guidelines

for

proper

grounding

and,

in

particular,

specifies

that

the

cable

ground

shall

be

connected

to

the

grounding

system

of

the

building,

as

close

to

the

point

of

cable

entry

as

practical

GFA-7000

FEATURES

•

Precision-matched

devices

used

throughout

the

signal

path.

•

120,000

pF

of

power

supply-filter

capacitance

for

greater

reserve

capacity.

•

Independent

power

supplies

for

each

channel.

•

Fewer

gain

stages

improve

signal

reproduction

accuracy.

•

Custom

toroidal

power

transformer

provides

better

regulation

and

greater

peak

current

capability.

•

Independent

thermal-overload

and

distortion

LEDs

for

all

5

channels.

•

High

quality,

gold-plated

5-way

binding

posts.

•

High

quality,

gold-plated

RCA

jacks.

•

Large

independent,

internal

heatsinks

for

greater

cooling

capability

of

output

devices.

•

Heavy

gauge,

anodized

aluminum

front

panel.

•

Powder-coated,

baked

chassis

and

top

cover

for

greater

durability.

•

Cooling

vents

for

greater

efficiency

and

cooler

operation

while

driving

low

impedance

loads.

•

Home

THX®

standard

DB-25

connector

to

simplify

installation

•

Made

in

the

USA

TABLE

OF

CONTENTS

INTRODUCTION

WHAT

IS

HOME

THX®?.2

WARRANTY

INFORMATION.2

DESCRIPTION

OF

UNIT

REAR

PANEL.3

FRONT

PANEL.5

INSTALLATION

&

HOOKUP

UNPACKING

THE

GFA-7000.7

PLACING

THE

GFA-7000.7

QUICK

CONNECTION

DIAGRAM.8

CONNECTING

THE

GFA-7000.9

CARING

FOR

YOUR

GFA-7000.10

TROUBLESHOOTING

RESOLVING

PROBLEMS.11

SERVICE

INFORMATION.12

SPECIFICATIONS.13

TRx

],

THX®,

and

Home

THX®

are

registered

trademarks

of

Lucasfilm

Ltd

Dolby

ProLogic®

and

Dolby

AC-3®

are

registered

trademarks

of

Dolby

Laboratories

Licensing

Corp

1

INTRODUCTION

Congratulations

on

your

decision

to

purchase

the

GFA-7000,

Home

THX®

certified,

5-

channel

power

amplifier.

Not

only

is

the

GFA-7000

certified

for

Home

THX®

systems,

but

it

will

also

integrate

with

any

other

home

theater

system,

such

as

Dolby

ProLogic®

or

Dolby

AC-3®,

You

have

made

a

wise

choice

that

will

reward

you

with

exceptionally

accurate

and

musical

sound

reproduction

for

years

to

come.

To

realize

the

full

potential

of

your

new

amplifier,

please

read

these

operating

and

installation

instructions

thoroughly

before

attempting

to

make

any

connections

to

it.

WHAT

IS

HOME

THX®

?

Home

THX®

is

the

system

developed

by

Lucasfilm

Ltd.

to

maximize

the

accuracy

of

film

soundtracks

in

a

home

environment.

It

is

important

as

soundtracks

and

their

related

special

effects

become

a

greater

and

greater

part

of

the

whole

film

viewing

and

listening

experience.

In

order

for

a

component

to

display

the

Home

THX®

system

mark,

it

has

to

conform

to

the

strict

series

of

standards

that

were

investigated

and

defined

during

the

1980’s

by

Tom

Holman

of

Lucasfilm

Ltd.

A

home

theater

surround

system

utilizing

Home

THX®

certified

components

throughout,

will

give

the

most

accurate

re-creation

of

the

original

sound

tracks

put

on

the

film

in

the

creative

“dubbing

stage”

by

its

director,

conductor

and

sound

designer.

Approved

Home

THX®

components

insure

all

the

necessary

improvements

to

deliver

the

intended

effects

of

a

film

in

home

theater

sound

reproduction.

The

benefits

are:

•

Clearer

dialog

•

Precise

front-stage

sound

localization

•

Expanded

depth

of

the

sound

field

•

Extended

and

smooth

frequency

response

•

Wider

dynamic

range

•

Smoother

sound

transition

among

channels

The

Adcom

GFA-7000

amplifier

is

designed

not

only

to

meet

these

standards,

but

to

exceed

them

and

deliver

the

most

accurate

reproduction

of

Home

THX®-encoded

films.

ADCOM

PROTECTION

PLAN

(USA

ONLY)

ADCOM

offers

the

enclosed

valuable

Limited

Warranty.

Please

read

the

details

on

the

Warranty

Card

carefully

to

understand

the

extent

of

the

protection

offered

by

the

Warranty,

its

reasonable

limitations,

and

what

you

should

do

in

order

to

obtain

its

benefits.

Be

sure

to

verify

that

the

serial

number

printed

on

the

rear

panel

matches

the

serial

number

on

the

outer

carton.

If

any

number

is

altered

or

missing,

you

should

notify

us

immediately

in

order

to

ensure

that

you

have

received

a

genuine

ADCOM

product

which

has

not

been

opened,

mishandled,

or

tampered

with

in

any

way.

Always

retain

your

original

sales

receipt

as

a

proof

of

purchase

2

DESCRIPTION

OF

UNIT

O

RR,

LR,

R,

C,

L

Inputs

The

audio

inputs

for

the

GFA-7000

are

through

high-quality,

gold-plated

RCA

jacks

to

minimize

high-frequency

losses,

noise,

etc.

They

will

accept

standard

RCA-type

plugs,

one

for

each

of

the

five

channels;

Left

(L),

Center

(C),

Right

(R),

Left

Rear

(LR),

and

Right

Rear

(RR).

To

insure

that

the

performance

designed

into

the

GFA-7000

is

preserved,

you

should

use

the

highest

quality

audio

cables

possible.

There

are

many

cables

which

are

Home

THX®

certified,

color-coded

and

specifically

designed

for

this

application.

Your

Adcom

dealer

can

help

select

the

best

cable

for

your

needs.

(See

CONNECTING

THE

GFA-7000

for

more

information).

©

RR,

LR,

R,

C,

L

Outputs

The

GFA-7000’s

connections

to

the

loudspeakers

are

made

through

high-grade,

5-way,

gold-plated

binding

post

terminals.

There

are

two

terminals

for

each

speaker,

which

are

colored

RED

for

the

positive

(+)

output

and

BLACK

for

the

negative

(-)

output.

The

binding

posts

will

accept

a

variety

of

connector

types;

the

most

secure

and

prevalent

of

these

is

the

“U”-type

spade

connectors

(at

least

0.25”

wide

and

maximum

width

of

0.57”),.

The

terminal

will

also

accept

bare

wire

(up

to

AWG10)

and

“banana"

type

plugs

(single

or

dual).

Pin

connectors

are

not

recommended

for

use

with

Home

THX®

equipment.

(See

CONNECTING

THE

GFA-7000

for

more

information).

Q

DB-25

Multichannel

Audio

Input

Connector

Input

connections

may

be

made

with

the

optional

DB-25

computer-type

connector,

which

is

a

Home

THX®

certified

option

when

your

Home

THX®

controller

is

provided

with

a

similar

output

connector.

Using

this

type

of

connecting

cable

would

override

the

need

to

use

the

RCA-

type

inputs

(O).

This

mode

of

connection

retains

the

same

high

level

of

signal

transfer,

simplifies

the

job

significantly

and

insures

automatic,

correct

connections

to

all

channels.

3

O

AC

Fuse

The

AC

Fuse

protects

the

electronic

circuits

of

the

GFA-7000.

This

fuse,

normally,

will

blow

only

if

there

is

an

overload

within

the

GFA-7000.

It

may,

however,

blow

if

the

amplifier

attempts

to

deliver

very

high

power

into

very

low-impedance

loudspeakers.

In

either

case,

BE

SURE

TO

REPLACE

THE

AC

Fuse

ONLY

WITH

AN

EXACT

REPLACEMENT

FUSE.

The

proper

fuse

values

are:

Fuse

Rating

BUSS®

Littlefuse®

For

115

volt

operation.15

Amp

250

Volt.ABC-15/250V.(3AG)

314015/250V

For

230

volt

operation.8

Amp

250

Volt.AGC-8/250V.(3AG)

312008/250V

WARNING

Before

attempting

to

replace

a

blown

fuse,

be

certain

to

unplug

the

AC

Power

Cord

from

the

AC

wall

outlet

to

prevent

possible

electrical

shock.

Replace

the

AC

Fuse

only

with

one

identical

in

type

and

rating

as

printed

on

the

rear

panel.

DO

NOT

USE

ANY

SUBSTITUTE

FUSES

WITH

DIFFERENT

RATINGS

OR

VALUES.

Failure

to

observe

this

precaution

may

cause

serious

damage

to

the

amplifier

circuits,

MAY

CREATE

A

FIRE

HAZARD,

AND

MAY

VOID

THE

WARRANTY.

_

If

the

Power

LED

(©)

does

not

glow,

it

may

be

an

indication

that

the

AC

fuse

has

blown.

If

you

are

not

sure,

or

the

amplifier

displays

other

symptoms,

please

consult

the

RESOLVING

PROBLEMS

section

on

page

11.

To

remove

the

fuse-holder

cap,

you

will

need

a

!4”

standard

flat-blade

screwdriver.

Place

the

screwdriver

in

the

recessed

slot

in

the

cap.

Turn

the

cap

Vs-

turn

counter-clockwise

(to

the

10:30

position),

until

the

cap

pops

out

towards

you.

Grasp

the

cap

with

your

fingers

and

pull

it

completely

out.

The

fuse

is

inserted

in

the

back

of

the

cap:

gently

pull

it

free.

Since

the

fuse

has

a

ceramic

body,

you

cannot

visually

examine

the

fuse

element,

it

is

therefore

suggested

that

you

replace

it

with

an

identical

substitute

or

bring

the

fuse

to

your

Adcom

dealer

so

they

may

check

its

integrity.

To

replace

the

fuse,

insert

it

in

the

back

of

the

fuse-holder

cap.

Place

the

cap

into

the

fuse-holder

with

the

arrow

Vs

-turn

to

the

left

of

center

(10:30

position).

Place

the

screwdriver

in

the

recessed

slot,

gently

press

in

and

turn

Vs-

turn

clockwise

(to

the

12

o’clock

position)

0

AC

Power

Cord

The

AC

cord

provides

power

to

operate

all

the

GFA-7000’s

circuits.

Its

plug

can

be

connected

to

a

standard

wall

outlet

provided

the

outlet

supplies

a

voltage

compatible

with

the

power

requirements

printed

on

the

rear

panel

of

the

GFA-7000.

The

GFA-7000's

power

cord

is

supplied

with

a

“polarized”

AC

plug

as

required

by

UL/CSA

standards

and

the

National

Electrical

Code.

To

minimize

the

risk

of

electrical

shock

and

to

insure

minimal

hum

from

the

system,

do

not

defeat

the

polarity

insuring

feature

of

the

plug

(one

wide

blade

and

one

narrow

blade).

To

prevent

electrical

shock,

do

not

use

this

polarized

plug

with

an

extension

cord

or

AC

outlet

unless

the

blades

can

be

fully

inserted

to

prevent

blade

exposure.

4

FRONT

PANEL

O

On/Off

Switch

The

On/Off

Switch

controls

power

to

the

power

transformer

and

circuits

of

the

GFA-7000.

Whenever

the

GFA-7000

is

energized

the

Power

LED

(©)

will

glow.

To

turn

the

GFA-7000

on,

press

the

push-button.

It

will

remain

in

the

“engaged”

position

while

the

unit

is

energized.

To

turn

the

GFA-7000

off,

press

the

push-button

in

and

release

and

it

will

move

to

the

“disengaged”

position.

O

Power

LED

This

LED

will

glow

whenever

the

On/Off

Switch

(©)

is

turned

on

and

the

GFA-7000

is

energized.

The

Power

LED

indicates

that

there

is

AC

voltage

being

fed

to

the

amplifier,

but

it

does

not

signify

that

all

the

amplifier’s

circuits

are

in

operation.

If,

for

example,

one

of

the

Thermal

Protection

LED

(©)

glows,

that

amplifier

channel

will

not

produce

sound

even

though

the

Power

LED

may

still

glow.

When

the

GFA-7000

is

turned

off,

the

Power

LED

will

take

some

time

to

fade

out

completely.

It

may

take

up

to

30

seconds

to

fully

extinguish.

Additionally,

the

internal

power

transformer

is

provided

with

a

thermostat

which

will

interrupt

power

into

the

transformer

if

its

temperature

exceeds

125°C.

This

high

temperature

will

seldom,

if

ever,

be

encountered

unless

the

amplifier

is

subjected

to

abnormal

conditions,

such

as

operation

into

loads

of

less

than

3

ohms

at

very

high

listening

levels,

etc.

If

the

AC

Fuse

(©)

is

not

blown,

the

Power

LED

is

out,

and

the

Thermal

Protection

LED

(O)

does

not

glow,

this

would

indicate

that

the

thermostat

within

the

transformer

has

opened.

Once

the

temperature

within

the

transformer

decreases

to

a

normal

level,

the

thermostat

will

reset

itself

automatically

and

normal

operation

will

resume.

If

you

are

to

avoid

continually

tripping

the

thermostat

in

the

transformer,

you

must

reduce

the

sound

level

demands,

correct

the

load

impedance

of

the

loudspeakers,

or

both.

5

O

Distortion

Alert

LEDs

The

Distortion

Alert

circuit

is

a

unique

ADCOM

distortion

detection

system

which

reads

all

forms

of

non-linear

distortion

such

as

THD,

IM,

slew-induced,

“clipping”,

etc.

The

Distortion

Alert

LEDs

will

light

when

distortion

reaches

1%

regardless

of

impedance,

voltage/current

phase

angle

or

the

reactance

of

the

loudspeakers

which

the

amplifier

is

driving.

Sometimes,

when

the

amplifier

is

in

use,

the

LEDs

may

occasionally

flicker

during

high

volume

listening,

particularly

if

you

are

driving

low

impedances.

This

flickering

is

no

cause

for

concern.

The

LEDs

are

simply

warning

you

that

the

amplifier

is

approaching

its

maximum

power

output

into

the

particular

loudspeakers

you

are

using.

If,

however,

the

Distortion

Alert

LEDs

glow

brightly

or

are

illuminated

most

of

the

time

during

playback,

you

are

overdriving

the

amplifier

and

should

turn

down

your

volume

control

to

reduce

the

listening

level,

otherwise

it

may

cause

the

Thermal

Protection

to

be

activated

or,

in

extreme

cases,

damage

your

loudspeakers.

O

Thermal

Protection

LEDs

The

GFA-7000

is

provided

with

a

thermal

protection

circuit

which

will

shut

down

the

individual

amplifiers

if

its

heatsink

temperature

reaches

85°C.

The

Thermal

Protection

LEDs

will

light

whenever

the

thermal

protection

circuit

on

its

respective

channel

has

been

triggered

and

the

amplifier

is

inoperative.

The

thermal

protection

circuitry

will

typically

be

triggered

by

very

high

power

demands

into

impedances

much

lower

than

the

amplifier

is

capable

of

driving

at

those

levels.

If

any

amplifier

channel’s

output

through

the

loudspeaker(s)

ceases

abruptly,

and

its

Thermal

Protection

LED

glows,

you

will

know

that

its

heatsink

temperature

has

become

unacceptably

high

and

the

circuitry

is

protecting

the

amplification

devices.

Please

note

that

the

Power

LED

(8)

will

remain

on

and

the

amplifier

will

still

be

energized.

Once

the

temperature

of

the

heatsink(s)

drops

to

a

safe

operating

level,

that

amplifier

will

automatically

resume

operation.

Activation

of

the

Thermal

Protection

circuitry

in

any

of

the

amplifiers

in

the

GFA-7000

is

an

indication

that

the

amplifier

has

been

overdriven

or

that

the

load

the

loudspeakers

are

presenting

to

the

amplifier

is

unreasonably

low.

If

you

wish

to

prevent

recurrent

activation

of

the

thermal

protection

circuitry,

you

must

reduce

the

volume-level

demands

or

correct

the

load-

impedance

condition

which

may

be

causing

activation

of

this

circuitry.

6

INSTALLATION

&

HOOKUP

UNPACKING

THE

GFA-7000

.

.

,

Before

your

new

GFA-7000

left

our

factory,

it

was

carefully

inspected

for

physical

imperfections

and

tested

for

all

electrical

parameters

as

a

routine

part

of

ADCOM’s

systematic

quality

control.

This,

along

with

full

operational

and

mechanical

testing,

should

ensure

a

product

flawless

in

both

appearance

and

performance.

After

you

have

unpacked

the

GFA-

7000

inspect

it

for

physical

damage.

Save

the

shipping

carton

and

all

packing

material

as

they

are

intended

to

reduce

the

possibility

of

transportation

damage,

should

the

amplifier

ever

need

to

be

shipped

again.

In

the

unlikely

event

damage

has

occurred,

notify

your

dealer

immediately

and

request

the

name

of

the

carrier

so

a

written

claim

to

cover

shipping

damages

can

be

initiated.

THE

RIGHT

TO

A

CLAIM

AGAINST

A

PUBLIC

CARRIER

CAN

BE

FORFEITED

IF

THE

CARRIER

IS

NOT

NOTIFIED

PROMPTLY

IN

WRITING

AND

IF

THE

SHIPPING

CARTON

AND

PACKING

MATERIALS

ARE

NOT

AVAILABLE

FOR

INSPECTION

BY

THE

CARRIER.

SAVE

ALL

PACKING

MATERIALS

UNTIL

THE

CLAIM

HAS

BEEN

SETTLED.

PLACING

THE

GFA-7000

During

normal

home

operation

the

internal

heatsinks

of

the

GFA-7000

may

become

warm.

However,

there

are

instances

during

high-level

playback

into

low

impedances

when

the

heatsinks

will

become

much

warmer

than

usual.

To

ensure

the

amplifier’s

long-term,

trouble-

free

operation

it

is

necessary

to

provide

adequate

ventilation

for

the

heatsinks.

Therefore,

the

GFA-7000

should

be

kept

away

from

external

sources

of

heat

such

as

radiators

and

hot-air

ducts.

The

GFA-7000

should

never

be

placed

with

other

heat-producing

components

in

a

cabinet

or

enclosure

lacking

free

air

flow.

The

top

and

bottom

panel

of

the

amplifier

s

chassis

have

been

provided

with

vents

to

allow

the

necessary

cooling

of

the

internal

components.

It

is

imperative

that

these

vents

are

not

obstructed

in

any

way.

We

recommend

that

you

do

not

stack

other

components

on

top

of

the

GFA-7000.

I

his

is

particularly

important

If

your

system

includes

low-impedance

loudspeakers

which

are

difficult

to

drive,

or

if

you

will

consistently

demand

high

volume

levels

from

the

amplifier

and

speaker

system,

Not

only

will

heat

generated

by

the

amplifier

affect

the

performance

of

equipment

stacked

on

top

of

the

GFA-7000,

but

the

free

flow

of

air

through

the

ventilating

slots

in

the

amplifier

may

be

partially

obstructed.

.

If

you

observe

these

recommendations,

the

GFA-7000

will

perform

reliably

in

any

reasonable

environment.

You

should

also

pay

attention

to

such

normal

considerations

as

protection

from

excessive

dust

and

moisture.

Occasional

vacuuming

of

accumulated

dust

on

the

chassis

panels

and

around

the

ventilating

slots

should

be

all

that

is

required.

The

optimal

performance

of

your

new

GFA-7000

will

ultimately

depend

on

the

care

with

which

you

make

the

connections

between

the

amplifier,

preamplifier,

surround

sound

decoder

and

the

loudspeakers.

All

input

and

output

signal

connections

should

be

made

only

with

high

quality,

low-loss,

low

capacitance

cables

following

the

recommendations

in

the

Inputs

and

Outputs

section

of

CONNECTING

THE

GFA-7000.

7

QUICK

CONNECTIONS

■

I

:°,

r

?

0

S

e

0f

,

y

0U

wh0

are

in

a

hurry

t0

hook

U

P

y°

u

r

amplifier

into

your

system,

we

have

included

this

quick-connection

section.

The

wiring

is

straight

forward

and

expeditious

if

you

use

the

proper

cables

and

follow

this

diagram

exactly.

If

you

have

any

difficulties

or

questions

please

refer

to

the

appropriate

section

of

this

manual

for

complete

descriptions

and

instructions.

WARNING

-

t0

or

!

r

°

m

the

GFA-7000

are

being

made,

be

certain

that

the

AC

On/Off

Switch

(O)

of

the

amplifier

is

in

the

OFF

position,

the

AC

Power

Cord

(O)

of

the

amplifier

is

disconnected

from

the

AC

wall

outlet

and

that

all

associated

components

are

turned

off.

K

Ustening/Viewing

position

8

CONNECTING

THE

GFA-7000

Remember,

that

the

Left

and

Right

designations

are

as

you

are

sitting

down

in

your

listening/viewing

area.

On

the

rear

panel,

the

inputs

and

outputs

are

grouped

in

5

bracketed

sets,

one

for

each

channel.

They

are

abbreviated

as

indicated:

RR.Right

Rear

LR.Left

Rear

R.Right

C.Center

L.Left

Olnputs:

To

preserve

the

correct

effects,

be

certain

to

connect

the

RCA

cables

to

the

proper

RCA-

input

connector.

If

the

cables

are

color

coded,

then

use

this

sequence

for

the

connections:

Blue.Left(L)

Red.Right(R)

Green.Center(C)

White

with

Blue

Stripe.Left

Rear(LR)

White

with

Red

Stripe.Right

Rear(RR)

Home

THX®

certified

RCA

cables

will

have

directional

arrows

printed

on

the

side

of

each

cable.

Make

certain

that

these

arrows

are

pointed

towards

the

GFA-7000.

The

recommended

maximum

RCA

cable

capacitance

should

be

less

than

or

equal

to

30pF

per

foot

when

measured

between

the

two

conductors,

and

less

than

or

equal

to

50pF

per

foot

when

measured

between

one

conductor

and

the

shield.

With

the

DB-25

computer-type

Multichannel

input

connector(O),

there

is

no

need

to

worry

about

color

coding

or

properly

connecting

the

RCA

plugs,

as

this

is

done

in

One

connector

with

one

cable.

The

DB-25

can

easily

transfer

all

five

channels

from

the

output

of

the

Home

THX®

processor

unit

to

the

input

of

the

GFA-7000

amplifier.

There

can

be

no

errors

with

the

DB-25,

it

is

shaped

so

that

it

can

only

be

connected

in

the

proper

direction.

Contact

your

dealer

to

locate

a

THX®

DB-25

signal

cable.

OOutputs:

NOTE:

The

GFA-7000

is

“polarity

correct”.

That

is

it

does

not

invert

phase

from

input

to

output.

Any

positive

signals

at

its

inputs

will

appear

as

a

positive

signal

at

its

outputs

In

connecting

the

amplifier

to

the

loudspeaker,

it

is

vital

to

maintain

proper

polarity

(positive

to

positive,

negative

to

negative).

On

the

GFA-7000,

the

positive

terminal

is

color

coded

RED

and

labeled

“+",

and

the

negative

is

color

coded

BLACK

and

labeled

The

positive

terminal

on

the

speaker

will

be

color

coded

RED,

or

will

be

labeled

“+”,

“pos”,

“positive”,

“8

ohms”,

or

“4

ohms”.

The

negative

terminal

on

the

speaker

will

be

color

coded

BLACK,

or

will

be

labeled

"neg”,

negative”,

“C”,

“Common”,

“G”,

or

“ground”.

It

is

recommended

by

the

Home

THX®

standards

that

your

speaker

cables

be

terminated

with

“U"

type

spade

connectors.

These

will

give

the

most

contact

area

insuring

long-term

reliability.

The

spade

connector

should

have

-

r

~

a

maximum

width

of

0.57

inches

and

an

„L

77

“

opening

width

of

no

less

than

0.25”

i

_l

(see

diagram

on

right).

-T-

7

9

To

properly

connect

the

speaker

cable

to

the

binding

posts,

turn

the

insulated

head

of

the

binding

post

clockwise

until

the

wire

or

connector

is

firmly

secured.

Finger

pressure

is

sufficient

and

you

should

not

use

pliers

or

other

tools

which

could

damage

or

over-tiahten

the

bindina-

post

assembly

.

The

binding

posts,

have

been

designed

in

such

a

way

that

finger

pressure

is

all

that

is

required

to

cause

a

“pinching”

action

among

the

different

metal

surfaces

to

ensure

proper

connection.

It

is

very

important

to

use

the

correct

size

of

wire

in

order

to

avoid

unnecessary

loss

of

amplifier

power

in

the

cable,

reduction

of

amplifier

damping

factor

and

other

undesirable

conditions.

Home

THX®

specifications

require

the

use

of

at

least

AWG16,

stranded,

copper

cable.

Recommended

capacitance

of

the

speaker

wire

should

not

exceed

50pF

per

foot.

This

insures

high

frequencies

will

not

be

rolled-off.

It

is

suggested

that

the

three

front

channels

follow

this

chart

for

speaker

lengths

and

wire

gauges.

These

recommendations

are

standardized

Home

THX®

performance

specifications.

up

to

24

feet.AWG16

up

to

36

feet.AWG14

up

to

58

feet.AWG12

Generally,

for

the

two

rear

surround

channels,

longer

runs

of

cable

are

needed,

but

since

less

program

material

is

being

transmitted

through

the

cable,

longer

runs

are

acceptable:

up

to

48

feet.AWG16

up

to

72

feet.AWG14

up

to

116

feet.AWG12

If

longer

runs

are

needed,

it

is

best

to

consult

with

your

Adcom

Dealer

to

maximize

the

performance

of

your

system

with

your

exact

conditions.

All

loudspeakers

having

a

nominal

impedance

down

to

4

ohms

can

be

connected

to

and

driven

by

the

GFA-7000.

The

amplifier

can

drive

these

low-impedance

speakers

at

more

than

adequate

power

levels

with

no

difficulty.

It

should

be

noted

here

that

many

loudspeaker

systems

which

are

nominally

rated

at

4

ohms

drop

in

impedance,

in

some

parts

of

their

frequency

range,

to

as

low

as

2

ohms

(and

sometimes

less).

You

will

not

experience

difficulties

even

with

these

very

low

impedance

loads

unless

you

demand

excessively

high

volumes

levels

from

your

system.

It

is

not

recommended

that

you

run

additional

sets

of

speakers

on

any

or

all

of

the

amplifiers

in

the

GFA-7000

in

order

to

insure

the

integrity

of

a

Home

THX®

system.

If

you

choose

to

add

remote

speakers

in

another

room,

it

is

strongly

suggested

that

a

switching

system

to

disconnect

the

non-home-theater

speakers

be

incorporated

when

the

surround

sound,

home-theater

mode

is

in

operation.

A

device

such

as

the

Adcom

GFS-3,

GFS-4

or

GFS-6

Speaker

Selector

is

strongly

recommended.

A

Speaker

Selector

enables

you

to

maintain

Home

THX®

integrity

while

giving

you

the

flexibility

to

add

speakers

throughout

your

house.

CARING

FOR

YOUR

GFA-7000

Great

care

has

been

taken

by

ADCOM

to

ensure

that

your

amplifier

is

as

flawless

in

appearance

as

it

is

electronically.

The

front

panel

is

a

heavy-gauge,

high-grade

aluminum

extrusion

carefully

finished

and

anodized

for

durability.

The

chassis,

top

cover

and

rear

panel

are

heavy-gauge

steel

that

has

been

powder

coated

and

baked

to

ensure

a

lasting

finish.

If

the

front

panel,

top

or

sides

become

dusty

or

fingerprinted,

they

can

be

cleaned

with

a

soft

lint-free

cloth,

slightly

dampened

with

a

very

mild

detergent

solution

or

glass

cleaner.

DO

NOT

SPRAY

OR

POUR

LIQUIDS

OF

ANY

KIND

ON

THE

GFA-7000.

10

TROUBLESHOOTING

RESOLVING

PROBLEMS

Use

the

chart

below

to

solve

common

situations

that

don't

require

professional

attention.

If

the

steps

stated

in

POSSIBLE

SOLUTION

do

not

resolve

your

problem,

then

please

contact

your

Adcom

Dealer

or

call

the

Adcom

Customer

Service

Department.

Any

problems

not

covered

here

should

be

brought

to

the

attention

of

your

Adcom

Dealer

or

Adcom

Customer

Service

Department.

A

special

note

on

“hum”

:

When

there

is

a

low-volume

“hum”

audible

throughout

your

speakers,

even

with

the

main

volume

turned

all

the

way

down,

you

have

a

common

phenomenon

known

as

a

“ground

loop”.

A

ground

loop

is

basically

a

difference

in

ground

voltages

between

two

or

more

components

which

are

connected

electrically

and

which

creates

multiple

current

paths

where

there

must

only

be

one.

This

difference

in

potentials

creates

a

60Hz

low-level

sound

(approximately

a

low

A

#

),

that

seems

to

“hum”,

hence

the

name.

It

can

be

caused

by

adding

new

components

to

your

system,

but

that

does

not

imply

there

is

anything

electrically

wrong

with

any

new

component.

With

the

advent

of

audio/video

and

home

theater

systems,

the

problem

has

become

commonplace.

Generally,

the

cause

is

the

Cable-TV

incoming

signal

line.

This

new

incoming

line

may

add

an

additional

ground

at

a

different

potential

to

the

AC

line

ground

of

your

other

equipment

(refer

to

Notel

and

2

below

to

troubleshoot

a

hum

problem).

SYMPTOM

|

|

POSSIBLE

REASON

|

|

POSSIBLE

SOLUTION

Power

LED

does

not

glow

No

sound

AC

Power

Cord(O)

not

plugged

in.

Plug

in

AC

Power

Cord(O).

AC

Fuse(O)

blown.

Replace

AC

Fuse(O).

Transformer

thermal

protection

engaged

Wait

until

unit

cools

down,

it

will

reset.

Power

LED

glows,

but

no

sound

Preamp

or

source

unit

is

not

on

Make

sure

whole

system

is

on.

Connections

in

rear

of

amp

are

loose.

Verify

all

connections

on

rear

of

amp

One

channel

not

producing

sound

INPUT(O)

or

OUTPUT(O)

connector

disconnected

or

loose.

Verify

both

connections

on

that

channel

Speaker

disconnected.

Verify

connection

at

speaker.

Internal

protection

engaged

Bring

to

Dealer

or

Service

Center

Hum

from

all

speakers

at

any

volume

Ground

loop

(difference

in

ground

voltages

between

components).

If

Cable

TV

is

present

(see

Note

1)

If

Cable

TV

is

not

present

(see

Note

2)

Hum

from

all

speakers

(hum

goes

up

or

down

with

volume)

Problem

with

source

unit

(CD,

tape,

etc.),

or

RCA

cable

connecting

that

source

unit

to

the

preamp.

Try

different

source

(tuner,

tape,

etc

)

and/or

different

RCA

cable

Hum

from

the

amplifier

itself

Some

major

appliance,

dimmer,

halogen

or

fluorescent

light

is

creating

interference

Make

sure

all

appliances,

dimmers

and

suspect

lights

are

off

Note

1

Cable

TV

systems

can

sometimes

contribute

to

ground

loop

problems

which

cause

“hum”

To

determine

if

your

cable

system

is

the

contributing

factor,

disconnect

the

Cable-TV

incoming

signal

line

(round,

750)

at

the

wall,

or

the

first

component

the

cable

is

connected

to

(i.e.

the

cable

box,

or

VCR)

If

the

hum

is

no

longer

present,

you

must

insert

a

“750

Ground

Loop

Isolator”

before

reconnecting

the

line.

You

should

check

with

your

Adcom

Dealer

to

obtain

one.

If

the

“750

Ground

Loop

Isolator”

works

only

partially

or

not

at

all,

then

please

read

Note

2

to

complete

the

troubleshooting

procedure

Note

2

Make

sure

that

the

power

amplifier

is

at

least

6"

from

the

Preamp

and/or

Processor.

Usually

putting

another

component

between

them

is

sufficient

to

minimize

the

hum

If

this

does

not

reduce

the

hum,

turn

the

system

off

and

disconnect

all

Inputs

from

the

amplifier.

If

the

hum

still

persists,

then

your

Dealer

or

Service

Center

must

examine

the

amplifier.

If

the

hum

disappears,

try

another

set

of

RCA

cables.

Connect

one

RCA

cable

at

a

time

to

see

if

one

specific

cable

is

responsible.

If

any

or

all

cables

cause

the

hum

to

appear,

then

the

preamp

or

processor

should

be

evaluated

for

proper

operation

by

your

Dealer

or

Authorized

Service

Center.

11

SERVICING

ADCOM

has

a

Technical

Service

Department

t

o

answer

questions

pertinent

to

the

installation

and

operation

of

your

unit.

In

the

event

of

difficulty,

please

contact

us

for

prompt

advice.

Please

have

the

following

information

readily

at

hand:

the

unit’s

model

and

serial

numbers,

and

dealer

from

which

it

was

bought.

If

your

problem

cannot

be

resolved

through

our

combined

efforts,

we

may

refer

you

to

an

authorized

repair

agency,

or

authorize

return

of

the

unit

to

our

factory.

To

aid

us

in

directing

you

to

a

convenient

service

center,

it

would

be

helpful

if

you

indicate

which

major

city

is

accessible

to

your

home.

Please

address

mail

inquiries

to:

ADCOM

Service

Corporation

11

Elkins

Road

East

Brunswick,

NJ

08816

USA

Phone

or

Fax

inquiries

to:

Voice:

908-390-1130

Fax:

908-390-9152

Monday

through

Friday

9:00

AM

to

5:00

PM

Eastern

Time

UNDER

NO

CIRCUMSTANCES

SHOULD

YOUR

UNIT

BE

SHIPPED

TO

OUR

FACTORY

WITHOUT

PRIOR

AUTHORIZATION,

OR

PACKED

IN

OTHER

THAN

ITS

ORIGINAL

CARTON

AND

FILLERS.

For

fax

inquires,

please

include

a

return

fax

or

voice

number

for

the

reply.

When

calling

or

writing

about

your

GFA-7000,

be

sure

to

note

and

refer

to

its

serial

number

as

well

as

the

date

of

purchase

and

the

dealer

from

whom

it

was

purchased.

In

the

event

the

unit

must

be

returned

to

our

factory

for

service,

you

will

be

instructed

on

the

proper

procedure

when

you

call

or

write

for

a

Return

Authorization.

For

warranty

coverage,

a

copy

of

the

original

proof

of

purchase

is

required.

If

you

have

no

original

copy,

please

contact

your

dealer

to

obtain

a

duplicate

copy.

If

the

original

shipping

carton

and

its

fillers

have

been

lost,

discarded,

or

damaged,

a

duplicate

carton

may

be

obtained

from

our

Service

Department

for

a

nominal

charge.

Always

ship

PREPAID

VIA

UNITED

PARCEL

SERVICE

(UPS)

OR

OTHER

APPROVED

CARRIER.

DO

NOT

SHIP

VIA

PARCEL

POST,

since

the

packing

was

not

designed

to

withstand

rough

Parcel

Post

handling.

FREIGHT

COLLECT

SHIPMENTS

CAN

NOT

BE

ACCEPTED

UNDER

ANY

CIRCUMSTANCES.

12

GFA-7000

SPECIFICATIONS

Power

Rating

(To

FTC

Requirements)

130

watts

continuous

average

power

into

8

ohms

at

any

frequency

between

20Hz

to

20kHz

with

ail

channels

driven

at

less

than

0

05%

THD

200

watts

continuous

average

power

into

4

ohms

at

any

frequency

between

20Hz

to

20kHz

with

all

channels

driven

at

less

than

0.05%

THD

IM

Distortion

(SMPTE)

1

watt

to

130

watts

into

8

ohms.

.

<0

05%

1

watt

to

200

watts

into

4

ohms.

.

<

0

05%

IM

Distortion

(CCIF,

Any

Combination

from

4kHz

to

20kHz)

130

watts

into

8

ohms.

.

.

...

.

<

0

02%

200

watts

into

4

ohms.

.

.

<

0

02%

THD

+

Noise

at

130

watts

into

8

ohms

(Typical)

20Hz.

0.0075%

1kHz

.

.

...

..

0

007%

10kHz.

.

...

0

015%

20kHz

.

..

.

0.025%

THD

+

Noise

at

200

watts

into

4

ohms

(Typical)

20Hz

.

.

..

.

0

015%

1kHz

..

.

.

.

0

010%

10kHz.

.

0

022%

20kHz

.

0

035%

Frequency

Response

@

1

Watt

into

8

ohms

(10Hz

to

20kHz).

+0,

-0

25dB

Power

Bandwidth

(-3dB)

.

.1

5Hz

to

100kHz

Dynamic

Headroom

into

4

ohms

.

.

1

9

dB

Signal

to

Noise

Ratio,

“A”

Weighted

(130

watts

into

8

ohms)

>11

5

d

B

Gain

.

.

29dB

Input

Sensitivity

for

1

Watt.

.

0.1

volts

for

130

Watts.

1

14

volts

Input

Impedance

50kQ

Damping

Factor

(20Hz

to

20kHz)

.

>

800

Rise

Time

(5kHz,

90V,

peak-to-peak

square

wave,

20%

to

80%)

.

..

2.7pS

Power

Consumption

(Continuous,

All

Channels

Driven)

Quiescent.

80VA

Maximum.

.

1440VA

130

watts

into

8

ohms.

1200VA

Power

(Available

in

230VAC

on

special

order)

Chassis

Dimensions.

Maximum

Dimensions..

.

Weight.

Weight,

Packed

.

.115VAC

-

50/60Hz

.

..

7”

(178mm)

x

17”

(432mm)

x

13

3

/4"

(349mm)

.

.

7

3

/b”

(187mm)

x

17"

(432mm)

x

14

7

/«”

(378mm)

...

411b

(18

6

kg)

.

46

lb.

(21

3

kg)

/DCOM

11

Elkins

Road

East

Brunswick,

NJ

08816

USA

Tel:

(908)

390-1130

Fax:

(908)

390-9152

95DG11

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