Valley International GATEX Noise Gate/Expander Operating Instructions

GATEX
Four ChannelNoiseGatelBxpander
OPERATING
INSTRUCTIONS
616 BrodleyCourt, Fronklin,TN 37064
WLLEY
INTERNANONAL.
INC.
o FAX(615)370-se07
(615)370-s90r
GATEX NOISE GATE/EXPANDER
1.
1. 1
General
Information
DESCRIP"TION
The Valley International, Inc. Gatex consists of four independent channels,
each capable of performing noise gating, expansion, keying, and envelope
following.
Selection of operating modes is very straightforward
thanks to the 3ttHardtt noise gating is
position
Mode switch.
achieved by placing the
switch in the gate position,
while I:2 expansion is accomplished in the
ttsofttt
exp 1 position.
2:3 expansion may be selected for apparen[ noise
reduction purposes by placing the switch in the exp 2 position.
Ful1 parametric control
front
is provided by three conti-nuously variable
panel controls.
Therefore, while remaining easy to operate, the-Gatex
offers sophisticated
control capability
to a1low successful application
for the most demanding situations.
The Gatex will
also accept external
signal sources in order to accomplish
keying.
By positioning
the Source switch in the key position,
sil external
audio slgnal will
trigger
the gating or expansi-on action of the device.
An easy-to-read
three LED display a11ows the operator to rnonitor the opttf
eration of the Gatex at a glance.
The green LED indicates
a
u11 ontt
or unity gain condition.
Ye11ow provides visual indication
of ongoing
expansion, while red shows maximum attenuation
as determined by the range
control.
Balanced input circuitry
capable of operation to levels of +24 dB is employed to assure compatability
recording and broadcast
with professional
equj-pment. The output line driver circuit
can deliver
+21 dB into 600
loads or transformers.
ohm resistive
Excellent
RFI suppression is incorporated on all inputs and outputs.
The package desi-gn of the Gatex a11ows instant
Hookrack installation.
connectors
up is quickly accomplished thanks to use of I/4" ring/tlp/sleeve
for all inputs and outputs.
RF attenuation
The package provides excellent
supby virtue
RF and transient
of its steel and alumj-num construction.
pression is also incorporated
in the Gatex power supply.
I.2
Note:
SPECIFICATIONS
The deslgnalion dB refers to 0 dB =0.775 Vrms.
made with rms-responding meters in 20 klHz noise
fications
subject to change without notice.
Noj-se measurements
bandwidth.
Speci-
Input
Input
Irnpedance:
>90 kohm balanced, >45 kohm
unbalanced
M a x i m u mf n p u t L e v e l i
+24 dB
External Input Impedance:
>90 kohm balancei,
unbalanced
>45 kohrn
o
External
-4O dB minimum for keying
Input Sensitivity:
0utput
Output Impedance:
S40 ohm, unbalanced
MaximumOutput Level:
+2L dB into
Quiescent Distortion:
<0.047" L kHz THD @ unity gain
with 0 dB input
< O . I % S M P T EI M D @ u n i t y g a i n
with 0 dB input
Output Noise and Hum:
@ unity gain <-83 dB 20 Hz to 20 kHz
@ shut off <-110 dB 20 Hz to 20 kHz
Expander Attack Ti-mes:
Program dependentn nominally
100 usr 5 lilsr 10 ms
Expander Slopes:
Nominally 1:10 (gate), LzZ (etp 1)'
2:3 (e*p 2)
Threshold Range of Adjustment:
-40 dB to +20 dB
R a n g e r o r M a x i m u mA t t e n u a t i o n :
0 dB to -80 dB
RFI Rejection:
@ unity gain, RF applied to signal
100 mV pk
input dlfferentially,
w/s07" AM @ I kHz. Output noise
increase <3 dB in 20 kHz noise
bandwidth, AM I kHz tone <-70 dB
at output
600 ohm or greater
Electrical
95-L4O Vac 4 3 - 6 2 H z i 1 9 0 - 2 5 0 V a c
43-62 Hz; L 2 V A m a x .
Power Supply Mains R e q u i r e m e n t :
Mechanical
Front Panel Controls:
-40 dB to +20 - dB ,
THRESHOLD
R E L E A S E0 . 0 5 s t o 5 s / 2 0 d B
RANGE0 dB to -80 dB
Front Panel Switches:
in/out /key (Source)
gatelexp L/ exp 2 (Mode)
tton"
Three LED display j-ndicates
t
t
e
x
p
a
n
d
t
'
(ye1low), and
(green),
m a x i m u mg a i n r e d u c t i - o n ( r e d ) , a s
d e t e r m i n e d b y t h e R A N G Ec o n t r o l
Metering:
I/4" diameter, 3 conductor jacks;
requires MIL-PJ 051, Switchcraft
#482 or equivalent, or Switchcraft
#260 or equivalent mating plugs
Connectors:
-4-
t
[.
P ac k a g i n g
Case and Rack:
Painted steel and anodized
aluminum rack package 1.75trH x
19" W x 8.5' fD (44mmH x 48 2m m WX
216mmD)
RF Attenuation
(package) :
0.100 MHz to 400 MHz electrical
field, )50 dB
Weight:
7 1b. (3.18 ke)
Shipping Weight:
L 2 . 5 1 b . ( 5 . 7 k g)
1 .3
INTRODUCTION
TO NOISE GATINGAND EXPANSION
A noise gate is an audio signal processing device that turns off or greatly
attenuates
a signal when the 1eve1 fa1ls below a user adjustable
threshold;
therefore
when the signal 1evel is below threshold,
it will
pass through
the device greatly
attenuated
so that low-level
hiss, noiser of leakage
will
not be heard.
When the signal is above threshold,
the noise gate
will
have no effect
on the signal,
and passes it through at unity gain.
Because a noise gate can be set, according to its 1eve1 sensitive
nature,
to discriminate
between desired audio signals and unwanted audio and ambient noise such as tape recorder hiss, ground hums, background room noise
and leakage from other instruments,
when properly
adjusted the device passes
what you want to record or to be heard ln a live situation,
and red.uces the
volume of or eliminates
undesired signals.
Percussive signals, due to their typically
short decay time, are the
easiest to process with a noise gate, while sustained signals,
due to
their unpredictability
and wide dynamic range, will
generally be more
difficult
to process.
Consider that a snare drum produces a series of
high-1eve1 transj-ents that normally fade away very quickly.
Subjective
tttightnessttwill
not be achieved if the drum resonance lasts too 1ong.
A noise gate with the threshold set at a relatively
high leve1 will
bring
the decay down quickly
after
each impact, thereby achieving
the desired
tttighttt
sound.
During the attack or ttturn ontt period,
the noise gate cannot remove
background noise, because it reacts to overall
leve1.
Due to this fact,
a noise gate may be only marginally
effective
on sustained instruments,
such as an organ or strings,
where unwanted noise may be heard through
the music.
And, i-ts appearance in time with the musi-c will
most assuredly prove more displeasing
than its presence in an unprocessed form.
Such ttmodulationtf of the noise floor
is a common shortcoming of dedlcated
noise gates when used on instruments
with substantially
long sustaj-n and
decay times.
The problem nay be partially
overcome by the use of relatively
long release times.
The release time of a noise gate is defined
as the rate tmevice
ffiru*
attenuation
after
the
signal which caused the device tottrttu.k'r
of turn otr is removed. The
majordisadvantageofusingagat"ffi.'gre1easetimesonsustained
instruments
is that a large portion
of the extraneous sounds and noj-se
which the gate is employed to eliminate
is passed through unaffected.
The most effective
method of reduclng unwanted noise from signals which
exhibit
long sustain and decay times is s><pgnsron. Expansion is so named
-5-
l,
F
I
to expand the dynamic range of
because the processor used is configured
of the signal I s highest 1eve1 to its lowest
the signal r or the ratio
perceptible
level.
This is accomplished by increasing
the gain of the
j
n the 1eve1 of the
expander by a fixed amount in response to an increase
F
o
r
i
f
a
the signal exhibits
signal being directlv
expanded.
example,
relative
i-ncrease in 1evel of 10 dB, the expander may increase its gain
This scheme obviously will
increase the dynamic range of the
by 20 dB.
j
u
s
t
signal being processed, but it
as obviously has a serious drawback:
the electrical
simply not a1low unconstraints
of any audio system will
quickly
headroom, thus the processing devicer oL expander, will
limited
run out of available
gain having reached a point after which additional
i-ncreases in input signal 1eve1 can no longer cause an increase in output signal 1evel because the device is already operating
at its maximum
signal
Thus the headroomr or -fgserve available
output 1evel capacity.
to
The solution
1eve1 above the normal operating
leve1, is exhausted.
this dilemma is a process called do-wnwardexpa,nsion.
Let us asume that
theexpanderisadjustedSothat etat0dB.A'ysigna1 appearing at the input with a leve1 of 0 db or greater will
cause the
expanderfs gain control element to exhibit
unity gain, thus the signal
passes through the device unaffected.
Now, assume the signal fa11s below
0 dB. The expander control circuitry
directs
the gain control device to
reduce its gain r of to attenuate
the signal by some preset amount f o.t
setting
each 1 dB decrease of the input signal 1eve1 below the threshold
of 0 dB.
This results
in the output 1evel of the device decreasing proportionally
more than the corresponding
decrease in input signal_.levg.l-.
If the control
circuitry
element to attenuate
directs
the gain control
the signal by 1 dB for each 1 dB of decrease in input signal 1eve1 below
the threshold,
the result
is, predictably,
a 2 dB decrease in output 1eve1
(1 dB input decrease minus 1 dB due to attenuation)
for each decibel decrement in the signal below threshold.
The ratio
of decrease below threshold of the input signal 1eve1 to the decrease in output signal leve1 is
the
the characteristic
slope of the expander.
In the example stated,
expansion slope is I:2 (t'one to twott) since a l dB decrease in input signal leve1 below the threshold setting
results
in a 2 dB reduction in output signal 1evel.
In this manner, the Gatex, ES well
increases the dynamic range of the
limitations
of direct expansi-on.
as all other top quality
processed signal without
expanders,
the serious
between expanding the
It must be noted that there exists a vast difference
noise.
dynamic range of the processed signal,
No existing
and eliminating
ttnoise reductionrt
system can discriminate
between signal and noise, passing
A11 noise reduction
noise in real time.
only the signal while eliminating
schemes use expansion or a combination of expansion and compression to
ttstretchtt
in a perthus resulting
the dynamic range of the input signal,
ttapparenttt
ceived or
reduction of noise level in the processed material.
upon the
The effective
use of a noise gate or an expander is contingent
ratio
between the nominal
existence of acceptably high signal-to-noise
operating leve1 of the system used and its quiescent,
or residual noise
1eve1:
Employment of expanders or ttgatestt provides a very useful method
in
of extending the dynamic range of the processed program thus resulting
reduction in percej-ved noise 1eve1s, but no device will
a noticeable
Iteliminatett noise.
in
The incorrect
use of these devices of ten results
objectionable
modulati-on and ttpumpingtt of the undesired noise
and obtrusive
and extraneous signals which these devj-ces are intended to eliminate.
j-nBearing this warning in mind, please carefully
study the following
structions.
-6-
)
2. L
Installation
and Use of
Gatex
C ON N E C T IONOF GA T EX
The Gatex quad noise gatefexpander incorporates
quasi-balanced
(ground
sensing) inputs for each channel to assure easy interfacing
to both ba1anced and unbalanced sources.
The output line driver
sections provide
sufficient
power capability
to drive resistive
loads or transformer networks with impedances of 600 ohm or greater to a maximum average 1eve1
of +2I dB (ref. 0.775 Vrms) thus allowing Gatex to be connected to all
types of professional
and semi-pro equipment.
Use of commonly available
I/4" 3-clrcuit
phone jacks for all inputs and outputs perrnits the Gatex
to be quickly and easily incorporated
in any audio system.
Illustrations
2-I and 2-2 show preferred methods of connecting Gatex
to balanced and unbalanced sources,
It should be noted that Gatex is
not designed to be driven by devices incorporating
line 1eve1s less than
-10 dB, such as musical instruments and microphones.
When usi-ng Gatex
to expand or gate musical instruments or microphones, the device should
be inserted after the preamplifier
to assure best signal-to-noise
performance.
In order to eliminate
ground current hum 1oops, the Gatex 0 Vdc reference,
or signal ground, is isolated
from the ac nains safety ground.
The operator should be aware that the 0 Vdc references
of all four channels are
connected internally,
thus care should be taken if Gatex is used to interconnect several signal chains exhibiting
different
ground potentials.
If
the signal sources feeding Gatex exhibit
hum due to ground current
loops
when directly
i-nterconnected, the operator should experiment by disconnecting shleld grounds at the Gatex inputs or at the outputs of the sources
feeding Gatex to achieve best results
when Gatex is in the signal chain.
The preferred method is to a11ow the output device of the =y"iu* (console,
power sflP, etc.)
to become the central
ground point and then to disconnect
the shields at the outputs of devices feeding Gatex, keeping in mind that,
due to the unbalanced output line driver circuitry
used 1n Gatex, the 0 Vdc
reference of Gatex will
assume the potential
of the ground exhibited
by
the device or devices sourced bv Gatex.
2.2
U S E O F G A T E XA S A N O I S E G A T E
Perhaps the most commonuse of noise gates is in tttighteningtt percussion
instruments.
Most recording engineers prefer to mike individual
components
of a drum kit in such a manner as to record the kick drum on a single track,
the snare on another, and so onr so that the sound of the kit may Uu tightly
controlled
during mixdown.. While in theory the multi-source
technique provides the engineer and producer with a valuable tool to control
the sound
of the kit despite the vagaries of room or booth acousti-cs, in practice
the leakage between microphones used to individually
record the var1ous
components of the drum kit propels the scienc.e of recording the kit on
multiple
integral
tracks into the realm of arcane arts.
After such extreme
measures such as feather pi11ows, baffles,
clip-on microphones, etc. fai1,
the recording engi nssr 1s faced with two distinct
choices:
he may either
accept the problers and hope that,
by some quirk of fate,
the final
mix is
acceptable,
or he may use noise gates to minimize the leakage.
A knowledgeable recordlng engineer rori11invariably
choose the latter
alternative:
experience in the field
proves conclusively
that engineers and producers
develope white hairs and ulcers in inverse proportion
to the number of
noise gates available
to mike andfor mix the drum kit.
Because drums
-7-
GATEXINPUT CONNECTIONS
To Gatex
Balanced Source
PREFERRED
3 CIRCUITPLUG
\
I
,
Balanced Source
To Gatex
/
2 CIRCUITPLUG
ACCEPTABLE
OF GATEXTO BALANCEDSOURCES
FIGURE2.I CONNECTION
To Gatex
Unbalanced Source
IEFERRED
3 CIRCUITPLUG
To Gatex
Unbalanced Source
2 CIRCUITPLUG
ACCEPTABLE
SOURCES
OF GATEXTO UNBALANCED
FIGURE2_2 CONNECTION
-8-
possess both an extremely high transj-ent content and a very short
ti-me, they lend themselves well to noi-se gating r or expansion at
exaggerated slopes.
decay
The Gatex, in its ttgatett mode, is an ideal processor for isolating
the
microphones used to record a drum kit.
The attack circuitry
compensates
for slight
differences
in rise time and peak leve1 inherent
in the style
of the drummer, and the exclusi-ve Program Controlled
Sustain a11ows the
engi-neer to either
fo11ow the natural
decay of the drumr or to shorten
the decay time to practically
nothing.
By manipulation
of the threshold
and release controls
the engineer or producer may accentuate,
for the
example the ttclaptt of the kick drumr oL soften the sound to a du1l thump.
To gate a drum kit microphone, the operator should insert
Gatex in the
signal chain following
the microphone preamp and EQ, if used, select gate
on the Mode switch,
and in on the Source switch.
The Range control
"f,oufO
be turned fully
counter-dockwise
to BO dB.
Set the Release control
to
.5. s/20 dB (mid-ralge)
initially,
and while listening
to the monitors.
ad3ust the Threshol? control unt:-L rhe desired ;;;;d- r" obl;tnlo*."" fnL
Release control
may now be adjusted to retain
or e1j-minate the natural decay of the drum.
In mixdown, the Gatex may be inserted
either
in the
pre-fader
patch pointr
or between the line patch output of the mixing console and the recording
ACN. In use for live performances,
the Gatex may
be inserted either in the pre or post-fader
patch point in the live console,
or directly
following
the microphone preamplifier
section.
When gating during multi-track
mixdowns, some pumping of tape hiss may be
evident as each single track is monitored,
however when the entire mix is
heard, the effect
will
probably not be noticeable.
Somewhat less dramatj-c
ttshut-offtr
maybe obtained, if desired, by re-adjusting
the Range control,
thus limiting
the maximum attenuation
to some value other than the 80 dB
shut-off
attenuation
which the Gatex is capable of performing.
2.3
USE 0F I:2
E X P A N S I O N( e x p 1 )
When general noise reduction
is required
to eliminate
ambient noi-ses
such as musical instrument amplifier
buzz, aj.r conditioning
rumble, and
other 1ow 1eve1 sounds such as tape hiss and leakage, it is usually desirable
to gently attenuate the unwanted sor:nds by use of L:2 expansion.
This Gatex operating mode is of particular
interest
to those who record
live performances r or operate sound reinforcement
systems in a concert
environment.
fn such applications,
the use of noise gates, with their
ttturn-ontt
well-defined
points and high slopes, contributes
to the sensation that the signal is being turned on and off.
This effect,
while
perfectly
innocuous when processing highly transient
sounds such as those
produced by percussion i-nstruments, is very annoying when accompanying
a vocal or string
sound.
By allowing
unobrusive attenuation
of 1ow-1eve1
in the absence of the desired si-gna1, I'.2 expansion can greatly
enhance
the signal-to-noise
ratio of a multi-track
mix or multi-microphone
live
system without creating the sensation that each source is being ttswitchedtt
off and on.
To configure the Gatex for I:2 expansion, select expl r^rith the Mode switch,
and set the Release control
initially
ll! with the Source switch,
to .5 s/
20 dB.
Adjustment of the Threshold control will
determine which signals
are passed through Gatex at unity gain, and which signals are attenuated.
Because the characteristic
slope of the Gatex in exp 1 is I:2, as the
input signal 1eve1 fa11s below the Threshold setting,
it will
be attenuated
so that for each 1 dB of 1eve1 decrease below threshold,
a 2 dB decrease
-9-
The Range
will
occur in the signal 1eve1 appearing at the output.
of
will
determine the point at which the attenuation
setting
control
the Threshold control so
setting
After first
stop.
the signal will
the
that the average 1eve1 of the desired signal passes unattenuated,
f
o
r
t
h
e most
R
e
l
e
a
s
e
c
o
n
t
r
o
l
R
a
n
g
e
a
n
d
c
o
n
t
r
o
l
t
h
e
s
h
o
u
l
d
a
d
j
u
s
t
operator
provide attenuation
will
pleasing sound.
The best release time setting
the sensation that the signal is being
of unwanted sounds without creating
ttpumped" up and down in leve1.
the highest
As in all audio processitg,
!
0
n
1
y
experience
e
a
r
i
s
t
h
e
p
r
o
p
e
r
d
e
v
i
c
e
t
h
e
o
p
e
r
a
t
i
o
n
o
f
o
n
authority
results.
yield completely satisfactory
will
gained through experimentation
b
o
t
h
the
p
e
r
f
o
r
m
i
n
g
e
x
p
a
n
s
i
o
n
,
I
:
2
The operator should note that when
have a prowill
setting
and the Release time setting
Threshold control
obtai-ned, and the
nounced effect
on both the amount of noise reduction
of the
There is no single optimum setting
audibility
of the process.
o
f
signals.
t
y
p
e
s
p
r
o
c
e
s
s
a
l
l
controls
to effectively
and unobtrusively
settings
c
o
n
t
r
o
l
require different
Strings and horns, for example, will
g
u
j
t
a
r
s
.
such as
vocal mikes or plucked instruments,
than will
2.4
U S E 0 F 2 2 3 E X P A N S I O N( e x p 2 )
to the recording
The subtle application
of expansion provides many benefits
or expansion at
While noise gatingr
engineer or broadcast operator.
ttsofttt gatingr or expansion
exaggerated slopes of 1:100, I:20, etc, and
noise reduction
at gentler slopes of Iz4 and Iz2 offer highly effective
these schemes offer
recording
and live performances,
during multi-track
To achieve apparent
litt1e
advantage when used on mixed program material.
the action of the processor
noise reducti-on in mixed program material,
the perceived dynamic
alter
must be unobtrusive.
It cannot noticeably
unattenuate
yet it should substantially
range of processed material,
wanted 1ow-leve1 signals such as tape hiss, record surface noise, etc.
ltsLretchingtt
By unobtrusively
during quiet passages in the program material.
Gatex, when used in the exp-Z mode,
the dynamic range of mixed material,
for mixed sources withcan provide 10 to 2A dB of apparent noise reduction
ttencode/decodett systems.
The gentle expansion
out the i-nconvenience of
Sustain a11ows the Gatex to
slope in conjunction
with the Program Controlled
the
perceptibly
shortening
with long decay times without
expand material
saY,
containing'
times found in material
natural
sustain or reverberation
release cirExpanders not incorporating
a pianor of in mixed material.
cui-try which modifies release time according to the content of the material
sound to the processed
processed tend to impart a certai-n ?fartificialtt
material
due to the fixed release rate.
by use of gentle expansion, the operaTo perform apparent noise reduction
and in with the Source switch.
exp 2 with the Mode switch,
tor must select
to just below the nominal
The Threshold control
should be set initially
The
level,
for example, 3t 0 dB for a +4 dB line feed.
1i-ne operating
set to .5 s/ZO dB, and the Range
Release control
should be initially
may be set between 10 and 15 dB.
control
the output of the Gatex, the operator should now adjust
While monitoring
to obtain the most pleasing sound.
the Threshold and Release controls
due to expansion may be
occurring
The amount of apparent noise reduction
of the Source
judged by alternately
selecting
the in and out positions
ci-rcuitry.
swj-tch, thus engaging and disengaging the expander control
the signal is passed
When the Source switch is in the out position,
ttbypassedtt
through the VCA at unity gain, thus the processor is effectively
It should be noted that
since no dynamic processing is taking place.
determine the
will
the setting
of the Threshold and Release controls
-10-
most effective
apparent noise reduction.
I,rlhile the Range control
setting will
affect
the audibility
of the processing.
Best results
generally
will
be obtained when a moderate amount of expansion, as
indicated
by the ye11ow LED status indicator,
is taking p1ace, and
when 10-15 dB of maximum attenuation
is allowed as determined bv the
Range control setting.
2.5
KEYING, ENVELOPE FOLLOWING, AND OTHER SPECIAL FUNCTIONS
Keving is defined as operation
of a noise gate in such a manner that
the presence of an external
audio signal is used to ttturn ontt the signa1 being processed.
For example, if a bass guitar
track is required
to appear in synchronization
with the appearance of the kick drum in
the mix, this effect
may be obtained by inserting
the Gatex in the bass
guitar
signal chain, then ttmultingtt the kick drum track line to the
The operator then selects
the gate position
of
!ry input of the Gatex.
the Mode switch,
and the key position
of the Source swiiEhr.
The Threshold control
is adjusted so that the kick drum turns on the bass guitar'
signal.
The Release control
is adjusted to impart the desired decay
characteristics
to the bass guitar
signal.
The Range control
will
usually
be set at or near maximum attenuation
for best isolation.
Envelope Following
is defined as a process in which the 1evel and dynamic
characteristics
of a signal are made to followr
or duplicate
those of
another external
signal.
Envelope following
may be considered ttsofttt
keying, and is frequently
used as such, but its greatest usefulness is
found in electronic
music and in the creation
of special effects
wherein
an instrument
having limited
dynamics, such as an organ or polyphonic
s y nt h e s rz e r
i s c a u s e d to fol l ow
the dynamj -cs of a vocal track or drum
track.
Envelope following
is performed with Gatex by inserting
Gatex in the
signal chain of the instrument
being processed.
The external
signal
whose dynamics are to be duplicated
is fed to the key input.
The
oper a to r
th e n s e l e c ts
e x !- I w i th the Mode sw i tch,
and l gl
w i th the
Source switch.
The fftresftofO control
is adjusted so that the externa1 signal causes a ful1 on condition
on high level peaksr 8S indicated
by the green LED status indicator.
The Release control
initially
is
set ful1y counter-clockwise,
or to .05 s/20 dB, and the Range control
is set for 60-80 dB.
While monitoring
the output of Gatex while in
operation,
the Threshold and Release controls
are then adjusted to
achieve the desired effect.
Control
of
Reverb Decav Times
By inserting
the Gatex in the echo return line of a recording
console,
denser returns may be achieved by offering
precise control
of the reverberation
decay time.
This application
enhances the sound of less
expensive reverberation
systems.
The reverberation
system is set for
a reasonably long decay time, and the Gatex is used in either
the
exp 1 or exp 2'mode.
The Source switch is set to the in position.
The Threshold control
is adjusted to a point near Lhe nominal operati-ng
1eve1 of the return 1ine.
The Range control is initially
set to 60 dB.
By monitoring
the processed return at the output of Gatex, the Release
control
is adjusted to provide the desired decay rate.
The Threshold
and Range controls
may require readjustment
to result
in a more pleasing
sound.
Correct control
settings
will
be determined by experimentation,
the desired effect
being that the return decay may be varied by adjusting
the Release control
without altering
the tonal quality
of the processed
return signal.
-11-
3.
Operation
Circuit
block diagram of one channel of the
the functional
Figure 3-l illustrates
and converter section produce a dc voltage that is
The rectifier
Gatex.
This dc
analogous to the 1og of the signal 1eve1 present at its input.
which determines the slope
circuitry
voltage is processed by the control
charges the
circuitry
The control
of the expander and the attack time.
is
The capacitor
associated with the track and hold circuit.
capacitor
sink is
The release current
sink.
discharged via the release current
which derives its i-nputs
circuit
by a two quadrant multiplier
controlled
susand the program controlled
potentiometer
from the release control
are performed
operations
algebraic
After appropriate
tain circuitry.
voltage and the voltage derived from the range control
with the dc control
sum of the two sources is applied to the
potentiometer,
the algebraic
amplifier.
People TA-101 voltage controlled
V
a
1
l
e
y
p
o
r
t
t
h
e
o
f
appropriate
l
e
v
e
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o
l
t
a
g
e
d
c
o
n
l
y
a
f
f
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c
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s
w
i
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c
h
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p
a
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a
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d
c
o
n
t
r
o
l
s
A11 front
a
u
d
io
t
h
e
i
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l
e
m
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n
t
s
t
h
e
o
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y
t
h
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s
c
i
r
c
u
i
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r
y
,
c
o
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t
r
o
l
plied to the
f
a
m
o
us .
V
C
A
'
P
e
o
p
l
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V
a
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y
t
h
e
i
n
p
u
t
a
m
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f
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,
signal chain are the
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r
a
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p
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o
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i
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o
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n
a
l
a
u
d
i
o
the
thioughout
is unsurThe result
free performance, and the line driver circuitry.
e
f
f
ective
c
o
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o
n
v
e
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i
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,
i
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p
e
r
f
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and
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p
erformance
l
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k
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a
n
d
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h
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d
i
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r
e
absent
package; noticeably
ttlow-costtt gates using FET or photo-resistor
technology.
by other
exhibited
-
| conf rol
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Vrect.
Thresh.
Range
Rel.
j
o
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K,.ll
o
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A
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l
3.
Operation
Circuit
block diagram of one channel of the
the functional
Figure 3-l illustrates
and converter section produce a dc voltage that is
The rectifier
Gatex.
This dc
analogous to the 1og of the signal 1eve1 present at its input.
which determines the slope
circuitry
voltage is processed by the control
charges the
circuitry
The control
of the expander and the attack time.
is
The capacitor
associated with the track and hold circuit.
capacitor
sink is
The release current
sink.
discharged via the release current
which derives its i-nputs
circuit
by a two quadrant multiplier
controlled
susand the program controlled
potentiometer
from the release control
are performed
operations
algebraic
After appropriate
tain circuitry.
voltage and the voltage derived from the range control
with the dc control
sum of the two sources is applied to the
potentiometer,
the algebraic
amplifier.
People TA-101 voltage controlled
V
a
1
l
e
y
p
o
r
t
t
h
e
o
f
appropriate
l
e
v
e
ls apv
o
l
t
a
g
e
d
c
o
n
l
y
a
f
f
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t
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w
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p
a
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a
n
d
c
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r
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s
A11 front
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l
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t
s
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o
n
l
y
t
h
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s
c
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i
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,
c
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t
r
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plied to the
f
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m
o
us .
V
C
A
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o
p
l
e
V
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l
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y
t
h
e
i
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p
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t
a
m
p
l
i
f
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r
,
signal chain are the
_a
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d
t
roublet
r
a
n
s
p
a
r
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n
c
y
f
o
r
i
t
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w
o
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d
p
r
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f
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s
s
i
o
n
a
l
a
u
d
i
o
the
thioughout
is unsurThe result
free performance, and the line driver circuitry.
e
f
f
ective
c
o
s
t
c
o
n
v
e
n
i
e
n
t
,
i
n
a
p
e
r
f
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r
m
a
n
c
e
and
passed functionality
p
erformance
l
a
c
k
l
u
s
t
e
r
a
n
d
t
h
e
d
i
s
t
o
r
t
i
o
n
a
r
e
absent
package; noticeably
ttlow-costtt gates using FET or photo-resistor
technology.
by other
exhibited
-
| conf rol
".\
Vrect.
Thresh.
Range
Rel.
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4.
4.T
Mai ntenance
REPAIRS
There are no user serviceable parts in Gatex. Repairs should be referred
to a competent electronic technician.
A schematic diagram and parts
overlay are included in Section 5 of t,his manual as a troubleshooting
aid to those users with sufficient
technical background to perform field
service.
CAUTION: Disassembly of the enclosure will expose hazardous line
Refer servicing to competent technical personnel.
4.2
voltages.
ADJUSTMENT
OF CONTROL
REJECTION
The trimmer potentiometer, which adjusts the amount of control voltage
feedthrough in each VCA, is accessible through the rear panel, and is
labelled Cntl.-_B"L
The control rejection characteristics
o f t h e V a l l e y:
People 1a-1ffi \tffi1s
quite good, but the long-gsrn stability
of Lhe
adjustment depends to some degree on component aging and temperature,
therefore the operator may desire to re-adjust this control periodically.
Degraded control rejection will result in a "thumptt in the audio signal
when the Gatex trattackst'; it will be especially noticeable in the gate
and exp I modes.
To adjust the control rejection in the field,
the operator should disconnect the audio input from Gatex. A high leve1 (+4 dB to +20 dB)
'drum
'sn'b're"-track,
signal, preferably a kick
br
is f ed to Gatex via
its Key fnput.
The Gatex Source switch is placed in the kev positj.on,
the Mode switch in gate.
Set the Release time control fully counterclockwise (.05 s/20 dB), the Range control fu1ly counter-clockwise (80 dB)
and adjust the Threshold control for maximumongoing expansion as indicated by flashing of the three status indicator LEDts. While monitoring the audio output, adjust the control rejection trimmer poLentiometer
for minimumsignal 1eve1. Note that the signal present at the output
in the configuration will sound very badly distorted:
that is normal.
Bench adjustment of control rejection requires the same set-up, but a
low-frequency signal (50-100 Hz) is fed to the Ksy Input, and the audio
output is measured eiLher with an oscilloscope 6i-ac uoftmeter, and the
control rejection tri-mmer is adjusted for minimumoutput voltage 1eve1.
4.3
WARRANTY
Va11ey People, Inc. warrants its products and their related enclosures
and power supplies to be free from defects in work-manshipand material
under normal use and service.
Saj-d warranty is to extend for a period of
twelve months after date of purchase. In the case that a Va11ey People,
Inc. product or any of its related enclosures or power supplies is belj-eved
to be defective, same may be returned wiLh transportation prepaid to Valley
People, Inc., within twelve months after date of purchase, accompanied by
proof of purchase. If the product is found by Valley People, Inc. ts inspection to be defective in workmanship or material, it will be repairedt
or replaced (at Va11eyPeople, Inc. ts election) free of charge and returned
transportation prepaid, to any point in the United States.
If inspection
by Va11ey, Inc. of such products does not disclose any defect in workmanship or material, Va1ley People, Inc.rs regular charges will apply.
This warranty is expressed in lieu
of any and all
-13-
other warranties,
whether
4.3 WARRANTY
Warranty
VALLEY INTERNATIONAL, INC. warrants its products and their relatedenclosuresand power suppliesto be free from defectsin workmanship
and material under normal use and service. Said warranty is to extend for a period of twelve months after date of purchase. In the case that
a VALLEY INTERNATIONAL, INC. product or any of its relatedenclosuresor power suppliesis believed to be defective, samemay be returned with transportationprepaid to VALLEY INTERNATIONAL, INC., within twleve months after date of purchase,accompaniedby proof of
purchase. If the product is found by VALLEY INTERNATIONAL, INC.'s inspection to be defective in workmanship or material, it will be
repaired or replaced (at VALLEY INTERNATIONAL, INC.'s election) free of charge and returned, transportation prepaid, to any point in
the United States.If inspectionby VALLEY INTERNATIONAL, INC. of suchproductsdoesnot discloseany defect in workmanshipor material,
VALLEY INTERNATIONAL, INC.'s regular chargeswill apply.
This warranty is expressed in lieu of any and all other warranties, whether expressed or implied, and the sole liability of VALLEY
INTERNATIONAL, INC. under this warranty is to either repair or replace (at VALLEY INTERNATIONAL, INC.'s election) the product or its related enclosure or power supply. Any incidental damages are expressly excluded.
The foregoing warranty is VALLEY INTERNATIONAL,INC.'s
are negated and excluded.
sole warranty, and all other warranties, expressed, implied, or statutoty,
Inc.
ValleyInternational,
616 BradleyCourt
Franklin,TN 37064
-14-
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