DBX 224X II Owners Manual

Page 1

allox

Model zzax

Type II
Noise-Reduction System
for Tape

Instruction Manual

Page 2

INSPECTION and INSTALLATION

Your unit was carefully packed at the factory in a protective carton. Neverthe-
less, be sure to examine both carton and contents for any signs of damage that may have
occurred during shipping. If there is such evidence, don't destroy the carton or any of
the packing material, and notify your dealer or distributor immediately.

In any case it is a good idea to save the carton and packing materials should you
ever need to ship your unit in the future.

In addition to a model 220x and this instruction manual, the carton should contain
a set of hookup cables with RCA phono, or pin, plugs, a warranty/registration card, and a
pair of brackets for mounting the unit into a standard audio equipment rack.

No special cooling or ventilation is required in any installation; other components
may be stacked above or below the 22LIX provided they don't generate excessive heat.

This symbol is intended to
alert you of the presence of

CAUTION uninsulated dangerous voltage
within the unit's enclosure that
WWIDPEN . . .
may be of suffiCient magnitude to

mm TO REDUCE THE RISK OF ELEG constitute a risk of electric shock

TRIC SHOCK. Do NOT REMOVE to persons.
covsn (on BACK).
N0 USERASERVICEABLE PAHTSINSlDEi , , .
REFER SERVICING TO QUALIFIED SER- This symbol is intended to

05 PERSONNEL alert you of the presence of
important operating and maintenance
instructions in the literature
accompanying the unit.

WARNING: To Prevent Fire or Shock Hazard, Do Not Expose This Appliance to
Rain or Moisture.

VOLTAGE CONVERSION

If you ever need to change the voltage setting, unscrew the small voltage cover
plate near the ac cord, move the switch with a small screwdriver, turn the plate upside
down (180°, in other words, which exposes the switch in its new voltage position), and
screw it back on. Don't turn the plate over.

For lOO-lZOV ac:

For 220-240V ac:

Important: This setting is only
for European model and not for
UL listed model.

AC 100 -120V

m <9 a
220 _ 240V _ AC 220-240V K. 100 _120V

Use a screwdriver
and slide .

"dbx" is a registered trademark of dbx, Newton, Mass. USA

Page 7

ABOUT NOISE REDUCTION

Analog taping has always been the major source of noise in most recorded music.
Faint and not-so-faint hiss was so common behind recorded and broadcast music that just
about everyone got used to it. In the late 19605, Dolby Laboratories devised a circuit
that mildly but significantly reduced tape hiss, and it's new standard on cassette decks.
(A stronger version was recently introduced.) Since then, recording techniques as well as
tapes have gotten much quieter, and many listeners are more alert to hiss anyway. And
now that the di ital era is finally here (which for most listeners means much quieter
source material , the need for completely effective tape noise reduction is urgent. This
is what your new dbx 221+X gives you.

For all audible intents and purposes, the 22llX eliminates tape hiss. But it also
increases the overall dynamic-range capacity of a tape deck, letting you record both
louder and softer sounds than you used to. (The difference between loudest and softest is
the definition of dynamic range.) The combined result is that the 224x will let you make
tapes with virtually nothing added, ones as quiet as (and in almost all cases indistinguish-
able from) the original. Being a two-step (encode/decode) process, dbx noise reduction
can't do anything to improve noisy original sources (records, broadcasts, other tapes) -
it won't make them quieter, in other words -- but it doesn't let any noise be added. (We
make dynamic-range expanders to help quiet, clean up, and "punch up" - restore impact
to - restricted and/or noisy programs.) With a really quiet source and a quiet deck, the
tape copy will be crystal-clear and just as wide in dynamic range.

If you haven't used dbx before, you may be startled at how close to identical the
tape copy sounds. Even the dynamic range potentially available from Compact Discs,
with their silent backgrounds, may be captured by your tape deck. This statement holds
for no other noise-reduction system.

Described simply, the dbx system works by compressing the dynamic range of the
source and altering its frequency response during recording (the "encoding" of the signal),
and then by expanding the dynamic range of the tape and "undoing" the frequency-
response alterations in perfect mirror-image fashion during playback ("decoding").
During recording, tape decks generate hiss below the taped signal by about 45-65 dB,
depending on the deck and the tape, and during dbx playback this noise gets pushed down
an additional l50-55 dB, depending on the deck, the tape, and the program material. The
result is an enormous potential dynamic range - enough room to tape even live perform-
ances. This figure depicts the process in simple terms:

Record
(encode 2 : I) Play
Loudesl (decode l : Z)
I

\
\ , , I
\ Distortion I
\
\

I
q:?:
Musics 55 dB

dynamic range 90 dB 90 dB

I
I k Record-surface

/ no noise or tape hiss

Quielesi
- Level ofinaudibilil) -