dbx 2BX User manual

db:>X Model 2BX
two band dynamic range enhancer
INSTRUCTION MANUAL

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dbx® is aRegistered Trademark of dbx. Inc.

INDEX
BRIEF OPERATING INSTRUCTIONS
INTRODUCTION
CONNECTIONS
OPERATION
EXPANSION
SIMPLE PRECAUTIONS WHEN USING ANY PROGRAM EXPANDER
HOWdbx EXPANDERS WORK '
SPECIFICATIONS "
dbx PRODUCT WARRANTY
FACTORY SERVICE "
SCHEMATIC "'
GLOSSARY "

BRIEF OPERATING INSTRUCTIONS
PILOT This L.E.D.
(light emitting diode),
above the POWER
switch, glows when the
2BX is ON.
GAIN CHANGE L.E.D.'s These
two rows of L.E.D.'s indicate
the amount of gain change
created in each of the 2BX's two
frequency bands. The red L.E.D.'s
indicate upward expansion
(volume increase), the yellow
L.E.D.'s indicate downward
expansion (volume decrease).
TRANSITION LEVEL When an
incoming signal is above the level set
by this control, the 2BX expands up-
wards; when an incoming signal is
below the level set by this control, the
2BX expands downward. Set the
control so that red GAIN CHANGE
L.E.D.'s glow during loud portions of
the program and yellow GAIN
CHANGE L.E.D.'s glow during the
quiet portions of the program.
SOURCE Push this
switch and the PRE
switch to expand
programs coming
from your phono-
graph, FM tuner or
other auxiliary
equipment.
TAPE Push this
switch and the
POST switch to
expand programs
coming from your
tape recorder. If
you do not have a
tape recorder, push
the SOURCE switch.
PRE Push this switch
to expand aprogram
before recording it.*
POST Push this
switch and the TAPE
switch to expand a
program played back
from your tape
recorder.
POWER Push this switch
once (IN) to turn the 2BX
ON; push again (OUT)
for OFF.
EXPANSION Adjust this slide
control for the desired amount of
expansion. A"1.4" setting means
that an input signal with a40dB
dynamic range will be expanded to
56dB, or that an input signal with
a50dB dynamic range will be
expanded to 70dB. A1.2 setting
would result in a20% increase
in dynamics; a1.4 setting would
result in a40% increase in
dynamics, etc.
(PRE/POST Summary) The PRE switch expands the signal before the tape recorder
input (PRE places the expander before the tape recorder input); the POST switch
expands the signal from the tape recorder's output (POST places the expander after
the tape recorder output). Pushing both PRE and POST switches simultaneously
bypasses the expander functions.
"Expansion will, in most cases, increase the dynamic range of aprogram beyond the
capabilities of your tape recorder. To capture this increased dynamic range on tape
requires adbx noise reduction system, which a/lows recording at levels below the
tape or tape head's saturation point To expand aprogram and then record it, we
recommend using any dbx tape noise reduction system and carefully setting record
and expansion levels. If you do not have adbx tape noise reduction system, we
recommend expanding aprogram upon playback (place the 1bx in TAPE and POST
mode).

RECORDER OUTPUTS* Connect
the cables from these outputs to the
Line inputs of your tape recorder.
If you do not have atape recorder,
do not connect any cables to these
outputs.
RECORDER INPUTS* Connect
the cables from your tape
recorder Line or Monitor outputs
to these inputs. If you do not
have atape recorder, do not
connect any cables to these inputs.
INPUTS Connect the cables from
the Tape Outputs of your receiver,
preamplifier, or integrated amplifier
to these inputs.
OUTPUTS Connect the cables from
these outputs to the Tape Inputs, or
Monitor Inputs of your receiver, pre-
amplifier, or integrated amplifier.
AC POWER CABLE In the U.S.A.
connect this cable to a117V AC, 50 or
60Hz AC power source. The 2BX
requires amaximum of 20 watts of AC
power. Models for use with power
sources outside the United States
are available. Contact the dbx factory
for information.
*/f you have adbx tape noise reduction system (such as any of
our 120 or 150 series) see Page 9for connection diagrams.

INTRODUCTION
If you're amusic lover or an audiophile (or both) you
have probably noticed that much of the excitement of a
live performance is missing in arecorded or broadcast per-
formance. The primary reason for this loss of excitement is
that the dynamic range of the recorded or broadcast per-
formance has been purposely restricted to fit the dynamic
range limitations of the recording or broadcast medium.
The 2BX is asophisticated expander that can restore the
dynamic range and excitement to arecording or radio
broadcast, adding considerably to your listening enjoyment
By expanding dynamic range, the 2BX lowers the
characteristic noise levels of atape, phonograph record or
FM broadcast. It restores the "punch" of loud passages and
the whisper of quiet ones. It can add new life to an old
record collection, and make FM broadcasts worth listening
to. The use of a2BX with adbx tape noise reduction
system (such as our 120 or 150 series), lets you make tape
copies of records, FM broadcasts or other tapes that actually
sound better than the original. With these capabilities, the
2BX will become one of the most valued components' in
your home music system.
CONNECTIONS
AC POWER
Connect the 2BX to a117V AC, 50 or 60Hz power
source only. The 2BX requires 20 watts of AC power
(maximum). As aprecaution, do not connect the AC
power cable until all signal connections have been made.
(Models for use with foreign power sources are available
Contact the dbx factory for information.)
SIGNAL CONNECTIONS
NOTES:
1. If you do not have atape recorder, do not connect
anything to the TO TAPE RECORDER, or the FROM
TAPE RECORDER jacks.
2. With the setup in Figure 2, changes in preamp volume
will require adjustment of the 2BX transition level.
3. If you do have atape recorder and wish to expand
before you record, use the connections shown in Figures 1
2or 3. *
4. If you have adbx tape noise reduction system see
Page 9.
Connect the 2BX to your system according to one of
the following diagrams:

LOCATION
FOR OPTIONAL
REVERB
LOCATION FOR
-OPTIONAL
GRAPHIC EQ
*NOTE: 2BX will
reduce reverb noise,
but will also shorten
decay time.
——OPTIONAL RECORDER —i
Fig. 1—How to Connect the 2BX to Your Receiver, Preamplifier
or Integrated Amplifier. This is the preferred hookup assuming a
tape monitor loop is available.
LEFT
x
D
LT<0
RT O
fo2ohOSojJ
oooo
PREAMP
dfc»
•LpH
AH
MAIN AMP
I
I
(.LOCATION OF
^•"^OPTIONAL REVERB
|OR GRAPHIC EQ*
I
*NOTE: 2BX will
reduce reverb noise,
but will also shorten
decay time.
OPTIONAL RECORDER .
Fig. 2-How to Connect the 2BX if atape monitor loop is
unavailable and you are using aseparate preamp and power amp
(or between preamp out and main amp in jacks).

Fig. 3-How to Connect the 2BX in the Tape Monitor Loop of
aGraphic Equalizer or Speaker Equalizer.

OPERATION
NOTES:
1. For adescription of control functions, see the BRIEF
OPERATING INSTRUCTIONS at the front of this manual.
2. If you do not have atape recorder connected as shown
in Figures 1through 3, press IN the SOURCE and PRE
buttons.
3. To avoid repetition, we will use the word "amplifier"
to refer to your receiver, preamplifier or integrated
amplifier.
EXPANSION
To Expand an FM Broadcast or aConventional Phonograph
Disc
1. With your amplifier's master volume control all the
way down, turn on the AC Power for your entire system.
2. Select the desired source (FM or disc) on your
amplifier's selector switch.
3. Place 2BX in SOURCE and PRE mode (SOURCE
and PRE buttons IN).
4. Set the EXPANSION RATIO and the TRANSITION
LEVEL (threshold) controls to approximately mid position.
5. With the music playing, readjust the TRANSITION
LEVEL control until red L.E.D. GAIN CHANGE indicators
glow on loud passages, and the yellow L.E.D. GAIN
CHANGE indicators glow on quiet passages*.
*The L.E.D. GAIN CHANGE indicators show the relative amount
of expansion produced by the 2BX in each of its two frequency
bands. When one or more red L.E.D. 's light in agiven band, the
2BX is raising the program level in that band. When one or '
more
of the yellow L.E.D. 's light, the 2BX is lowering the program
level in that band. The number of L.E.D. 's that light correspond
to the relative amount of expansion up to the maximum dis-
playable range. More upward or downward expansion can be
achieved than is shown on the display.
6. Slowly bring up your amplifier's master volume
control to the desired listening level.
7. Readjust the EXPANSION control for the desired
amount of expansion. This will depend on the program
being expanded. For agood classical phonograph disc, an
expansion ratio of 1:1.1 or 1:1.2 (settings of 1.1 or 1.2)
may be optimum. For ahighly compressed FM broadcast,
an expansion ratio of 1:1.4 or 1:1.5 (settings of 1.4 or 1.5)
may produce better results. If you're not sure where to
set the EXPANSION control, start at alow setting, and
move it higher until it sounds extreme, then move the
control back so the sound is natural again.
The degree of expansion desired also depends on the
mood of the listeners. Generally, you will desire larger
amounts of expansion when you are totally involved with
the music.
To Expand aTape During Playback
Follow the instructions above for expanding an FM
broadcast or conventional phonograph disc, except place
the 2BX in TAPE and POST mode (TAPE and POST
buttons IN). It is not necessary to expand adbx-encoded
tape after decoding (during playback) if the tape has already
been 2BX-expanded prior to recording.
If you have two tape recorders only one TAPE input, and
you use one recorder primarily for playback, plug it into your
amplifier's AUX INPUTs; then follow the directions for Ex-
panding an FM Broadcast or aConventional Phonograph Disc
(as already described).
How to Expand and Tape Record aProgram
NOTE: Expanding aprogram and then recording it may
cause the dynamic range of the program to exceed the
dynamic range of your tape recorder. This could add
distortion and/or excessive tape noise to the recording.

(An exception would be for very highly compressed
programs, where expansion prior to recording adds only a
modest margin to the dynamic range.) To avoid these
problems, dbx recommends the use of adbx tape noise
reduction system when expanding before recording
(see next page for how to connect your system).
1. With your amplifier's master volume control and your
recorder's input level controls all the way down, set your
recorder to the "record ready" (RECORD and PAUSE).
2. Select the desired source on your amplifier's
selector switch.
3. Place the 2BX in SOURCE and PRE mode (SOURCE
and PRE buttons IN).
4. Play the source (start the phonograph disc or listen to
the FM station you will be recording). Set the TRANSI-
TION LEVEL control so that the red L.E.D. GAIN
CHANGE indicators glow on loud passages, and the yellow
L.E.D. GAIN CHANGE indicators glow on quiet passages.
Set the EXPANSION control for the desired amount of
expansion. If you're not sure where to set the EXPAN-
SION CONTROL, start at alow setting, and move it higher
until it sounds extreme, then move the control back until
the sound is natural again.
5. Bring up the amplifier's master volume control to the
desired listening level.
6. Now adjust the input level controls on your tape
recorder for normal VU meter readings. You may find that
slightly lower record levels are necessary when recording
an expanded program in order to avoid tape saturation.
7. Restart the program and record it normally.
If your tape recorder has tape monitoring provisions
(a three-head machine), and you wish to monitor the
recording as it is being made, place the 2BX in TAPE
mode (TAPE button IN). This Monitors the signal coming
from the tape recorder's outputs without changing the
expander's input to the tape recorder.
SIMPLE PRECAUTIONS WHEN USING ANY
PROGRAM EXPANDER
The 2BX (or any expander) places greater demands,on
your power amplifier and speakers. Whether or not agiven
amplifier is of adequate power rating is not always easy to
determine; it depends partially on the sensitivity of the
speakers, and partially on the distortion characteristics of
the amplifier.
Set for 1:1.5 expansion, the 2BX will expand agood
60dB classical recording to about 90dB of dynamic range.
Full realization of the benefit of this dynamic range
requires both ahefty power amplifier and speakers that
can take the high power. If you have such equipment, the
results will be breathtaking. Fortunately, such components
are not mandatory for full enjoyment of the 2BX.
The most important point is this: if the speakers and
amplifier cannot handle wide dynamic range, and if the
expander "tries" to drive them to awide dynamic range,
excessive clipping distortion (overdrive) may occur. To
avoid this unpleasant effect, use good speakers and areason-
ably large amplifier. If distortion still occurs, it will probably
be noticed only with programs that have agood dynamic
range to begin with, and which do not need expansion to
much greater dynamics. In such cases, areduction in the
transition level and the expansion ratio setting will avoid
distortion. Agood expander is apowerful tool, and, as
with any powerful tool, it can be used to excess. Used
properly, the expander can turn an old record collection
into atreasure of new listening enjoyment, and it can turn
aboring selection of compressed and limited FM broad-
casts into an exciting new source of listening pleasure.

Fig. 4-Combining the 2BX with adbx Tape Noise Reduction System

HOW dbx EXPANDERS WORK
Dynamic Range
Dynamic range is the difference in level between the
oudest and the quietest portions of aprogram, expressed
in dB .Since the quietest parts of arecorded program are
usually restricted by noise, the dynamic range of arecording
susually defined as the difference in level (in dB) between
the loudest parts of the program and the noise level.
Restricting Dynamic Range
i™Lh D
ec°^ deTuS0Unds alive Performance may reach
121WB SPL. The quietest sounds, however, will not be
heard if they are much quieter than the ambient room
noise (people coughing, air conditioning or other noises)
Ihe ambient room noise in avery quiet auditorium is some-
what over 30dB SPL The useable dynamic range of alivT
performance is therefore derived by subtracting the room
noise (30dB SPL) from our tolerance of extremely loud
sounds (120dB SPL), giving amaximum of about 90dB
nr!rd'Sdi0S u3"6l6SS r00m noise and advnamic range
of over 100dB can be realized.
The dynamic range of arecorded program is purposely
restricted to far less than 100dB in order to fit within the
dynamic range limitations of the recording or broadcast
medium. For example, the dynamic range of astudio
quality tape recorder is about 65dB. Tape noise restricts
the quietest sounds that can be recorded, and tape
Z,h fn^Z0r "de f^et "'f 3Unit of We^on for sound level or
1Z1ofs hound:°ne decibel is usually described as the smallest
detectable change msound level. The threshold of human hearina
OOOHT,:an Und ¥°U can.?erceive ^emidrange frequency oT
7000Hz) is approx,mately "OdB SPL "(Sound Pressure Level) and
TouThlh d°'dofpa,n (the rintat Which ft*H»£2*
tZate f§0Z7pT^13bOUi12°dB SPL-Some »*°Ple ™"
&A?<;smofpain "is *» —*
NOTF Thl «a"8e Limitations of the Tape Recording Process.
hL; TFk lWaVef°rm IS not asinewave signal; it is the •envelope-
describing the program's volume changes. envelope
saturation (distortion) restricts the loudest sounds that
can be recorded. Home tape recorders, especially cassette
and cartridge recorders, have an even more restricted
dynamic range .. . often .only 50dB. (dbx tape noise
reduction systems can nearly double the dynamic range
capabilities of any tape recorder.)
The maximum dynamic range of only the very best
phonograph discs is about 65dB, and this is seldom achieved
(see footnote on next page). The quietest sounds on adisc
are restricted by the "grain" of the vinyl, and other surface
irregularities that create noise; the loudest sounds are
restricted by the maximum excursion of the groove. Loud
levels are aso restricted by the ability of the phonograph
needle to track" the record. To allow more playing time
per side, the dynamic range of many records is often
restricted to less than 50dB.

The dynamic range capability of aradio program is
about 60dB for FM broadcasts, or 50dB for AM broadcasts.
The quiestest sounds are restricted by broadcast interfer-
ence and noise, like FM hiss; the loudest sounds are
limited by the maximum allowable modulation of the
transmitter (100%). Above 100% modulation, the trans-
mitted signal would be distorted, and the station would
interfere with adjacent radio stations, near the same radio
frequency. Compression is used to prevent overmodulation
and to raise the average level, thus raising apparent loudness,
so that most broadcasts have much less than 50 or 60dB
dynamic range ...popular AM stations often compress the
program to average less than 10dB dynamic range.
NOTE: By using dbx II noise reduction during the manu-
facture of phonograph discs, the dynamic range can be
extended to 100dB. Surface noise is reduced to inaudibility
and the full dynamics of aperformance can be captured,
dbx-encoded discs are commercially available, and can be
decoded with any of the dbx 120 and 140 series noise
reduction systems.
Compression and Limiting
Compression and limiting are the electronic techniques
used to reduce the dynamic range of alive program to fit
within the restrictions of the recording or broadcast medium.
Acompressor may be aLINEAR COMPRESSOR: such a
device increases the level of quiet passages, and decreases
the level of loud passages. The COMPRESSION RATIO is
the ratio in dB of the compressor's input dynamic range to
its output dynamic range. For example, if the compression
ratio is 2:1, the output level will only change 1dB for every
2dB change at the input (thus restricting, or "compressing''
the dynamic range). The THRESHOLD is the level at which
the compressor decides to increase or decrease levels. The
compressor decreases the level of input signals that are
above the threshold, and increases the level of input
signals that are below the threshold. Those which act only
on levels that are above the threshold level, and let any
signal that is below the threshold pass unchanged are called
ABOVE THRESHOLD COMPRESSORS. ALIMITER is an
above threshold compressor that has acompression ratio of
10:1 or higher. The threshold of alimiter is usually adjusted
so that it acts only on musical peaks, preventing them from
exceeding the threshold by more than avery small margin.
The restriction of dynamic range created by compression
and/or limiting is undesirable because it removes much of
the excitement from arecorded performance. However,
without this restriction, the quietest parts of the program
could be lost in noise, and the loudest parts of the program
could be severely distorted. Fortunately, there are ways to
overcome this dynamic range restriction, by restoring
"lost" program dynamics.
program
Fig. 6—Linear Compression Linear compression reduces the entire
dynamic range of the music irrespective of input signal level.

Fig. 7-Above Threshold Compression Above threshold com-
pression has no effect on low level signals. When signal level reaches
the adjustable threshold, the dynamic content of the music is
decreased but only above that threshold. Higher compression ratios
may be used in above threshold compression than in linear com-
pression; however, all ratios are available. This is known as limiting
if the compression ratio is 10:1 or higher.
dbx Expanders
An EXPANDER is adevice that decreases the level of
quiet musical passages, and increases the level of loud
musical passages. It is the opposite of acompressor. The
EXPANSION RATIO is the ratio of the expander's input
dynamic range to its output dynamic range. An expander
with a1:1.4 expansion ratio will have an output level
change of 1.4dB for an input level change of 1.0dB.
Given an expander with an expansion ratio of 1:1.4, and
an input program that has adynamic range of 60dB,' the
output dynamic range will be (60 x1.4 =84) or 84dB.
The TRANSITION LEVEL (threshold) is the level at which
the expander decides whether to increase or decrease
program levels. When an input signal is above the threshold,
the expander increases its level; when an input signal is
below the threshold, the expander decreases its level.
All expanders have alevel detection circuit. This
detection circuit is used to sense the input signal level
and to determine whether it is above or below the threshold.
However, the method used to detect input signal level is
different on various expanders. The detection technique is
vital, as detailed below.
Peak Detection
Some expanders sense musical peaks in the input signal
to determine whether the input signal level is above or below
the threshold. The effect of this peak detection is that the
expander acts somewhat erratically, and may expand the
program when it detects anoise spike or brief musical
transient that isn't really representative of the program level.
Average Detection
Some expanders sense the average level of the incoming
program to determine whether the signal is' above or below
the threshold. Average detection circuits will not overreact
on musical peaks, but may respond too slowly to accurately
expand aprogram. The expander may respond too late to a
rapid increase in program level after the actual input signal
has begun to decrease again, causing an unnatural or swishing
sound.
RMS Detection
The 2BX uses RMS detection, which acts on the RMS
(Root-Mean-Square) value of the input signal. RMS
detection is different from either peak or average detection.
An RMS detection circuit will not overreact on musical
transients or noise spikes, yet it responds quickly to
significant musical transients. In fact, the human ear judges

sound levels by their RMS values, which means that the
RMS detection circuit in the 2BX electronically parallels
the way the human ear hears music. Until recently, however,
RMS detection was very complex and costly, dbx has
pioneered the development of moderately priced RMS
detection circuitry, and has led the industry in applying
RMS detection to expanders, compressor/limiters and
tape noise reduction systems.
Linear dB Expansion
Once the signal has been "detected," the expander
knows when to increase or decrease its level. The circuit
that actually performs this level change is known as a
"voltage controlled amplifier" or "VCA." The "AVC"
(automatic volume control), and "ALC" (automatic level
control) on many cassette recorders are examples of
voltage controlled amplifiers, as are the level changing
circuits in any modern expander, compressor or limiter.
The voltage from the detection circuit increases or
Fig. 8-Linear Expansion Linear Expansion operates over the
entire dynamic spectrum of music irrespective of input signal level,
making loud passages louder and quiet passages quieter, reducing^
audible noise. Expansion ratios are adjustable. For example: 1.0 -
0% increase in dynamic range; 1.2 =20%; 1.5 =50%; 2.0 =100%.
decreases the gain of the VCA which increases or
decreases the level of the program. While some expanders
may increase or decrease the program level by afixed
amount, the 2BX increases or decreases the level of the
program on a"linear decibel" basis. This means that the
output dynamic range and the input dynamic range are
linearly related by the "expansion ratio" over the entire
dynamic range (as described earlier) for asmooth, natural
sound.
Attack and Release Times
The expander must decide how fast to react to changes
in program level. The length of time between an increase
in input signal level and its corresponding expansion is
known as the ATTACK TIME. After the expansion of an
input signal, the expander allows the input signal to return
to its normal level. The amount of time to return to
normal is known as RELEASE TIME. These terms also
apply for compressors and limiters.
Different attack and release times are desirable for
different types of music. For example, asmooth classical
string quartet may sound best when expanded with aslow
attack and release time. Other programs may sound best
with faster attack and release times. The point is that the
_
attack and release times should be allowed to vary according
to the program content for the most natural sound. The
2BX does just that.
The 2BX's attack and release times automatically and
continuously follow the rate of change of the "envelope" of
the program.* In fact, because they are not fixed, the
2BX's release times are specified as rates which change in
response to different program envelopes. Furthermore, the
attack and release rates are scaled differently in each of the
*The envelope is agraph of the program level versus time.

2BX's two frequency bands, to provide an expansion
characteristic that best suits the music. The result is a
smooth action that does not alter the character of the
music as dynamics are expanded and noise is lowered.
dbx Tape Noise Reduction
dbx tape noise reduction systems allow aprogram of up
to 100dB dynamic range to be recorded on tape (or on an
encoded phonograph disc) without losing the quiet passages
in the noise or distorting the loud passages. Professional
recording studios throughout the world are using dbx
professional tape noise reduction systems, and dbx has
become the new established leader in the field, dbx II noise
reduction systems, such as our 120 series, are available for
use by the audiophile and home recordist. Like the original
dbx tape noise reduction system, dbx II noise reduction
systems make it possible to tape record up to 100dB of.
dynamic range, and in addition, dbx II noise reduction
systems also facilitate playback of special dbx encoded
discs (see footnote, page 11).
Fig. 9—dbx Tape Noi
below the level of tape
>ise Reduction Loud passages are decreased in level allowing them to be recorded
saturation; very quiet signals are placed on tape significantly above the tape noise level.

SPECIFICATIONS
bXrAIMblUlM KAI IU 1.0 to 1.5 (0 to 50% increase), Iinear in decibels
DYNAMIC RANGE 110dB (peak signal to weighted background noise ratio)
TRANSITION LEVEL RANGE 30mV to 3V (threshold)
ATTACK AND RELEASE RATES Variable, determined by program loudness and rate of change
FREQUENCY RESPONSE ±0.5dB, 20Hz to 20kHz at an expansion ratio of 1:1 .0
TOTAL HARMONIC 0.1% typical at 1.0 expansion, 20Hz to 20kHz
Ulo 1Un 11UI\J
IM DISTORTION 0.1 5% typical
irvim it" in/ifir naMf»r
INPUT IMPEDANCE High (50 kohms)
OUTPUT IMPEDANCE Low (the 2BX is designed to feed atape monitor input or tape deck with long cables)
MAXIMUM OUTPUT LEVEL 6volts RMS at 1kHz
CONTROLS Interlocking Tape &Source switches, Interlocking Pre &Post switches,
Power ON/OFF, Transition Level, Expansion
INDICATORS Power ON L.E.D., (10) Gain Change L.E.D.'s for each of 2bands (20 total)
CONNECTORS FROM PREAMP TAPE OUTPUT (x 2)
(Phono jacks) TO TAPE RECORDER AUXILIARY OR LINE INPUT (x 2)
FROM TAPE RECORDER OUTPUT (x 2)
TO PREAMP TAPE OR MONITOR INPUT (x 2)
POWER REQUIREMENTS 117V AC, 50 or 60Hz.
POWER CONSUMPTION .20 watts, maximum
DIMENSIONS 17-3/4" Wx3-3/4" Hx10-1/2" D
(45.1cm Wx9.5cm Hx26.7cm D)
WEIGHT 8lbs., 5oz. (3.8 kg)
Specifications subject to change without notice or obligation.

dbx PRODUCT WARRANTY
All dbx products are covered by alimited warranty.
Consult your warranty card or your local dealer for full
details.
FACTORY SERVICE
The dbx Customer Service Department is prepared to
give additional assistance in the use of the product. AM
questions regarding interfacing dbx equipment with your
system, service information or information on special
applications will be answered. You may call during normal
business hours -Telephone: [phone],
Telex: 92-2522, or write to:
dbx, Inc.
71 Chapel Street
Newton, MA 02195
Attn: Customer Service Department
Should it become necessary to have your equipment
factory serviced:
1. Please repack the unit, including anote describing
the problem along with the day, month and year of
purchase.
2. Send the unit, freight prepaid, to:
dbx, Inc.
224 Calvary Street
Waltham, MA 02154
Attn: Repair Department
3. We recommend that you insure the package and send
it via United Parcel Service wherever possible.
4. Please direct all inquiries to dbx Customer Service
Department.
Outside the U.S.A. -contact your nearest dbx dealer for
the name and address of the nearest authorized repair
center.

SCHEMATIC
17
Other patents pending.

NOTES