User manual | 308 VCA Volume Control/Loudness EQ

308
VCA Volume Control/Loudness EQ
A P P L I C AT I O N S
Retail Stores
308
VCA VOLUME CONTROL/
LOUDNESS EQ
Restaurants
PWR
Boardrooms
Offices
The Symetrix 308 VCA
Volume Control/Loudness
EQ provides remote level
control and loudness EQ for
engineered sound systems
featuring foreground or
background music and/or
paging. The 308 uses two
voltage-controlled amplifiers
(VCAs) to control the volume
of a stereo signal in a single
zone or mono signals in two
zones.
It features a loudnesscompensating EQ circuit that
improves the sound quality of
background music systems,
which typically play music at
lower levels. The 308’s
Loudness EQ action refines
the frequency response of
program signals by reducing
the midrange when volume is
lowered. This effectively
enhances the bass and treble
frequencies, and improves
the sound of low volume
audio. The Loudness EQ
compensation automatically
follows the VCA level
adjustments, and disappears
at higher listening levels.
Remote volume
control for
virtually any
installed
sound system
ACCESSORIES
F E AT U R E S
Zone Operation
Control the volume of a stereo signal in a single
zone or mono signals in two zones.
Loudness EQ Circuit
Enhances program frequency response as volume
is lowered.
Remote Level Control
Installers set the amount of
Loudness EQ compensation
via rear panel trimpots. This
feature is easily defeated if
remote volume control
without loudness compensation is desired. For tamperproof operation, all audio and
control connections are
provided on removable
Euroblock connectors
mounted on the rear panel.
The compact half-rack size of
the 308 allows it to be shelfmounted next to a mixer/amp
or it may be rackmounted.
Volume control by use of Symetrix RC-3 Remote
Control, or linear potentiometers* located up to
500 ft. from unit, or DC control voltages of 0 to
10V range*. Stereo signals may be adjusted by one
control.
Audio Inputs & Outputs Rear-panel Euroblock connectors accept balanced
or unbalanced line-level signals.
*User-supplied
19" Rackmount Tray
Height 1U.
Filler Panel
Covers unused half of rack tray.
Model FP-3
Y Power Cable
Connects a 308 with another 300
Series product to same power supply.
Model PY-3
For use with the 308.
Model RC-3
Remote Control
Model RM-3
CONTROL
POWER
INPUT
CONNECT TO
SYMETRIX
PS-3 OR PS-3E
POWER
SUPPLY ONLY.
EQ DEPTH
THIS PRODUCT CONTAINS NO USER SERVICABLE PARTS.
FABRIQUÉ AUX E.-U. PAR SYMETRIX INC., LYNNWOOD, WA USA.
RÉFÉREZ TOUTE RÉPARATION À UN TECHNICIEN QUALIFIÉ.
SIGNAL FLOW DIAGRAM
DEPTH
BALANCED
OUTPUT
SUBTRACT
EQ
VCA
BANDPASS
FILTER
EQ VCA
DC
CONTROL
10V REF
REMOTE
CONTROL
LEVEL VCA
DC
CONTROL
ONE CHANNEL
RAMP
OUT
1
2
AUDIO IN
1
2
A R C H I T E C T S A N D E N G I N E E R S S P E C I F I C AT I O N S
LEVEL
VCA
BALANCED
INPUT
AUDIO OUT
1
2
(VOLUME CONTROL POTS 10K OHMS LINEAR TAPER)
RAMP1 GND1 GND2 RAMP2 +24V
CTL1 +10V CTL2 GND
308
MANUFACTURED BY SYMETRIX INC. LYNNWOOD, WA USA
VCA VOLUME
CONTROL/
LOUDNESS EQ
R E A R PA N E L
The VCA volume control / loudness EQ
shall provide two channels of remote
level adjustment and automatic loudness EQ compensation for controlling
a stereo signal in one zone or mono
signals in two zones. There shall be a
voltage controlled amplifier (VCA) in
each channel controlled by either a 0
to 10 VDC ramp signal or by a 10k
ohms linear taper potentiometer or
other compatible remote control, such
as the Symetrix RC-3. Potentiometers
may be located up to 500 feet from
the VCA volume controller. The loudness EQ will be flat at full volume and
the output gain will be at unity. At
lower volumes, the loudness EQ shall
automatically effectively boost the
bass and treble frequencies by lowering the midrange response. The maximum midrange attenuation will be
–15 dB @ 1 kHz.
The VCA volume control / loudness EQ
shall provide two balanced line-level
audio inputs on Euroblock connectors.
The input impedance shall be at least
20k ohms balanced, 10k ohms unbalanced. The maximum input level shall
be +20 dBu balanced, +20 dBu unbalanced. There shall be two balanced
line-level audio outputs on Euroblock
connectors. The output impedance
shall be 400 ohms balanced, 200 ohms
unbalanced. The maximum output
level shall be +22 dBu balanced, +18
dBu unbalanced.
Screwdriver adjustable trimpots shall
be provided for selecting the amount
of loudness EQ compensation for each
channel. Nine inputs for remote control connections shall also be provided
on Euroblock connectors. These inputs
shall consist of: Ramp Out, Control In,
Ground for each channel; +10 VDC
Out; Ground; +24 VDC Out.
A front panel power indicator shall be
provided.
The frequency response shall be +0,
– 0.5 dB, measured between 20 Hz and
20 kHz. THD+N shall be less than
0.025% measured at unity gain. Power
consumption shall be 12W maximum.
The unit shall occupy half of the width
of one rack space. The physical dimensions shall be 1.75 in. (H) x 8.5 in. (W)
x 6.5 in. (D) / 4.445 cm (H) x 21.59 cm
(W) x 15.875 cm (D).
The VCA volume control / loudness EQ
shall operate by means of a Symetrix
PS-3 connected to 115 VAC nominal,
(95–130 VAC), 60 Hz or a Symetrix
PS-3E connected to 230 VAC nominal,
(165–255 VAC), 50 to 60 Hz.
The VCA volume control / loudness EQ
shall be a Symetrix model 308 VCA
Volume Control / Loudness EQ.
S P E C I F I C AT I O N S
Input/Output
Analog Control continued
Maximum Input Level
+20 dBu balanced, +20 dBu unbalanced
Gain
Maximum Output Level
+22 dBu balanced, +18 dBu unbalanced
Ramp Out
Input Impedance
Output Impedance
>20k ohms balanced, >10k ohms unbalanced
>40 dB
Performance Data
20 Hz to 20 kHz +0, – 0.5 dB
(with no equalization applied)
20 Hz to 20 kHz +0, –1.5 dB (at unity gain with max EQ depth)
THD+N
Connections
Inputs, Outputs, Control Ports
Euroblock
AC Power In
7-pin DIN
Physical
Size (H x W x D)
– 95 dBu typical at unity gain
Gain Control
0 dB (unity) to – 65 dB
Equalization
–15 dB max @ 1 kHz
1/2 rack unit
1.75 in. x 8.5 in. x 6.5 in. / 4.445 cm x 21.59 cm x 15.875 cm
<0.025% at unity gain, 0 dBu in/out
Residual Output Noise
Buffered duplicate of the Control In voltage
+24 VDC ±10%, 100 milliamps max continuous load
Auxiliary Power Out
200 ohms balanced, 100 ohms unbalanced
Input Common Mode Rejection
Frequency Response
Unity at +10 VDC and max attenuation at 0 VDC
Shipping Weight
Electrical
Power Requirements
PS-3
Analog Control
Control inputs accept any of
(a) 10k linear rheostat to ground
4.5 lbs.
PS-3E
12W maximum, Symetrix PS-3 or PS-3E only
115V, 60 Hz AC nominal
230V, 50 to 60 Hz AC nominal
(b) 10k linear potentiometer from +10 reference output to ground
(c) 0 to 10 VDC control voltage
(d) Symetrix RC-3 Remote Control
Symetrix, Inc.
14926 35th Avenue West
Lynnwood WA 98037 USA
Tel 425.787.3222
Fax 425.787.3211
www.symetrixaudio.com
© 2000 Symetrix, Inc. All rights reserved. All
specifications are subject to change without
notice. Symetrix products are manufactured
in the USA.

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