Symetrix 562E User manual

562E
Windowing
Expander/
Gate
User’s Guide
562E

i
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 Warranty 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-
tion storage and retrieval system, without permission,
in writing, from Symetrix, Inc.
6408 216th St. SW
Mountlake Terrace,WA 98043 USA
Tel [phone]
Fax [phone]
Email: [email protected]
562E

562E
1
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 microsec-
onds of "how fast", Symetrix is rewriting the rules
on how to open. The dual channel 562E
WindowingExpander/Gateexploitsournewly-
developed, proprietary technology to enhance
gatingandexpandercontrol. Ultimatelythe562E
delivers unparalleled fidelity to any audio signal.
GATING:Gatesmaybeusedtocleanup
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.
WindowAdvanceisaproprietarysystemfor
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.
WindowAdvancepermitstheusertosubtlydelay
the signal energy, centering it within the enve-
lope. 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.
WindowAdvanceeliminatesthenoisesand
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 smooth-
ing 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
leadingedges. Incontrast,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. AutoWindowingyieldsanenvelope
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: The562Ealsopermitsusersto
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 modula-
tion 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
gatetechnologywiththeSymetrix562EWindow-
ingExpander/Gate.
0
TIME RELEASE TIME
1 Sec 500ms
EXPANDER RATIO
GATE RANGE
1:380
2.5 Sec4 Sec 30ms
CHANNEL 2CH2 SIDECHAIN PROCESSING
TIME(dB) ATTACK
0 60ms
GAIN (dB)
REDUCTI0N
ABOVE
BELOW
30
MAX 12
3
THRESHOLD
300ms+20 AUTO
60
OFF -40
MIN
HIGH CUT
20K
200Hz1K
50Hz 4K
OUTPUT
15Hz
KEY LISTEN
ASSIGN 20Hz
LOW CUT
40K
1K 400Hz
IN GATE/EXP. 10Hz
W/FILTER
WINDOW
ADVANCE
50ms
HOLD
CHANNEL 1
TIME GATE RANGE EXPANDER RATIO
500ms 0
HOLD
TIME
ATTACK
TIME
60ms 1 Sec
RELEASE
1:3
2.5 Sec 80dB 4 Sec300ms 50ms 30ms
(dB)
THRESHOLD
ABOVE
BELOW
0
HIGH CUT
WINDOW
30
MAX 12
20K
4K ADVANCE 3
REDUCTI0N
GAIN (dB)
-40 +20
60
OFF
40K
400Hz MIN AUTO
LOW CUT
OUTPUT
200Hz15Hz
ASSIGN 20Hz 50Hz
EXT.KEY
E
KEY LISTEN
1K10Hz
IN GATE/EXP.
BYPASS W/FILTER
562
WINDOWING
EXPANDER/GATE
CH1 SIDECHAIN PROCESSING
1K
BYPASS
EXT.KEY
CHANNEL 1 INPUT
UNBALANCED
BALANCED/
BALANCED
KEY
INPUT
BALANCED/
BALANCED
OUTPUTS
UNBALANCED
CHANNEL 1 OUTPUT
BALANCED
TYPICAL CONNECTIONS
13
SIDECHAIN
1
3
2
LOW(-)=PIN 3
HIGH(+)=PIN 2
GROUND=PIN 1
1/4"BALANCED
BALANCED
INPUTS
TIP=HIGH(+)
RING=LOW(-)
BALANCED
SLEEVE=GROUND GROUND
SIDECHAIN OUT
KEY INPUT
2
SIDECHAINSIDECHAIN
UNBALANCED
BALANCED/KEY
INPUT
CHANNEL 2 OUTPUT
BALANCED
E 562 WINDOWING EXPANDER/GATE
MANUFACTURED IN LYNNWOOD, WASHINGTON USA
UNBALANCED
BALANCED/
AC INPUT
18 WATTS
MAXIMUM
FABRIQUÉ AUX E.-U. PAR SYMETRIX INC., LYNNWOOD, WA USA.
RÉFÉREZ TOUTE RÉPARATION À UN TECHNICIEN QUALIFIÉ.
CHANNEL 2 INPUT
Front panel
Rear panel

562E
2
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.
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 mainte-
nance (servicing) instructions in the literature
accompanyingthe562E(i.e. this manual).
Caution To prevent electric shock, do not
use the polarized plug supplied
with the 562E with any extension
cord, receptacle, or other outlet
unless the blades can be fully
inserted.
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
extra emphasis. A Note generally
supplies extra information to help
you to better use the 562E.
Equipment Markings
Operator Safety Summary Chapter 2
Caution Identifies information that, if not
heeded, may cause damage to the
562E or other equipment in your
system.
Warning Identifiesinformationthat,if
ignored,maybehazardousto
yourhealthorthatofothers.
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.
Dangerfrom lossof 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.
Properpowercord - Use only thepowercord
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 condi-
tions: explosive atmospheres, in wet locations,
in inclement weather, improper or unknown AC
mains voltage, or if improperly fused.
Stayoutof the box-To avoid personal injuryor
injury to others, do not remove the product
covers or panels. Do not operate the product
without the covers and panels properly
installed.
AVIS:
NE PAS OUVRIR
Il ne se trouve a l’interieur aucune piece pourvant entre reparée l’usager.
SEE OWNERS MANUAL. VOIR CAHIER D’INSTRUCTIONS.
S’adresser a un reparateur compétent.
RISQUE DE CHOC ELECTRIQUE
N
o user serviceable parts inside. Refer servicing to qualified service personnel
.
CAUTION
WARNING:
TO REDUCE THE RISK OF FIRE OR
ELECTRIC SHOCK DO NOT EXPOSE
THIS EQUIPMENT TO RAIN OR MOISTURE
DO NOT OPEN
RISK OF ELECTRIC SHOCK

562E
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 connec-
tions may be found on pages 12-13 of this manual.
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: Lethalvoltages are presentinside thechassis. There areno user
serviceablepartsinside thechassis.Referallservicetoqualified
servicepersonnelortothefactory.
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) 40K
WINDOW ADVANCE MAX
THRESHOLD -10
ATTACK TIME AUTO
HOLD TIME (GATE ONLY) 50ms
RELEASE TIME 300ms
GATE RANGE (IF GATING) 80dB
EXPANDER RATIO (IF EXPANDING) 1:3
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.









Fast Setup
Chapter 3





562E
4
Sidechain Processing Section
EXT.KEY/BYPASS/INswitch-
The EXT. KEY switch position
activates the KEY INPUT on the
rear of the 562E, and allows
externally-triggeredgating/
expansion. The EXT. KEY
switch position must be chosen
in order to use an external
signal, applied to the KEY
INPUT, to control the gating and
expanding action, or to route
the external key signal to the
output of the 562E. The BYPASS switch position disengages the expander and gate functions.
The INswitch position engages the expander and gate functions, using the 562E’s internal
sidechain signal to control the gating and expanding action. The INswitch position also
allows you to route the internal sidechain signal to the output of the 562E. The INswitch
positionisthe normaloperatingswitchsettingforthe562E.
Note If you set the EXT.KEY /BYPASS/INswitch 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.switchpositionisthenormaloperatingpositionforthe562E.
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.
Front Panel Overview Chapter 4
HIGH CUT
WINDOW
MAX
20K
4K
ADVANCE
OFF
40K
400Hz MIN
LOW CUT
OUTPUT
200Hz15Hz
ASSIGN
20Hz 50Hz
EXT.KEY KEY LISTEN
1K10Hz
IN GATE/EXP.
BYPASS W/FILTER
CH1 SIDECHAIN PROCESSING
1K

562E
5
(dB)
THRESHOLD
ABOVE
BELOW
0
T
I0N
d
B)
-40 +20
A
CHANNEL 1
TIME E
X
500ms
HOLD
TIME
ATTACK
TIME
60ms 1 Sec
RELEASE
2.5 Sec4 Sec300ms 50ms 30msAUTO
GATE RANGE
EXPANDER RATIO
0
E
1:3
S
ec 80dB
(dB)
THRESHOLD
ABOVE
BELOW
-10
30
X
12
3
REDUCTI0N
GAIN (dB)
-40 +20
60
F
GAIN REDUCTION LED display- The GAIN REDUCTION display
indicates how much the expander/gate has reduced the level
of the input signal.
ABOVE/BELOW LEDdisplay- The ABOVE LED indicates that
the input signal is above threshold. The BELOW LED indicates
that the input signal is below threshold.
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
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
timeofzero.
HOLD TIME control - Determines the amountof 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
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.
The Expander/Gate Controls
THRESHOLD control - Sets the signal level below which the expander/
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.

562E
6
Rear Panel Overview Chapter 5
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 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.
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.
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 repro-
duced on the back panel of the 562E.
Note: Remember to set the front panel EXT. KEY/BYPASS/INswitch to the EXT.
KEY position when using the KEY INPUT.
BALANCED/UNBALANCED OUTPUT - 1/4-inch tip-ring-sleeve
(TRS)phonejack,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.
BALANCED OUTPUT -XLR-3maleconnector,wiredPin
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.
E562 WINDOWING EXPANDER/GATE
MANUFACTURED IN LYNNWOOD, WASHINGTON USA
U
AC INPUT
18 WATTS
MAXIMUM
FABRIQUÉ AUX E.-U. PAR SYMETRIX INC., LYNNWOOD, WA USA.
RÉFÉREZ TOUTE RÉPARATION À UN TECHNICIEN QUALIFIÉ.
CHANNEL 1 OUTPUT
BALANCED
BALANCED/
UNBALANCED
KEY
INPUT
SIDECHAIN
CHANNEL 1 INPUT
UNBALANCED
BALANCED/
BALANCED

562E
7
The Controls in Detail
Threshold
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.
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
THRESHOLDcontrol to “0dB”, andthe EXPANDER RATIOcontrol for a 1:3ratio. 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.)
GateRange
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 adjust-
able 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.
Chapter 6
AUDIO INPUT
LEVEL
THRESHOLD LEVEL
GATE CONTROL
VOLTAGE
AUDIO OUT
ATTACK
RANGE
CONTROL
HOLD
RELEASE

562E
8
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 above-
threshold 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 HOLD TIME 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).