Page 1
562E
Windowing
Expander/
Gate
User’s Guide
562E
Page 2
Table of Contents
Chapter 1 Introduction 1
Chapter 2 Operator Safety Summary 2
Chapter 3 Fast Setup 3
Chapter 4 Front Panel Overview 4
Chapter 5 Rear Panel Overview 6
Chapter 6 The Controls in Detail 7
Chapter 7 Connecting to Other Gear 11
Chapter 8 Applications 14
Chapter 9 Troubleshooting 19
Chapter 10 Specifications 20
Chapter 11 W arranty and Service 21
Chapter 12 Declaration of Conformity 23
Rev A.02, 15 Dec, 1997
Symetrix part number 53562E0A02
Subject to change at our whim and fancy without
notice.
©1997, Symetrix, Inc. All right reserved.
Symetrix is a registered trademark of Symetrix, Inc.
Mention of third-party products is for informational
purposes only and constitutes neither an endorsement
nor a recommendation. Symetrix assumes no
responsibility with regard to the performance or use
of these products.
Under copyright laws, no part of this manual may be
reproduced or transmitted in any form or by any
means, electronic or mechanical, including
photcopying, scanning, recording or by any informa-
562E
tion storage and retrieval system, without permission,
in writing, from Symetrix, Inc.
Mountlake Terrace, WA 98043 USA
Email: symetrix@symetrixaudio.com
6408 216th St. SW
Tel (425) 778-7728
Fax (425) 778-7727
i
Page 3
IntroductionChapter 1
Typical gate setups, such as drum miking or
cleaning up multitrack recordings, all face the
same difficulty: how to apply a precise trigger to
imprecise, organic signal sources. Much to the
frustration of audio engineers, instruments and
vocalists produce natural audio waveforms, and
nature is rarely consistent. When nature meets
machine in audio processing, the results can
sound like the snap, crackle and pop you’d prefer
in your cereal, not your audio. Most gates offer
only one solution to this problem: open faster.
While they measure performance in microseconds of "how fast", Symetrix is rewriting the rules
on how to open. The dual channel 562E
Windowing Expander/Gate exploits our newlydeveloped, proprietary technology to enhance
gating and expander control. Ultimately the 562E
delivers unparalleled fidelity to any audio signal.
GATING: Gates may be used to clean up
virtually any type of musical instrument or audio
sound effect, but perhaps their most common use
is on drum and percussion tracks. The 562E
employs two unique tools for detecting and
controlling these audio events.
Window Advance is a proprietary system for
recognizing the signal to be gated. In simple
terms, it virtually creates the impossible: a gate
that opens just ahead of the audio signal. It
creates this impression by moving the statistical
energy center of the gated signal forward in time.
Window Advance permits the user to subtly delay
the signal energy, centering it within the envelope. Through this function, the 562E’s gate
passes the entire leading edge of the audio
waveform. It accomplishes this because the gate
opens before the signal passes through the VCA.
Window Advance eliminates the noises and
chopped-off waveforms created by traditional
gates that struggle to open as quickly as possible
after the signal arrives.
AutoWindowing is a processing technique that
allows the user to maintain better control of the
gate envelope parameters. Its dynamic smoothing process reduces “pops” and “clicks” that can
occur at fast attack settings. These nasty noises
are typically produced by envelope edges,
overshoot and instabilities. Even gates that claim
to open within microseconds fail to recognize the
reality underlying these problems: naturally
occurring waveforms do not have consistent
leading edges. In contrast, AutoWindowing
derives its trigger signal from the “time center” of
the leading edge of the audio waveform. This
reduces trigger uncertainty, jitters, and attack
distortion. AutoWindowing yields an envelope
that is consistent and natural-sounding. It also
increases envelope consistency by eliminating
the artificial “drop off” that occurs in most gates
at the end of the release cycle. In the 562E the
signal smoothly and continuously decreases at
the end of the release cycle, creating a much more
pleasing sound.
EXPANSION: The 562E also permits users to
have a distinctive choice between gating and
expansion. A downward expander is similar to a
gate, but the expander substitutes RATIO control
for the gate’s RANGE control. The expander is
ideal for tasks requiring more subtle control. To
all possible uses for an expander, the 562E
delivers superior performance through unique
technology. Even the 562E’s ratio circuitry is
special. The ratio automatically reverts to 1:1
when the signal approaches 25dB below the
threshold. This prevents any low level modulation of the expanded signal.
For the first time, open your ears to all the clear
audio you wanted without any revenge from the
processor. Experience a quantum leap forward in
gate technology with the Symetrix 562E Window-
ing Expander/Gate.
562
WINDOWING
EXPANDER/GATE
EXT.KEYEKEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
CH1 SIDECHAIN PROCESSING
LOW CUT
OUTPUT
ASSIGN
20Hz 50Hz
1K10Hz
GAIN (dB)
HIGH CUT
REDUCTI0N
WINDOW
ADVANCE
4K
3
12
20K
1K
200Hz15Hz
400Hz
ABOVE
MAX
30
BELOW
MIN
40K
OFF
60
THRESHOLD
(dB)
0
-40 +20
ATTACK
TIME
60ms 1 Sec
AUTO
CHANNEL 1
HOLD
TIME
4 Sec300ms 50ms 30ms
Front panel
562
AC INPUT
18 WATTS
MANUFACTURED IN LYNNWOOD, WASHINGTON USA
MAXIMUM
FABRIQUÉ AUX E.-U. PAR SYMETRIX INC., LYNNWOOD, WA USA.
RÉFÉREZ TOUTE RÉPARATION À UN TECHNICIEN QUALIFIÉ.
E
WINDOWING EXPANDER/GATE
BALANCED/
UNBALANCED
CHANNEL 2 OUTPUT
BALANCED
Rear panel
RELEASE
TIME
500ms
2.5 Sec
INPUT
GATE RANGE
EXPANDER RATIO
0
1:3
80dB
BALANCED/KEY
UNBALANCED
EXT.KEY
BYPASS
IN GATE/EXP.
CHANNEL 2 INPUT
BALANCED
KEY LISTEN
W/FILTER
OUTPUT
ASSIGN
HIGH CUT
LOW CUT
50Hz
20Hz
1K
200Hz
15Hz
400Hz
1K
10Hz
TYPICAL CONNECTIONS
132
BALANCED
INPUTS
1/4"BALANCED
SLEEVE=GROUND GROUND
RING=LOW(-)
TIP=HIGH(+)
4K
40K
GROUND=PIN 1
LOW(-)=PIN 3
HIGH(+)=PIN 2
20K
WINDOW
ADVANCE
SIDECHAIN
SIDECHAIN OUT
MAX
MIN
OFF
1
KEY INPUT
3
GAIN (dB)
REDUCTI0N
2
3
12
30
60
BALANCED
OUTPUTS
ABOVE
BELOW
THRESHOLD
-40
BALANCED/
UNBALANCED
ATTACK
TIME(dB)
0 60ms
CHANNEL 1 OUTPUT
BALANCED
CHANNEL 2CH2 SIDECHAIN PROCESSING
300ms+20 AUTO
HOLD
TIME
1 Sec 500ms
50ms
SIDECHAINSIDECHAIN
KEY
INPUT
RELEASE
TIME
GATE RANGE
EXPANDER RATIO
2.5 Sec4 Sec 30ms
BALANCED/
UNBALANCED
0
1:380
CHANNEL 1 INPUT
BALANCED
562E
1
Page 4
Operator Safety Summary Chapter 2
N
.
The information in this summary is intended
for persons who operate the equipment as well
as repair personnel. Specific warnings and
cautions are found throughout this manual
wherever they may apply.
The notational conventions used in this
manual and on the equipment itself are
described in the following paragraphs.
Equipment Markings
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
TO REDUCE THE RISK OF FIRE OR
WARNING:
SEE OWNERS MANUAL. VOIR CAHIER D’INSTRUCTIONS.
o user serviceable parts inside. Refer servicing to qualified service personnel
Il ne se trouve a l’interieur aucune piece pourvant entre reparée l’usager.
The lightning flash with arrowhead symbol
within an equilateral triangle is intended to alert
the user of the presence of uninsulated
"dangerous voltage" within the product's
enclosure that may be of sufficient magnitude
to constitute a risk of electric shock to persons.
The exclamation point within an equilateral
triangle is intended to alert the user of the
presence of important operating and maintenance (servicing) instructions in the literature
accompanying the 562E (i.e. this manual).
Caution To prevent electric shock, do not
ELECTRIC SHOCK DO NOT EXPOSE
THIS EQUIPMENT TO RAIN OR MOISTURE
RISQUE DE CHOC ELECTRIQUE
AVIS:
NE PAS OUVRIR
S’adresser a un reparateur compétent.
use the polarized plug supplied
with the 562E with any extension
cord, receptacle, or other outlet
unless the blades can be fully
inserted.
Caution Identifies information that, if not
heeded, may cause damage to the
562E or other equipment in your
system.
Warning Identifies information that, if
ignored, may be hazardous to
your health or that of others.
CAPITALS Controls, switches or other
markings on the 562E's chassis.
Boldface Strong emphasis.
Power source - This product is intended to
operate from a power source that does not
apply more than 255Vrms between the power
supply conductors or between either power
supply conductor and ground. A protective
ground connection, by way of the grounding
conductor in the power cord, is essential for
safe operation.
Danger from loss of ground - If the protective
ground connection is lost, all accessible
conductive parts, including knobs and controls
that may appear to be insulated, can render an
electric shock.
Proper power cord - Use only the power cord
specified for the product. Use only a power
cord that is in good condition.
Operating location - Do not operate this
equipment under any of the following conditions: explosive atmospheres, in wet locations,
in inclement weather, improper or unknown AC
mains voltage, or if improperly fused.
Stay out of the box - To avoid personal injury or
injury to others, do not remove the product
covers or panels. Do not operate the product
without the covers and panels properly
installed.
Terms
Several notational conventions are used in this
manual. Some paragraphs may use Note,
Caution, or Warning as a heading. Certain
typefaces and capitalization are used to
identify certain words. These are:
Note Identifies information that needs
562E
2
extra emphasis. A Note generally
supplies extra information to help
you to better use the 562E.
Page 5
Chapter 3
Fast First-Time Setup
Follow these instructions to get your 562E up-and-running as quickly as possible. The intent of
this section is fast setup. If you need something clarified, then you’ll find the answer elsewhere in
this manual.
Connect the line-level signal source to either the female XLR connector or the 1/4-in.
TRS (tip-ring-sleeve, stereo, 3-conductor) input jack. If the source is unbalanced, then
use a 1/4-in. TS (tip-sleeve, mono, or guitar) plug fully inserted into the TRS input jack.
Connect the line-level signal return to either the male XLR connector or to the 1/4-in.
TRS output jack. If you use the 1/4-in. jack, then use a TRS plug for balanced circuits
or use a TS plug for unbalanced circuits. Additional information on the signal connections may be found on pages 12-13 of this manual.
Fast Setup
Repeat for the second channel. Ignore the SIDECHAIN (KEY INPUT) connections for now.
Connect the AC input to an AC power source of the proper voltage and frequency, as
marked on the rear of the unit.
Caution: Failure to connect the 562E to the proper AC mains voltage may
cause fire and/or internal damage.
Warning: Lethal voltages are present inside the chassis. There are no user
serviceable parts inside the chassis. Refer all service to qualified
service personnel or to the factory.
Make your initial switch and control settings as follows:
SWITCH SETTING
EXT.KEY/BYPASS/IN IN
KEY
LISTEN//W/FILTER//GATE/EXP.GATE/EXP.
LOW CUT (CCW) 10Hz
HIGH CUT (CW) 40 K
WINDOW ADVANCE MAX
THRESHOLD
ATTACK TIME AUTO
HOLD
TIME (GATE ONLY) 50ms
RELEASE TIME 300ms
GATE RANGE (IF GATING) 80dB
EXPANDER RATIO (IF EXPANDING) 1:3
-10
With the 562E’s controls and switches now set according to the preceding section, the 562E
should pass signal. Fast setup is complete.
Refining Your Settings
Refine the THRESHOLD setting so that the expander/gate reduces the gain when the input signal
falls below the threshold setting. Adjust the ATTACK TIME, HOLD TIME and RELEASE TIME controls to
suit the audio that is being fed to the 562E. Percussive sounds usually call for fast attack, hold and
release times; speech and music generally work best with slower times. You can make the expander/
gate stay open for momentary lapses in signal by increasing the setting of the RELEASE and/or
HOLD TIME control. This also affects the rate-of-release once the signal falls below threshold. If
you feel that the expander/gate is dropping the signal too much, try a lower GATE RATIO/EXPANDER
RANGE setting. Remember these settings are just guidelines; you can use whatever settings work
best for you.
562E
3
Page 6
Front Panel Overview Chapter 4
Sidechain Processing Section
CH1 SIDECHAIN PROCESSING
200Hz15Hz
HIGH CUT
1K
400Hz
4K
WINDOW
ADVANCE
20K
40K
LOW CUT
OUTPUT
ASSIGN
EXT.KEY KEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
output of the 562E. The BYPASS switch position disengages the expander and gate functions.
The IN switch position engages the expander and gate functions, using the 562E’s internal
sidechain signal to control the gating and expanding action. The IN switch position also
allows you to route the internal sidechain signal to the output of the 562E. The IN switch
position is the normal operating switch setting for the 562E.
Note If you set the EXT.KEY /BYPASS/IN switch to the EXT.KEY position, with no audio
applied to the KEY INPUT jack on the rear of the 562E, the 562E’s gate/expander will
release (close).
OUTPUT ASSIGN switch - The KEY LISTEN switch position allows you to route the external key
audio or the internal sidechain audio to the output of the 562E. This is useful for monitoring
an external signal that you are applying to the KEY INPUT or for monitoring the internal
sidechain signal. It is also helpful in fine tuning any EQ changes that you are making to the
external signal before it reaches the KEY INPUT of the 562E. The W/FILTER switch position
allows you to monitor the external key audio or the internal sidechain audio at the output of
the 562E, after it has been processed by the LOW CUT and HIGH CUT filters . This is helpful in
fine tuning the effect of the LOW CUT and HIGH CUT filters on the key/sidechain audio. The
GATE/EXP. switch position routes the gated/expanded audio to the output of the 562E. The
GATE/EXP. switch position is the normal operating position for the 562E.
20Hz 50Hz
1K10Hz
EXT. KEY/BYPASS/IN switch The EXT. KEY switch position
activates the KEY INPUT on the
rear of the 562E, and allows
externally-triggered gating/
expansion. The EXT. KEY
MAX
switch position must be chosen
MIN
in order to use an external
OFF
signal, applied to the KEY
INPUT, to control the gating and
expanding action, or to route
the external key signal to the
LOW CUT control - Adjusts the cutoff frequency (3dB-down point) of a high-pass filter that is
applied to the sidechain audio. Sidechain audio at frequencies above the cutoff frequency is
uniformly passed. Use the LOW CUT control to rolloff any rumble and other low frequency
information that you do not want the 562E to use for control.
HIGH CUT control - Adjusts the cutoff frequency (3dB-down point) of a low-pass filter that is
applied to the sidechain audio. Sidechain audio at frequencies below the cutoff frequency is
uniformly passed. Use the HIGH CUT control to rolloff high frequencies that you do not want
the 562E to use for control (example: use it to filter out the hi-hat cymbals when you are using
the 562E to gate the toms on a drum set).
WINDOW ADVANCE switch - Subtly delays the audio signal energy that is fed to the expander/
gate, relative to the audio signal in the sidechain. It permits the expander/gate to open before
the audio signal passes through the VCA, thereby preventing the expander/gate from clipping
the leading edge of the audio signal waveform. Use the MAX switch setting for more delay
(good for drums), and use the MIN switch setting for less delay (great on cymbals). The OFF
position bypasses the WINDOW ADVANCE feature.
562E
4
Page 7
A
X
The Expander/Gate Controls
THRESHOLD control - Sets the signal level below which the expander/
B)
I0N
ABOVE
BELOW
THRESHOLD
(dB)
0
-40 +20
gate begins to operate. When the input signal falls below the level
indicated by the THRESHOLD control, the expander/gate begins reducing
the gain. The GAIN REDUCTION LED display indicates how much the
expander/gate has reduced the gain.
CHANNEL 1
1:3
HOLD
TIME
RELEASE
TIME E
500ms
2.5 Sec4 Sec300ms 50ms 30msAUTO
GATE RANGE/EXPANDER RATIO control - This control determines the
amount of attenuation that occurs during gating or expansion of the input
signal. For gating, use the settings from 0 (twelve o’clock) to 80dB
(counterclockwise). These settings define the number of dB below unity
gain that the gated signal will be dropped, when gating occurs. For
expansion, use the settings from 0 (actually 1:1, at twelve o’clock) to 1:3
(clockwise). These settings define how much the output level will change
in relation to changes in the input level. For example, at the 1:3 setting, a
5 dB drop below threshold in the input signal would result in a 15dB drop
in the output signal. When this control is set to twelve o’clock, you will
not have any expander or gate action, because the twelve o’clock position
ATTACK
TIME
60ms 1 Sec
HOLD TIME settings to prevent the gate from closing during short pauses between words.
RELEASE TIME control - Determines the speed at which the expander/gate closes (i.e. returns to
full attenuation) when the input signal falls below threshold, at the end of the HOLD TIME.
GATE RANGE
EXPANDER RATIO
0
80dB
ec
corresponds to 0dB change for gating, and to a 1:1 ratio (change in input equals change in
output) for expansion.
ATTACK TIME control - Determines the speed at which the
expander/gate reaches zero attenuation when the input
signal rises above threshold. The “AUTO” ATTACK TIME
setting is meant to be used in conjunction with the 562E’s
WINDOW ADVANCE feature, to give you an effective attack
time of zero.
HOLD TIME control - Determines the amount of time
that the gate continues to stay open (the amount of
time that the gate continues to pass signal at zero
attenuation) after the input signal has fallen below
threshold. When the audio source is speech, use long
GAIN REDUCTION LED display - The GAIN REDUCTION display
GAIN (dB)
REDUCTI0N
3
12
ABOVE
30
BELOW
60
THRESHOLD
(dB)
-10
-40 +20
indicates how much the expander/gate has reduced the level
of the input signal.
ABOVE/BELOW LED display - The ABOVE LED indicates that
the input signal is above threshold. The BELOW LED indicates
that the input signal is below threshold.
562E
5
Page 8
Rear Panel Overview Chapter 5
U
E
562
AC INPUT
18 WATTS
MAXIMUM
FABRIQUÉ AUX E.-U. PAR SYMETRIX INC., LYNNWOOD, WA USA.
RÉFÉREZ TOUTE RÉPARATION À UN TECHNICIEN QUALIFIÉ.
Power Cord - IEC power receptacle. Connect the power cord to an appropriate source of AC
power. Observe the marked power supply voltage on rear panel.
BALANCED/UNBALANCED OUTPUT - 1/4-inch tip-ring-sleeve
CHANNEL 1 OUTPUT
BALANCED/
UNBALANCED
BALANCED
(TRS) phone jack, wired tip= high(+), ring =low(-) and
sleeve=ground. Use this jack when you need a 1/4-inch
balanced or unbalanced output. The nominal signal level
here is +4 dBu. The wiring diagram for the BALANCED/
UNBALANCED OUTPUt connector is reproduced on the back
panel of the 562E. Note: connecting an unbalanced cable
here will result in an output level that is 6dB lower than the
output level you get if you use a balanced cable.
MANUFACTURED IN LYNNWOOD, WASHINGTON USA
WINDOWING EXPANDER/GATE
BALANCED OUTPUT - XLR-3 male connector, wired Pin
1=ground, Pin 2=high(+) and Pin3=low(-). Use this connector when you need a balanced XLR
output. The nominal signal level here is +4 dBu. The wiring diagram for the BALANCED OUTPUT
connector is reproduced on the back panel of the 562E.
SIDECHAIN
KEY
INPUT
BALANCED/
UNBALANCED
KEY INPUT - 1/4-inch tip-ring-sleeve connector, wired tip=return, ring=send and
sleeve=ground. To trigger the expander/gate from an external audio source,
use the tip of this connector to connect the audio signal that you wish to use
as a key signal to trigger the expander/gate. To externally process the
sidechain signal, use the ring of this connector to feed the sidechain signal to
an external processing device, and use the tip as the return from the external
processing device. The wiring diagram for the KEY INPUT connector is reproduced on the back panel of the 562E.
Note: Remember to set the front panel EXT. KEY/BYPASS/IN switch to the EXT.
KEY position when using the KEY INPUT.
CHANNEL 1 INPUT
BALANCED/UNBALANCED INPUT - 1/4-inch TRS phone
jack. This connector is wired in parallel with the XLR
input connector. Connect either balanced or unbalanced
sources here. Use a tip-sleeve plug for unbalanced
sources and a tip-ring-sleeve (stereo) plug for balanced
sources.
562E
6
BALANCED
BALANCED INPUT - XLR-3 female connector. This
connector is wired in parallel with the TRS input
connector. Use this connector when you need a
balanced XLR input.
Page 9
Chapter 6
Threshold
The Controls in Detail
The THRESHOLD control of the 562E sets the audio
signal level at which the expander/gate begins
working. The expander/gate begins working once
the signal has fallen below the threshold level.
The THRESHOLD control setting also determines
the degree or amount of gain reduction (in
conjunction with the GATE RANGE/EXPANDER RATIO
control). An expander/gate with a high threshold
setting will expand or gate the signal much more
than an expander/gate with a low threshold
setting. Clockwise rotation of the THRESHOLD
control (i.e. setting a higher threshold level)
raises the level that the signal must exceed to
trigger the expander/gate to open, so that the
signal can pass through untouched.
The expander/gate has the effect of “shutting off” the signal once it falls to, and then drops
below, the threshold level. The amount that the signal is “shut off” is determined by the GATE
RANGE or EXPANDER RATIO control setting.
AUDIO INPUT
THRESHOLD LEVEL
GATE CONTROL
LEVEL
VOLTAGE
AUDIO OUT
HOLD
RELEASE
ATTACK
RANGE
CONTROL
Expander Ratio
The 562E uses a downward expander, which only acts on signals that are below threshold.
The EXPANDER RATIO of the 562E dictates how much the output changes for a below-threshold
change in the input. A linear amplifier (like a simple preamp) has a ratio of 1:1 because a
change of 1 dB at its input results in a 1 dB change at its output.
A downward expander magnifies output changes for a below-threshold input change. Thus,
once the input signal falls below threshold, the expander changes the output by the amount
dictated by the ratio. The 562E’s downward expander allows the user to vary the ratio of the
expander from 1:1 to 1:3. When the EXPANDER RATIO control is set to 1:3, a below-threshold
input signal that gets 5 dB quieter causes a 15 dB decrease at the output. In other words, a
small drop in the input signal level (5 dB), occurring below threshold, turns into a much larger
drop in signal level at the output (15dB).
A special feature of the 562E’s ratio circuitry is that the ratio automatically reverts to 1:1 when
the input signal approaches 25dB below threshold. For example, let’s say that you set the
THRESHOLD control to “0dB”, and the EXPANDER RATIO control for a 1:3 ratio. Once the
input signal falls below 0dB, for every 1dB that the input signal drops, the output will drop by
3dB. As the input signal approaches -25dB, the output signal will approach -75dB. However
when the input signal reaches -25dB, the ratio will revert to 1:1 from that point on. This means
that, with the EXPANDER RATIO set to 1:3, when the input drops to -26dB, the output will drop to
-76dB. When the input decreases to -27dB, the output will decrease to -77dB, and so on. This
is to prevent any low level modulation of the expanded signal. (Such modulation can be very
annoying.)
Gate Range
The range of a gate is the amount that the output level drops when the gate is triggered
“closed” by the input signal dropping below threshold. The gate range of the 562E is adjustable from 0 to 80dBu. If you set the GATE RANGE control to 80dBu, and set the THRESHOLD
control to -10dBu, then every time that the input signal to the 562E drops below -10dBu, the
gate of the 562E will drop the signal by 80dBu. Thus an input signal of -12dBu would result in
-92dBu at the output of the gate. Obviously, when the input signal level is so low that
engaging the gate causes it to drop to a level that is lower than the noise floor of the unit, the
output signal level of the 562E will no longer decrease by 80dBu from the input signal level.
562E
7
Page 10
Attack
The attack control of a gate/expander allows the user to shape the leading edge of the sound
envelope by manipulating the attack time. The ATTACK TIME control setting can make the transfer
between silence and sound graceful, or it can make the transfer abrupt.
The attack time represents the amount of time that an expander or a gate needs to react to an
input signal rising above threshold. Generally, gating is associated with short attack times
and expansion is associated with longer attack times. For expander applications, such as
removing background noise from speech, you do not want to make the attack time lightning
fast because it can make the audio sound “chopped up”. A slower ATTACK TIME setting is
preferable, so that the expander makes a more graceful transition between silence and speech,
retaining a more natural character to the audio.
For gating applications, such as isolating drum kit microphones, a faster attack time is desired,
so that the gate can open quickly when the input signal rises above threshold (when the drum
is struck). Since much of the audio signal in this case occurs at the moment of impact, a gate
that opens slowly would miss most of the audio signal.
Note The fastest attack time setting on the 562E is the “AUTO” position, which is meant to be
used in conjunction with the WINDOW ADVANCE Feature. The 562E’s WINDOW ADVANCE
feature is designed to open the gate before the audio signal passes through the VCA.
Engaging the WINDOW ADVANCE feature and setting the ATTACK TIME control to “AUTO”
will ensure that the gate will not miss any of the impact portion of the audio signal
generated when the drum is struck.
Release
The release control of a gate/expander allows the user to shape the trailing edge of the sound
envelope by manipulating the release time. The RELEASE TIME control setting can make the
transfer between sound and silence graceful, or it can make the transfer abrupt.
Release time is the length of time required for the gain to recover to the no-signal state. When
you are using the 562E in GATE mode, release time is the length of time required for the gate to
close, because the no-signal state for an audio gate is the closed state. When an abovethreshold signal disappears, the RELEASE TIME control governs how long it takes for the
expander or gate to reduce the gain to the no-signal state.
The RELEASE TIME control permits tailoring of the expander’s or gate’s recovery time to the
program material. Generally, gating is associated with short release times and expansion is
associated with longer release times.
For gating applications, such as isolating drum kit microphones, a faster release time is
desired, so that you can achieve better isolation and less leakage into the microphone from the
other drums in the drum kit. In the case of drums, a “choppy” sound can also be used as a
desired effect (like the infamous gated reverb, commonly used on a snare drum).
Hold
The HOLD TIME control sets the amount of time that the gate passes audio before it begins to
release. A long hold time will give a more natural sound. For example, when the program
material is speech, a long hold time can be used to prevent the gate from releasing (closing)
between words. A short hold time gives tighter control over the audio.
Note: The H OLD T IME only functions in the gate mode.
Hint: If you hear “jitter” (the gate rapidly toggling between the open and closed state), it means that
you have set the HOLD TIME too short, and you need to use a longer hold time setting (unless,
of course, you want that sound).
562E
8
Page 11
Interpreting the Displays
The 562E has ABOVE and BELOW LED’s on each channel. These are indicators to show you
whether the signal at the input to the 562E is above or below the threshold. When the BELOW
LED is lit, and either the ratio is set for greater than 1:1, or the range is set for greater than
zero, gain reduction is occurring. When the ABOVE LED is lit, the signal is above threshold,
and gain reduction is not occurring.
The 562E also has one GAIN REDUCTION LED display per channel. The GAIN REDUCTION indication displays the amount of attenuation, in dB, that the 562E is applying to the input signal
(how far the gain is being reduced from unity). Here’s another way of looking at this: if the
GAIN REDUCTION display says 12dB of gain reduction, switching the unit to bypass will result in
a 12dB increase in the output level.
Using the Sidechain Key Input
The sidechain KEY INPUT is a patch point in the control circuit of a dynamic range processor, which
provides access to the part of the circuitry that tells the VCA what to do. The 562E’s sidechain is
routed through a TRS jack labeled KEY INPUT, which is located on the rear panel. This is an input
for any line level audio signal (not a DC voltage) that you may wish to use as a key signal, to
control the opening and closing of the expander/gate. The KEY INPUT jack also functions as a
sidechain insert point, providing send and return paths for external processing of the 562E’s
sidechain signal.
To apply a key signal to the 562E, set the EXT. KEY/BYPASS/IN switch to the EXT. KEY position.
Then, connect your key signal source to the KEY INPUT jack of the 562E. Now you can adjust the
THRESHOLD and GATE RANGE/EXPANDER RATIO controls for the amount of gating/expansion that you
want. You can then fine-tune your sound, using the ATTACK, HOLD and RELEASE TIME controls, as
well as the WINDOW ADVANCE feature. A typical application for using the KEY INPUT in this manner
would be: passing the bass guitar track through the 562E while using the line-level output of a kick
drum trigger to control the gating action.
If you want the 562E to respond more (or less) to certain frequencies in the key signal, the key
signal can be equalized to accentuate or diminish certain frequencies before it reaches the 562E’s
key input. This makes the action of the 562E’s expander/gate frequency dependent. Because the
audio signal and the control signal remain completely separate, you can equalize the sidechain
without changing the EQ in the main audio path.
To make the 562E more sensitive to high frequencies in the key input signal, use an equalizer
(graphic or parametric), inserted in the key signal path after the key signal source, and before the
562E, to boost the high frequencies in the sidechain signal. This increases the sensitivity of the
control circuits to those particular frequencies, so the expander/gate responds more to those
frequencies than any others.
Cutting a frequency creates the inverse effect, making the 562E less sensitive to the frequencies
that are removed from the control signal. The 562E provides you with overlapping LOW CUT and
HIGH CUT sidechain filters for this purpose. These filters cover the frequency spectrum from 10hz
to 40Khz. If you prefer, you can use the inserted equalizer to perform the function of cutting
selected frequencies.
ALL SIGNALS
ABOVETHESE
SETTINGS ARE
UNAFFECTED
SIGNAL LEVEL
10Hz 1KHz
LOW CUT RANGE
Frequency ranges of the LOW CUT and HIGH CUT sidechain filter controls.
ALL SIGNALS
BELOWTHESE
SETTINGS ARE
UNAFFECTED
SIGNAL LEVEL
400Hz 40KHz
HIGH CUT RANGE
562E
9
Page 12
The 562E’s internal sidechain signal can also be equalized in this manner. To insert an equalizer in the
E
sidechain, set the EXT.KEY/BYPASS/IN switch to the EXT. KEY position. Connect an insert cable from the
KEY INPUT of the 562E to the input and output of your equalizer as illustrated in the drawing below.
CHANNEL 2 INPUT
ANCED/
LANCED
BALANCED
EQ
TYPICAL CONNECTIONS
GROUND=PIN 1
BALANCED
132
RING=LOW(-)
TIP=HIGH(+)
LOW(-)=PIN 3
HIGH(+)=PIN 2
INPUTS
1/4"BALANCED
SLEEVE=GROUND GROUND
1
2
3
SIDECHAIN
SIDECHAIN OUT
KEY INPUT
CHANNEL 1 OUTPUT
BALANCED/
BALANCED
OUTPUTS
UNBALANCED
Return
(from EQ output)
Send
(to EQ input)
BALANCED
SIDECHAIN
KEY
INPUT
CHANN
BALANCED/
UNBALANCED
Return
Send
Ground
The 562E’s KEY INPUT jack is wired : TIP=RETURN, RING=SEND, and SLEEVE=GROUND.
If the expander/gate is being triggered by an unwanted high frequency signal (such as a squeaky
kick drum pedal), you can prevent the expander/gate from responding to that portion of the key
signal by cutting high frequencies and/or boosting low frequencies in the key signal. This can be
accomplished by careful adjustment of the corresponding threshold control, combined with the
boost/cut provided by the HIGH CUT filter and/or the EQ in the sidechain.
Note See also “Preventing False Triggering by Hi-hat and Kick While Gating a Snare Drum” on page 15.
If low frequency signals transmitted through a desk or podium are triggering the 562E’s expander
unnecessarily, use the LOW CUT filter to remove the low frequencies from the control signal, or use
an equalizer in the sidechain to boost the voice-range frequencies in the control signal.
Hint: You can save time, and make your life easier, by listening to the equalized external key
signal or to the equalized internal sidechain signal (instead of the 562E’s GATE/EXP.
output). When using an external equalizer, listen to the equalized key/sidechain signal by
setting the EXT.KEY/BYPASS/IN switch to the E XT.KEY position, and the OUTPUT ASSIGN
switch to the KEY LISTEN W/FILTER position. If you are not using an external equalizer, and
you want to hear the effect of the LOW CUT and HIGH CUT filters on the internal sidechain
audio, set the EXT.KEY/BYPASS/IN switch to the IN position, and the OUTPUT ASSIGN switch
to the KEY LISTEN W/FILTER position. Listening to the EQ’d key/sidechain signal allows you
to hear the signal that will control the 562E, and to more easily find the range that you wish
to emphasize or de-emphasize. When you are done listening to the EQ’d key/sidechain
signal, return the OUTPUT ASSIGN switch to the GATE/EXP. position for normal operation.
Keep in mind that the threshold level becomes a function of the amount of overall gain through the equalizer,
including the boost. If you increase the overall gain in the sidechain signal, by boosting selected frequencies
with the equalizer, you will need to also raise the THRESHOLD setting, in order to maintain the same signal level:
threshold level relationship that you had before boosting the frequencies.
Note There is no substitute for good mic technique. The more that you isolate the desired
signal from any undesired signal, using the rear-axis rejection characteristics of a
directional mic to your advantage, the easier it will be for you to achieve optimum gating
performance. For example, when miking a snare drum that is to be gated, it is generally a
good idea to mic the snare drum with the rear of the mic towards the hi-hat cymbal, to
reduce the amount of hi-hat leakage into the snare mic, thus reducing the possibility of the
562E
gate being falsely triggered by the hi-hat. The sound picked up by each mic should be
primarily the sound of the desired signal.
10
Page 13
Connecting to Other GearChapter 7
Matching Levels vs Matching Impedances
In any audio equipment application, the question of “matching” inevitably comes up. Without
digging a hole any deeper than absolutely necessary, we offer the following discussion to (hopefully) clarify your understanding of the subject.
Over the years, we have all had impedance matching pounded into our heads. This is important
only for ancient audio systems, power amplifiers, and RF. Technically speaking, the reason is
power transfer, which reaches a maximum when source and load are matched. Modern audio
systems are voltage transmission systems and source and load matching is not only unnecessary,
but undesirable as well.
r Ancient audio systems operate at 600 ohms (or some other impedance value), and must be
matched, both at their inputs and at their outputs. Generally speaking, if you are dealing
with equipment that uses vacuum tubes, or was designed prior to 1970, you should be
concerned about matching. These units were designed when audio systems were based on
maximum power transfer, hence the need for input/output matching.
r Power amplifiers are fussy because an abnormally low load impedance generally means a
visit to the amp hospital. Thus, it’s important to know what the total impedance of the pile
of speakers connected to the amplifier really is.
r RF systems are matched because we really are concerned with maximum power transfer
and with matching the impedance of the transmission line (keeps nasty things from
happening). Video signals (composite, baseband, or otherwise) should be treated like RF.
Some folks seem to believe that balanced/unbalanced lines and impedances are related; or even
worse that they are associated with a particular type of connector. Not so. Unbalanced signals are
not necessarily high-impedance and balanced signals/lines are not necessarily low-impedance.
Similarly, although 1/4 inch jacks are typically used for things like guitars (which are high-impedance and unbalanced), this does not predispose them to only this usage. After all, 1/4 inch jacks
are sometimes used for loudspeakers, which are anything but high-impedance. Therefore, the
presence of 3-pin XLR connectors should not be construed to mean that the input or output is lowimpedance (or high-impedance). The same applies to 1/4 inch jacks.
So, what is really important? Signal level, and (to a much lesser degree), the impedance relation
between an output (signal source) and the input that it connects to (signal receiver).
Signal level is very important. Mismatch causes either loss of headroom or loss of signal-to-noise ratio.
Thus, microphone inputs should only see signals originating from a microphone, a direct (DI) box, or an
output designated microphone-level output. Electrically, this is in the range of approximately -70 to -20
dBm. Line inputs should only see signals in the -10 to +24 dBm/dBu range. Guitars, high-impedance
microphones, and many electronic keyboards do not qualify as line-level sources.
The impedance relation between outputs and inputs needs to be considered, but only in the
following way - Always make sure that a device’s input impedance is higher than the output
source impedance of the device that drives it.
Some manufacturers state a relatively high-impedance figure as the output impedance of their
equipment. What they really mean is that this is the minimum load impedance that they would like
their gear to see. In most cases, seeing a output impedance figure of 10,000 (10K) ohms or higher
from modern equipment that requires power (batteries or AC) is an instance of this type of rating. If
so, then the input impedance of the succeeding input must be equal to or greater than the output
impedance of the driving device.
Symetrix equipment inputs are designed to bridge the output of whatever device drives the input
(i.e. to be greater than 10 times the actual source impedance). Symetrix equipment outputs are
designed to drive 600-ohm or higher loads (600-ohm loads are an archaic practice that won’t go
away). You don’t need to terminate the output with a 600-ohm resistor if you aren’t driving a 600ohm load. (If you don’t understand the concept of termination, you probably don’t need to
anyway.)
562E
11
Page 14
The two facts that you need to derive from this discussion are:
r Match signal levels for best headroom and signal-to-noise ratio.
r For audio, impedance matching is only needed for vintage equipment and power amplifier
outputs. In all other cases, ensure that your inputs bridge your outputs (meaning the
inputs are in the range of 2 to 200 times the output source impedance) .
Signal Levels
The 562E is designed around studio/professional line levels: +4 dBu or 1.23 volts RMS. The unit is
quiet enough to operate at lower signal levels such as those found in semipro or
musical-instrument (MI) equipment (-10 dBu or 300 millivolts).
I/O Impedances
The 562E is designed to interface into almost any recording studio or sound reinforcement application. This includes:
r 600-ohm systems where input and output impedances are matched.
r Unbalanced semiprofessional equipment applications.
r Modern bridging systems where inputs bridge and outputs are low source impedances
(voltage transmission systems).
The 562E’s input impedance is greater than 20-kilohms balanced or 10K unbalanced. The inputs
may be driven from any source (balanced or unbalanced) capable of delivering at least -10 dBu into
the aforementioned impedances.
The 562E’s output impedance is 600 ohms balanced, 300 ohms unbalanced. The output line driver
delivers +22 dBm into 600-ohm balanced loads or +18 dBm into 600-ohm unbalanced loads.
Polarity Convention
The 562E inputs and outputs use the international standard polarity convention of pin 2 hot.
Therefore, if your system uses balanced inputs and outputs, and uses the 562E this way, then the
polarity convention is unimportant. If your system is both balanced and unbalanced, then you
must pay attention to this, especially when going in and coming out through different connector
types (like input on an XLR, output on a phone jack).
X LR 1/4" Phone Signal
Pin 1 Sleeve Ground
Pin 2 Ti p High
Pin 3 Ring Low
Input and Output Connections
The illustration on the next page shows how to connect the 562E to balanced and unbalanced
sources and loads.
To operate the 562E from unbalanced sources, run a 2-conductor shielded cable (that’s two
conductors plus the shield) from the source to the 562E. At the source, connect the low/minus side
to the shield, these connect to the source’s ground; connect the high/plus side to the source’s
signal connection. At the 562E, the high/plus wire connects to pin 2, the low/minus wire connects
to pin 3, and the shield (always) connects to pin 1. This is the preferred method as it makes best
use of the 562E’s balanced input (even though the source is unbalanced). The other alternative
shown in the illustration converts the 562E’s balanced input into an unbalanced input at the input
connector. This works, but is more susceptible to hum and buzz than the preferred method. There
562E
is no level difference between either method.
12
Page 15
You can drive unbalanced loads with the 562E’s outputs by using the XLR connector with pin 3
S
left open. In an emergency (the show must go on), you can ground pin 3, but if you have the
choice...leave it open. If you must ground pin 3, it is must be grounded at the 562E, rather than at
the other end of the cable. The price, regardless of whether or not pin 3 is grounded is 6 dB less
output level. If your system is wired with pin 3 hot, and you are driving an unbalanced load, pin 2
must float.
The 1/4-inch input jack is paralleled with the XLR-input. In a large installation, it is permissible to
use one of the connectors as the input connection and to use either or both of the remaining
connections for paralleling other inputs with the 562E.
The 1/4-inch output jack is a TRS (tip-ring-sleeve) jack wired for balanced operations. This jack may
also be used for unbalanced operation. The unbalanced output is always 6 dB lower in level than the
balanced output.
FROM BALANCED OUT
FEMALE XLR
PIN 1 = GROUND
PIN 2 = HIGH
PIN 3 = LOW
FROM BALANCED OUT
MALE TRS PLUG
TIP = HIGH
RING = LOW
SLEEVE = GROUND
FROM UNBALANCED OUT
MALE TS PLUG
SLEEVE = GROUND +
TIP = HIGH
LOW
MALE RCA PLUG
SLEEVE = GROUND +
TIP = HIGH
LOW
FROM BALANCED OUT
TERMINAL STRIP
(+) = HIGH
(-) = LOW
= GROUND
2
3
1
SLEEVESLEEVE
TO BALANCED IN
1
3
2
TO BALANCED IN
TIPTIP
RINGRING
TO UNBALANCED IN
MALE TS PLUG
TIP = HIGH
SLEEVE = GROUND +
MALE RCA PLUG
TIP = HIGH
SLEEVE = GROUND +
TO BALANCED IN
MALE XLR
PIN 1 = GROUND
PIN 2 = HIGH
PIN 3 = LOW
MALE TRS PLUG
TIP = HIGH
RING = LOW
SLEEVE = GROUND
LOW
LOW
TERMINAL STRIP
(+) = HIGH
(-) = LOW
= GROUND
FROM BALANCED OUT
(TO UNBALANCED IN)
TERMINAL STRIP
(+) = HIGH
(-) = NOT USED
= GROUND
FROM ELECTRONIC, NON-TRANSFORMER
BALANCED OUTPUT (TYPICAL OF SYMETRIX PRODUCTS)
PIN 1 = GROUND + LOW
TO UNBALANCED INPUTS
FEMALE XLR
PIN 2 = HIGH
PIN 3 = NOT USED
MALE TRS PLUG
TIP = HIGH
RING = NOT USED
SLEEVE = GROUND+
LOW
2
3
1
TIP
RING
LEEVE
TO BALANCED IN
(FROM UNBALANCED OUT)
TERMINAL STRIP
(+) = HIGH
(-) = UNUSED
= GROUND
TO UNBALANCED IN FROM
TRANSFORMER COUPLED OR
FLOATING BALANCED OUTPUT
MALE TS PLUG
TIP = HIGH
SLEEVE = GROUND +
LOW
MALE RCA PLUG
TIP = HIGH
SLEEVE = GROUND +
LOW
562E
13
Page 16
Applications Chapter 8
The 562E Auto Windowing Expander Gate can provide signal processing capabilities ranging from
essential to esoteric. Some of the following techniques are standard and straightforward. Other
techniques may be used less commonly, but are worthy of investigation. These examples are
intended to give you some sample setups that you can use right away, but they are not intended to
represent every possible use of the Symetrix 562E.
Perhaps the most common use for gates in music production is on drum and percussion tracks. In
addition, gates may be used on virtually any type of musical instrument or audio sound effect to
remove unwanted room noise and ambience, to modify reverb and other time-related effects, and to
create special effects.
The downward expander is ideal for tasks requiring more subtle control. Expanders can provide
single-ended noise reduction for tape recorders, workstations, effects devices, companding (when
used with a compressor), and noise and interference suppression for studio and live sound.
Noise Elimination
The 562E is capable of eliminating noise on a track or channel that becomes objectionable when
not masked by the desired signal. For general and gentle noise suppression (especially on voice),
use expansion. For more “hardline” noise suppression, use gating.
You can use the 562E to reduce body noises picked up by an announce microphone, to reduce amp
noise from a noisy guitar amp, or to reduce the amount of room sound in a guitar track that was
recorded a little too loosely in a room that was a little too noisy. For sound reinforcement, the 562E
is useful for tending an announce mic that needs to be left on, when you really don’t want it
picking up every whisper in its vicinity or going into feedback.
Setup for these applications is easy. With no signal and the GATE RANGE/EXPANDER RATIO control
either clockwise (for expanding) or counterclockwise (for gating), adjust the THRESHOLD control
counterclockwise until you begin to see gain reduction on the LED display. Continue until you
hear the degree of expansion/gating that you want. When the signal is present, you may need to
refine the setting so that the 562E doesn’t reduce the gain during momentary pauses. You can slow
things down a bit via the HOLD and RELEASE controls, which help prevent expansion/gating during
momentary pauses. Remember: The HOLD control only functions while gating.
CHANNEL 1
ATTACK
TIME
60ms 1 Sec
AUTO
CHANNEL 1
ATTACK
TIME
60ms 1 Sec
AUTO
HOLD
TIME
4 Sec300ms 50ms 30ms
HOLD
TIME
4 Sec300ms 50ms 30ms
RELEASE
TIME
500ms
2.5 Sec
RELEASE
TIME
500ms
2.5 Sec
GATE RANGE
EXPANDER RATIO
0
1:3
80dB
GATE RANGE
EXPANDER RATIO
0
1:3
80dB
OUTPUT
ASSIGN
EXT.KEY KEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
OUTPUT
ASSIGN
EXT.KEY KEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
CH1 SIDECHAIN PROCESSING
LOW CUT
20Hz 50Hz
CH1 SIDECHAIN PROCESSING
LOW CUT
20Hz 50Hz
HIGH CUT
1K
200Hz15Hz
400Hz
1K10Hz
HIGH CUT
1K
200Hz15Hz
400Hz
1K10Hz
GAIN (dB)
REDUCTI0N
WINDOW
ADVANCE
4K
20K
40K
WINDOW
ADVANCE
4K
20K
40K
MAX
MIN
OFF
MAX
MIN
OFF
3
12
30
60
GAIN (dB)
REDUCTI0N
3
12
30
60
ABOVE
BELOW
ABOVE
BELOW
THRESHOLD
(dB)
0
-40 +20
THRESHOLD
(dB)
0
-40 +20
Isolating and Tightening Up Drum Sounds
The damping effect achieved by applying duct tape to a drum head is very similar to the effect of
applying gating or expanding to the drums. The duct tape reduces the decay (sustain) of the
instrument, and helps get rid of annoying ring frequencies. Using the 562E to reduce the decay of
562E
individual drums allows the drummer to play with the full power of his or her drums, at live perfor-
14
Page 17
mance levels, while providing the engineer with the kind of control that is necessary for a good,
tight track.
In a live sound reinforcement situation, gating drums can tighten up the drum sound. Equally
important, gates allow the sound engineer to turn up the drums louder than would normally be
possible without feedback. This is because a correctly set gate can suppress feedback while the
feedback is at a lower level than the setting of the gate’s threshold (before the feedback has a
chance to take off).
Careful adjustment of the ATTACK and RELEASE controls allow the relative balance between the
drum’s impact and decay to be changed. Short ATTACK, HOLD and RELEASE times emphasize the
impact portion of the sound, but may sound artificial in some situations. Longer ATTACK, HOLD and
RELEASE times generally sound more natural, but allow more ringing and feedback. The WINDOW
ADVANCE feature can be used to ensure that the gate opens in time to catch all of the impact portion
of the sound. The GATE RANGE/EXPANDER RATIO will affect the ATTACK and RELEASE times, so use as
much attenuation as needed, but no more than necessary. Be prepared for some serious fine
tuning of these controls.
CHANNEL 1
ATTACK
TIME
60ms 1 Sec
AUTO
HOLD
TIME
4 Sec300ms 50ms 30ms
RELEASE
TIME
500ms
2.5 Sec
GATE RANGE
EXPANDER RATIO
0
1:3
80dB
OUTPUT
ASSIGN
EXT.KEY KEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
CH1 SIDECHAIN PROCESSING
LOW CUT
20Hz 50Hz
HIGH CUT
1K
200Hz15Hz
400Hz
1K10Hz
GAIN (dB)
REDUCTI0N
WINDOW
ADVANCE
4K
20K
40K
MAX
MIN
OFF
3
12
30
60
ABOVE
BELOW
THRESHOLD
(dB)
0
-40 +20
Note Be sure to select microphones with good off-axis rejection (including high frequencies)
and use the directional patterns of your microphones to isolate the desired signal as much
as possible at the source. The sounds picked up by the microphones must be primarily the
desired sounds, or the gate won’t be able to discriminate between the desired sound and
an unwanted sound.
Preventing False Triggering by Hi-hat and Kick While Gating a Snare Drum
A common problem that engineers run into when they try to gate a snare drum is false triggering.
This is most often caused by audio leakage into the snare mic from the hi-hat and/or kick drum.
The 562E’s LOW CUT and HIGH CUT filters are designed to eliminate just such a problem.
First, and foremost, employ good mic technique to reject as much of the sound that is causing the
false triggering as possible. Start with the 562E’s LOW CUT knob in the full counterclockwise
position, the HIGH CUT knob in the full clockwise position, the THRESHOLD knob in the counterclockwise position and the GATE RANGE knob in the full counterclockwise position. While the
drummer plays just the snare and hi-hat, adjust the THRESHOLD control clockwise until gating
occurs (even though the hi-hat may trigger the gate at this point).
Next, set the OUTPUT ASSIGN switch to the KEY LISTEN W/FILTER (center) position. Rotate the HIGH
CUT control to its full counterclockwise position. The hi-hat should now be much less audible, and
the snare should be a muffled “thud”.
Set the OUTPUT ASSIGN switch to the GATE/EXP. position. You may need to readjust the THRESHOLD
control slightly to make the gate trigger properly. The snare should now be gated without any
CH1 SIDECHAIN PROCESSING
LOW CUT
OUTPUT
ASSIGN
20Hz 50Hz
EXT.KEY KEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
HIGH CUT
WINDOW
ADVANCE
4K
20K
1K
200Hz15Hz
400Hz
1K10Hz
40K
MAX
MIN
OFF
GAIN (dB)
REDUCTI0N
3
12
ABOVE
30
BELOW
60
THRESHOLD
(dB)
0
-40 +20
CHANNEL 1
ATTACK
TIME
60ms 1 Sec
AUTO
HOLD
TIME
4 Sec300ms 50ms 30ms
RELEASE
TIME
500ms
2.5 Sec
GATE RANGE
EXPANDER RATIO
0
1:3
80dB
15
562E
Page 18
false triggering by the hi-hat.
With the OUTPUT ASSIGN switch still in the GATE/EXP. position, have the drummer play the snare
again, but this time with kick drum accompaniment. If the kick drum is falsely triggering the snare
gate, rotate the LOW CUT control towards the clockwise position until the kick drum no longer
triggers the gate.
Gated Reverb
You knew this was coming, didn’t you?
The obvious method to gate reverb is to feed the reverb to the input of the 562E, and to use the
internal triggering. However, if you use a HOLD TIME setting that is too short, you can run into
jitter problems when the reverb signal starts to decay.
To avoid this, and still be able to use a short HOLD TIME setting, feed a separate send of only the
dry signal to the KEY IN of the 562E. Set the EXT. KEY/BYPASS/IN switch to the EXT.KEY position.
Feed the reverb to the audio input of the 562E. This will give the gate a trigger with a well-defined
beginning and end.
Be sure to experiment with the WINDOW ADVANCE feature, especially on instrument sounds with a
sharp attack, such as drums.
Set the other controls as shown in the following illustration.
CHANNEL 1
ATTACK
TIME
60ms 1 Sec
AUTO
HOLD
TIME
4 Sec300ms 50ms 30ms
RELEASE
TIME
500ms
2.5 Sec
GATE RANGE
EXPANDER RATIO
0
1:3
80dB
OUTPUT
ASSIGN
EXT.KEY KEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
CH1 SIDECHAIN PROCESSING
LOW CUT
20Hz 50Hz
HIGH CUT
1K
200Hz15Hz
400Hz
1K10Hz
GAIN (dB)
REDUCTI0N
WINDOW
ADVANCE
4K
20K
40K
MAX
MIN
OFF
3
12
30
60
ABOVE
BELOW
THRESHOLD
(dB)
0
-40 +20
Noise Reduction and Feedback Control In Vocal Monitors
Here is one of the golden uses of the 562E - increasing gain before feedback and cleaning up the
audio in stage monitor systems. This use of the 562E requires some fine tuning of the THRESHOLD,
LOW CUT and HIGH CUT controls, but it can make a huge contribution towards ease of life for the
monitor mixing engineer.
First, set up the 562E, using the downward expander, with a fairly fast release time. The threshold
should be set to trigger on normal level speech.
Set the OUTPUT ASSIGN switch to KEY LISTEN W/FILTER. If the stage setup does not include a drum
kit, you can skip the next step.
If the stage setup includes a drum kit, start turning the HIGH CUT control from fully clockwise
toward counterclockwise until you have eliminated as much of the sound of the cymbals as
possible, without detracting from the vocals.
If you wish, apply some rolloff to the lows using the LOW CUT control. This will help prevent the
downward expander from triggering if the singer likes to rock the mic stand.
EXT.KEY KEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
562E
16
CH1 SIDECHAIN PROCESSING
LOW CUT
OUTPUT
ASSIGN
20Hz 50Hz
200Hz15Hz
1K10Hz
HIGH CUT
1K
400Hz
GAIN (dB)
REDUCTI0N
WINDOW
ADVANCE
4K
20K
40K
MAX
MIN
OFF
3
12
30
60
ABOVE
BELOW
THRESHOLD
(dB)
0
-40 +20
CHANNEL 1
ATTACK
TIME
60ms 1 Sec
AUTO
HOLD
TIME
4 Sec300ms 50ms 30ms
RELEASE
TIME
500ms
2.5 Sec
GATE RANGE
EXPANDER RATIO
0
1:3
80dB
Page 19
Return the OUTPUT ASSIGN switch to the GATE/EXP. setting and do your final threshold adjustments
as well as any filter fine tuning.
You may prefer to use the 562E’s gate if the downward expander is not providing enough signal
attenuation for you.
Cleaning Up Backing Vocals
A common problem with recording backing vocals, especially when layering multiple tracks of
them, is that the beginnings and endings of lines or phrases can get sloppy. All it takes is for a
singer to be a fraction of a second early in starting or late in stopping. The following technique,
using the 562E, won’t help with timing differences during the line or phrase, but it will help greatly
in tightening up backing vocals with uneven starts and stops. This can make a valuable contribution to your mix, as the beginnings and endings of lines and phrases are the points when timing
problems are most obvious to the listener.
Mix all of the backing vocals into one subgroup (two for stereo), and feed the subgroup output(s)
to the 562E input(s). Select the backing vocal track with the best timing, and send it to an auxiliary
mixer output. Feed this auxiliary output into the KEY INPUT of the 562E. This will be the signal that
you use to trigger the gate.
Set the EXT.KEY/BYPASS/IN switch to EXT.KEY, set the OUTPUT ASSIGN switch to GATE/EXP. and set
the WINDOW ADVANCE switch to MAX. Set the THRESHOLD control counterclockwise, set the ATTACK
TIME and RELEASE TIME controls to a medium setting, set the HOLD TIME counterclockwise, and set
the GATE RANGE control counterclockwise.
Begin rotating the THRESHOLD control clockwise until gating occurs. Then, fine-tune the THRESH-
OLD, ATTACK TIME and RELEASE TIME controls for the best sound.
CHANNEL 1
ATTACK
TIME
60ms 1 Sec
AUTO
HOLD
TIME
4 Sec300ms 50ms 30ms
RELEASE
TIME
500ms
2.5 Sec
GATE RANGE
EXPANDER RATIO
0
1:3
80dB
OUTPUT
ASSIGN
EXT.KEY KEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
CH1 SIDECHAIN PROCESSING
LOW CUT
20Hz 50Hz
HIGH CUT
1K
200Hz15Hz
400Hz
1K10Hz
GAIN (dB)
REDUCTI0N
WINDOW
ADVANCE
4K
20K
40K
MAX
MIN
OFF
3
12
30
60
ABOVE
BELOW
THRESHOLD
(dB)
0
-40 +20
Midi Control Of The 562E
OK, you can’t directly control the 562E by MIDI. However, there is a clever trick you can use to
control it indirectly, if you have a midi-controlled synthesizer output that you can spare.
Connect the synth output to the KEY IN of the 562E, and set the EXT.KEY/BYPASS/IN switch to
EXT.KEY. Now, when the synthesizer plays a sustained note at a constant level, with fast attack
and decay, it will act as a switch to turn the gate off and on. Simply write your midi program so that
the synthesizer is playing a note for the duration of the time that you want the 562E to be passing
signal.
562E
17
Page 20
Noise Reduction for Effects Returns
One of the most overlooked noise sources in sound reinforcement or recording systems is signal
processing. Devices such as reverberation units, digital delays, harmonizers, etc. all have the
potential to enhance the sound, but each device added to the signal chain is going to add a certain
amount of noise, thus diminishing the overall signal-to-noise ratio. The very nature of compressors and limiters raises the apparent noise floor of a signal as the dynamic range is squashed.
The 562E’s downward expander can help you overcome this problem. Try patching the 562E
between the effects sends and the effects returns on the console. Use slower HOLD TIME and
RELEASE TIME settings to preserve the natural decay times of reverbs, etc.
CHANNEL 1
ATTACK
TIME
60ms 1 Sec
AUTO
HOLD
TIME
4 Sec300ms 50ms 30ms
RELEASE
TIME
500ms
2.5 Sec
GATE RANGE
EXPANDER RATIO
0
1:3
80dB
OUTPUT
ASSIGN
EXT.KEY KEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
CH1 SIDECHAIN PROCESSING
LOW CUT
20Hz 50Hz
HIGH CUT
1K
200Hz15Hz
400Hz
1K10Hz
GAIN (dB)
REDUCTI0N
WINDOW
ADVANCE
4K
20K
40K
MAX
MIN
OFF
3
12
30
60
ABOVE
BELOW
THRESHOLD
(dB)
0
-40 +20
Noise Reduction for Console Outputs
If you have a noise problem at your console outputs, it is best to find the source of the noise
problem, and fix it at the source. However, in a crunch, the 562E can greatly improve the apparent
signal-to-noise ratio of sound reinforcement consoles. One 562E can be used to gate the mono or
stereo output of the board, or multiple 562E’s can be used to gate the subgroup outputs.
When using the 562E on the main output(s) of the console, use gating with a mid to slow release
time, or use downward expansion.
When using the 562E on the subgroup outputs of the console, use gating for the outputs carrying
a fast transient signal (for example: drums or percussion). For subgroup outputs dedicated to
signal sources with gentler dynamics, such as vocals, use slower ATTACK TIME, RELEASE TIME and
HOLD TIME settings when gating, or use downward expansion.
CHANNEL 1
ATTACK
TIME
60ms 1 Sec
AUTO
HOLD
TIME
4 Sec300ms 50ms 30ms
RELEASE
TIME
500ms
2.5 Sec
GATE RANGE
EXPANDER RATIO
0
1:3
80dB
OUTPUT
ASSIGN
EXT.KEY KEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
CH1 SIDECHAIN PROCESSING
LOW CUT
20Hz 50Hz
HIGH CUT
1K
200Hz15Hz
400Hz
1K10Hz
GAIN (dB)
REDUCTI0N
WINDOW
ADVANCE
4K
20K
40K
MAX
MIN
OFF
3
12
30
60
ABOVE
BELOW
THRESHOLD
(dB)
0
-40 +20
EXT.KEY KEY LISTEN
BYPASS W/FILTER
IN GATE/EXP.
562E
18
CH1 SIDECHAIN PROCESSING
LOW CUT
OUTPUT
ASSIGN
20Hz 50Hz
200Hz15Hz
1K10Hz
HIGH CUT
1K
400Hz
GAIN (dB)
REDUCTI0N
WINDOW
ADVANCE
4K
20K
40K
MAX
MIN
OFF
3
12
30
60
ABOVE
BELOW
THRESHOLD
(dB)
0
-40 +20
CHANNEL 1
ATTACK
TIME
60ms 1 Sec
AUTO
HOLD
TIME
4 Sec300ms 50ms 30ms
RELEASE
TIME
500ms
2.5 Sec
GATE RANGE
EXPANDER RATIO
0
1:3
80dB
Page 21
TroubleshootingChapter 9
Troubleshooting Chart
SYMPTOM PROBABLE CAUSE
No output Check cables and connections. Are inputs driven by outputs, and
outputs driving inputs? Verify cables, source and load by patching
input and output connections together, at the unit. Check for AC power
presence. Did you connect the input cable to the KEY IN jack, instead of
the INPUT jack? Check input by plugging headphones halfway into the
Key In jack and listening for input signal. Check output by plugging
headphones into output connector.
Hum or buzz in output Check input and output connector wiring (refer to page 13). Ground
loop: check related system equipment grounding. Are all system
components on the same AC ground?
Distortion Check input signal. Is it too hot, or is it already distorted? Check the
output loading. It should be above 600 ohms. Is the input of the device
following the 562E clipping? Is something else clipping?
Noise (hiss) Check input signal levels. The 562E is intended to operate at or near
“line” level (-10 dBu or greater). Make sure that the signal you are
feeding to the 562E is a line level signal, not mic level. Check gain
settings on downstream equipment. The system gain structure should
be such that the 562E operates at or near unity gain. Is the input signal
already noisy?
No gating or expansion Did you connect the output cable to the KEY IN jack, instead of the
OUTPUT jack? Is the EXT.KEY/BYPASS/IN switch set to BYPASS? Is
the EXT.KEY/BYPASS/IN switch set to IN? If the EXT.KEY/BYPASS/IN
switch is set to EXT.KEY, check cable connections at KEY IN and at the
output of any audio source that is being used as a trigger, or at the
input and output of any external device that is being used to process
the sidechain signal (i.e. an EQ). Check that any audio source or
external device that is connected to the KEY IN has power and is turned
on. Check that any cable that is plugged into the KEY IN is also connected to an audio source or external processing device.
No LED display Is the unit plugged in, and turned on? Is the AC outlet OK?
“Jitter” when gating Use a longer HOLD TIME setting. Longer ATTACK TIME and
RELEASE TIME settings may also be necessary.
Unit not plugged in, Call us.
but works anyway
Notes
562E
19
Page 22
Specifications Chapter 10
Architects and Engineers Specifications
The Dual Channel Expander/Gate shall provide
two independent channels of dynamic range
expansion for wide band, wide range audio
signals. The unit shall occupy one rack space
(1U).
The Expander/Gate shall incorporate
AutoWindowing™ and Window Advance™
circuitry to deliver virtually instantaneous
attack times without any audible “clicks” or
“pops”. There shall be continuously variable
controls for Threshold, Attack Time, Gate Hold
Time, and Release Time. Gate Range and
Expander Ratio shall be continuously variable
via a single front panel control.
There shall be separate, tunable high pass and
low pass filters in series within the control
sidechain. The cutoff frequencies shall be
individually adjustable via front panel controls.
There shall be an External Key input on the
rear panel and a Key Listen mode shall be
available that will monitor the control signal
either pre or post Key Filter. There shall be a
front panel control to select either External
Key, Internal Key, or Bypass mode.
Each channel shall have a four segment LED
meter that shall indicate gain reduction
amount. The meter shall have a range of 60dB.
There shall also be LED indicators that display
the input signal level relative to the Expander/
Gate threshold.
Pre-filter control loop access will be available
via a 1/4" TRS female jack. This shall be wired
Tip=Return, Ring=Send, Sleeve=Ground.
The inputs shall be active balanced bridging
designs terminated with 3-pin XLR (AES/IEC
standard wiring) and 1/4” TRS connectors. The
input circuitry shall incorporate RFI filters. The
outputs shall be active servo-balanced designs
having equal source impedances and terminated with 3-pin XLR (AES/IEC standard
wiring).
The inputs shall accommodate +22 dBu signals
without distortion, and the balanced outputs
shall be capable of delivering +22 dBm into a
600 ohm load. Overall frequency response (+0,
-1dB) shall be 20Hz to 20kHz. THD+N shall not
be greater than 0.03%, 0dB g/r, 1kHz into a 600ohm load. Dynamic range shall be 110dB.
The unit shall have a built-in power supply and
operate from 117V nominal AC (105-130V) 50/
60 Hz or 230V nominal AC (207-253V) 50 Hz.
The unit shall be a Symetrix Incorporated
model 562E Windowing Expander/Gate.
Specifications
Number of audio channels
Connectors
Maximum input level
Maximum output level
Input impedance
Output impedance
THD+Noise @ 1kHz
Signal/Noise
Dynamic range
Frequency response
Attack time
Attenuation
562E
20
XLR and 1/4" TRS
+22 dBu
+22 dBu
>20K Balanced, >10K Unbalanced
600 ohms Balanced
.03% @ +4 dBu
94 dB
112 dB
+0, -3dBm, 10 Hz to 40 kHz
Program Dependent to
300 milliseconds
80 dB max, adjustable
Chassis size
2
AC requirements
Power consumption
In the interest of continuous product improvement,
Symetrix, Inc. reserves the right to alter, change, or
modify these specifications without prior notice.
©1997, Symetrix, Inc. All rights reserved.
1.75"H x 19"W x 4.25"D
117V ac, nominal
230V ac, nominal
18 watts, maximum
Page 23
562E Limited Warranty
Warranty and ServiceChapter 11
Symetrix, Inc. expressly warrants that the product
will be free from defects in material and
workmanship for one (1) year. Symetrix's
obligations under this warranty will be
limited to repairing or replacing, at Symetrix's
option, the part or parts of the product
which prove defective in material or workmanship within one (1) year from date of
purchase, provided that the Buyer gives
Symetrix prompt notice of any defect or
failure and satisfactory proof thereof.
Products may be returned by Buyer only
after a Return Authorization number (RA)
has been obtained from Symetrix. Buyer will
prepay all freight charges to return the
product to the Symetrix factory. Symetrix
reserves the right to inspect any products
which may be the subject of any warranty
claim before repair or replacement is carried
out. Symetrix may, at its option, require
proof of the original date of purchase (dated
copy of original retail dealer's invoice). Final
determination of warranty coverage lies
solely with Symetrix. Products repaired
under warranty will be returned freight
prepaid by Symetrix via United Parcel
Service (surface), to any location within the
Continental United States. At Buyer's
request the shipment may be returned via
airfreight at Buyer's expense. Outside the
Continental United States, products will be
returned freight collect.
The foregoing warranties are in lieu of all
other warranties, whether oral, written,
express, implied or statutory. Symetrix, Inc.
expressly disclaims any IMPLIED warranties, including fitness for a particular
purpose or merchantability. Symetrix's
warranty obligation and buyer's remedies
hereunder are SOLELY and exclusively as
stated herein.
This Symetrix product is designed and
manufactured for use in professional and
studio audio systems and is not intended for
other usage. With respect to products
purchased by consumers for personal, family,
or household use, Symetrix expressly
disclaims all implied warranties, including
but not limited to warranties of merchantability and fitness for a particular purpose.
This limited warranty, with all terms, conditions and disclaimers set forth herein, shall
extend to the original purchaser and anyone
who purchases the product within the
specified warranty period.
Warranty Registration must be completed
and mailed to Symetrix within thirty (30) days
of the date of purchase.
Symetrix does not authorize any third party,
including any dealer or sales representative,
to assume any liability or make any additional warranties or representation regarding
this product information on behalf of
Symetrix.
This limited warranty gives the buyer certain
rights. You may have additional rights
provided by applicable law.
Limitation of Liability
The total liability of Symetrix on any claim,
whether in contract, tort (including negligence) or otherwise arising out of, connected with, or resulting from the manufacture, sale, delivery, resale, repair, replacement or use of any product will not exceed
the price allocable to the product or any part
thereof which gives rise to the claim. In no
event will Symetrix be liable for any inciden-
tal or consequential damages including but
not limited to damage for loss of revenue,
cost of capital, claims of customers for
service interruptions or failure to supply, and
costs and expenses incurred in connection
with labor, overhead, transportation, installation or removal of products or substitute
facilities or supply houses.
562E
21
Page 24
Servicing the 562E
If you have determined that your 562E requires repair services and you live outside of the
United States please contact your local Symetrix dealer or distributor for instructions on
how to obtain service. If you reside in the U.S. then proceed as follows:
At the Symetrix factory, Symetrix will perform in-warranty or out-of-warranty service on any
product it has manufactured for a period of five years from date of manufacture.
Before sending anything to Symetrix, contact our Customer Service Department for a
return authorization (RA) number. The telephone number is (425) 778-7728, Monday
through Friday, 8AM (800 hours) though 4:30 PM (1630 hours), Pacific Time.
In-warranty repairs
To get your 562E repaired under the terms of the warranty:
1. Call us for an RA number.
2. Pack the unit in its original packaging materials.
3. Include your name, address, daytime telephone number, and a brief
statement of the problem.
4. Write the RA number on the outside of the box.
5 . Ship the unit to Symetrix, freight prepaid.
We do not accept freight collect shipments.
Just do these five things, and repairs made in-warranty will cost you only one-way freight
charges. We'll prepay the return (surface) freight.
If you choose to send us your product in some sort of flimsy packaging, we'll have to
charge you for proper shipping materials. If you don't have the factory packaging materials,
then do yourself a favor by using an oversize carton, wrap the unit in a plastic bag, and
surround it with bubble-wrap. Pack the box full of Styrofoam peanuts. Be sure there is
enough clearance in the carton to protect the rack ears (you wouldn't believe how many
units are returned with bent ears). We won't return the unit in anything but Symetrix
packaging for which we will have to charge you. Of course, if the problem turns out to be
operator inflicted, you'll have to pay for both parts and labor. In any event, if there are
charges for the repair costs, you will pay for the return freight. All charges will be COD
unless you have made other arrangements (prepaid, Visa or Mastercard).
Out-of-warranty repairs
If the warranty period has passed, you'll be billed for all necessary parts, labor, packaging
materials, and freight charges. Please remember, you must call for an RA number before
sending the unit to Symetrix.
562E
22
Page 25
Declaration of ConformityChapter 12
Declaration of Conformity
We, Symetrix Incorporated,
6408 216th St. SW, Mountlake Terrace, Washington, USA,
declare under our sole responsibility that the product:
562E Windowing Expander/Gate
to which this declaration relates,
is in conformity with the following standards:
EN 60065
Safety requirements for mains operated electronic and related
apparatus for household and similar general use.
EN 50081-1
Electromagnetic compatibility - Generic emission standard
Part 1: Residential, commercial, and light industry.
EN 50082-1
Electromagnetic compatibility - Generic immunity standard
Part 1: Residential, commercial, and light industry.
EN 55022
Limits and methods of measurement of radio interference
characteristics of information technology equipment.
The technical construction file is maintained at:
Symetrix, Inc.
6408 216th St. SW
Mountlake Terrace, WA, 98043
USA
The authorized representative located within the European Community is:
World Marketing Associates
P.O. Box 34
Newquay, Cornwall, TR7 1TU, U.K.
Date of issue: 15 June, 1997
Place of issue:Mountlake Terrace, Washington, USA
Authorized signature:
Dane Butcher, President, Symetrix Incorporated.
562E
23
Page 26
562E
24
Symetrix, Inc.
6408 216th St. SW
Mountlake Terrace, WA, 98043
USA
Tel: (425) 778-7728
Fax: (425) 778-7727
Website: http://www.symetrixaudio.com
Email: symetrix@symetrixaudio.com
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