BGW 85 Owner's Manual

13130

SOUTH

YUKON

AV~NUE

HAWTHORNE,

CAL-JFORNJA

90250

PHONE

(213)

973-8090

TEL-EX NO,

66-4494

.,

"'

OWNER'S MANUAL

MODEL 85

BROADCAST POWER AMPLIFIER

TABLE

OF

CONTENTS

DESCRIPTION

FORM NUMBER

,"

Important

• .

· 00601

Description

• • • • •

· 00831

Option

Page

• •

• 00835

Specifications

• • 00940

Unpacking and

Set-Up

•

. . . . . . .

02510

Rack

Mounting

Hints

. .

. . . . . . .

02650

Input

Connections.

•

• 03060

Output

Connections.

•

• • 03520

Speaker

Fuse

Nomagraph.

03530

Damping

Factor

Nomagraph

03510

Stereo

Headphone

Connections

• .

03590

Mono

Operation.

• . . . •

03680

Power Mains

Connection

.

04000

Opera

tion . . . . . . .

05200

f ' :

Circuit

Description

• • . • • • • • .

. . 06265

Schematic

Diagram,

Amplifier

• • •

15720

Schematic

Diagram,

Power

Supply. 15730

Chassis

Interconnection

Wiring • . . • . . .

1574-0

Option

-06/07

Transformer

Input

Connections.

.

1574-1

Option -01

Active

Input

Connections.

1574-2

Block

Diagram

• . . . . . . . . .

15710

Parts

List . • • . . . . 15790

Product/Option

Matrix.

16000
Warranty 17000
Service

Authorization

Form

17020
Warranty

Registration

Form

.

17030

OUb<J!-!

-

IMPORTANT-

PLEASE. READ THIS PAGE BEFORE OPERATING

YOUR

BGW

POWER AMPLIFIER

Your new

BGW

amplifier

is

designed to provide

years

of

trouble

free

performance.

Observing

these

few

precautions

will

insure

proper

operation:

Read all

Instructions

before

connecting

any

AC power

to

your power

amplifier.

Retain

this

Manual

for

future

reference.

Heed all warnings on

the

top

or

rear

of

the

power

amplifier.

The

amplifier

should

not

be used

near

water -for

example,

near a bathtub,

washbowl,

kitchen

sink, laundry tub, in a

wet

basement,

or

near

a swimming pool,

etc.
The

amplifier

should be

situated

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

a bookcase or

cabinet

that

may

impede

the

flow of

air

through

the

ventilation

openings.

The

amplifier

should be

situated

away

from

heat

sources

such

as

radiators,

heat

registers,

stoves,

or

other

appliances

that

pr.oduce

heat.

The

amplifier

should be

connected

to

a power supply only of

the

type

described

in

the

operating

instructions

or

as

marked

on

the

rear

panel.

Precautions

should be

taken

so

that

the

grounding

means

of

the

amplifier

is

not

defeated.
The power supply

cord

should be

routed

so

that

it

is not

likely

to

be walked on or

pinched by

items

placed

upon or

against

it,

paying

particular

attention

to

cord

at

the

plug,

convenience

receptacles,

and

the

point

where

they

exit

from

the

amplifier.
Care

should be

taken

so

that

objects

do

not

fall into, and liquids

are

not spilled into

the

amplifier

through

openings.

00601-2

'!he

amplifier

should

be

serviced

by

qualified

sezvice

personnel

when:

'!he

IXMer

supply

cord

or

the

plug

has

been

damaged;

or

abj

acts

have

fallen

into,

or

liquid

has

been

spilled

into

the

amplifier:

or

has

been

exposed

to

rain;

or

does

not

~

to

operate

normally

or

exhibits

a marked c.hange

in

perfo:cnance;

or

has

been

dropped,

or

the

enclosure

has

been

damaged.

All

connections

should

be

made

to

the

power

amplifier

with

the

power OFF.

Speaker

fuses

should

be

used

to

afford

maxilm.un

speaker

protection.

Never

connect

the

rut:put

of

one

channel

to

that

of

another.

Connect

the

IXM9r

cord

to

the

proper

voltage

mains

as

in:li.cata:1. CI'l

tie

rear

of

the

amplifier.

Conversion

to

arxXharvolta;)e

req..rires

intemal

~.

I):)

not

rencve

the

amplifier's

cover.

Amplifiers

may

not

be

covered

\.ll'Der

warranty

if

they

are

tanpered

with.

'!here

are

NO

adjustments

within.

Potentially

lethal

voltages

exist

within

the

amplifier.

Iefer

all

se:rvicE

YJOrk

to

an

authorized

EGi

sern.ce

station.

DESCRIPTION

The

BGW

Model 85 is one

of

the

most

advanced

solid

state,

full

complementary,

bridgeable,

stereo

power

amplifiers

available.

Features

of

the

Model 85 include

Magnetic

Circuit

Breaker/Power

Switch,

Input

Level

Controls,

Headphone

Jack,

and

Power

Indicator,

~"

input

connectors,

separate

circuit

and

chassis

grounds, and

small

size.

The

Front

Panel

includes

two

Input

Level

Controls,

Power

Switch,

Headphone

Jack,

and Green LED

Power

Indica

tor.

The

Rear

Panel

includes

AC Input

Cord,

two

Yt.

Phone

Jack

Input

Connectors,

Mono/Stereo Switch

to

convert

amplifier

to

a fully

bridged

Mono

amplifier

and

a 6

point

screw

terminal

strip

for

the

output

of

each

amplifier

and

ground

circuits.

Both

the

circuit

and chassis grounds

are

connected

to

separate

barrier

strip

terminals

on

the

rear

of

the

amplifier.

They

are

connected

together

by a

removeable

link.

By

removing

the

link,

the

circuit

grounds

of

all

active

units

(amplifiers,

preamplifiers,

mixers,

etc.)

can

be

tied

to

earth

ground

at a common

point.

This aids

in

eliminating

ground loops.

The

size

of

the

Model 85 is

convenient

for a wide

variety

of

applications.

However,

please

note

the

following

precautions:

1)

Do

not

use

the

front

panel

as

the

sole

support

for

the

amplifier.

Side rails

or

rack

shelves

should

be

employed.

2)

Do

not

stack

Model 85

amplifiers. A minimum

of 1

3/4

inches

above

each

amplifier

should be provided for

free

air

circulation.

The

output

voltage

follower

stage

of

your

amplifier

uses

the

most

advanced

type

of

transistors

available.

These

large

geometry,

150

watt

complementary

power

devices

have

large

safe

operating

areas

and

extended

power

bandwidth.

Electrostatic

and

other

highly

reactive

speaker

systems

present

no

difficulties

for

the

Model 85.

All of

the

semiconductors

in

the

output

area

are

in

intimate

contact

with

the

heat

sink. The bias

stage

is

mounted

on

the

same

heat

sink

as

the

output

transistors

and

provide

temperature

compensated

bias

current

to

the

output

stage.

The input

stage

utilizes

NPN

matched

low noise

transistors

connected

as

a

differential

pair.

This

stage

drives

two common

emitter

voltage

stages

in

Push

Pull. The

output

of

the

voltage

amplifier

stage

is loaded

by a current

mirror

stage,

bias

stage

and

the

complementry

Darlington

output

stage.

The Model 85

is

wired for use

at

120

VAC

only

I

...."

J

The-

ampUfler should

be

serviced

by

qualWed

service

personnel when:

nr

I'

The

power

supply

card

.

or

the

plug

has

been

damaged;

or

objects have

fallen

intc~

or

Uquici ·hu

been

spilled

1ntD

me

amplifier;

or

has

been

expcsed

to

rain;

or

aces

no't

appear

to

oper&'te normally

or

extUbit:s a

marked c:hange in

perlcrmance;

or

has

been

drop~

«

the

enc:icsure has

been

damqed.

All

camectioas

shoWci

be

made

to

the

power

amplifler

with

the

power

OFF.

Speaker fuses should

be

'4sed

to

affCX"d

maximum speaker pro'teeCon.

Neve"

ecnnec:t

Ute

output

at ene d1annei

to

that

at another.

Connect

the

pow

..

=rd

to

the

proper

voltage

mains

as

indicated

on

the

rear

ot

the

amplWer. Convenicn

to

anather

voltage

requires

in'tem&L

rewiring.

00

nC't remove Ute

amplifiers

=ver.

Amplifiers

may no't be covered under

warnnty

if

they

are

tampered

.

with.

There are NO adjustments

within.

Potentially

lethal

voltages

exist

within

the

amplifier.

Reter

all

service

work

to

an authorized

SGW

service

staticn.

'

00835

OPTIONS

FOR

'mE

r-DDEL

85

'!he

Model

85

may

be

ordered

with

the

follor.ori.rq

options:

85-01

Dlal

C1"lannel

Active

Balanced

Inputs

(with

70

dB

omR)

85-06

Dlal

Cllannel

Transfonner

Balanced

Inputs

85-20

XIR

Unbalanced

Inputs

THE

BGW

85

BROADCAST POWER

AM

PLIFIER

Exacting

design

standards

and unique

features

establish

the

BGW

amplifier

as

the

industry

leader

in

power

amplifier

technology.

Features

such

as

all

steel

chassis

and

covers,

metal-case

output

transistors,

totally

modular

construction

and

large

alumimum

heat-sink

have

set

the

industry

standard

in audio

power

amplifiers.

Delivering

at

least

35

watts

per

channel

into

8 ohm loads and using

the

latest

in

full

complementary

circuitry

techniques,

the

Model 85

offers

reliability

and

performance

unparalleled

in

the

industry.

SPECIFICATIONS:

BGW

MODEL 85

OUTPUT POWER

35

watts

minimum

sine

wave

continuous

average

power

output

per

channel

with

both

channels

driving 8-ohm loads

over a power

band

from

20tfz

to

20kHz. The

maximum

Total

Harmonic

Distortion

at

any power

level

from

250-milliwatts

to

25

watts

shall

be

no

more

than

.05% from 20Hz

to

5kHz

then

rising

linearly

to

a

maximum

of

.10%

at

20kHz.

45

watts

minimum

sine

wave

continuous

average

power

output

per

channel

with

both

channels

driving 4-ohm loads

over a power

band

from

20Hz

to

20kHz. The

maximum

Total

Harmonic

Distortion

at

any power

level

from

250-milliwatts

to

45

watts

shall

be

no

more

than

.10% from 20Hz

to

5kHz

then

rising

linearly

to

a

maximum

of

.20%

at

20kHz.

90

watts

minimum

sine

wave

continuous

average

power

output

monaural

driving an

8-ohm load

over a power

band from 20Hz

to

20kHz. The

maximum

Total

Harmonic

Distortion

at

any

power

level

from

250-milliwatts

to

90

watts

shall

be

no

more

than

.10%

from

20Hz

to

5kHz

then

rising

linearly

to a maximum

of

.20%

at

20kHz.

*"

All

specifications

and

features

are

subject

to

change

without

notice.

Intermodula

tion

Distortion:

Small Signal

Frequency

Response:

Hum and Noise Level:

Input

Sensitivity:

Input

Impedance:

Damping

Factor:

Output

Impedance:

Slew

Rate:

Rise

Time:

Power

Requirements:

Semiconductor

Complement:

Dimensions:

Weight:

SPECIFICATIONS

Less

than

0.04%

from

250

milliwatts

to

rated

power.

+0, -3dB, 1Hz

to

100kHz,

+0, -0.25dB, 20Hz,

to

20kHz.

Better

than

105dB below

rated

8 ohm

output

(unweighted,

20Hz

to

20kHz).'

0.84

volts

for

rated

8 ohm

power

output.

Voltage gain 26dB (20

times).

15k ohms.

Greater

than

300 to 1

at

8 ohms below

1kHz.
Designed for any

load

impedance

equal

to

or

greater

than 4 ohms.

18

V/u

S

2.4 u S.
120 volts

A.C.,

50-60

Hz

at

2.5

amps

2

Ultra-low

noise

matched

differential

pairs,

18

transistors,

12

diodes,

1 LED.

1 3/4" by 19"

standard

rack

front

panel.

Depth

behind fron

panel

11Y2".

(4.45cm

x 48.26cm x 29.21cm)

14

Lbs.

Net,

18

Lbs. shipping.

6.36 Kg.

Net,

8.18 Kg. shipping.

02'10

UNPACKING AND SET-UP

Your

BGW

Power Amplifier is shipped in an advanced packing

container.

SA

VE

THE CONT AINER

AND ALL PACKING MATERIAL!

The

container

should be saved in

the

event

the

unit is moved or shipped

at

some

future

date.

Replacement

containers

are

available

from

BGW

Systems.

Inspect

the

unit for

damage

in

transit

immediately

upon

receipt.

If

damage

is

found,

notify

the

transportation

company

immediately.

Only

the

consignee

may

institute a claim

with

the

carrier

for shipping

damage.

BGW

will

cooperate

fully in

such an

event.

Be

sure

to

save

the

container

as

evidence

of

damage

for

the

shipper

to

inspect.

The

amplifier's

mounting position

must

be

chosen

carefully,

so

that

the

air

flow

around

the

unit is

not

restricted.

Inadequate

ventilation

may

cause

failure

of

the

amplifier.

For

rack

mounting,

the

four rubber

feet

on

the

bottom

of

the

unit

may

be removed and no

hardware

wiJ1

be loosened inside

the

unit.

The

size

of

the

amplifier

is

convenient

for a wide

variety

of

applications.

However, please

note

the

following

precautions:

1.) Do not use

the

front

panel

as

the

sole

support

for

the

amplifier.

Side

ralls or

rack

shelves should be

employed.

2.)

Do

not

stack

amplifiers.

A minimum of 1 3/4" above

each

amplifier

should be provided for

free

air

circulation.

DO NOT PLUG THE AMPLIFIER

IN

YET!

AU

connections should be made

before

power is

applied.

RACK MOUNTING HINTS

KEEPING

IT

COOL

A power

amplifier

draws

energy

from a primary

electrical

?ervice,

usually a

l20

VAC

outlet,

to

drive

loudspeaker

systems

with an audio

signal.

Typically,

only

half

of

the

energy

can

be

delivered

to

the

loudspeakers;

remaining

energy

is

converted

into

heat,

and

must

be

dissipated

(ventilated)

into

the

air.

Air

circulating

past

heat-producing

components

absorbs

the

heat

and

carries

it

away. To

accomplish

this,

low and

medium

power

amplifiers

rely

on

natural

convection

currents,

while

most high power

amplifiers

use

fans.

If

the

air

flow

is

impeded,

the

resulting

rise

in

heat

may

cause

an

amplifier

to

stop

working or

fail.

Circulating

air

currents

must

not

be

cut

off

when

installing

power

amplifiers

in

racks.

Power

amplifiers

using

convection

cooling

require

spacing

between

amplifiers

to

permit

air

flow

between

them.

Power

amplifiers

using

forced-air

cooling,

on

the

other

hand,

can

usually be

stacked

closer

to

each

other

and

may

not

need

any blank panel

spacing

between

amplifiers.

To

improve

natural

convection

currents

within a

rack, a chimney

can

be

created

by

closing

the

back

of

the

rack

and

venting

the

rack

at

the

bottom

to

let

in

fresh

air,

and

at

the

top

to

exhaust

hot

air.

Vents should be

large

rectangular

slots

approximately

19"

wide by

4"

high.

The

rack

cabinet

will

require

some

type

of blower if a

large

air-flow

is

required.

It

is

best

to

exhaust

air

from

the

top

of

the

rack

rather

than

to

blow

it

in

from

the

bottom.

There

will be less dust and

dirt

in

the

rack

this

way, if

the

bottom

vent

is

sufficiently

large.
INST ALLING THE UNITS
Use

care

when

mounting

equipment

in a

rack.

Place

the

heaviest

units

near

the

bottom

of

the

rack

and fill in

all

unused

rack

spaces

with

blank

panels.

Equipment

cannot

always be

supported

by

front

panels

alone.

This is

especially

true

of

amplifiers

whose

depth

is

more

than

twice

their

height.

Uniform

support

can

be

insured

by

installing

bottom

or side

rails.

When racks

are

to

be

transported

or used in a

mobile

installation,

some

means

of

securing

the

rear

of

the

equipment

are

required.

Angle

brackets

either

attached

to

the

bottom,

side

rails

or

rear

panel

are

practical

approaches.

03060

STEREO INPUT CONNECTIONS

1/4 inch phone jacks

are

provided on

the

rear

of

the

amplifier

for

input

connections.

1/4 INCH PHONE JACKS

The 1/4" phone

jacks

are

for

unbalanced

lines only (single

conductor,

shielded).

Simply

connect

the

shield to

the

outer

sleeve

of

the

plug and

the

inner

conductor

to

the

tip, or buy

ready-made

cables.

See diagram

below.

CONNECT

SHI]

HE~

=t1J-_-r---

1

t1)

CONNECT INNER CONDUCTOR HERE

SLEEtE

'TIP

FOR

MONO

(BRIDGED) OPERA TrON

To

operate

the

unit

as

a mono

amplifier,

use

the

left

channel

input

only.

DO

NOT

use

the

right

channel

input.

Remember

to

place

the

stereo/mono

switch

in

the

mono position.

..,

03520

STEREO OUTPUT CONNECTIONS

A six

(6)

station

screw

barrier

block on

the

rear

panel,

serves

as

output

connectors,

with

one plus (+)

and

one minus (-)

for

each

channel.

Left

Channel

leads

go

to

barrier

stations

marked

LEFT;

right

channel,

to

those

marked

RIGHT.

Output

leads

are

best

connected

to

the

amplifier

with

the

use of

tinned

wires.

Make

certain

that

the

speakers

are

properly

phased.

Connect

the

black

or minus (-)

terminal

on

the

speaker

cabinet

to

t!:1e

appropriate

minus (-)

barrier

on

the

amplifier.

Connect

the

red

or

plus (+)

terminal

to

the

plus (+)

barrier.

Check

to

see

that

the

stereo-mono

switch

on

the

rear

of

the

amplifier

is in

the

stereo

position.

SPEAKER PROTECTION

All

speakers

can

be

damaged

by having too much power

applied

to

them.

Fuse

protection

is

an

effective

and inexpensive

way

of

preventing

this

from

occurring.

If

your

speaker

system

does

not

contain a fuse

or a

circuit breaker, a fuse

should

be

placed

in

series

with

each

speaker

and

the

wire

going

to

the

red

terminal

on

the

rear

of

the

am plif

ier

.

Maximum

protection

can

be

obtained

with

fast-acting

fuses.

Use

the

value

recommended

by

the

manufacturer.

If

no

value

is

specified,

use

the

chart

provided

to

select

the

correct

value.

(MFRM 03530)

To

use

the

chart,

take a straightedge,

such

as a ruler,

and

line

up

the

speaker's

impedance

with

its

peak

music

power

rating.

The

proper

fuse

value

can

then

be

read from

the

center

column.

Choose a

fuse

that

is

closest

to,

and

below,

the

value

indicated.
WIRE SIZE AND DAMPING FACTOR
The high damping

factor

of

BGW

amplifiers

results

in a very

dean

bass

response.

Excessively long, and

small

diameter

speaker

wires

can

lower

the

damping

factor

and

distort

the

lower

frequencies.

A

damping

factor

of

at

least

50

should be

maintained

to

insure good audio

quality.

The

relationship

between

wire

length

and

diameter,

and

damping

factor

can

be

calculated

using

the

chart

(MFRM 03510) on

the

following

page.

Proceed

as

follows:

1.

Using a

straight-edge,

line

up

the

gauge of

the

speaker

wire

with

its

length.

Mark

off

the

resul

ting

source

resistance

where

this

line

crosses

the

center

column.

2. Line

up

the

source

resistance,

determined

in

step

Ill,

with

the

manufacturer's

impedance*

of

the

speaker

system.

The

damping

factor

can

now be

read.

*The

impedance

of a

speaker

system

can

be

approximated

by

measuring

the

resistance

across

the

speaker

terminals,

with

the

amplifier

disconnected.

Multiplying this

result

by 1.33, gives you

the

approximate

impedance.

Note:

This

method

cannot

be used with

electrostatic

speakers.