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 Input Common Mode Rejection >20k ohms balanced, >10k ohms unbalanced >40 dB 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 Performance Data 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. 6408 216th St. SW Mountlake Terrace WA 98043 USA Tel 425.778.7728 Fax 425.778.7727 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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