Carvin FET1000 Instruction Manual - Page 34

FET

Series

Power

Amplifiers

About

the

PET

Series

Amps

Section

3

Professional

Accessory

Group

The

signal

processors

built

into

the

FET450

and

FET1000

amps

are

controlled

by

a

group

of

DIP

(Dual

In

-line

Package)

switches

located

on

the

mar

panel.

In

order

to

access

the

DIP

switches

you

must

first

remove

the

plastic

cover.

Under

the

cover

are

sixteen

gold

contact

switches.

The

switches

are grouped

according

to

the

channel

that

they

control.

The

"Si"

group

of

switches

(switches

S1-1

through

S1-8)

controls

the

functions

for

CH

1

and

the

"S2"

group

(switches

S2-1

through

S2-8)

select

the

functions

for

CH

2.

Switches

-1

and

-8

in

both

the

"Si"

and

"S2"

groups

must

be

switched

as

a

pair.

Switches

S1-1

and

S2-1

select

the

input

"Y"

connection

option

while

switches

S1-8

and

S2-8

select

either

the

"Stereo"

or

"Mono

bridged"

mode

of

the

amplifier.

The

remaining

switches

control

the

various

accessories

for

each

channel

and

can

be

operated

independently

of

one

another.

Always

replace

the

plastic

cover over

the

switch

group

to

assure

maximum

air

cooling.

S

1-1

&

S2-1

Input

"Y"

Configuration:

This

feature

allows

the

two

channels

of

the

amp

to

be

driven

from

one

input.

The

channels

are

driven

with

similar

polarity

i.e.

"in

phase".

S1

-2&S2-2

XLR

Ground

Lift:

Use

this

switch

to

float

the

ground

on

the

XLR

input

connector

when

you

need

to

break

a

ground

loop

between

the

mixer

and

the

power

amp.

This

switch

does

not

affect

the

1/4"

input

grounding.

S

1-3&

S2-3

The

Low

Cut

Filter:

This

switch

cuts

the

bass

below

30

Hz.

Use

it

to

eliminate

subsonic

noise

during

li

ve

performances.

By

attenuating

power

wasting

subsonic

energy

the

low

cut

filter

also

helps

to

conserve

amplifier

power

and

reduces

woofer

cone

excursion.

We

recommend

that

this

switch

always

be

set

"ON"

for

concert/live

performances.

For

studio

monitoring

applications,

you

will

probably

not

want

to

use

the

low

cut

filter

in

order

to

take

advantage

of

the

wide

bandwidth

of

the

amplifier.

S1

-4&S2-4

The

High

Cut

Filter:

The

high

cut

filter

attenuates

high

frequency

material

above

25k

Hz.

Because

of

the

wide

bandwidth

of

the

FET

series

amplifiers

(5

Hz

to

80k

Hz),

it

may

be

prudent

to

eliminate

ultra

-sonic

frequencies

above

25k

Hz

in

live

sound

situations.

This

helps

protect

horn

drivers,

in

particular,

from

any

ultrasonic

oscillations

that

may

be

generated

by

gear

ahead

of

the

power

amps

due

to

"rats

nest"

cable

connections

or

from

less

than

ideal

grounding.

In

the

studio

(as

a

control

room

monitor

amplifier)

you

may

wish

to

utilize

the

full

bandwidth

of

the

amplifier

for

the

most

accurate

response

possible.

For

studio

monitoring

we

recommend

that

you

leave

both

the

"low

cut"

and

"high

cut"

filters

in

the

OFF

position.

S

1-

5

&

S

2

-

5

The

Compressor:

The

action

of

the

compressor

is

virtually

inaudible

in

normal

operation.

However,

by

reducing

the

volume

of

peak

program

levels,

the

compressor

allows

increased

overall

loudness

before

the

onset

of

audible

distortion.

Setting

the

compressor

switch

(-5)

set

to

the

"ON"

position

with

switches

-6,

and

-7

off

provides

the

maximum

level

of

compression

and

will

limit

the

average

output

of

the

amp

to

about

10%

of

rated

power

by

providing

up

to

10

dB

of

gain

reduction.

Switching

on

-6

raises

the

compressor

threshold

to

allow

only

about

6

dB

of

gain

reduction.

Switching

on

-7

(with

-6

off)

raises

the

compressor

threshold

even

further

and

allows

only

about

3

dB

of

gain

reduction.

Use

of

the

compressor

is

recommended

for

live

sound

reinforcement.

S1

-8&S2-8

Mono

Bridge

Mode:

The

FET450

and

FET1000

can

be

switched

to

Mono

Bridge

mode

to

allow

the

two

channels

to

operate

as

one

power

amplifier.

When

switched

to

the

mono

mode

the

FET

Amps

can

deliver

the

full

rated

power

of

both

channels

into

a

single

load.

(see

section

4

for

more

detail

on

bridging)

3-7

Carvin FET1000 Instruction Manual - Page 34

Professional, Accessory, Group

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