Used dbx 163X Over Easy Compressor / Limiter

Well-loved dbx 163X Over Easy Compressor / Limiter from the early 90's that I had in my old bass rig. Manufactured by AKG in Hong Kong. Includes the integrated 6' two-prong AC power cable. I do not have rack ears or any of the original packaging. Below is the select text from the manual.
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The dbx 163X provides traditional dbx sonic quality and performance for
the working musician, DJ, studio operator or anyone who needs a friendly
compressor/limiter/preamp. The 163X incorporates dbx OverEasy com-
pression with soft knee threshold, a patented dbx VCA and human-ear
compatible true RMS detection. Key operating parameters are integrated
and controlled by a single front panel slide control. After a simple level-set
adjustment, the desired amount of compression can be rapidly and easily
set or adjusted with the slider — without requiring the adjustment of sepa-
rate Threshold, Ratio and Output controls as found on conventional com-
pressors.

Front panel inputs allow quick and complete system hookup and opera-
tion that can be switched over to instrument or microphone just by “plug-
ging in” to the front panel. This front panel Hi-Z input includes a preamp
(with rear panel trim) for bass, guitar, synthesizer or other Hi-Z devices, in-
cluding a Hi-Z mic (or Lo-Z mic with appropriate transformer). The stand-
ard input and output jacks on the rear panel are designed for operation at
line levels from -30dBu to +1 OdBu.

UNDERSTANDING COMPRESSION

The primary purpose of a compressor is to reduce and control the dy-
namic range of a program: from gentle taming of overall levels to limiting
of peaks to squashing ail dynamics. Control is the key idea.

Another major use for compressors is to add punch to flabby, loose
sounds. A compressor can do this by making the level of an instrument or
a sound more consistent, or by reducing the volume of the more sus-
tained sections of a note, which comparatively accentuates the leading
edge (the transient attack).

Still another use is to increase the “sustain” of instruments, especially gui-
tars and bass guitars, by raising the volume of low-level trailing edges of a
note, which gives solid presence to the instrument. It also makes the note-
by-note volume more even.

A compressor does all this by changing its gain in response to the signal.
When the input is low in level, the compressor gain remains fixed, usually
at OdB (unity gain) or greater. When the input increases above the thresh-
old of compression, the gain begins to decrease (i.e., the amount of gain
reduction increases). For very large inputs, the gain can decrease consid-
erably. Therefore, as signals get larger, the gain reduction will increase,
depending where the MORE and LEVEL SET controls are set. Up to
40dB of gain reduction is available.

The front panel slider allows you to determine how much of the signal you
want to compress. Severe compression will result at the far-right settings:
gentle (or no) compression will be produced by settings to the left. Experi-
ment to familiarize yourself with the different sounds available. Educate
your ear — and then use it to guide you.

Here are some slider examples for getting started;

Lower settings (with the slider to the left), greatly reduce the overall
dynamic range of a program, and are useful for compression of overall
mixes and to provide a safety net for PA systems, since high compres-
sion ratios will be triggered only when input signals increase to high lev-
els.

Moderate settings, which affect overall dynamics, are often good for
smoothing out bass guitar and vocals. Typically they’re used during
mixdowns.

Higher settings (with the slider to the right) will provide leveling for in-
struments and vocals. These settings will also fatten kick drums, in-
crease sustain, and generally squash program. High settings can
sound unnatural, so be sure to listen closely. Fortunately, the 163X’s
OverEasy circuit prevents extreme compression from sounding too un-
natural; the ratio changes gradually from 1:1 (no compression) to Infin-
ity: 1 (full compression).

About The 163X Circuit

The 163X is a special type of compressor: it combines several features
into a versatile, easy-to-use unit that’s helpful for a wide variety of situ-
ations but is quick to adjust and set up. We made it sophisticated on
the inside so it could be friendly on the outside. Figure 1-A shows the
OverEasy compression curve compared with the so-called hard-knee
behavior of other compressors, ranging from none (the left side of the
graph where input and output are the same) to infinite compression
(the right side, where output is the same no matter what the input).
This incredible range means that as signal levels increase, the output
level increases toward a certain maximum but (except for short tran-
sients) will NEVER go above it no matter how much signal is put in.

With dbx’s OverEasy characteristic, every possible ratio is available,
from 1:1 to lnfinity:1, dependent on the signal level.

To allow user control over the amount of compression, the OverEasy
curve may be moved to the left and right by the slider. When the con-
trol is moved to the right, the curve moves left (see Figure 1-B) and
more of the input is compressed. Consider any specific input level:
when the curve moves to the left, the input lies closer to the (right-
hand) flat part of the OverEasy curve, where the compression ratio is
highest.

Actually, the slider varies the threshold of compression, the point
above which signals begin to be compressed. More compression re-
sults from lower threshold settings. The 163X is especially useful be-
cause the OverEasy characteristic simultaneously provides every
compression ratio, so varying the threshold causes the ratio to vary
automatically — in just the way you’d want.

You may have noticed that as the slider is moved, the part of Figure 1-
B showing 1:1 compression (where the angle of the line is 45°) moves,
too. The slope (steepness) of the line doesn’t change, but the move-
ment indicates that as more compression is set, more gain is dialed in
as well. The LEVEL SET control is used to set the amount of this extra
gain, as shown in Figure 1 -C.

OPRATING CONTROLS

Front Panel

POWER LED Indicator: The red POWER indicator illuminates when
AC power is applied to the unit via the captive power cord.

STEREO SLAVE LED Indicator: The yellow STEREO SLAVE indica-
tor indicates that the unit has been set by its rear panel switch to be
the Slave in a connected pair of 163Xs.

Gain Reduction LEDs: These 12 LEDs display in dB how much the sig-
nal is being compressed (i.e., the amount of gain reduction).

COMPRESSION Slider: Moving this to the right (MORE) increases the
amount of compression — compressing more of the signal sent to it
(the compression “reaches down” to lower levels) as well as compress-
ing the signals more (the compression ratio for any given signal level
gets higher).

LEVEL SET Control: This control sets the operating (output) level that
the 163X will always “aim toward” as compression is increased; the cir-
cuit automatically adjusts the gain to maintain a constant output level.

Hi-Z INPUT Jack: This jack connects to the 163X’s internal low-noise
FET preamp. The gain is such that virtually all low-level instruments
(guitars, basses, keyboards, even some high-impedance mics) can be
plugged in directly using V 4 " phone connectors. If necessary, use the
rear panel Hi-Z TRIM to curb the gain of very hot instruments (e.g.,
some synthesizers). Note that this jack overrides the rear panel line-
level INPUT.

Rear Panel

INPUT Jack: Use mono (or TRS) phone connectors to connect this
input to your line-level audio source (e.g., instrument, microphone or
mixer).

OUTPUT Jack: Use mono (or TRS) V 4 " phone connectors to connect
these outputs to the iine inputs on your load (e.g., mixer, amplifier, etc.).

Hi-Z TRIM Control: This screwdriver-adjustable control sets the gain
of the preamp for the Hi-Z INPUT only (see Front Panel). The gain is
factory-set at +20dB (all the way right, or clockwise) and shouldn’t be
changed unless your instruments output is very hot. All the way left
(counter-clockwise) is unity gain (OdB).

STEREO STRAPPING Jack and Button: Connect this jack to the
same jack on another 1 63X and you have a true RMS-detecting stereo
compressor/limiter. Use TRS V4" stereo phone connectors only. Press
the button In to set the unit as the SLAVE. For normal mono use (as
well as for the stereo MASTER), leave the switch Out.

AC Cord: Plug into mains power. Note that the 1 63X does not have a
power switch. It is recommended that the 163X be “On” at all times.
Power consumption is low. If you do not plan to use the 163X for an ex-
tended period of time, unplug it.

WARNING: Be sure to verify both your actual line voltage and the volt-
age for which your Model 163X was wired, as indicated on the rear
panel of your unit. Connection to an inappropriate power source may
result in extensive damage which is not covered by the warranty.

OPERATING NOTES

Preparation/Level Adjustments

For best operation, the 163X should be reset for your application each
time it’s used in a different studio or with a different set of performance
gear.

1. Set the LEVEL SET Control

To determine the amount of gain to add to your sound, adjust the
LEVEL SET Control according to the following steps;

A. Play your instrument (or the track to be compressed) at a typical,
moderate level through the 163X with the COMPRESSION Slider
all the way to the left. Concentrate on how loud it sounds.

B. Move the COMPRESSION Slider all the way to the right and play
the same way again (or play the same passage from the tape).
Again, listen to how loud it sounds.

C. Now adjust the level by turning the LEVEL SET Control so that the
volume with the slider right is the same as with the slider left.

When properly adjusted, there will be little difference in level
as you move the slider, but to the right, the sound will be
fatter, with more sustain, evenness, and bite to the attacks.

2. Set the COMPRESSION Slider

This is the heart of the 1 63x. Move the slider to the right and more of
the input signal is compressed; the compression ratio is increased and
more gain is added. That’s why it’s labeled MORE — you get more ef-
fect.

In actual use, start by playing music through the 163X with the slider to
the left, then gradually move it right until you hear enough compres-
sion. Remember that dbx’s OverEasy compression curve keeps the
music sounding natural even under extreme amounts of compression,
so listen carefully to gauge the right amount.

3. Set the Hi-Z TRIM (if necessary)

This trim rarely requires adjustment in practical applications. It should
be reset ONLY if you hear distortion (overdriving) while using the front
panel Hi-Z INPUT even when the slider is all the way to the right. The
instrument is probably overdriving the Hi-Z INPUT and the gain must
be changed (with the TRIM).

Specific Applications

Smoothing Out Bass Guitar

Bass lines often are inconsistent in level and lack the sustain needed to
give a solid bottom end. Set the MORE slider so that peaks cause 10dB
to 12dB of compression. Use more for increased sustain and for more per-
cussive attacks on the transients.

Fattening Kick Drums and Compressing Other Drum Sounds

Weak, flabby kick drums often have too much boom and not enough slap.
Tighten them up by setting the slider for 15dB of compression on the peak
of the kick. Because the 163X takes some time to react, this will empha-
size the slap at the beginning of the note and reduce the boominess of its
body. The 163X also works well for tightening snare drums and tom toms
and can be used with drum machines to effectively alter the character of
any electronic drum sound.

Variations in Mic Levels

The 163X works with microphones used in musical applications, paging
systems, churches, speaking events, etc. As the distance between the mi-
crophone and a speaker or vocalist changes, signal levels change. Set
the slider so that average levels cause 6dB to 8dB of compression, as in-
dicated on the front meter. Use more for less-experienced speakers or vo-
calists. Ask them to help out by backing off on the mic a bit when
speaking louder or singing especially loud notes.

Variations in Instrument Levels

To smooth out instrument levels, set the slider so that 8dB or more of
compression occurs on all peaks. Be careful, however: large amounts of
compression used on a mixed stereo program can become quite audible.
Compression is much less noticeable if the separate tracks are com-
pressed before mixing.

Raising the Signal Out of a Mix

Since reducing dynamic range can increase the average signal level and
meter readings, a single track can be brought up put of a mix by boosting
its level slightly and applying compression. Set the slider for 4dB to 6dB.

SPECIFICATIONS

(NOTE: OdBV = 1 .OVRMS; OdBu = 0.775VRMS) Specifications are subject to change.



Frequency Response


20Hz- 20kHz; ±1.0dB


Input

Front Panel
Maximum Tnput Level
Connector Type
Rear Panel

Maximum Input Level
Connector Type


Instrument, Unbalanced: 391 kO

+18dBu

V 4 " Phone Jack

Instrument, Unbalanced: SPlkH
+18dBu

Phone Jack


Output
Rear Panel

Minimum Load Impedance
Maximum Output Level
Connector Type


Unbalanced: 220
>6000

+18dBu into 6000
V/TRS Phone Jack