dbx 160S User manual

¨
Stereo
Compressor/Limiter
160S
Owner’s Manual
Mode d’emploi
Bedienungsanleitung
Modo de empleo

WARNING
FOR YOUR PROTECTION, PLEASE READ THE FOLLOWING:
WATER AND MOISTURE: Appliance should not be used near water (e.g. near a bathtub, wash-
bowl, kitchen sink,laundry tub,in a wet basement,or near a swimming pool, etc). Care should
be taken so that objects do not fall and liquids are not spilled into the enclosure through open-
ings.
POWER SOURCES: The appliance should be connected to a power supply only of the type
described in the operating instructions or as marked on the appliance.
GROUNDING OR POLARIZATION: Precautions should be taken so that the grounding or polar-
ization means of an appliance is not defeated.
POWER CORD PROTECTION: Power supply cords should be routed so that they are not likely to
be walked on or pinched by items placed upon or against them, paying particular attention to
cords at plugs, convenience receptacles, and the point where they exit from the appliance.
SERVICING: To reduce the risk of fire or electric shock, the user should not attempt to service
the appliance beyond that described in the operating instructions. All other servicing should be
referred to qualified service personnel.
FOR UNITS EQUIPPED WITH EXTERNALLY ACCESSIBLE FUSE RECEPTACLE: Replace fuse
with same type and rating only.
MULTIPLE-INPUT VOLTAGE: Thisequipmentmayrequire the use of a different line cord,attach-
ment plug, or both,depending on the available power source at installation. Connect this equip-
ment only to the power source indicated on the equipment rear panel.To reduce the risk of fire
or electric shock, refer servicing to qualified service personnel or equivalent.
SAFETY INSTRUCTIONS
NOTICE FOR CUSTOMERS IF YOUR UNIT IS EQUIPPED WITH A POWER CORD.
WARNING: THIS APPLIANCE MUST BE EARTHED.
The cores in the mains lead are coloured in accordance with the following code:
GREEN and YELLOW - Earth BLUE - Neutral BROWN - Live
Ascolours ofthe coresin themainslead ofthis appliancemay notcorrespond with
the coloured markings identifying the terminals in your plug, proceed as follows:
• The core whichis coloured green and yellow mustbe connected tothe ter-
minal in the plug marked with the letter E, or with the earth symbol, or
coloured green, or green and yellow.
• The core whichis coloured blue must beconnected to the terminalmarked
N or coloured black.
• The core which is coloured brown must be connected to the terminal
marked L or coloured red.
This equipment may require the use of a different line cord, attachment plug, or
both, depending on the available power source at installation. If the attachment
plug needs to be changed, refer servicing to qualified service personnel who
should refer to the table below. The green/yellow wire shall be connected direct-
ly to the unit's chassis.
WARNING: If the ground is defeated, certain fault conditions in the unit or in the
system to which it is connected can result in full line voltage between chassis and
earth ground. Severe injury or death can then result if the chassis and earth
ground are touched simultaneously.
LIVE
E
NEUTRAL
EARTH GND
CONDUCTOR
L
N
BROWN
BLUE
GREEN/YEL
BLACK
Normal Alt
WIRE COLOR
WHITE
GREEN
U.K. MAINS PLUG WARNING
A moulded mains plug that has been cut off from the cord is unsafe. Discard
the mains plug at a suitable disposal facility. NEVER UNDER ANY CIRCUM-
STANCES SHOULD YOU INSERT A DAMAGED OR CUT MAINS PLUG INTO A
13 AMP POWER SOCKET. Do not use the mains plug without the fuse cover
in place. Replacement fuse covers can be obtained from your local retailer.
Replacement fuses are 13 amps and MUST be ASTA approved to BS1362.
The symbols shown above are internationally accepted symbols that warn of
potential hazards with electrical products. The lightning flash with arrowpoint in
an equilateral triangle means that there are dangerous voltages present within the
unit. The exclamation point in an equilateral triangle indicates that it is necessary
for the user to refer to the owner’s manual.
These symbols warn that there are no user serviceable parts inside the unit. Do
not open the unit. Do not attempt to service the unit yourself. Refer all servicing
to qualified personnel. Opening the chassis for any reason will void the manufac-
turer’s warranty. Do not get the unit wet. If liquid is spilled on the unit, shut it off
immediately and take it to a dealer for service. Disconnect the unit during storms
to prevent damage.
CAUTION
ATTENTION: RISQUE DE CHOC ELECTRIQUE - NE PAS OUVRIR
WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC
SHOCK DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE
RISK OF ELECTRIC SHOCK
DO NOT OPEN
ELECTROMAGNETIC COMPATIBILITY
This unit conforms to the Product Specifications noted on the Declaration of Conformity.
Operation is subject to the following two conditions:
• this device may not cause harmful interference, and
• this device must accept any interference received, including interference that
may cause undesired operation.
Operation of this unit within significant electromagnetic fields should be avoided.
• use only shielded interconnecting cables.
DECLARATION OF CONFORMITY
ManufacturerÕs Name: dbx Professional Products
ManufacturerÕs Address: 8760 S. Sandy Parkway
Sandy, Utah 84070, USA
declares that the product:
dbx 160S
conforms to the following Product Specifications:
Safety: EN 60065 (1993)
IEC65 (1985) with Amendments 1, 2, 3
EMC: EN 55013 (1990)
EN 55020 (1991)
Supplementary Information:
The product herewith complies with the requirements of
the Low Voltage Directive 73/23/EEC and the EMC
Directive 89/336/EEC as amended by Directive
93/68/EEC.
dbx Professional Products
Vice-President of Engineering
8760 S. Sandy Parkway
Sandy, Utah 84070, USA
March 31, 1997
European Contact: Your Local dbx Sales and Service Office or
International Sales Office
68 Sheila Lane
Valparaiso, Indiana
46383, USA
Tel: [phone]
Fax: [phone]

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Why you need compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
The difference between compressors and limiters . . . . . . . . . . . . . . . . . . . . . .4
The compression and limiting effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Limiters and PeakStopPlus™ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Connection To Your System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Operating Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Front Panel Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Rear Panel Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Operating Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
OverEasy® and hard knee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Using the Compression Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Using the Stereo Couple Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Using the Auto Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Setting the Attack and Release Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Using PeakStop®/PeakStopPlus™ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Specific Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Sidechain Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Technical Support/Factory Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109
Warranty Registration Card
160S
contents Manual

WhyYou Need A Compressor
A remarkable feature of the human ear is that it can detect an extremely wide range of amplitude
changes - from the slightest whisper to a deafening clap of thunder. If one tries to record or reproduce
this wide spectrum of sound with the help of amplifiers, cassette recorders, records, or even digital
recorders, one is immediately restricted by the physical limitations of electronic and acoustic sound
reproduction technology.
The useable dynamic range of electronic audio equipment is limited as much at low levels as at high
levels. The thermal noise of electrons in the components results in an audible noise floor and thus rep-
resents the bottom limit of the transmission range. In such equipment, this is referred to as “hysteresis”.
Referring to any magnetic media, hysteresis is the amount of electrical impulse it takes for the tape
recorder to begin to rearrange the magnetic particles of the tape (record signal onto the tape). The more
energy it takes, the more noise is introduced onto the tape, making the noise floor more audible. The
amount of hysteresis varies depending on the brand of tape used, and depends on the materials used
in the manufacture of the tape.
When magnetic tape was first used to record audio, hysteresis was a real concern, because it made the
useable dynamic range of magnetic tape very narrow. In the early 1960s, it was discovered that if a tape
recorder supplied an extremely high frequency tone to its record head (much higher than the magnetic
tape could possibly record), the tape’s hysteresis was greatly reduced, or, it took less electrical activity
to start to rearrange the magnetic particles of the tape. The result: a much lower noise floor level and a
wider dynamic range. This tone is called a “bias tone” or “bias frequency.” Today tape manufacturers
produce tape optimized for specific bias frequencies, and studio technicians align tape recorders’ heads
according to these specifications, in order to take full advantage of the tape recorders’ electronics, and
the magnetic tape’s ability to record sound on its magnetic particles.
The upper limit of useable dynamic range is determined by the levels of the internal operating voltages;
if they are exceeded, audible signal distortion is the result. Although in theory the useable dynamic range
sits between these two limits, it is considerably smaller in practice, since a certain reserve must be main-
tained to avoid distortion of the audio signal if sudden noise peaks occur. Technically speaking, we refer
to this reserve as headroom--usually about 10-20dB. A reduction of the operating level would allow for
greater headroom, i.e. the risk of signal distortion due to high level peaks would be reduced. However
at the same time, the basic signal to noise ratio of the program material would be increased significant-
ly. It is therefore useful to keep the operating level as high as possible without risking signal distortion
in order to achieve optimum transmission quality. It is possible to further improve the transmission qual-
ity by constantly monitoring the program material with the aid of a volume fader, which manually
changes the level of the program material. During low passages the gain is increased, and during loud
passages the volume is decreased. Of course it is fairly obvious that this kind of manual control is rather
restrictive; it is difficult to detect signal peaks and almost impossible to level them out. Manual control
is simply not fast enough to be satisfactory.
The need therefore arises for a fast acting automatic gain control system which will constantly monitor
the signals and which will always adjust the gain to maximize the signal-to-noise ratio without incurring
signal distortion. This device is called a compressor or limiter.
3
160S Introduction

The Difference Between Compressors and Limiters
By measuring the dynamic range of musical instruments in live recording situations, you will experience
extreme amplitudes which will often lead to overload in subsequent signal processing equipment.
Especially in broadcasting and digital recording, these signal peaks can lead to heavy distortion. To avoid
this kind of distortion or, to avoid loudspeakers being damaged by overload, compressors and limiters
are used.
The principle function of these devices is automatic gain control, as mentioned in the previous para-
graphs, which reduces the the amplitude of loud passages and therefore restricts the original signal
dynamics within a desired range. This is useful, especially in conjunction with microphone recording
techniques, to compensate for level changes which are caused by inconsistent microphone techniques
on the part of the player, or to restrict the natural dynamic range of voices or intruments to achieve a
more even level.
Although compressors and limiters perform similar tasks, one essential point makes them different:
Limiters abruptly limit the signal above a certain level, while compressors control the signal “gently” over
a wide range. A limiter continuously monitors the signal and intervenes as soon as an adjustable level
is exceeded. This level is called the “threshold”. Any signal exceeding this threshold level will be imme-
diately held below the set threshold level.
A compressor also monitors the program material continuously and also has a set threshold level.
However, in contrast to the limiter, signals exceeding the threshold are not reduced abruptly, but grad-
ually. Above the threshold the signal is reduced in level relative to the amount the signal exceeds this
point.
Generally, threshold levels for compressors are set below the normal operating level to allow for the
upper dynamics to be musically compressed. For limiters, the threshold point is set above the normal
operating level in order to provide peak signal limiting and thus protects subsequent equipment.
4
Operating Level Headroom
Clipping
Noise Floor
Useable dynamic range
Clipped signal heavily distorted
Audio levels below here are not heard, because of noise
i i
Dynamic
Range
160S
Introduction

The Compression and Limiting Effects
On a compressor, there is a relationship between the input signal, and the threshold level, input, out-
put, and ratio settings. Look at an input signal applied to the inputs of two compressors. The threshold
level of the second unit is set ten decibels higher than the threshold of the first unit. Since a compres-
sor only affects signals that exceed the threshold level, it is obvious that the signal of the first compres-
sor will be compressed more, because it exceeds the threshold level more than the level of the second
unit, because the second compressor’s threshold level is set higher.
The difference between compression and limiting is shown visually below. In the first diagram below,
compression “squashes” the signal. Its peaks are lowered, but the overall level of the signal is raised due
to applied make-up gain (Output Gain). In the second diagram, the peaks are lowered to the threshold
level, but the rest of the signal has not been altered.
Obviously, there is a large difference between these two signals in relation to their dynamic range and
the processed signal. In the third figure, it is shown to have been compressed, and in the fourth figure,
it has been limited. 5
+10
0
-10
-20
time Figure 1
input
dBu
+10
0
-10
-20
time
+10
0
-10
-20
time
input
dBu
Figure 2 Figure 1
input
dBu
Input of compressors at
different threshold set-
tings.
= threshold
Figure 3 Figure 4
+10
0
-10
-20
time
+10
0
-10
-20
time
output
dBu
output
dBu
160S Introduction
Difference in output of
compressors and limiters.
= threshold

6
Furthermore, it is interesting to note that by comparing the input and output waveforms for the com-
pressed mode, the quietest sections of the input signal have been effectively raised in level, where-
as the loudest sections have been effectively decreased in level. The overall effect is that both ends
of the dynamic range have been pushed toward the middle. This squashing effect of compression is
important to remember and highlights the major difference between compressing and limiting.
Compressing and limiting differ in one more aspect: the dynamic settings for attack and release times.
Attack time is defined as the time taken to for a compressor to respond to program levels which have
exceeded the threshold point. Release time is the amount of time a compressor takes to return the
program level to its original level, after the last excursion over the threshold point. For compression,
a preferably longer attack and release time are generally the best in order to keep the overall output
signal within a specified dynamic range. For limiting applications, considerably shorter attack and
release times are necessary to control fast transient signals or to increase headroom.
To achieve inaudible compression, it is advisable to work with program dependent attack and release
times. The advantage of program dependent compression is most apparent when processing musi-
cal material that is varied.
The dbx 160S Stereo Compressor is suitable for all applications because of its ability to be manually
set at both attack and release parameters.
Limiters and PeakStopPlus™
Lower frequencies work best when compressed with slower attack times. When compressing a mix
that includes a wide range of frequencies, a compromise is made when setting the attack time. The
attack setting would generally suit the lowest frequency components of the material. For general
dynamic range control with a compressor, this is of no serious consequence.
However, in a “limiting” situation, where we are restricting the peaks of our signal to a maximum
operating level to avoid distortion in subsequent devices, a slow attack time is not acceptable. This
would result in very fast high frequency signal transients passing through unaffected by gain reduc-
tion. These transients could then cause distortion in the following equipment such as tape recorders
and radio transmitters. It is therefore necessary to choose an attack time which is as close to “zero”
attack as possible, independent of the frequency.
This makes the limiter necessary, and it’s why we include a peak limiter on almost all of our com-
pression products. The dynamics of the dbx limiters are set to handle these fast transients through a
process called PeakStop® and the newer, improved two-stage process called PeakStopPlus®.
The first stage of PeakStopPlus is the Instantaneous Transient Clamp™ which clamps the signal with a soft log-
arithmic clamp function. This logarithmic function assures that the signal will not exceed the level set by the
PeakStopPlus™ LEVEL control by more than 2 dB typically, and that it will not introduce harsh artifacts. The
second stage is a unique program limiter featuring Intelligent Predictive Limiting™. Its function is to monitor
the input signal and intelligently predict the amount of gain reduction needed to keep the output signal below
the ceiling set by the Instantaneous Transient Clamp™. Note, since the PeakStopPlus™ limiter is a fail-safe lim-
iter it must come after the OUTPUT GAIN control. If the output gain is set too high as compared to the
160S
Introduction

7
PeakStopPlus™ Level control, continuous limiting can occur. While PeakStopPlus™ is typically used as a pro-
tective function, creative effects can be achieved by intentionally driving the signal into heavy PeakStopPlus™
limiting. Great care has gone into the design of the PeakStopPlus™ limiter to keep it acoustically transparent.
Appropriate use of it can protect your gear while keeping the signal free of artifacts.
For best results the Limiter functions of your compressor should be used in conjunction with the
Compressor functions.
When we at dbx decided to make a premium compressor that would perform to the industry’s high-
est standards, it became readily obvious that every component and design strategy had to be chosen
with high-performance foremost in mind. After the evolutionary process of engineering design and
implementation was complete, the result was stunning. Here is a partial list of the features found on
the 160S. You won’t hear about most of them anywhere else, but they are critical to the amazing
specs, comprehensive functionality, and visionary design of the 160S Stereo Compressor.
• New dbx V8™ VCA module exhibits a dynamic range of 127dB
with extremely low distortion!
• V8™ VCA is encased in a specially-designed zinc-aluminum hous-
ing for shielding and thermal characteristics. This allows for peak
performance of the VCA in any environment.
• Precision 0.1% and 1% metal film resistors.
• Gold-palladium-nickel board-to-board connectors.
• Jensen® transformers.
• Gold-plated Neutrik® XLR connectors.
• Rare earth magnet relays with gold contacts in a hermetically
sealed nitrogen environment.
• Military-grade glass epoxy circuit boards.
• Double-shielded Toroid transformer ensures no self-generated
power supply noise enters the audio path.
• High-drive output transformers are capable of driving 1000 feet of
Belden 8451 cable to +30dBm.
• Striking blue custom-machined, 1/4” thick front panel.
• Hand-crafted, solid aluminum knobs.
• LEDs mounted in machined, stainless steel housings.
• Custom dbx VU meters with peak indicators.
• Heavy-gauge chassis.
• Switchable OverEasy®/hard knee characteristics enable the 160S to
sound like the traditional 165A as well as the old and still popular
160.
• Program dependent Auto mode, or fully variable attack and
release.
• PeakStop/PeakStopPlus™ switchable limiting topologies, the per-
fect complement to the 160S feature set.
• Sidechain capabilities, switchable from the front panel.
160S Introduction

9
The 160S is connected for operation using the rear panel XLR connectors. Note that the two rear panel
input sections have a push-switch which lifts the contact on pin #1 (ground). Keep this switch in the
OFF position (pin #1 connected) until all connections are made. Be sure that your input and output
cables are wired in the “pin 2-hot” configuration, which is printed on the rear panel of the 160S. For
more information on other types of connections, refer to the section entitled Operating Notes.
When connecting the 160S, refer to the following steps:
• Turn OFF all equipment BEFORE making any connections.
• Mount the 160S in a 2U rack space. (Optional)
The 160S requires a two rack-space height and a standard 19 inch rack-
space width. It can be mounted above or below anything that doesn’t
create excessive heat, since it requires no special ventilation. Ambient
temperatures should not exceed 113°F (45°C) when equipment is pow-
ered.
Caution: Never remove the cover. There are no user serviceable parts inside.
• Make connections via XLR connectors.
• Plug in AC power cable and power ON the unit.
Note:Check the line voltage printed on the rear panel of the 160S and verify that it
is correct for your area.
Two Basic Compressor Setups:
A: Channel One shows processing of a
group or aux master output. Signal goes
to the 160S input from the output/insert
send of the console, and returns to the
console via the input/insert return of
the same group/aux on the console.
B: Channel Two shows connections for
processing a signal from a single chan-
nel. Input of the 160S is fed by the
channel insert output/send, and returns
to the console via the insert
input/return.
Connections
OUTPUT OPTION
SIDECHAIN
INPUT
INPUT
SEND RETURN
OUTPUT
OUTPUT INPUT OUTPUT
CHANNEL ONE
CHANNEL ONE
CHANNEL TWO
CHANNEL TWO
INPUT OUTPUT
PIN 1
LIFT GROUNDUNBAL
SIDECHAIN
SEND RETURN
PIN 1
LIFT GROUNDUNBAL
PROFESSIONAL PRODUCTS
A HARMAN INTERNATIONAL COMPANY
SALT LAKE CITY,UTAH
MADE IN USA MODEL 160S

XLR:
PIN 1
PIN 2
PIN 3
CONNECTOR
POLARITY
45 WATTS

POWER

100-120V
50/60Hz
FUSE:
500mA 250V
SLOW
BLOW

¨
WARNING: TO REDUCE THE RISK
OF FIRE OR ELECTRIC SHOCK DO NOT
EXPOSE THIS EQUIPMENT TO RAIN OR
MOISTURE
RISK OF ELECTRIC SHOCK
DO NOT OPEN
ATTENTION: RISQUE DE CHOC
ELECTRIQUE - NE PAS OUVRIR
CAUTION: TO REDUCE
THE RISK OF FIRE REPLACE
ONLY WITH SAME TYPE FUSE.
ATTENTION: UTILISER
UN FUSIBLE DE RECHANGE DE
MEME TYPE.
AB
OUTPUT OPTION
SIDECHAIN
INPUT
SEND RETURN
OUTPUT
CHANNEL ONECHANNEL TWO
INPUT OUTPUT
PIN 1
LIFT GROUNDUNBAL
SIDECHAIN
SEND RETURN
PIN 1
LIFT GROUNDUNBAL
PROFESSIONAL PRODUCTS
A HARMAN INTERNATIONAL COMPANY
SALT LAKE CITY,UTAH ¥ MADE IN USA
MODEL 160S

XLR:
PIN 1
PIN 2
PIN 3
CONNECTOR
POLARITY
50 WATTS

POWER

120V
50/60Hz
FUSE:
500mA 250V
SLOW
BLOW

¨
WARNING: TO REDUCE THE RISK
OF FIRE OR ELECTRIC SHOCK DO NOT
EXPOSE THIS EQUIPMENT TO RAIN OR
MOISTURE
RISK OF ELECTRIC SHOCK
DO NOT OPEN
ATTENTION: RISQUE DE CHOC
ELECTRIQUE - NE PAS OUVRIR
CAUTION: TO REDUCE
THE RISK OF FIRE REPLACE
ONLY WITH SAME TYPE FUSE.
ATTENTION: UTILISER
UN FUSIBLE DE RECHANGE DE
MEME TYPE.
MANUFACTURED UNDER ONE OR MORE OF THE
FOLLOWING U.S. PATENTS: 4,234,804 4,316,107
4,329,598 4,331,931 4,377,792 4,403,199 4,409,500
4,425,551 4,434,380 4,454,433 4,471,324 4,473,793
OTHER PATENTS PENDING
160S Connection
to your system

10
OverEasy® Switch: This switch activates/deactivates the OverEasy® characteristics of the 160S. When
the switch is IN, the 160S is in O
VER E ASY mode. OverEasy is a process which allows the user to com-
press a signal more gently than a hard knee compressor through the threshold region. This action
produces a much smoother “natural-sounding” compression effect. When the OverEasy switch is
OUT, the regular, hard knee action of the compressor is active. Hard knee operation can produce a
much harder (hence the nick-name “hard knee”) compression effect as the signal passes over the
threshold level. Note that when the OverEasy switch is IN, the yellow LED above the Threshold
control lights whenver the input signal level is in the OverEasy region of compression. In HARD KNEE
mode the signal is either below the threshold and not being compressed, or it is above the thresh-
old and is being compressed, and therefore the yellow LED does not light. See the section entitled
Operating Notes later in this manual for a more in-depth discussion of the differences between
OverEasy and hard knee compression.
Threshold Control: This control adjusts the signal amplitude (volume, or level) above which com-
pression occurs. In O
VER E ASY mode the threshold of compression is defined as the approximate mid-
dle of the OverEasy region. The markings around the Threshold control are measured in dBu
(where 0dBu = .775V) and range from -40dBu (7.8mV rms) on the low end, to +30dBu (24.5V rms)
at the high end of the scale.
Threshold LEDs: These LEDs (above the Threshold control) indicate the relationship between the
input signal and the threshold set by the Threshold control. The green LED lights when the input
signal is below the set threshold. The yellow LED lights when the 160S is set in O
VER E ASY mode via
the OverEasy switch, and the input signal level is in the OverEasy threshold range. The red LED
lights when the input signal level is above the set threshold. (See the section entitled Operating
Notes for a discussion on the differences between OverEasy® and hard knee compression.)
Compression Control: This control adjusts the amount of compression that is applied to the input sig-
nal level when it exceeds the set threshold level. The amount of compression is expressed in a ratio
formula, where the first number of the ratio indicates the amount of input signal level in dB, and
the second number indicates the amount of output signal level, in dB, when the threshold is exceed-
ed. For example, in
HARD KNEE mode, the compression ratio of 5:1 means that for every 5dB of sig-
nal level that exceeds the set threshold level, the resultant output signal level is 1dB. Therefore if
the threshold level is exceeded by 15dB, and the compression ratio is set to a 5:1 ratio, the output
signal level will be 3dB. In O VER E ASY mode, the ratio set by the Compression control is not reached
until the signal has pased through the OverEasy region of compression (the yellow LED turns off
and the red LED lights). When the ratio of ∞:1 is selected, the input signal level is “limited” to a 0dB
Front Panel Controls
160S
controls
Operating
STEREO
COUPLE
POWER
¨
160S
COMPRESSOR
LIMITER
SIDECHAIN
1.5k
4k
400
70
10
dB / Sec
RELEASE
200
400
80
10
1
dB / mSec
ATTACK BYPASS
PEAK
PeakStopPlus
+10
+6
+4
+20
+25
OFF
dBu
STOP LEVEL
6:1
5:1
15:1
2:1
1.5:1
1:1
4:1
3:1
COMPRESSION
-20
0
+10
+20
dB
-10
OUTPUT GAIN
-40 +30
-10 0
dBu
THRESHOLD
+20
-20 +10
SIDECHAIN
1.5k
4k
400
70
10
dB / Sec
RELEASE
200
400
80
10
1
dB / mSec
ATTACK BYPASS
PEAK
PeakStopPlus
+10
+6
+4
+20
+25
OFF
dBu
STOP LEVEL
6:1
5:1
15:1
2:1
1.5:1
1:1
4:1
3:1
COMPRESSION
-20
0
+10
+20
dB
-10
OUTPUT GAIN
-40 +30
-10 0
dBu
THRESHOLD
+20
-20 +10
DECIBELS
20 10 753
-15
-20 -10
-25 -5
-30 0
03
+
-
¨
DECIBELS
20 10 753
-15
-20 -10
-25 -5
-30 0
03
+
-
¨
METER SELECTION
INPUT G.R.OUTPUT
METER SELECTION
INPUT G.R.OUTPUT

increase in output level, regardless of how far the set threshold level is exceeded. This occurs in
both OverEasy® and hard knee operation. Note that when a compressor is set to a compression
ratio of 10:1 or more, it may be considered to be LIMITING the input signal, especially when a fast
attack time is selected.
Auto Switch: This switch sets the 160S for automatic or manual operation. When the Auto switch is IN
(A
UTO mode), the compressor automatically adjusts its attack rate and release time to suit the pro-
gram envelope. (This A UTO mode sets the compressor for the same attack and release characteristics
as dbx Models 160, 161, 162, 163 and 164 compressor/limiters.) When the Auto switch is OUT ( MAN -
UAL mode), the front panel Attack and Release rate controls determine the maximum rate of gain
change and the behavior of the level detector circuitry.
In A
UTO mode, the 160S utilizes the patented dbx RMS level detector with its program-dependent
attack/release characteristics to obtain natural-sounding compression or limiting. For special effects
and certain signal situations, however, it is often desirable to set fixed attack and release character-
istics. M ANUAL mode affords this capability. The A UTO mode is recommended for vocals as well as
instruments. Because the A UTO mode has a program dependent variable attack rate, the compressor
may compress or limit some program material smoother than in the MANUAL mode which has a fixed
attack characteristic. This is especially true on vocals.
Attack and Release Controls: Attack time is defined as the time taken for a compressor to respond
to program levels which have exceeded the threshold point. For the 160S, this control ranges from
400dB/mS (extremely fast) to 1dB/mS. Release time is the amount of time a compressor takes to
return the program level to its original level, after the last excursion over the threshold point. The
160S’s release times range from 4000dB/second (very fast release time), to 10dB/second (slow release
time). A very fast attack setting (control maximum counterclockwise) will cause the compressor to
act like a peak limiter even though RMS detection circuitry is used. Slower attack settings cause the
compressor to act like an RMS or averaging detecting compressor/limiter. To achieve inaudible com-
pression, it is advisable to work with program dependent attack and release times (A
UTO mode). The
advantage of program dependent compression is most apparent when processing musical material
that is varied. For compression, longer attack and release times are generally the best in order to
keep the overall output signal within a specified dynamic range. For limiting applications, consider-
ably shorter attack and release times are necessary to control fast transient signals or to increase
headroom.
Stop Level Control: This control adjusts the maximum peak output level of the 160S regardless of any
other control. The PeakStop limiter comes after the compression and all other circuitry, except the
output gain; this provides for an absolute peak limit to be put on the peak excursions at the output
via the Instantaneous Transient Clamp™.
Since the PeakStopPlus™ limiter is a fail-safe limiter it must come
after the Output Gain control. If the output gain is set too high as compared to the PeakStopPlus™ Level
control, continuous limiting can occur. While PeakStopPlus is typically used as a protective function, creative
effects can be achieved by intentionally driving the signal into heavy PeakStopPlus™ limiting. Like the range
of the Threshold control, the scale of the Stop Level control is measured in dBu. The control ranges
from +4dBu, all the way to “OFF” (+30dBu). The top end of the scale is marked “OFF” because its
internal setting, +30dBu, is the actual maximum output level of the 160S, and therefore signal pass-
ing through the unit will pass untouched, up to the maximum output level of the 160S. Because of
this, the limiter is effectively rendered “inactive” in the OFF setting.
11
controls
160S Operating

PeakStopPlus™ Switch and LED: The dynamics of the dbx 160S are set to handle fast transients
through PeakStop® limiting and the newer PeakStopPlus™. PeakStop is the process first introduced
on the dbx 165A compressor/limiter, which is still very popular today. PeakStop is made up of an
extremely fast-reacting detector, called Instantaneous Transient Clamp. The sound of PeakStop
became popular as the 165A permeated the audio industry, and quickly became the standard looked
for by many top artists of the day. The latest implementaion of this limiter topology is PeakStopPlus,
first introduced in 1996 on the dbx 1066. PeakStopPlus is made up of two different parts or stages.
The first stage is the Instantaneous Transient Clamp™ which clamps the signal with a soft logarithmic clamp
function. This logarithmic function assures that the signal will not exceed the level set by the PeakStopPlus™
Level control by more than 2 dB typically, and that it will not introduce harsh artifacts. The second stage is a
unique program limiter featuring Intelligent Predictive Limiting™. Its function is to monitor the input signal and
intelligently predict the amount of gain reduction needed to keep the output signal below the ceiling set by
the Instantaneous Transient Clamp™.
Note that since the PeakStopPlus™ limiter is a fail-safe limiter it must come after the Output Gain control. If
the output gain is set too high as compared to the PeakStopPlus™ LEVEL control, continuous limiting can
occur. While PeakStopPlus™ is typically used as a protective function, creative effects can be achieved by inten-
tionally driving the signal into heavy PeakStopPlus™ limiting. Great care has gone into the design of the
PeakStopPlus™ limiter to keep it acoustically transparent. Appropriate use of it can protect your gear while
keeping the signal free of artifacts.
A bi-color LED associated with both the Stop Level control and the PeakStopPlus switch indicates
when PeakStopPlus is activated. By pushing the PeakStopPlus switch to the IN position, the LED
lights in a green color when the signal level at the limiter circuit is BELOW the stop level set by the
Stop Level control. When the signal level attempts to exceed the level set by the Stop Level con-
trol, the LED lights in a red color.
When the limiter is in P
EAK S TOP mode, the LED does not light in a green color, and only lights in a
red color when the signal attempts to exceed the set stop level, showing that the signal is being
reduced in level by the limiter.
Sidechain Switch and LED: This switch/LED provides access/visual feedback to the sidechain con-
trol. When the switch is IN, the LED is lit, and the 160S is operating in
SIDECHAIN mode. This means
that the compressor is set react to the audio signal presented at the Sidechain Return connector,
rather than to the audio signal presented at the regular audio input of the 160S. The circuitry of the
160S was designed in such a way as to make the audio path of the sidechain section very short and
clean. The selection of the sidechain function is made via “relay” switching, not allowing the signal
to pass through any unnecessary switches. The sidechain functions are convenient in many applica-
tions, such as broadcast engineering, where engineers are asked to provide “ducking” functions, as
well as de-essing. Frequency-specific and sustain-related compression are also possible with the use
of the sidechain functions of the 160S. See the section entitled Operating Notes.
12
160S
controls
Operating

Bypass Switch and LED: This switch activates a hard-wire relay bypass system, which allows the
audio signal to pass through the compressor directly from input to output, even when the 160S is
turned off. That is to say that the XLR Pin 2 at the input connector is directly connected to the XLR
Pin 2 at the output connector, and the XLR Pin 3 at the input connector is directly connected to the
XLR Pin 3 at the output connector. When the 160S is in
BYPASS mode the LED directly above the
Bypass switch is lit.
Note: Bypass mode can be very useful for applications such as A-B comparisons, comparing processed signal with
un-processed signal.
Output Gain Control: This control adjusts the amount of gain in the 160S’s output amplifier stage. The
signal can be attenuated or boosted by a full 20dB relative to a “0” center setting, representing unity
gain. This control is independent of the threshold or compression ratio settings. Because 20dB of gain
can be added at the 160S output, it is possible to cause clipping even when the input level is with-
in the specified range. When the compression ratio is set at a low number, extreme clockwise rota-
tion of the Output Gain control could cause the 160S output stage to clip audio program peaks.
Therefore, for normal operation we suggest setting the Output Gain control to “0dB” (12 o’clock
position) as a starting postion. Where the circuit fed by the 160S has a high input sensitivity, lower-
ing the output gain setting can avoid the need for an attenuation pad in subsequent equipment.
Peak LED: This LED is located to the left of the VU Meter. It is set to light when the signal level at
the output level reaches +27dBu. This represents a headroom measurement of approximately 3dB
before hard clipping will occur, due to the maximum output level of the 160S (+30dBu).
VU Meter: The custom designed analog meter is made to serve 3 different functions: first, it measures
the amount of input signal presented at the input connector corresponding to its channel. Second, it
measures the output signal at the output connector, after all processing has taken place, including
output gain. Third, it shows the amount of gain reduction being induced into the input signal, mea-
sured after both the compressor settings and limiter settings. Note that the meter, in
INPUT and OUT -
PUT mode, measures accurately from -30dB to +6dB. There is 17dB between the upper end of the
meter, and the setting at which the Peak LED lights. Be aware that while the occasional “pegging”
of the meter will likely not effect the internal dynamics of the 160S, due to its unheard-of dynamic
range (123dB), it is possible that the output signal from the 160S could cause distortion in subsequent
gear, if the output signal stays above the +6dB marking on the meter for an extended period of time.
The dynamic range of the 160S is meant to provide an extremely low noise floor at optimum oper-
ating level (“0”dB, which is +4dBu), and to provide protection for the occasional excursion above
the nominal operating range. It was not meant to provide continuous operation in the 17dB of “no-
man’s-land” between the upper end of the analog meter and the setting of the Peak LED.
In G AIN R EDUCTION mode, the meter moves to indicate the amount of gain reduction, in dB, the com-
pressor/limiter settings are imposing on the output signal. When first activated, the meter’s needle
will jump to the “0” mark of the lower scale on the meter (only if there is no gain reduction hap-
pening), indicating “zero gain reduction”, and will move to the left indicating the amount of gain
reduction in the signal level, up to a maximum of 30dB of gain reduction.
13
controls
160S Operating

Note that the gain reduction scale is linear in dB as opposed to the standard VU markings on the
upper scale on which input and output levels are monitored. This allows for easy visual indication
of gain reduction, as it can be read in a fraction of a second, with only a fleeting glance from the
engineer.
Input Meter Selection Switch and LED: Selecting this mode via the switch allows the user to
monitor the incoming signal on the logarithmic (upper) scale of the VU meter. When in
INPUT mode,
the LED above the switch will light in a green color, indicating that INPUT mode is selected.
Output Meter Selection Switch and LED: Selecting this mode via the switch allows the user to mon-
itor the outgoing signal on the logarithmic (upper) scale of the VU meter. When in
OUTPUT mode, the
LED above the switch will light in a yellow color, indicating that OUTPUT mode is selected.
Gain Reduction Meter Selection Switch and LED: Selecting this mode via the switch allows the
user to monitor the amount of gain reduction in dB, applied to the signal on the linear (lower) scale
of the VU meter. When in
GAIN REDUCTION mode, the LED above the switch will light in a red color,
indicating that gain reduction mode is selected. In GAIN REDUCTION mode the meter displays the
amount of gain reduction resulting from the settings of both the compressor and PeakStopPlus lim-
iter.
Stereo Couple Switch and LED: This switch activates the stereo linkage between channels one and
two. When the switch is in the IN position, the two channels of the 160S are linked together, and the
oversized yellow LED directly above the switch lights to indicate the selection. In
STEREO mode chan-
nel one (the left side of the 160S) is the “master” and channel two (the right side of the 160S) is the
“slave”. When the two channels are linked together, the controls on the master side control the set-
tings of both channels of the 160S. The controls on the slave side are disabled, although the meter
moves synchronous to the meter on the master side. In STEREO mode, the 160S uses a process called
True RMS Power Summing™. True RMS Power Summing combines the RMS signal energy (power)
of the audio signal of both channels and allows the 160S to operate based on the signal information
from both the right an left channels of audio signal.
Power LED: The Power LED is located directly above the Stereo Couple switch, at the center point
of the 160S. It is a custom designed oversized, blue LED, in keeping with the dbx Blue Series con-
cept of innovative engineering, and revolutionary design. It remains lit while the 160S is connected
to an appropriate power supply, and the Power switch is in the ON position.
14
160S
controls
Operating

15
Audio Input and Output Connectors: Each audio input connector on the rear panel of the 160S is
a gold-plated Neutrik® XLR female connector. The no-compromise approach to the 160S required
that we use gold-plated connectors, due to their high conductivity and low EMI/RFI susceptibility.
The connectors are default wired in
BALANCED mode (pin 2 hot, AES convention), although supplying
an unbalanced signal presents no difficulty to the 160S.
Pin1 Lift Switch: Associated with each input connector is a switch labeled Pin 1 Lift. Depressing this
switch lifts pin 1 of the input XLR from all ground references. This may be necessary to break a trou-
blesome ground loop which is causing hum in the system.
Unbalance Switch: The Unbalance switch is associated only with the Output connectors of the 160S.
When it is in the IN position, the output of the 160S is switched from balanced to unbalanced. (See
wiring diagram below.) In the OUT position, the 160S’s outputs are balanced in the “pin 2 hot” con-
figuration. Note that when the output is unbalanced via the switch, there is a 6dB drop in output sig-
nal level. If you do not wish to experience the 6dB drop in output signal level, you may short pin 3
of the output cable to ground, rather than using the Unbalance switch.
Ground Switch: The Ground switch, when in the IN position, references the center tap of the output
transformer to the chassis ground. This ensures that the signal from the 160S, regardless of previous
grounding systems earlier in the audio chain, can deliver a chassis-grounded output signal free of
hum and interference to the output connector. The combination of the three switches associated with
the audio input/output connectors ensures that the 160S is versatile enough to interface with any
equipment and can deliver clean audio to the output, free of hum and interference. (See the follow-
ing diagram for details of the Ground switch operation.)
Rear Panel
controls
160S Operating
OUTPUT OPTION
SIDECHAIN
INPUT
SEND RETURN
OUTPUT
CHANNEL ONECHANNEL TWO
INPUT OUTPUT
PIN 1
LIFT GROUNDUNBAL
SIDECHAIN
SEND RETURN
PIN 1
LIFT GROUNDUNBAL
PROFESSIONAL PRODUCTS
A HARMAN INTERNATIONAL COMPANY
SALT LAKE CITY, UTAH ¥ MADE IN USA
MODEL 160S

XLR:
PIN 1
PIN 2
PIN 3
CONNECTOR
POLARITY
50 WATTS

POWER

120V
50/60Hz
FUSE:
500mA 250V
SLOW
BLOW

¨
WARNING: TO REDUCE THE RISK
OF FIRE OR ELECTRIC SHOCK DO NOT
EXPOSE THIS EQUIPMENT TO RAIN OR
MOISTURE
RISK OF ELECTRIC SHOCK
DO NOT OPEN
ATTENTION: RISQUE DE CHOC
ELECTRIQUE - NE PAS OUVRIR
CAUTION: TO REDUCE
THE RISK OF FIRE REPLACE
ONLY WITH SAME TYPE FUSE.
ATTENTION: UTILISER
UN FUSIBLE DE RECHANGE DE
MEME TYPE.
MANUFACTURED UNDER ONE OR MORE OF THE
FOLLOWING U.S. PATENTS: 4,234,804 4,316,107
4,329,598 4,331,931 4,377,792 4,403,199 4,409,500
4,425,551 4,434,380 4,454,433 4,471,324 4,473,793
OTHER PATENTS PENDING
2
1
3
Jensen¨
Output 
Transformer
Jensen¨
Output 
Transformer
10k 1W
GND
Switch
GND
Switch
BALANCED FLOATING OPERATION UNBALANCED FLOATING OPERATION
Chassis
Ground
Chassis
Ground
Chassis
Ground
Ground Switch open
Unbalance Switch open Ground Switch open
Unbalanced Switch closed
(6dB drop in output level)
+
-
+
-
2
1
3
Chassis
Ground

Sidechain Send and Return Connectors:When the front panel Sidechain switch is in the IN posi-
tion, the 160S RMS level detection is “listening” to the audio signal presented at the Sidechain
Return connector. Each channel features separate sidechain capabilities using the same quality gold-
plated Neutrik® XLR connectors as for the main audio input and output connections. Each channel’s
sidechain connections are marked “send” for the output, and “return” for the input. Note that input
and output cables may be permanently installed here without disrupting the 160S’s normal signal
path; sidechain functions are only active and available while the unit is in
SIDECHAIN mode, selected
from the front panel. This feature makes the 160S ideal for permanent mounting in a large rack sys-
tem, with connections going to a patch bay. When selected, the sidechain Send connector (XLR
male) “sends” the audio signal from the 160S to the outboard gear in the sidechain loop. (ie: dbx 20
or 30 Series Graphic Equalizer or digital delay. See the section marked Operating Notes for more
information on the sidechain functions of the 160S.) The audio is processed, and sent from the out-
put of that device back to the 160S via the Return connector (XLR female). As the signal is brought
back into the 160S, its RMS level is used to trigger the compression/limiting. This allows the 160S to
be very versatile in many applications, from ducking to frequency-specific compression or limiting.
Two separate cables are used in favor of the conventional single “Y” cable, because they supply bal-
anced signal to the sidechain gear, and are much more convenient to locate and use in a fast-paced
studio or live sound environment.
The signal path of the sidechain function is “relay-selected” in order to keep the signal path short
and clean.
Chassis Ground Binding Post: ( ) The green Chassis Ground binding post is supplied to give
the user another method to provide comprehensive grounding options for any installation. It is easy
to think of the binding post as being synonymous with the ground pin on any AC power cord. (The
ground pin on an AC cord should NEVER be removed, shorted out, or “lifted”.) The post allows the
chassis ground to be connected to another ground source if desired. (ie: a chassis ground system
provided by another piece of gear) Wire may be connected to the binding post by securing the
stripped end of the wire through the hole in the post, located under the hardened plastic nut-top of
the post. Access to the hole is gained by unscrewing the top part of the post far enough to reveal
the hole underneath. Insert the stripped end of the wire and tighten the top (nut) part of the bind-
ing post to secure the connection.
16
Jensen¨
Output 
Transformer
Jensen¨
Output 
Transformer
10k 1W
GND
Switch
GND
Switch
BALANCED GROUND-
REFERENCED OPERATION
UNBALANCED GROUND-
REFERENCED OPERATION
Chassis
Ground
Chassis
Ground
Ground Switch closed
Unbalance Switch open Ground Switch closed
Unbalance Switch closed
(6dB drop in output level)
+
-
+
-
2
1
3
Chassis
Ground 2
1
3
Chassis
Ground
160S
controls
Operating

Signal Ground Binding Post: ( ) The black Signal Ground binding post is located next to the
Chassis Ground binding post, and works in much the same way, providing comprehensive ground-
ing options for any installation. Some systems are built on a “star” grounding principle, where all the
signal grounds are brought directly to one central point and grounded to earth at the same location.
The Signal Ground binding post allows easy access to the signal ground system of the 160S with-
out having to remove the cover of the 160S and locate a good place to take the signal ground out
of the box.
Note: Typically the shorting link between chassis ground and signal ground should be left installed, unless
another grounding scheme is used.
AC Power Switch: Located beside the AC Power connector, the AC Power switch turns the 160S
ON and OFF. When the switch is in the DOWN position, revealing the red portion of the switch,
the AC power to the 160S is ON. When the switch is in the UP position, no AC power is being
supplied to the 160S, regardless of other power connections.
AC Power Connector: The AC Power connector is a standard IEC 320 power inlet receptacle, for use
with any IEC-type power cord (included with the 160S). Connect this cable to any 50Hz or 60Hz AC
power source of the correct line voltage for your area. Make sure this voltage is also correct for the
voltage marked on the back of the 160S. Always make AC power connections with the AC power
switch in the OFF position (see above). The 160S consumes a maximum power of 50 watts.
Warning: Be sure to verify both your actual line voltage and the voltage for which your 160S
is wired, as indicated on the back panel of the unit. Connection to an inappro-
priate power source may result in extensive damage which is not covered by the
warranty.
Output Option Panel: This panel is removed when an output option card is installed in your 160S.
Connecting a custom designed digital output module in the option port provides full 24-bit AES/EBU
and S/PDIF output capabilities for the 160S. The digital outputs of the 160S operate simultaneously
with the analog outputs, providing the possibility of running to three different devices at the same
time: analog, AES/EBU, and S/PDIF. For more information on the digital output option, contact dbx
customer service. Be sure to fill out your warranty registration card, provided in this manual, and
return it to dbx as soon as possible. This will enable us to notify you of other output options that
will become available in the future.
17
controls
160S Operating