Jbl D50sms7 Manual

BULLETIN

SB1209

I

D50SMS7

This

J

BL

loudspeaker

system

was

designed

to

meet

the

nced

for a

compact

professional

monitor

capable

of

reproducing

the

full

frequency

and

dynamic

range

of

master

recordings.

Its

exceptionally

smooth

response,

uniform

dispersion,

and

high

power-handling

capacity

have

made

it

the

first

cho

ice

of

record

manufacturers

and

broadcasting

n

etworks.

The

D.50SMS7

is

equally

well

suited

to

the

demands

of

medium-size

auditoriums,

thea-

ters,

and

other

in

sta

llations

requiring

sound

reproduction

or

reinfor

"e

ment

of

th

e

highest

quality.

In

sound

reinforcement

applications,

the

absen

ce

of

response

peaks

or

directional

lobe

s

means

that

greater

acoustic

intensity

can

be

obtained

without

approaching

the

point

of

acoustic

feedback

.

The

efficiency

of

the

D.50SMS7 is

considerably

higher

than

that

of

other

"infinite baffle"

loudspeaker

systems.

In

spite

of

its

modest

proportions,

it is only 6-8

db

less efficie

nt

than

very

larg

e JBL

horn-load

ed

th

eater

systems.

Its

high

sensitivity

,

plus

full

60

watt

power

-h

and

ling

ability,

allow

s

the

stud

io

monitor

to

be

used

in

the

most

demanding

applications

without

distortion

or

danger

of

overload.

C50SM ENCLOSURE

WITH

S7 SPEAKER

SYSTEM

INSTALLED

• Profess

io

nal two-way

loudspeaker

components:

15

-inch long-excursion low frequency

loudspeaker

and

horn-loaded high frequency

assembly

with

acoustic

lens.

•

Smooth

response,

uniform

spatial

distribution,

and

high power-handling

capacity

through

the

full

range of audible

frequencies

.

• Supplied with its own built

in

audio power

source.

JBL Solid

State

Energizer brings

out

full potential

of

S7

speaker

system

components.

• Rigidly

constructed

enclosure

provides

optimum

acoustic

loading for

the

loudspeaker

components,

yet

is

modest

in

size.

• System may be wall-hung or

used

as

a

freestanding

reproducer

.

James

B.

LanSing

Sound,

Inc.,

3249

Casitas

Avenue, Los Angeles, Calif.,

90039

Height

...

30"

Width

...

23*"

Depth

..

.

20"

Professional audio

consultants and

engineers are

invited

to

compare

the

]BL

D50SMS7

with other monitor

loudspeakers,

both on the basiJ

ofacoustical

measurements

alld extended

listening tests.

JBL

D50SMS7

The

photo

at

right

shows a

rear

v

iew

of

the

sy

stem

with

the

JBL

So

lid

State

Energizer

installed.

The

Energizer

is

a

matching

audio

power

source

which

mounts

direct-

ty

in

the

rear

panet

of

the

encto

s

ure

.

It

is

descr

ibed

more

fully

on

the

last

page

of

this

bulletin.

REAR VIEW

C50SM ENCLOSURE

Although

modestly

proportioned

,

the

C50SM

provides

six

cubic

feet

of

internal

volume

to

bring

out

the

full bass

capabilities

of

the

low

frequency

loud-

speaker.

All

panels

are

madc

from

:y,

-inch

stock,

ri

gidly

braced

find

strutted

to

prevent

unwanted

resonflnce.

Joints

are

l

ock-mitred

and

wood-welded.

Interior

surfnces

are

lin

ed

with

heavy

absorptive

padding.

The

wrap-around

grille of

the

enclosure

is

not

a

mere

decorative

tou

ch -

the

lateral

high

frequency

dispersion

of

the

acoustic

lens

is

so

wide

that

a

substantial

amount

of

energy

is

propaga

ted

at

right

angles

to

the

axis

of

the

transducer

and

must

not

be

obs

truct

ed.

\10del

Cf)OS~

1

is

finished in S:1tin

Gray

and

supplied

with

Silver

Gray

gr

ille fabric.

It

c,\11

also

he

furnished

as

an

unfini

shed

enclosure.

It

can

be

safely

supported

hy

br:1ckets

bolted

to

lhe

rear

or side panels.

In

wall-hung

inst:1lbtions,

the

enclosure

ma)'

be

inverted

if

desired.

This

unretou

ched

photo

showS

the

actual

acoustic

output

of

the

LE15A

when

dri

ven

by

60

watts

of

continuous

sine

wave

power

at

a

frequency

of

40

cps. A

cali

brat

ed

labora-

tory

microphone

was

used

to

pick

up

the

sound

from

the

D50SMS7.

The

signal

from

the

microphone

was

con

nected

directly

to

an

oscilloscope,

and

the

tra

ce

photographed

.

Naturally,

sus

tained

performance

at

th

is

ear-splitting

In-

tensity

would

never

be

required

during

normal

use. A 60-

watt

sine

wave

Signal

repre

sents

a

far

more

difficult

job

for

the

speaker

than

its

rated

power

capaci

ty

of

60

watts

program

mater

ial. Yet

it

can

be

seen

that

the

acoustic

out-

put

of

the

LE

15A is

an

almost

perfect

sine

wave.

Moreover,

the

rugged

edge

wound

cop

per

ribbon

voice

coil

and

Lans-

a-

lOY

cone

suspension

enable

the

LE15A

to

operate

indefi-

nitely

without

breakdown,

even

at

highest

power

level

s.

S7 SYSTEM COMPONENTS

Low

frequencies

are

reproduced

by

the

JBL

LEI5A,

a 15-

inch

Linear

Efficiency bass

driver

with

4-inch

edgewould

coppcr

ribbon

voice coil.

The

free

air

resonancc

of

the

LE15A

is

20

cps.

The

flux

density

ill

the

voice coil

gap

is

9500

gauss

and

thc

total flux

is

450

,

000

maxwells.

Because

of

the

sophisticated

magnetic

circuit

and

voice coil configuration,

the

coupling

cocfficient of

the

speaker

is

exceptionally

high

-10 wntts of DC into

the

voice coil

terminals

produces

5V2

pounds

of

force

acting

on

the

cone

assembly.

The

outer

edge

of

the

LE15A

cone

is

terminated

in a

molded

ring

of Lans-a-Ioy.

This

material, cleveloped

by

JBL

engineers,

allows

the

cone

to

move

through

wide

excursions

with

a

lincar

force

/d

i

splaceme

nt relationship.

The

Lans-a-Ioy

tcrmination

also

acts

as a

Don-rcflective

acoustic

termination

for

spur

ious

wave

energy

travelling

through

the

material

of

the

cone.

Above

a crossover

frequency

of

SOO

cps,

the

LE8S

high

frequency

driver

operates

smoothly

through

a

range

greater

than

five

octaves.

The

diaphragm

of

the

LE85

is

hvdro-pneumatic<1l1y

drawn

to

shape

from

.002"

dural

alloy

and

is

driven

by

a 1J,;.i"

edgewound

aluminum

ribbon

voice coil

operating

in a field

of

19

,000

gauss. A

pure

silver

impedance-controlling

ring

counteracts

the

voice coil

inductive

component,

result-

ing

in

grcatly

improved

efficicncy

through

the

highest

octave

of

audible

frequencic

s.

Sound

from

the

diaphragm

is

conducted

to

thc

horn

throat

through

concentric

channels

of

a

mathematically

determined

phasing

plug.

Sound

waves

are

conducted

to

the

horn

throat

in

constant

phase

relationship.

The

LE85

is

coupled

to a

heavy

cast

aluminum

exponential

hom

and

slant-plate

acoustic

lens.

The

TBL

L9I

lens

is

designed

according

to

advanced

wave

propagation

theory

and

acts

exactly as a

divergent

optical

lens.

Th

e

formula

for

hyperbolic

cylindrical

lenses

is

used to

determine

the

basic

parameter

s

of

the

L91.

The

lens

employs

eleven

plates

set

at

an

angle

of

.38

degrees

and

spaced

0.25

inches

center

to

center.

Because

of

the

precisely

calculated

hyperbolic

curvature

of

the

front of the lens,

sound

is

spread

evenly

through

a 120

degree

lateral

angle,

but

restricted

to

approximately

40

degrees

in

the

vertical

direction.

The transition between

low

and

high

frequency

transducers

is

made

by

a crossover

network whose circuit

was

determined

by

extended acoustic tests

with the

components

of

the S7 system.

The network includes

special

react

ive

components

to

compensate

for the

complex impedance

characteristics

of the

transducers, and

to

maintain the desired

12

db

per octave slope

in

terms

of

actual

acoustic output. A

th

ree-position switch

allows the intensity

of

the high frequency

driver

to

be balanced

to the "Iiveness"

of

the

listening environment.

The attenuation

circuit

uses

a tapped

autotransformer rather

than resistive pads

so that

the

coupling

between amplifier

and

transducer

is

not

affected

by

the

setting

of

the control.

JBL

D50SMS7

JBL STEREO ENERGIZER

JBL

has long recognized

the

intimate

relationship

between

a

loudspeaker

system

and

the

signal

power

source.

By

controlling

generator

impedance

for critical

damping

and

making slight corrective

adjustments

in

the

frequency response

contour, it

is

possible to achieve

performance

noticeably

superior

to

that

obtained

when

the

same

speaker

system

is

connected

to an all-purpose

power

amplifier.

The

JBL

Solid

State

Energizer

takes the

place

of a conventional stereo

power

amplifier-it

supplies

a

signal precisely tailored

to

the

requirements

of

the

D50SMS7

and

is

installed directly

in

one

loudspeaker

enclosure. Problems of

heat

, microphonics,

tube

replacement

are

eliminated.

In

professional applications,

Energizer

inputs can

be

bridged

across

standard

500-600

ohm

program

lines.

When

each

pair

of monitor loudspeakers

is

self-energized, there are

none of the usual difficulties associated

with

impedance

matching,

power

losses in long

lines,

or

controlling the intensity of individual loudspeakers.

The

D50SMS7

may

be

ordered

in stereo pairs

with

the

Energizer

factory-installed in

one enclosure.

Where

existing

power

amplifiers

are

to

be

used,

the

D50SMS7

can be

supplied

without

the

Energizer.

S8 SYSTEM COMPONENTS Those users

who

wish to take

advantage

of the distinctive

qualities of

the

JBL

375

driver

may

purchase

the C50SM

with

the JBL

S8 system in-

stalled.

The

S8 uses the same low frequency

driver

and

crossover network as

the

S7,

but

the massive

375

high frequency driver takes

the

place of the

LE85.

A special cast

aluminum

horn

is

used to couple

the

375

driver to

the

slant-plate acoustic lens.

PERFORMANCE

Whether

the

S7

or S8 components are installed

in

the C50SM, perform-

ance represents

the

closest

approach

to perfection at the

present

state

of the art. Recording

studios

and

ac

oustic consultants

who

have

tested the

performance

of these systems in

their own laboratories have

been

universally enthusiastic in

their

reports.

The

D50SMS7

is

used

by

numerous

broadcast

and

recording

studio

s in

the

United

States

and

abroad.

Professional userS include Capitol Records, Columbia Records, CBS Television,

Decca

Records,

and

MGM Verve.

If

you require more detailed information

regarding

specific applications, please feel free

to

write

to

the

JBL

Technical

Service

Department.

REPRE

SEN

TED

BY

(lENE

NOUN

/I

A880CIATElJ

.

INa.

W

adSWO

rftJ

Drive

-----

.......

Beth

esda

14.

M

d..

·

~·lli~:

Jti5-6113

.

..\;.~Jq

8

••

J.m

..

B. IAn.'". Sound.

Inc..

3249

C.s

...

s

Avenue,

Los

An",,,,

Cellif.

9C)03g

JBL D50SMS7 Manual

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