dbx 222 User manual

dbr'Mod et222
type ll noise reduction system
for tape & disc
INSTRUCTION MANUAL

INDEX
BR I EF OPERATI NG INSTRUCTIONS
Rear Panel
Front Panel
How to Use the Function Select Buttons on Your 222
2
2
3
4
OUICK-REFERENCE GUIDE TO dbx 222 OPERATION
INTRODUCTION
CONNECTIONS & OPERATION
Basic Signal Connections and Operation
Dubbing a dbx Encoded Disc onto a Tape in Encoded Form
Dubbing a dbx Encoded Disc onto a Tape in Non-Encoded Form
Using the 222in Conjunction with a Graphic Equalizer
Using the 222 with an Equalized Speaker System
Copying a dbx-Encoded Tape
Making a Non-Encoded Copy of a dbx-Encoded Master Tape
Making a dbx-Encoded Copy from a Non-Encoded Tape
7
7
8
I
9
10
10
10
12
SETTING THE LEVEL ADJUST CONTROLS 13
dbx PRODUCT WARRANTY & FACTORY SERVICE 14
SPECIFICATIONS 15
SCHEMATIC 16
WARNING: TO PREVENT FIRE OR SHOCK
HA,ZARD, DO NOT EXPOSE THIS APPLIANCE
TO RAIN OR MOISTURE.
dbx@ is a Registered Trademark of dbx, lnc.

BRI EF OPERATING INSTRUCTIONS
Fig. 1 - dbx Model 222Rear Panel
Notes: To avoid repetition, the word "preamp" is used to mean receiver,
preamplifier, integrated amplif ierlpreamplifier, or the tape monitor loop of
an equalizer, reverb unit or other device. See Figures 3 through I for
connection diagrams.
Preamp or Receiver Connections Tape Recorder Connections
INPUTS Connect cables from
your preamp's TAPE OUTPUTS
(REC OUT of the Tape Monitor
Loop) to these inputs.
OUTPUTS Connect cables
from these outputs to Vour
preamp's TAPE INPUTS
(PLAY lN of the Tape
Monitor Loop).
INPUTS Connect cables from
your tape recorder's LINE,
PLAY or MONITOR outputs
to these inputs.
OUTPUTS Connect cables
from these outputs to the
RECORD or LINE inputs of
your tape recorder. (lf you
are using the 222 only for
decoding dbx discs. you need
not connect any cables to
these jacks.)
Level Adjust
TAPE REC & PLAY/ DISC PLAY fhese screwdriver adjustable
controls are for maintaining the same average signal level with or
without 222 processing. Adjustment is not critical for proper
encoding and decoding. See page 13 for details of their adjustment.
AC Mains Connection
AC POWE R CABLE Connect this cable to a 1 17 V AC, 50 or
60 Hz AC power source only. Models for use with other power
sources are available outside the continental United States. Contact
the dbx factory for information.

Fig. 2 - dbx Model 222 Front Panel Processor Function Selectors
NOTE: BECORD, BYPASS, and PLAY are interlocking pushbuttons; only one button is to be
pressed in at a given time.
RECORD Press this button
when you want to make a dbx
encoded tape from a normal
(non-encoded) program. When
set for recording, a green LED
above the button is illumin-
ated; be sure the "dbx DISC"
button is not engaged (its
LED should be OFF).
Power
Press in this button to turn ON the
AC power to the 222; press again to
release the button and turn power
OFF. A red LED above the button
is illuminated when the unit is ON.
BYPASS Press this button
when you want to make a
conventional tape recording
(i.e., a non dbx-encoded tape)
from a non-encoded program,
or when you want to play a
conventional non-encoded
tape. When set for bypass, a
red LED above the button is
illu minated.
PLAY Press this button
when you want to play back
a dbx encoded tape or a dbx
encoded disc (or when you
want to simultaneously
listen to an encoded disc while
making an encoded tape
recording of that disc).
When set for playback, a
green LED above the button
is illuminated; for disc play-
back, be sure to also press
the adjacent "dbx DISC"
button.
dbx Disc
Press this button and the PLAY
button when you want to listen to
(decode) a dbx encoded disc (or when
you want to simultaneously listen to
an encoded disc while making an
encoded tape recording of that disc).
The red LED above the button is
illuminated when set for disc decoding.

How to Use The Function Select Buttons on Your 222
NOTE: With RECORD, PLAY & BYPASS, push only one button at a time.
BUTTON(SI PRESSED IN FUNCTION OBTAINED
RECORD BYPASS PLAY dbx DISC
oTO MAKE A dbx ENCODED TAPE
Program coming into the 222's "FROM PREAMP TAPE OUTPUT" jacks will be
encoded and sent to the "TO TAPE RECORDER INPUT" jacks of the 222.
oTO PLAY A dbx ENCODED PROGRAM
Program coming into the 222's "FROM TAPE RECORDER OUTPUT" jaeks will
be decoded and sent to the "TO PREAMP TAPE INPUT" jacks oI the 222.
oFOR NO PROCESSING OF THE TAPE
Program coming into the 222's "FROM PREAMP TAPE OUTPUT" jacks will be
sent directly to the "TO TAPE RECORDER INPUT" jacks, and program coming
into the 222's "FROM TAPE RECORDER OUTPUT" jacks will be sent directly
to the 222's "TO PR EAMP TAPE INPUT" jacks with no encoding or decoding.
o o dbx DISC/SOURCE DECODING
Program coming into the 222's "FROM PREAMP TAPE OUTPUT" jacks will be
decoded and fed to the "TO PREAMP TAPE INPUT" jacks. (The encoded disc
program fed to the "F ROM PR EAMP TAPE OUTPUT" jacks will also be fed to
the "TO TAPE RECORDER INPUT" jacks without decoding.)

OUICK-REFERENCE GUIDE TO dbx 222OPERATION
To Make a dbx-Encoded Tape Recording
1. Press in the dbx 222's RECORD button. (The
dbx DISC button should be out.)
2. Place the tape recorder in Record mode, and
adjust record level controls for an average level of -5
on average-reading meters. (For some tape recorders
and under certain conditions, more precise settings are
required. For more information, please refer to page 13,
Tape Level Adjustment.)
3. Do not switch the 222 while making the recording.
4. lf your tape recorder has 3 heads, and you wish to
monitor the encoded tape as it is being made. you will be
listening to the encoded program lthe 222 can only per-
form one function at a time, encoding or decoding).
This will verify that a recording is being made, but since
encoded program is not particularly pleasant sounding,
you may prefer to switch the preamp's TAPE MONITOR
switch to SOURCE and listen to the unencoded program
ahead of the 222.
To Play a dbx-Encoded Tape Recording
1. Set the preamp's TAPE MONITOR switch to TAPE.
2. Press in the dbx 222'sPLAY button, and play the
encoded tape. (The dbx DISC button should be out.)
To Play a dbx-Encoded Phonograph Disc
1. Press in the dbx 222'sDISC and PLAY buttons.
2. Set the preamp's INPUT SELECTOR to PHONO,
set its TAPE MONITOR switch to TAPE, and play the
dbx-encoded disc.
To Make or Play a Conventional, Non-Encoded
Tape Recording
1. Press in the dbx 222's BYPASS button. (The dbx
DISC button should be out.)
2. Play the tape (or make the recording) as you
normally had done before using the Model 222.
To Make a Non-Encoded Tape Recording from a dbx-
Encoded Disc
1 . Turn off the preamp and reconnect the 222 and
tape recorder to the preamp as shown in Figure 4.
2. Turn the preamp on.
3. Press in the dbx 222'sDISC and PLAY buttons.
4. Set the preamp's INPUT SELECTOR to PHONO,
and set the TAPE MONITOR switch to TAPE.
5. You can monitor the recording of the decoded disc
by listening through your loudspeakers.

6
INTRODUCTION
The tape recording process traditionally hacbeen one
of the major sources of noise in recorded music. The dbx
tape noise reduction system virtually eliminates tape hiss.
ln addition, dbx processing permits recordings to be
made at levels that avoid much of the distortion which
normally occurs in tape recording. As a result. the dbx
tape noise reduction system not only reduces noise. it
can vastly improve tape recorder performance. With dbx
processing, virtually the only noise heard on playback is
that noise which was present in the original program.
Taped records, upon playback, will sound just like the
original disc, taped FM broadcasts, upon playback. will
have no more noise than was present in the qriginal
reception of the program; and recordings of live music,
conversation, and so forth, will be indistinguishable
from the live event. These genuine improvements in the
quality of tape recordings are due to a phenomenal
increase in recordable dynamic range and the dramatic
absence of tape-induced noise.
The dbx Model 222 has two channels of noise
reduction processing, switchable as a pair for either
encoding or decoding a stereo program. This dbx Type ll
system provides in excess of 30 dB broadband tape noise
reduction with a simultaneous 10 dB improvement in
headroom in the tape recording process.
The Model 222 also may be used to decode special
dbx encoded phonograph discs. These discs, available
through leading hi-fi and record dealers, are up to 40 dB
quieter than a conventional disc, and provide tremendous
musical dynamic range.
The 222's dbx disc decoding circuitry is not designed
to reduce noise on conventional phonograph records.
Neither can the 222's dbx tape noise reduction circuits
reduce hiss on a tape which has already been recorded
without the corresponding dbx processing during the
recording process.
The dbx 222is fully compatible with all other dbx
Type ll units, including the 224, Model 21, 1 20 series
and 140 series. The 222is not compatible with dbx
Type I Professional equipment, and vice-versa. The
difference between the two systems results from the
design consideration for higher speeds and larger tape
format used in live recording with professional equip-
ment, and the corresponding slower speeds and smaller
tape format used in home high fidelity equipment. This
means that the Type ll noise reduction system is supe-
rior for use with home high fidelity equipment,
Alone. thA dbx 222 will dramatically improve the
quality of your live tape recordings, and will preserrie the
quality when you are copying previously recorded
programs.
When used properly, dbx tape noise reduction makes
an extremely valuable addition to your sound system
and to your listening enjoyment. This manual describes
how your dbx 222 functions, and how you can obtain
maximum benefit from its use,

CONNECTIONS & OPERATION
Basic Signal Connections and Operation
CAUTION: Make sure that the power is OFF on all
equipment when installing the dbx unit. As a further
precaution, turn down your amplifier VOLUME control
prior to switching on the dbx 222fot the first time.
lnadvertent decoding of non-encoded programs 1222in
PLAY model can create surging to high volume levels.
NOTE: Never connect any other electronic equipment
betnreen the dbx 222 and your tape recorder's inputs or
outpuE. This could cause inaccurate encode/decode
tracking and los of quality in the recorded signal.
The basic functions of the dbx 222 are presented in
the Brief Operating lnstructions on page 2.
SPKR O
8F.*r55tE
our LEFr<O <O >O E
Fig. 3 - Basic signal connections to fr1e dbx 222

IDubbing a dbx Encoded Disc onto a Tape
in Encoded Form
This process allows you to preserve the low noise and
wide dynamic range of the dbx noise reduction system
when transferring an encoded disc to a tape. Such tapes
are then played back through the Model 222 in the same
manner as any dbx Type I I encoded tape. No special
connections are necessary (Figure 31.
1. Press in the 222's DISC and PLAY switches.
2. Set your preamp as follows: TAPE MONITOR
switch to TAPE, and INPUT SELECTOR switch to
PHONO.
3. Set your tape recorder to Record, and record
normally.
4. The tape copy will be dbx encoded, and you will
hear the program in decoded form while monitoring
this operation.
5. After the tape is recorded, it can be played back
in decoded form by releasing the 222's dbx DISC button.
Leave the dbx PLAY button in, and the preamp TAPE
MONITOR in TAPE position (or set its INPUT
SELECTOR to TAPE).
Dubbing a dbx Encoded Disc onto a Tape
in Non-Encoded Form
This process is for transferring a dbx-encoded disc in
non-encoded form onto a tape for future playback with-
out dbx processing (such as in an automobile tape
pl ayer).
lf your tape recorder is equipped for off-the-tape
monitoring and you wish to listen to the tape as it is
being recorded, you can plug a pair of headphones into
the recorder'3 phones jack. Alternately, you can connect
your tape recorder's PLAY OUTPUTS directly to your
preamp's TAPE INPUTS (Monitor ln), and set the pre-
amp's TAPE MONITOR OR INPUT SELECTOR to
TAPE mode. (See Figure 4.)
Fig, 4 - Connections for making a non-encoded recording from a dbx encoded disc.