371 SPL Computer A P P L I C AT I O N S Restaurants Retail Stores Casinos Offices The Symetrix 371 SPL Computer automatically raises and lowers sound system levels in response to changes in ambient noise conditions. Designed for installations featuring foreground music and/or paging, it ensures that music and announcements are always clearly audible and distinct, but never too loud. Proprietary AmbiSense™ technology enables the 371 to continuously monitor changing ambient noise levels—not just during gaps in the audio program—so it can respond quickly to sudden changes. A simple set of step-through menus displayed on the front panel LCD guides you through setup of the 371. You set the parameters of the acoustic environment and then set the way you want the unit to respond to changes in it. In operation, the 371 tracks environmental noise levels, internal signal levels and all the control settings. It makes appropriate gain changes whenever it finds measured noise levels that deviate from the stored performance characteristics. Menu adjustments determine how much the gain is changed, and how quickly that change occurs. Transit Stations Hospitals Simple calibration, precise performance, and value priced. Backed by our 15-year history of SPL processing innovation, the Symetrix 371 offers a complete and affordable solution for audio level management. F E AT U R E S Uses Microphone for Noise Sensing The 371 uses an external microphone to measure changes in the ambient noise level. Continuously Monitors Proprietary AmbiSense™ technology responds to Ambient Noise Levels environmental noise changes in real time—not just during gaps in audio program. Headphone Monitoring Monitor the sense signal using a separate front panel headphone output. Sense Signal 3 Operating Modes Display numeric reading and relative bargraph of the signal appearing at the sense terminals. Easy Calibration Perform calibration under typical installation conditions. No waiting for the quietest or noisiest ambient environment. Phantom Power Sense input provides microphone with 15V phantom power. Enable or disable through front panel menu adjustment. Ratio Adjustment Choose an adjustment ratio of SPL change vs. program level change. Gain Controls Set minimum and maximum limits for SPL gain range between +20 to –30 dB. Active—Indicates continuous measurement of the ambient noise level. Adjust gain of sense input and line output through menu selection. Connect an external trim pot to the 371's rear panel to control output gain remotely. History—Displays the lowest and highest SPL readings from when the unit was last reset. Bypass—Bypasses the gain control of the SPL controller and the AGC. Signal Path Controls mono or stereo signals through Euroblock connectors. Averaging Time Choose integration time of the running average SPL. Ducker Control Ducker input provides momentary reduction of program level (from 0 db to –40 dB) and inhibits sense operation for the duration of externally supplied control signal. R E A R PA N E L SIGNAL FLOW DIAGRAM LINE INPUT LEFT 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 BAL INPUT VCA LINE OUTPUT LEFT VCA LINE OUTPUT RIGHT RMS DETECT LINE INPUT RIGHT BAL INPUT DUCK / PAGE TRIGGER INPUT BAL INPUT AVERAGE LEVEL DETECT ADJUST SPL CPU CALIBRATE REMOTE GAIN TRIM DC AMP MENU EXIT MENU NEXT PHANTOM POWER SENSE INPUT MIC /LINE INPUT SENSE GAIN RMS DETECT SENSE MONITOR VOLUME BANDASS FILTER SENSE HEADPHONE AC C E S S O R I E S 19" Rackmount Tray height is 1U #RM-3 Filler Panel covers unused half of rack tray #FP-3 Y Power Cable connects a 371 with any other 300 Series product #PY-3 RC-3 Remote Control controls one volume channel #RC-3 S P E C I F I C AT I O N S Input/Output Maximum Input Level Program Input Impedance The Ambient Level Controller (ALC) shall control the output level of the sound system in response to the observed acoustical noise level within the controlled space during system operation. The ALC shall utilize an external microphone to sense the ambient noise level. These measurements shall be made continuously. The ALC shall accommodate musical or paging program signals. Provision shall be made for the user to monitor the audio signal used by the ambient sense system by using headphones. The ALC shall provide useradjustable parameters to alter the way that it responds to changes in the ambient noise level. These parameters are: minimum and maximum gain through the device, gain:sense ratio, and averaging time. In addition, the ALC shall provide active mode, bypass mode, and a history mode that collects and displays ambient noise history from the controlled space. The sense input shall accept either mic or line level signal. The sense input gain shall be adjustable, and 15 volt phantom power shall be available. A master output level control shall also be provided. The ALC shall provide two independent line level balanced inputs and outputs that control two audio signals. The maximum input level shall be +20 dBu and the maximum output level shall be +26 dBu (+22 dBm into 600 ohms) balanced. The balanced input impedance shall be 20,000 ohms and the output source impedance shall be 200 ohms balanced, 100 ohms unbalanced. The gain control range shall be –30 dB to +20 dB. The frequency response shall be 20 Hz to 20 kHz +0/–1 dB with THD+N less than 0.025% at +4 dBu over the same range of frequencies. The output noise of the device shall be less than –95 dBu (20 kHz noise bandwidth, unity gain). The input and output configuration shall be active balanced. All connections shall utilize barrierstyle terminal strips. In addition to the audio input/output connections, there shall be a connection provided for a ducker input. The ducker circuit will have an adjustable threshold and will inhibit response to changes in ambient level when signals applied to the ducker input are above the threshold level. A front panel power indicator shall be provided. A liquid crystal display shall be provided to communicate operating parameters and setup information with the user. A lockout function shall be available to prevent parameter setting changes by unauthorized users. The ALC shall occupy half of the width of one rack space and shall be housed in a metal enclosure. It shall use an external, safety agency approved, power supply. The Ambient Level Controller shall be the Symetrix model 371 SPL Computer. +20 dBu balanced, +20 dBu unbalanced >20 k ohms balanced, >10 k ohms unbalanced Input Common Mode Rejection >40 dB Maximum Output Level Output Impedance Connections +26 dBu balanced (20 k ohm load) Line Inputs, Sense Input, Ducker Control, +22 dBm balanced (600 ohm load) Remote Gain, Line Outputs 200 ohms balanced, 100 ohms unbalanced Power In Euroblock 7-pin DIN Headphone 1/4 in. TRS, will drive mono or stereo headphones Performance Data Program Frequency Response Program Path THD+N Output Gain Limits Sense Channel Frequency Response Sense Channel Gain Additional Headphone Monitor Gain Program Channel Output Noise Master Output Level Adjustment Range 20 Hz to 20 kHz, +0, –1 dB <0.025% (+4 dBu in, +4 dBu out) Physical Size (H x W x D) –3 dB at 300 Hz and 6000 Hz 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 +20, –30 dB Shipping Weight 4.5 lbs./ 2.03 kg selectable, 0 dB to +70 dB 28 dB maximum –95 dBu @ unity gain, typical +/–10 dB internal, +10 dB to –50 dB remote Symetrix, Inc. 6408 216th St. SW Mountlake Terrace WA 98043 USA Electrical Power Requirements PS-3 PS-3E Tel 425.778.7728 Fax 425.778.7727 www.symetrixaudio.com 10 W maximum, Symetrix PS-3 or PS-3E only 115 V, 60 Hz AC nominal 230 V, 50 Hz to 60 Hz AC nominal © 2001 Symetrix, Inc. All rights reserved. All specifications are subject to change without notice. Symetrix products are manufactured in the USA.
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