Carvin FX44 Instruction Manual - Page 26

FX44

Mixer

Special

Features

of

the

FX44

Mixers

Section

4

If

you

are

calibrating

your

console

to

+4dBv,

you

will

perform

the

same

procedure

explained

above,

except

that

your

volt

meter

will

be

reading

1.23

Volts

A.C.

when

you

calibrate

your

meters

to

"0"

VU.

Note

on

the

zero

stop:

Each

VU

meter

has

a

small

screw

hole

directly

underneath

it,

on

the

face

of

the

meter

panel.

This

is

a

mechanical

adjustment

used

to

set

the

zero

stop

of

the

meter.

By

turning

this

screw

you

can

set

the

far

left

"zero"

for

each

of

the

VU

meters.

This

adjustment

is

pre-set

at

the

factory

and

should

not

normally

require

adjustment,

however,

after

a

lot

of

transporting

and

vibration

the

meters

may

eventually

require

a

slight

adjustment

to

"zero"

them.

It

is

an

easy

adjustment

to

make

and

can

be

done

by

simply

using

a

small

screwdriver

to

turn

the

adjustment

screw

until

the

meter

rests

at

the

far

left

small

"0"

(not

OVU),

WITH

THE

MIXER

TURNED

OFF.

4)

Speaker

Impedance

On

powered

mixing

consoles

it

is

very

important

that

you

do

not

go

below

the

unit's

minimum

impedance

with

your

speaker

system.

What

this

means

is

that

you

cannot

connect

too

many

speakers

in

parallel

to

your

powered

mixing

console.

Speakers,

as

a

rule,

are

connected

in

parallel.

This

means

the

'+'

(Red)

of

the

first

speaker

is

connected

to

the

"+"

of

the

second

speaker.

Calculate

the

impedance

for

your

speakers,

on

each

channel

(Left

and

Right)

and

be

sure

that

it

does

not

fall

below

the

MINIMUM

LOAD

impedance

that

your

mixing

console

is

rated

to

handle.

On

all

CARVIN

powered

mixers

the

MINIMUM

RECOMMENDED

impedance

is

4

ohms

(4Q)

per

speaker

jack.

You

may

of

course

use

higher

impedances.

In

order

to

figure

the

impedance

of

your

speaker

system

you

should

use

the

following

formula:

FORMULA

FOR

PARALLEL

IMPEDANCE

Find

the

rated

impedance

of

each

of

your

speakers.

Is

should

be

written on

the

cabinet

rear

or

bottom.

It

will

typically

be

8

ohms

(8Q),

4

ohms

(40.),

3

ohms

(311),

or

16

ohms

(16c2),

but

others

do

exist.

Invert

these

numbers

(i.e.

make

a

fraction

out

of

them).

Example:

sa

would

become

1/8

452

would

become

1/4

Add

each

of

these

fractions

together

and

divide

the

denominator

(bottom

number)

by

the

numerator

(top

number).

The

result

will

be

your

load

impedance

produced

by

your

speaker

system.

Example:

You

have

two,

8.Q

speakers

connected

in

parallel,

the

impedance

of

them

is

calculated.

Add

speaker

impedances

1/8

+

1/8

=

2/8

Divide

denominator

8

by

numerator

2

This

equals

8/2

=

4Q

total

load

impedance

Example:

Speaker

ratings:

sa.

+

1652

+

1652

So

1/8

+

1/16

+

1/16=

4/16

Divide

16

/

4

=

4S2

total

load

impedance

Usually

whenever

you

are

simply

plugging

one

or

more

speakers

into

the

back

of

your

unit,

you

are

running

this

type

of

parallel

connection.

And,

the

above

calculation

will

give

you

an

accurate

indication

of

what

impedance

your

speaker

system

(in

ohms)

is

loading

on

to

your

amplifier.

Understanding

that

your

console's

amplifier

does

have

limits

regarding

how

many

speakers

you

can

hook

up

to

it,

and

that

the

minimum

limit

is

4

ohms

(4Q)

Left

and

4Q

Right,

is

insurance

that

you

are

operating

your

mixer

properly

and

that

it

will

be

reliable.

This

information

should

be

all

that

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Carvin FX44 Instruction Manual - Page 26

written

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