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Symetrix 572 SPL User Manual

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572 SPL Computer

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  • Page 1 572 SPL Computer...

  • Page 2: Table Of Contents

    Symetrix part number 53572-0A00 Subject to change without notice. ©1999, 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.

  • Page 3: Chapter 1 Introduction

    Chapter 1 Introduction The Symetrix 572 SPL Computer is an automatic level controller that maximizes intelligibility by changing gain in proportion to environmental noise level changes; in essence, controlling the volume of the background/paging system by measuring the volume of the ambient noise and then adjusting the system gain accordingly.
  • Page 4 Do You Have The Right Unit? Symetrix makes two different SPL computers: the 571 and the 572. Although both units perform essentially the same task, they are different. The 571 requires an external sensing microphone(s) to monitor ambient conditions. The 571 works in real time;...

  • Page 5: Chapter 2 Operator Safety Summary

    Chapter 2 Operator Safety Summary Equipment Markings connection, by way of the grounding conductor in the power cord, is essential for safe operation. CAUTION Grounding The chassis of this product is grounded through the grounding conductor of RISK OF ELECTRIC SHOCK DO NOT OPEN the power cord.

  • Page 6: Chapter 3 Setup

    Setup Chapter 3 What You’ll Need To install a 572, you’ll need the following items: The 572. Access to the power amplifier input (line level), mixer output (line level), power amplifier output (speaker level), speaker line connections. Background music feed (usually the mixer line output). Paging feed (line or mic level or both) preferably separate from the background music feed.
  • Page 7 MANUFACTURED IN LYNNWOOD WASHINGTON, FUSE UNITED STATES OF AMERICA POWER THIS UNIT CONTAINS NO USER SERVICABLE PARTS. FABRIQU AUX E.-U. PAR SYMETRIX INC., LYNNWOOD, WASHINGTON. É R F REZ TOUTE R PARATION UN TECHNICIEN QUALIFI . É É É À...

  • Page 8: Calibration Checklist

    Calibration Settings Table Set the controls and switches on the front and rear panel as shown below. Front Panel Control Setting Rear Panel Setting switch out (NORM) Connect to power amplifiers. YPASS UTPUT gain 12:00 o’clock Connect balanced, low-impedance page microphone here. switch out (HIGH) Connect line-level music source here.

  • Page 9: Chapter 4 Front & Rear Panel Overview

    Chapter 4 Front & Rear Panel Overview CALIBRATE OPTIONS SAMPLE PAGE OVER RATIO (dB) INTERVAL (MIN) MUSIC (dB) BYPASS PAGE SENSE LEVEL SET (dB) GAIN GAIN (dB) GAIN BYPASS HIGH PAGE/MUSIC MODE NORM A B C D INPUT ERROR BYPASS SPL COMPUTER SENSE MUSIC/...
  • Page 10 LYNNWOOD WASHINGTON, FUSE UNITED STATES OF AMERICA POWER THIS UNIT CONTAINS NO USER SERVICABLE PARTS. FABRIQUÉ AUX E.-U. PAR SYMETRIX INC., LYNNWOOD, WASHINGTON. RÉFÉREZ TOUTE RÉPARATION À UN TECHNICIEN QUALIFIÉ. Rear Panel Overview Feature Description [Please send in the completed warranty card.]...
  • Page 11 Terminal Strip Connections Feature Term. # Description TB2(10,9) Connect speakers used for sensing and sound system PEAKER usage here. Speakers may be speaker impedance or constant voltage. TB2(8,7) Connect amplifier here. Amplifier output may be speaker impedance or constant voltage. TB2(6,4,2) Connect to circuit ground inside the 572.

  • Page 12: 572 Basics

    572 Basics Chapter 5 An SPL computer periodically samples the ambient sound in a room. Having this information, the SPL computer uses a combination of historical data and information stored during the unit's initial calibration to determine the optimum gain setting for the sound system. How Does It Work? The 572 uses the combination of analog circuitry and digital circuitry under the control of a microprocessor.
  • Page 13 Where Should I Put the Sensing Microphone? The sensing microphone needs to “hear” the ambient sound within the controlled space. In large spaces it may be better to only use a few of the sound system speakers for sensing. In the remain- der of this manual, we’ll use the term “sensing speaker”...

  • Page 14: Chapter 6 Technical Tutorial

    Symetrix equipment inputs are designed to bridge (be greater than 10 times the actual source impedance) the output of whatever device drives the input. Symetrix equipment outputs are designed to drive 600-ohm or higher loads (600-ohm loads are an archaic practice that won’t go...
  • Page 15 The two facts that you need to derive from this discussion are: Match signal levels for best headroom and signal-to-noise ratio. For audio, impedance matching is only needed for antique equipment and power amplifier outputs. In all other cases, ensure that your inputs bridge (are in the range of 2 to 200 times the output source impedance) your outputs.
  • Page 16 Condenser Microphones and the 572 The 572’s paging microphone input is not equipped with phantom powering for condenser micro- phones. If you wish to use a phantom powered microphone you must provide a power source exter- nally. Note The microphone input is direct coupled: there are no dc blocking capacitors. If you use a phantom powered microphone, the phantom supply voltage must be 15 volts or less.

  • Page 17: Chapter 7 Using The 572

    Chapter 7 Using the 572 This section is intended for more advanced users. If you are a first-time user, we recommend that you start out by using the procedure found in Chapter 3, “Setup.” Installation The 572 may be installed freestanding or rack- mounted. Multiple unit installations require no additional breathing space between units.
  • Page 18 PAGE MIC LINE GAIN OUTPUT PR ES S PAGE MIC SPEAKER FROM PAGE LINE INPUTS HARDWARE BYPASS PAGE OVER MUSIC SAMPLE PAGE INTERVAL DETECTOR RATIO SENSE GAIN MULTIPLEX AND A/D CONVERTER MUSIC BYPASS MUSIC LINE INPUT "GAIN" DISPLAY EXTERNAL CONVERTER RELAY CONTROLL MICROPROCESSOR...
  • Page 19 Calibration Calibration must be performed when the ambient noise in the loudspeaker coverage area is at its normal minimum level for the area. (NOT dead quiet, unless that is normal.) Complete all input and output connections. There must be program audio present at a connection before calibration can be completed.
  • Page 20 indication should fall between the 5 dB and 26 dB LEDs on the calibration display. If necessary, use the S switch on the front panel. Don't leave S engaged as it prevents ENSE ENSE normal operation! Option C enables sample averaging. If option switch C is down, the 572 computes the gain change solely on the basis of the current sample.
  • Page 21 572 system will increase disproportionately with the noise level of the noisy equipment. Disconnect the speakers from the system, connect them to the input of a balanced, low-impedance microphone preamp (like the Symetrix 302 shown in Figure 7-3) and listen in headphones to what the 572 “hears” when it is sampling! Check Chapter 9 in this manual.
  • Page 22 ) are not connected. When the 572 samples it only looks at the single OWER speaker for a reference level of ambient noise. In these cases the Symetrix 571 should have been specified for the job. Using the 572 With Planar or Low Output Speakers Some speakers make lousy microphones.
  • Page 23 The 572 provides a contact EXTERNAL D.C. COIL RELAY closure through a transistor LOW(-) switch to operate the external LOW(-) HIGH(+) relay. This closure can be HIGH(+) found on the rear panel barrier 1N4002 OR EQUIVALENT strip TB2-5 which is labeled DIODE .
  • Page 24 Calibration Issues If you want the 572 to operate correctly then proper calibration is an absolute necessity. The calibration procedure establishes the high and low limits (level-wise) for the sound system. It also establishes the baseline noise level for the space. Therefore, it is imperative that the calibration be performed at a time when the space is at or near its nominal minimum and that you have the ability to operate the sound system at its maximum desired level for short periods of time.

  • Page 25: Chapter 8 Applications

    Chapter 8 Applications Here are a few applications that the 572 lends itself to. It’s important in every one of these applica- tions (actually, any 572 application) that the unit has been properly calibrated and that the program material has sufficient silence periods for ambient sensing. Factories In this application, the 572 monitors the ambient noise level within a factory and adjusts the sound system’s operating level to ensure that it is always audible.
  • Page 26 Off-Track Betting Parlors and Casinos In these facilities, the crowd reaction is likely to be sudden and intense. If the program material doesn’t have long enough silent spots for sensing, the 571 is a better idea since it works in real time.

  • Page 27: Chapter 9 Troubleshooting

    Chapter 9 Troubleshooting Symptom: Probable cause There is no output signal: Check cables and connections. Are inputs driven by outputs, and outputs driving inputs? Determine that there really is a signal coming from the source and that it is getting to the 572. Is the signal chain after the 572 functioning? Check for AC power presence.

  • Page 28: Chapter 10 Specifications

    10 kilohms. The device shall be housed in an all steel chassis designed to be mounted in a 1U (1.74") space in a standard 19" rack. The ambient sensing automatic level controlling device shall be the Symetrix model 572 SPL Computer.

  • Page 29: Chapter 11 Warranty & Service

    In no event will Symetrix be liable for any incidental or consequential damages including but not limited to damage for loss of...
  • Page 30 (you wouldn't believe how many units are returned with bent ears). We won't return the unit in anything but Symetrix packaging for which we will have to charge you. Of course, if the problem turns out to be operator inflicted, you'll have to pay for both parts and labor.

  • Page 31: Appendix A External Sensing & Multi-Unit Installations

    Appendix A External Sensing & Multi-Unit Installations switch D enables the external sense input and prevents both periodic sensing and silence- PTION based sensing. When O switch D is UP, sensing only occurs when TB2-3 is held low PTION (grounded). The unit remains in sense mode for as long as TB2-3 is grounded and you must ground the external sense line for a minimum of one second.
  • Page 32 FROM LINE INPUTS DOWN SPEAKER RELAY SENSE OUTPUT PAGE SPARE CNTRL TRIG OPTIONS MASTER FROM LINE INPUTS A B C SPEAKER RELAY SENSE OUTPUT PAGE SPARE CNTRL TRIG OPTIONS SLAVE UNIT #1 FROM LINE INPUTS SPEAKER RELAY SENSE OUTPUT PAGE SPARE CNTRL TRIG...

  • Page 33: Appendix B Connections

    TERMINAL STRIP (+) = HIGH (-) = NOT USED = GROUND FROM NON-TRANSFORMER (ELECTRONIC) BALANCED OUTPUT (TYPICAL OF SYMETRIX PRODUCTS) TO UNBALANCED IN MALE TS PLUG FEMALE XLR TIP = HIGH PIN 1 = GROUND + LOW SLEEVE = GROUND +...
  • Page 34 Symetrix, Inc. 6408 216th St. SW Mountlake Terrace , WA, 98043 Tel: (425) 778-7728 Fax: (425) 778-7727 Website: http://www.symetrixaudio.com Email: symetrix@symetrixaudio.com...

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