dbx 140X User manual
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27
Introduction
FrontPanel
RearPanel
Connecting
Your
l
40X
to
YourSystem
Sys
tem
Co
nne
ctions
Multi-Channel
Connect
ions
BasicOperation
SpecificApplications
Understanding
dbx
NoiseReduction
InstallationConsiderations
Input
Cable
Configurations
Output
Cab
le
Considerations
Mounting
th
e
140
Xina Rack
Maintenance
and
TechSupport
Ma
inte
nance
and
Troubleshoo
ting
T
ech
ni
cal
Support
Facto
rySeNice
Shippi
ng
In
structions
Specifications
Schematics
Registration,
Feedback
27
Registration
Card
27
Warranty
27
User-Fee
dback
Form
Manufactured
under
one
or
more
of
the
following
U.S.
patents
:
3,3n,792;
3,681 ,618; 3,714,462;3,789,143;4,097,767; 4,329,598;
4,403,199;4,409,500; 4,425,551: 4,473,795.
Other patents
pencing.
This dbx-branded product has
been
manufactured
by
AKG
Acoustics
,
Inc
.
This
manual
is
part
number95094-000-01
C
Copyright 1990
by
AK
G
Acoustics,
Inc
.
dbx Professional Products
a division
of
AKG
Acoustics, Inc.
1525Alvarado Street, San Leandro,
CA
945TT USA
Telephone (1) 415/351-3500 Fax: (1) 415/351-0500 Telex:
17
-1480
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' .
dbx 140X
Introduct
io
n
Congratulations on purcha
si
ng the dbx l40X Type II Noise Reduction System. This
owner's manual provides
you
with instructions for connecting your
140X
to
your system
and
basic operating infonnation to help
you
get the most
from
yo
ur
140X.
The dbx Model 140X Type II System is
an
e
ncod
e-
decode "Compression/Expansion" or
companding system based on patented True
RMS
™ detector circuitry. It is designed for
applications where bandwidth
is
limited, where it yields:
• Doubling
of
effec
tive
dynamic range
• Agreaier
than
40dB
improvement in S/N
with
typical media
The
140X
may be us
ed
in home-studio
and
professional audio production applications.
Wh
en
used
with a high-quality tape
ma
chine, its perfonnance exceeds that
of
16-bit digi-
tal. Use
it
with:
• Reel-to-reel tape
decks
operating
at
7.5
IPS
orslower
•
Cassette
dec
ks
• PCM Digital sys
iems
(DAT,
Fl,
etc.)
• Digital samplers (8-
to
16-bit)
In broadcast industry applications use the
140X
with:
• Cartmachines
• Videotape recorders
• Studio Transmission Links (S11.s)
• Telephone lines
• "Captive" in-house audio production
The versatile 140X features:
•
Two
independe
nt
channels
of
Type
Il
encoding
•
Two
independentchannels
of
Type
II
decoding
• Hardwire bypasson all inputs and outputs
• Adjustable-24
10
+l
OdBu
nominal operating level
Input:
• Electronically balanced inputs
• Balanced
or
single-ended operation
• Gain trim
fo
r signalfromtape deck
Output:
• Electronically balanced outputs
• Balanced or single-ended operation
• Gain trim for signal
10
tape deck
The 140X is fully compatible with previous dbx Type II professional products (Models
140,
140A, 142,
148
, 941/942, 941N)42A and 408). It is also compatible with the "dbx
consumer" NR found in
many
cassette recorders
and
home-recording tape machines. The
140X includes hardwarenecessary formounting
in
19"
rack cabinets.
....
INTRODUCTION
1.
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FRONT PANEL
0
POWER
•
dbx
1
40X
1YPE
I
NOISE
A£DUCT10N
D
2
dbx
140X
Front Panel
---
CHANNEL~
---
---
CHANNEL
[ID
--.
-
J~~
•
-
•PLAY
_j
Figure
1:
FrontPanel
Power
LED:
lliuminates when the 140X is receiving power.
Channel
A
RECORD
button:
Press in to engage
the
dbx encoder.
The
OUT
position is a hardwire bypass switch.
The
inputs are connected directly
to
the outputs.
1be
140X will
pass
signal in this positioneven
if
it
is not receiving AC
power.
Channel
A
PLAY
button:
Pressin
to
engage thedbx decoder.
The
OUT
position is a hardwire bypass switch.
The
inputs are connected directly
to
the outputs.
The
140X will pass signal in this position even
if
it is not receiving AC
power.
Channel
A
RECORD
trimpot:
'This adjusts the gain through the encoder circuit for
levelmatching purposes.
Channel
A
PLAY
trimpot:
'This adjusts the gain through the decoder circuit for level
matching purposes.
Channel B functions are identical.
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..
f •
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dbx 140X REAR PANEL
Rear Panel
• r
FRO
M
----.
r:
TO
~
db
e
ULJCSA
I
CO
N
SOLE
I I
TAPE
R
EC
I X
~~ONAL
AC
120V
8 A 8 A
l-»(
..
~
A
DM910H
Of
n,g
ACOUSTICt
INC.
60
Hz.
1'1N
h.
(I)
(I) (I)
(I)
O
DD
O
w.=~
m
AV
I
S•
1119QUE
DE
CHOC
MADE 1N HONG KONG
' ' ' ' I
....
.
uc-;,
.....
I
~n-::
·
EUROPE
• I
"'
TO j I F
RO
M j
~---~
~-------.
41»7,767 4.426.661
AC
220V-24f11/
LcO
N
SOLE
4APE
REC
l
ut.
ALE
NO.
E6CM0
7I
:;ll;;A::
:~~:~
~
Hz,
1'1N
Figure
2:
Rear Panel
From Console Aand B -Encoder
in
puts: Connect these
to
your line-
level
audio
so
urce.
Typically,
this
is amixer orrecording console output
bus
.
To
Tape
Rec Aand B-Encodero
utpu
ts:
Connect
these
to theline inputs on yourtape
deck.
In
other applications, these send
the
encoded
signal
to
the transmission line or
other audio channel. Connect these to a line
amplifier,
di
stribution amplifier,
etc
.
From
Tape
Rec
Aa
nd
B- Decoder inputs: Connect these to the outputs
on
your
tape
deck.
In
other applications, these receive an encoded signal
from
the transmission
line orotheraudio channel output
To
Co
nsole Aand B-
Deco
deroutputs: Connect
the
se to the tape playback (tape
monitor) inputs on your mixer or recording
console.
In
other applications, these
send
the decoded signal(s)
to
the input(s)
of
the
transmitter,
mixer,
orsimilar output
de-
vice.
AC
Vo
ltage Switch: Setfor either
120V
or
240V
operation before installing the
140X
.
AC
Co
rd
: Plug into mains power. Note that the 1
40X
doe
s not have a powerswitch. It is
recommended that the
140X
be "on" at all
times
.
Pow
er
co
ns
umption
is
low
.
0
3
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CONNECTING YOUR 140X TO YOUR SYSTEM dbx 140X
4
Connecting
Your l 40X
to
Your System
System Connections
Type NTyplcal Appllcatlon -'Wraparound"
140x
II
operat6d
01
part
of
tape
deck
or tranamllllon
llne
To
tape
or
tranamllllon
lln•
Monitor
Level,
Here
uox uox
Channel
A
~---------111
Channel A
tape
deck
or tranamlalon llne
'--+----'
~------'
From
tape
or
trONmllilon
lln•
'From
Corwole'
(encode)
'From
Tape
Rec'
(decode)
Monitor
Levell
Here
Figure 3:
Sy
stem
Connecti
o
ns
Nonnally, the
140X
will be wired directly to
the
inputs
and outpu
ts
of
atape deck orv
id
eo
recorder.
1be
encode-decode electtonics "wrap around"
the
recording
devi
ce.
1be
140X
is
co
nsidered
part
of
the
recorder or
line
amplifier and
the
trims
are
set for precise le
ve
l
matching
.
1bere are
two
basicoperating rul
es
to
rem
e
mber:
1)
Once
the
level of the tape
de
ck or
transm
ission line
has
been
se
t,
monitor
and
vary
lev-
els
only before
the
encoder
or
after
the
dec
oder.
Small variations
won
't cause
Type
II
to
mi
sbehave, butthis
is
a
good
habit
to
learn.
2)
Nev
er introduce any change
into
an
encoded
signal with a
mixer,
tone conttol, equal-
izer,
orby forcing magnetic
tape
into saturation. Follow encode with decode,
then
mi
x
and EQ,
and
then re-encode.
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dbx 140X CONNECTING
YOU
R 140X TO YOUR SYSTEM
Multi-Channel Connections
lypoll
From Console
To
Tape Rec
type.
lypoll
~c
=•~•
~~
Trim
From Tape Rec
To
Console
8VPaM
Figure
4:
Multi-channel Connections
If
required, the 140X can
be
wired
to
a patchbay and allowed
to
"float" so
it
can
be
con-
nected to whichever device
is
in use at the time. Thefollow
in
g precautions must
be
taken:
If
the entirestudio is wired
for
balanced operation, aTRS
jaclc
may be used in
the
patchbay
for
all
140X
inputs and outputs.
If
the studio is
wired
for a mix
of
bal-
anced
and
single-ended operation, use three-conductor balanced phone plugs for
the inputs
to
the
140X
. For
the
outputs
from
the 140X, it
is
bestto useeither
(1
) a
three-conductor phone plug
(balanced)
or (2) a three-conductor phone plug with
the ringdisconnected
(s
ingle-ended
). See"OutputConnections
,"
for
afull discus-
sion.
The simplified block diagram in Figure 6 shows the two independent channels
of
encod-
ing and two separate channels
of
decoding.
If
required, Channel A can simultaneously encode asignal for Device 1 and de-
code a signal
from
Device 2, while Channel B
is
in Bypass
for
both
recording
and
playback.
.....
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BASIC OPERATION dbx 140X
6
Basi
c Operation
Tape
Recording: Adjusting Input
and
OutputLevels
While
dbx
Type
II is a "friendly
and
forgiving" system, dbx Noise Reduction is part
of
a
total system including the tape deck's electronics, heads, bias, EQ, and outputelectronics.
The fewer anomalies that occurwithin the recorder, the better.
Before encoding
Type
II audio or video tapes, make sure that the recording heads are
clean, demagnetized, and aligned properly. Where appropriate, make certain that the tape
deck bias
and
EQ are properly
set
Re-bias and align when changing tape formulations
and
speed, justas you would for optimum performance without noise reduction.
Level Adjustments
The trimpots for Record and Play levels
are
accessible from the front panel.
Use
these
to
keep levels matched. These settings are not critical to proper performance
of
the
140X
processor. They are provided so
the
140X
matches as many different levels
as
possible.
Trimpot range is
from
-24dBu
to+
IOdBu.
Record Adjust
Don't expect the console meters and the tape recorder meters to match at frequencies
above lkHz because
of
the encoder's preemphasis.
If
you use 400Hz
or
some other mid-
band tone, you may continue
to
use that, but be sure to use the same tone consistently.
1)
Putthe 140X in Bypass, and send a lkHztone
from
the console
or
audio source
at
your
chosen 0VU. -
2) Setthe tape deck's meter(s) to the nominal calibration point-0VU in this case.
3) Switch the 140X IN, and turn the RECORD Level Adjust trimpot on each channel as
necessary to bring the deck's meter reading to 0VU again.
Playback
Ad
just
1)
Putthe 140X in Bypass. Using an
aligr:unent
tape, send a lkHztone
from
the tape deck
uovu
-
2)
Check
the
console meter(s)
and
set them at a
nomi
n
al
0VU.
3)
Switch the 140X IN, and tum the
PLAY
Level Adjust trimpot on each channel
as
nec-
essary
to
bring the meter reading
to
0VU again.
Compensating for an Encoded Signal
The hotter
you
record (or transmit) a dbx-encoded signal, the better the overall dynamic
range and signal-to-noise will be. This holds true until
yo
u
hi
t tape saturation. at which
point theplaybackquality will deteriorate.
With
Type
II NR,
the
chance
of
tape saturation is reduced even more than with
Type
I due
to
additional high-frequency preemphasis applied in the encoder. On a professional tape
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dbx 140X BASIC OPERATIO~
machine running at7.5,
15,
or 30
IPS
you
will
be able
to
record
well
above
the traditional
levels.
After a signal has been encoded, peaks are
50
%
lower.
You
are safe recording atleast
50%
hotter.
If
you
have peak-reading meters on your deck, set the record levels onthe machine
so that the signal never exceeds the tape's
headroom
and
you
'11
be
fine.
With
VU
or
averaging meters, the best
way
to
find
optimum
recording levels is to experi-
ment.
When recording
too
hot
you
will
begin
to
notice the effects
of
tape saturation
on
playback.
When
you
find
a nominal operating level
which
so
un
ds good, calibrate
yo
ur
equipment
and
then ignore the meters on
the
tape machine(s).
Tape
Masteringand Alignment
Tones
Alignment tones on tape
sho
uld not be
encoded.
The typical
lOOHz
-lkHz -I0kHz tone
on head or tail should be recorded without
Type
II processing. Some engineers also pro-
vide an encoded lkHz
tone,
with the program material following. Remember that profes-
sional recording studios have standardized on Type I
NR.
Fo
r in-house use, this is not a
concern.
If
a tape is going to
an
outside facility,
it
should
be
clearly
marked
"dbxType II."
Other Applications: Adjusting Input
and
Outp
utLevels
The procedure is the same
as
with a
tape
r
ecorder.
Since
the
signal is compressed
2:
1,
yo
u
may
transmit at a hotter level (but
do
not
exceed
the
headroom
of
the transmission line).
Once levels
are
set, meterthe signal before
and
afterthe 140X.
Type
II
and
Digital
Recording
dbx
Type
II
wo
r
ks
with 16-bit digital
recorders
(e.g.,
DAT
machines). The encoding pro-
cess increases the machine's
dynam
ic r
ange
by
at least 20dB. Since the
au
dio is another
20dB
higher than the noise
floo
r,
non-linearities associated with very quiet signals are
eliminated.
At
the same time, the dbx compression
he
l
ps
avoid digital clipping, making
fo
r
a
fail
-safe field recording
system
.
The same is true for sampling synthesizers.
Any
12-,
14-,
or
even 8-bit sampler gives bet-
ter sound with
Type
II
NR
as a permanent add-on at input and output (provided the sam-
pler does nothave some sort
of
companderbuilt
in).
7
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SPECIFIC APPLICATIONS dbx 140X
Specific Applications
Radio Broadcast
The
140X
is designed for in-house production where cart machines
are
used, ortape decks
typically run
at
7.5 IPS
or
slower.
1be
140X
is compatible with existing Type II proces-
sors (Models 140,
140A,
142,
148,
941/942, 941A/942Aand 408).
8
The
140X
may be used
to
upgrade
the
performance
of
telephone lines (input
and
output
matching transformers
are
recommended). A pair
of
140Xs may
be
inserted into S1Ls to
improveSignal to noiseRatio
and
dynamic range.
Television Studio
The
140X
will aiso
add
high fidelity audio to videotape recorders. It is especially suited
for
use
in
the
field
or
for remote broadcast where a live stereo audio
feed
is
used.
The
140X
is useful during editing, where the audio Signal to noise Ratio can
be
compro-
mised by repeated recording. This generation loss
is
virtually eliminated
if
dbx
TYPE II
encoding is used. In
the
encoded
form
the
audio can be edited (spliced).
However,
the
audio cannotbemixed orequalized without decoding and re-encoding.
Type II yields a radical improvement
in
noise-free performance, so decoding
and
re-en-
coding will not degrade
the
soundtrack.
As
many audio generations as necessary
may
be
made, as long as no hiss or
hum
is introduced in the mixing process.
dbx
NR can do
noth-
ing to improve noisy source material.
To
improve source material
which
suffers
from
con-
stanthiss, use the dbx 563X Hiss Reducer (or its equivalent in the 900 Series, the 929),
or
a downward expander/noise gate like
the
463X Over-Easy Noise Gate (orits equivalentin
the
900series, the 904).
The
140X
is excellent for in-house audio production. It is relatively immune to audio re-
corder frequency response anomalies. (For best performance, be sure the tape machines
are aligned and calibrated.)
Audio Production
and
Recording Studios
The typical audio recording studio
has
standardized upon dbx
Type
I NR for tape
ma-
chines with flat frequency response (20Hz -20kHz). Most record
and
CD mastering
la~
candecode
Type
I without any trouble (make sure your masters are marked "dbxType
I'')
.
Type I NR is typically found onboard
tape
machines such as those
from
Tascam.
Type
II
does have studio applications, however.
While
the
formats are
not
compatible,
Type
Il
improves dynamic
range
and signal to noise
as
well as
Type
I docs.
If
the
audio production is "captive" (in a corporate
NV
studio, for
example),
Type
II is a more ecooomical choice since it can be
applied
to more situations.
In
utility applications, Type II often worts well with reverb and
delay
systems.
If
the studio owns digital sampling keyboards, drum machines or
rack
mount samplers, a
140X
can often improve
the
linearity
of
sampled sounds.
As
long as a sampler does not
have a companding front end, performance
of
8-, 12-, and 14-bit samplers will benefit
greatly from using a
140X
.
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It
I 1
r
I.
dbx
140X
UNDERSTANDING dbx NOI
SE
REDUCTION
Understanding dbx Noise
Red
uc
ti
on
Encoding audio signals with dbx results in doubling the usable dynamic range up to a
maximum
of
115dB.
At its maximum, this dynamic range exceeds that
of
16-bit digital
systems
and
of
Dolby SR. Depending on the transmission medium you will see at least
40dB improvement in Signal
to
noise Ratio.
dbx
uses
linear companding over a
115dB
range. The encoded signal
is
compressed by a
2:1
ratio with a carefully tailored frequency-response preemphasis. When decoded, the
signal
is
expanded 1
:2
with a precise, complementary deemphasis.
While Type I
and
Type Il employ identical companding, the detectors react differently
to
the
amount
of
HF preemphasis which is applied within the 140X processor. This means
thatType I and
Type
II are not compatible.
~
Typically, recording studios standardize on Type I NR. In the studio environment, ma-
chines are operated
at
15
IPS or better, which is where Type I excels. Type I also works
well withdigital tape machines and otherhighquality tape machines operating at
7.5
IPS.
D:pe
II
Type
II has been developed for media where high- and low-frequency response is not as
flat as with professional tape recording decks; and where high-frequency headroom is re-
duced (due to tape saturation, 75µs preemphasis, etc.). The filters in the 140X prevent
problems which might occur
if
Type
I were used
(e.g.
mistracking due to HF rolloff
or
LP
irregularities).
This means that Type II NR is ideal for broadcast applications. It delivers the same in-
creased dynamic range and signal-to-noise ratio
as
Type I and the same frequency re-
sponse specifications. The difference lies in the amount
of
preemphasis applied to the
audio signal, and also the audio bandwidth
the
Type
II
detector reacts to.
Figure 5 shows the audio spectra to which the
RMS
detectors react during Type I
and
-
Type II encoding. Note that the
Type
nencoder will compress more in the presence
of
high frequencies
(lOOOHz
-8000Hz) inorder to prevent tape saturation.
Since
the
Type
II processor reacts to a limited bandwidth,
it
ignores the extreme low
and
extreme high end (responding only between 60Hz and
lOk.Hz).
Outside this band, prob-
lems such
as
low-frequency head bumps and high frequency peaks and dips can cause
"pumping and breathing" withType I circuitry.
9
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UN
DERSTANDING dbx NOISE REDUCTION dbx 140X
10
29,
9
dB
19
,9
0,0
-
18,8
-
28
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20
208
2
000
28000
Hz
Figure
5: DetectorResponse
Curve
s
Noise
Modulation
TYPl 1
lYPE
2
1be
worse
the
signal-to-noise ratio
of
the
tape recorder or transmission line,
the
harder it
is
for
full
-bandwidth companding
to
di
sc
riminate
between
the
signal and the
background
noise
.
When
the SIN ratio
is
poo
r
enough,
sometimes
you
hear
"noise modulation"
when
the
program
signal is quiet
and
close
to
the noise
floo
r.
When
high frequencies
are
present.
they "mask" noise modulation artifacts.
Howev
e
r,
on
very
quiet sounds with little or no high-frequency content (solo
piano
oracoustic
bas
s
are
good
examples) th
ey
may
be
heard
.
Additionally, there
is
a
natural
noise modulation which occurs at low levels
in
magnetic
tape
recording. This noise
modulation
may
be
noticeable
fo
r
the
first time when
noi
se
re
-
duction clears
away
the
re
st of
the
masking
hi
ss.
This may
be
reduced
by
optimizing
the
tape
bias
fo
r minimum m
od
ulatio
n
noi
se. This
can
frequently
be
most easily
achieved
by
doing a standard alignment and then recording ormonitoring a
25Hz
tone.
1be
tone will
ge
nerally
be
suppressed in
the
process, but
th
e
tape
's inherent noise
modu
lationwill
be
re-
vealed
. The
bias
can then
be
adjusted
to
minimi
ze
this
, and
the
rest
of
the
alignment
pro
-
cedure
followed
as
usual.
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l.
dbx 140X INSTALLATION CONSIDERATION~
Installation
Co
nsider
ation
s
InputCable Configurations
1.
Prepare f
or
Aud
io
Inp
ut
and
OutputConnections
Since
the
140X
has hardwire bypass on
all
inputs
and
outputs, it is simplest
to
wire the
unit as balanced-in/balanced-out for both channels, orsingle-ended-in/single-ended-out
for bothchannels.
NOTE:
If
a single
140X
is used as
two
separate encode/decode units for two separate
mono devices, the balanced in/unbalanced out setup may
be
inappropriate. For
exam-
ple,
if
Channe
l Ais pennanently
wired
to a tape deck while Channel B is pennanently
wired
to
a videotape recorder,
the
audio deck can be balanced in and out
while
the
VTR
is
single-ended inand out.
1.
ConnectAudio Inputs (From Console /
From
Tape Rec)
Both se
ts
of
inputs are electro
ni
cally balanced.
The
input impedance is
75kn
balanced
and
54k0 unbalanced, allowing operation
from
virtually any source. Nominal operat-
ing
level
is
+4dBu, and can be set for levels ranging
from
-24
to
+
lOdBu.
The input
connectors areTRS
¼"
phone jacks,
'lip
Hot
(on
dbx
equipment,
'lip=
XLRPin3).
2. Wire the
From
Console
and
From Tape Rec input
cable
s for fully
bal
-
anced
operati
on
or
unba
l
anced
operation.
Refer
to
the
examples on the following pages. Refer
to
the type
of
operation and type
of
connector
you
are
using.
NOTE:
For best
hum
rejection, start
by
grounding the shield(s) [Pin 1 on the
XLR,
Sleeve
on
a
¼"
TRS]
only atthe output(s).
If
hum
persists,
try
grounding
the
shield(s)
atthe
inpu
t(s)
as
well.
11
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INSTALLATION CONSIDERATIONS
dbx
140X
!
t40XInputs:
Fo
r
Fully
Balanced OperationI
(Q)EJ~C-J
-~
TRI
b
12
~M
TAPE
\_
NO
CONNECTION
MACHINE
OR
CONSOLE
Connecting
XLR Connectors
to
140X (TRS)
TR
S
FROM
TAPE
MACHNE
OR
CONSOLE
NO
CONNEC110N
_/
Connecting
W'
TRS to
140X
(l'RS)
TO
1.«JX
INPUTS
TO
1.«>X
INPUTS
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••
I •
,!
l.
dbx 140X
!
t40X
Inputs: ForSingle-Ended Source"Unbalanced" OperationI
T s T
FROM
TAPE
MACHINE
OR
CONSOLE
Connecting¼" Mono to 140X
('TRS)
NOTES
for
using
W'
connectors:
•
Connect
the
Sleeveto the
wire's
Shield.
•
In
an
emergency
, W'Mono cables
will
work
(for
inputs
only)
.
FROM
TAPE
MACHINE
OR
CONSOLE
Connecting RCAPhono Plugs to 140X
INSTALLATION CONSIDERATION~
S R T
TO 1.-0X
,,-,,urs
S T
TO 1.-0X
INPUTS
13
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INSTALLATION CONSIDERATIONS dbx 140X
Lh
..:.
14
Output Coble Confi
gurations
1.
Connect
Audio Out
puts
The
140X will drive either balanced
or
unbalanced loads
as
long as the cables are
wired according to the following figures. Remember, always use a TRS plug for the
output
of
the 140X.
IMPORTANT:
The output amplifiers
on
the 140X are not designed to drive a short to Ground.
NEVER ground the high
or
low sides
of
the "To Tape Rec" and "To Console"jacks at
any point between the 140Xand the next device. While this will notdamage the 140X,
distortion will increase and you will have level problems.
All outputs are electronically balanced
fo
r driving loads
of
6000
or
greater. Nominal
operating level is +4dBu, and can be
set
for levels ranging from
-24
to
+lOdBu. Out-
put impedance
is
440
balanced and
220
unbalanced. J'he output jacks are
1RS
¼"
phonejacks, Tip Hot (on dbx equipment,
Tip=
XLR Pin3).
2. Wire t
he
To
Console
and
To
Tape R
ec
output
cable
s for fully balanced
ope
r
at
ion or un
balanced
operat
i
on
Refer to the examples
on
the following pages. Refer to the type
of
operation and type
of
connector you are using.
NOTE:
For
best hwn rejection, start by grounding the shield(s) [Pin 1 on the XLR,
Sleeve on a ¼" TRS] only at the output(s).
If
hwn persists, try grounding the shield(s)
atthe input(s) as well.
3.
Check
Input/Output Polarity for Balanc
ed
Sy
stems (OPTION
AL)
After the
140X
has been wired into the system, use a cable checker
or
ohmmeter to
make sure that signal polarity has notbeen reversed within a cable. Set all four front-
panel buttons
to
OUT.
A. Check that Pin 1 is continuous through Channel A - From Console to the other
end
of
thecablecoming from Channel A - ToTape Rec. Check Pins 2 and 3.
B.
Repeatfor Channel B.
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I:
dbx 140X INSTALLATION CONSIDERATION I
!t40X Outputs: Fully Balanced Operation!
6i"[lti£
--j
--
C~1
\:](W)
_/
TO
TAPE
FROM
1'40X
OllTPUTS
(USE
ONLY
T/R/S
PLUG)
NO
CONNECTION
O~~E
T R
Connecting 140X to XLR Connector
s T
R
s
FROM
TAPE
MACHINE
OR
CONSOLE
NO
CONNECTION
_/
Connecting 140X
to¼"
TRS
NOTESforusing ¼" TRS connectors:
TO
1'40X
INPUTS
•
If
the
l40X is wired into a patchbay,
never
inserta
mono
plug into
the
patch
bay.
15
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INSTALLATION CONSIDERATIONS
db
x 140X
16
!
t40X
to
aSingle-
Ended
Inpu
t:
"Unbalanced" OperationI
FROM
1.0C
NO
CONNECTION
OUTPUTS
(USE
ONLY
T/R/S
PLUG)
Connect
140X
to
Y4
"
Mono.
s T
TO
TAPE
MACHNE
OR
CONSOLE
..:.
NOTES for u
sing
¼"
connectors:
•
If
you are
using
a
TRS
plug at
the
tape machineorconsole,tie
the
Ring
and
Sleeve to-
gether, and connect the Sleeve
IO
the wire's Shield.This is equivalent
IO
a cable
with
l/4" Mono plugson
both
ends.
FROM
UOX
OUTPUTS
(USE
ONLY
T/R/S
PLUG)
NO
CONNECTION
TO
TAPE
MACHINE
OR
CONSOLE
Connect 140X
to
RCA
NOTES for using
RCA
connectors:
• TheRing conductoris neverconnected
IO
anything when
th
e
140X
is driving single-
ended inputs. Leave itfloating. ·
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