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
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