421m AGC-Leveler
Contents
1. Chapter 3 Front amp Rear Panel Overview This chapter provides a basic overview of the 421m by describing the input and output connec tions power connection operating controls and front panel LED indicators Front panel view left a C DOWNWARD EXPANDER NR AGC LEVELER o AUTO RELEASE RECOVERY THRESHOLD Vu RELEASE LEVEL RATE RATIO TARGET OUTPUT LEVEL 35 1 21 421m SR AS E Fast E 4 SLOW AGC LEVELER 2 45 EXPAND O O ACTIVE O O O AUTO BYPASS FAST SLOW LOW HIGH BYPASS 41 DECREASE INCREASE O Fi RECOVERY RATE TARGET EXPAND LED LEVELER button o UTPUT LEVEL DOWNWARD EXPANDER ACTIVE LED AGC AUTO RELEASE RATIO control THRESHOLD control control DOWNWARD EXPANDER RELEASE control DOWNWARD EXPANDER THRESHOLD Determines the level below which the downward expander operates which reduces the gain at a 1 2 dB ratio At the max CCW setting of the control the threshold setting is automatic determined by the setting of the AUTO RELEASE control In this case the downward expander acts more like a gate very high ratio NOTE the silence detector thinks that acoustic feedback is silence At the max CW setting the threshold setting is low enough that all signals are above threshold therefore the expander is bypassed DOWNWARD EXPANDER RELEASE Determines the rate of decay for the downward expander EXPAND LED Tells when the downward expander is active2. s enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons The exclamation point within an equilateral triangle is intended to alert the user of the presence of important operating and maintenance servicing instructions in the literature accom panying the product i e this manual Caution To prevent electric shock do not use the polarized plug supplied with the unit with any extension cord receptacle or other outlet unless the blades can be fully inserted Terms Several notational conventions are used in this manual Some paragraphs may use Note Caution or Warning as a heading Certain typefaces and capitalization are used to identify certain words These are Note Identifies information that needs extra emphasis A Note generally supplies extra information to help you to better use the 421m Identifies information that if not heeded may cause damage to the 421m or other equipment in your system Identifies information that if ignored may be hazardous to your health or that of others Controls switches or other markings on the 421m s chassis Caution Warning CAPITALS Boldface Strong emphasis Important Safety Instructions Please read and keep these instructions Heed and follow all warnings and instructions Install in accordance with the manufacturer s instructions Power Source This product is intended to op erate from a power source that does no
3. The fuseholder accepts 5 x 20mm diameter fuses For 117VAC operation the correct value is 0 25A 250VAC standard For 230VAC operation the correct value is 0 125A 250VAC standard Proper Microphone and Cable To prevent hazard or damage ensure that only microphone cables and microphones designed to IEC 268 15A are connected Operating Location Do not operate this equipment under any of the following condi tions explosive atmospheres in wet locations in inclement weather improper or unknown AC mains voltage or if improperly fused Do not install near any heat source such as radiators heat registers stoves or other appa ratus including amplifiers that produce heat Unplug this apparatus during lightning storms or when unused for long periods of time Stay Out of the Box To avoid personal injury or worse do not remove the product covers or panels Do not operate the product without the covers and panels properly installed Only use accessories specified by the manufacturer Clean only with a damp cloth User serviceable parts There are no user serviceable parts inside the 421m In case of failure refer all servicing to the factory Servicing is required when the 421m has been damaged in any way such as when a power supply cord or plug is damaged liquid has been spilled or objects have fallen into the ap paratus the apparatus has been exposed to rain or moisture does not operate normally or has been dropped
4. The mic level input shall accommodate 8dBu signals There shall be separate gain trim controls for the mic and the line inputs and the mic input shall provide 48v phantom power Overall frequency response shall be 20 Hz to 20 kHz 1dB measured at 4 dBm output There shall be no more than 0 02 harmonic distortion measured under the following conditions 4 dbu input 4 dBm output BYPASS switch out 1000 Hz Residual noise output shall be no greater than 90 dBm measured with a 20 kHz noise bandwidth When the unit is inoperative either by loss of power or viathe BYPASS switch the inputs and outputs shall be wired together There shall be no transients transmitted to the output terminals during either turn on turn off or bypass operation unless something upstream generates transients Access to the AGC s sidechain shall be provided via a single TRS female connector The ring connection shall be the sidechain output and the tip connection shall be the sidechain return The AGC shall be capable of operating by means of its own built in power supply connected to 115V nominal ac 105 to 130V 50 60 Hz 230V nominal 210 to 260V ac 50 Hz where applicable The AGC shall be listed by Underwriters Laboratories Inc UL or other equivalent nationally recognized safety testing agency The unit shall be a Symetrix Incorporated model 421m AGC Leveler etrix Troubleshooting Chapter 8 No output signal Check cables and connectio
5. and satisfactory proof thereof Symetrix will make every reasonable effort to ensure that parts are available to support the repair of our products under warranty In the event that a product or component part thereof becomes obsolete unavailable or irreparable Symetrix reserves the right to refund a prorated portion of the purchase price in full satisfaction of all warranty claims In order to serve you better we require that the Buyer shall prior to shipping Product to Symetrix for warranty service contact Symetrix and secure a Return Authorization Number that shall be included with the returned Product This will facilitate our efforts to keep track of your Product and process your warranty repair as quickly as possible Buyer will prepay all freight charges to ship the Product to Symetrix for warranty inspection and service This warranty is subject to Symetrix s inspection of the Product at its facilities and upon Symetrix s request satisfactory proof of purchase dated copy of original retail dealer s invoice Symetrix reserves the right to effect repairs to the product with reconditioned components parts Products once repaired under warranty will be shipped to Buyer freight prepaid by Symetrix via United Parcel Service surface or any similar shipper to any location designated by buyer within the Continental United States At Buyer s request and expense Product will be returned via airfreight Outside the continental United States repair
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7. electronically balanced line level low impedance outputs XLR pin 1 is ground pin 2 is high and pin 3 is low The 1 4 connector tip is high ring is low and sleeve is ground The screw terminal output is wired in parallel to the and XLR connectors Rear panel view right TYPICAL CONNECTIONS XLR PHONE _ SIGNAL PINI SLEEVE 7 GROUND XLR PHONE SIGNAL PIN27 TIP HIGH XLR PHONE SIGNAL PINS RING LOW BALANCED UNBALANCED LINE INPUT BALANCED MICROPHONE INPUT PHANTOM LEVEL POWER TRIM m 48V LOF EARTH SIG GND GND epee S MIC INPUT connector LNE BUT nes LINE INPUT LEVEL TRIM MIC LEVEL TRIM LINE INPUT These connectors are electronically balanced line level bridging inputs The 1 4 connector tip is high ring is low and sleeve is ground The screw terminal input is wired in parallel to the 1 4 connector MICROPHONE INPUT This connector is a balanced low impedance input The female XLR pin 2 is high pin 3 is low and pin 1 is ground MIC LEVEL TRIM Adjusts the gain of the microphone preamp from a minimum of25dB to a maximum of50dB PHANTOM POWER Applies or removes microphone phantom power at the MICROPHONE INPUT connector gt Symetrix etrix Installation Chapter 4 Before you plug the 42 Im into a wall socket carefully read the information in the following chapter AC L
8. fight them and win with the 421m AGC Leveler Secondary Sound System Feeds Many sound systems derive secondary feeds for ancillary systems that serve related areas of a facility In arenas or large stadiums this might be the outer concourses PA shadow zones conces sion areas rest rooms dressing rooms etc In a church it might be the lobby or cry room Ina TV studio it could be the IFB interrupted foldback system Symetrix etrix Tape Duplication Anytime you change recording media especially between a professional format and a consumer format how about DAT to consumer cassette patch a 421m into the recording chain to perform a gentle squeeze to match the signal level to the input of the next device and peak limiting Try 2 1 RATIO setthe TARGET OUTPUT LEVEL control for the average level that you need and use the limiter to control the peaks Many churches record the Pastor s message sermon and make it available on tape by the end of the service Considering the speed with which this must occur a 421m might be just the thing to keep the average levels hot while still preventing overload Teleconferencing Many teleconference users want to record the content of the conference Of course audio levels are all over the map one participant shouts another is timid Try a 421m between the audio mixer and one track of the tape machine and another between the telephone interface and another track of the tap
9. with miscellaneous issues Of particular interest to sound system providers or installers is Title III which says that many of the places where you find sound systems must provide assisted listening devices for persons with sensory impairment Some of the solutions employed are headphone jacks at certain seats low powered AM or FM transmitters broadcasting to Walkman R type radios or to facility supplied radios and infrared transmission systems Regardless of the transmission method these systems all require a signal of reduced dynamic range so that the users can hear both the softest and loudest parts of a performance The 421m is ideally suited to this application Try moderate to high ratios 2 1 and up and long release times Pick an AUTO RELEASE level that keeps the AGC action somewhat unobtrusive Use the peak limiter to keep the transmitter out of clipping 10 Lectern Mounted Microphones A common and thoroughly vexing problem is that of the ubiquitous lectern microphone A staple of hotels public meeting places courtrooms and churches the podium microphone gets used and misused by one and all Anyone who uses a microphone has their own idea of how and where to place the microphone relative to their lips of course and how they should speak into it Some get their cues from TV which any self respecting audio person knows is usually wrong and some just make it up as they go Some stick the mike near their navel just like on T
10. 421m AGC Leveler Users Guide O Symetrix etrix Table of Contents Chapter 1 Introduction Chapter 2 Operator Safety Summary Chapter 3 Front amp Rear Panel Overview Chapter 4 Installation Chapter 5 Operation Chapter 6 Applications Chapter 7 Specifications Chapter 8 Troubleshooting Chapter 9 Warranty and Service Appendix 4 Declaration of Conformity April 2000 01 Symetrix Inc All rights reserved Symetrix Part Number 53421M0C00 The information in this guide is subject to change without notice Symetrix Inc shall not be liable for technical or editorial errors or omissions contained herein nor is it liable for incidental or consequential damages resulting from the furnishing performance or use of this material Mention of third party products is for informational pur poses only and constitutes neither an endorsement nor a recommendation Symetrix assumes no responsibility with regard to the performance or use of these products Under copyright laws no part of this user guide may be reproduced or transmitted in any form or by any means electronic or mechanical without permission in writing from Symetrix Inc If however your only means of access is electronic permission to print one copy is hereby granted i oN WY N 10 13 14 15 17 O Symetrix 6408 216th St SW Mountlake Terrace WA 98043 USA Tel 425 778 7728 Fax 425 778 7727 Email symetrix symetrixaudio com Chapter 1 Introducti
11. D all linked slave units revert to bypass when the bypass button on the master unit is out On any individual slave unit that has been STEREO LINKED STEREO LINK button OUT this button has no effect INPUT LED This meter indicates the input signal level to the 421m It is a VU calibrated peak reading meter OUTPUT LED This meter indicates the output signal level of the 421m It is a VU calibrated peak reading meter 4 Rear panel view left BALANCED UNBALANCED LINE OUTPUT 421m _AGCLEVELER Q Symetrix aan SIG EARTH au MANUFACTURED IN AC INPUT 4 N LYNNWOOD WA USA COMERTE GND GND 20 WATTS MAXIMUM POER Bee i 1 FABRIQUE AUX E U PAR SYMETRIX INC LYNNWOOD WASHINGTON ior Aun CONNECTOR REFEREZ TOUTE REPARATION A UN TECHNICIEN QUALIFIE SERIAL NUMBER AC INPUT connector STEREO LINK connector OUTPUT connectors AC INPUT This connector accepts nominal AC power sources of 115 volts or 230 volts see Appendix A Specifications for voltage tolerance ranges See chapter 4 Installation for details on the detachable IEC power cable SERIAL NUMBER Write this down in a safe place how about the front of this user s guide STEREO LINK This 5 pin DIN female connector is used to link two 421m s for stereo operation Refer to the STEREO INTERCONNECT section on page 6 for additional information OUTPUT CONNECTORS These are
12. ITER by adjusting the THRESHOLD control either for the absolute maximum output level desired as read on the threshold control s panel scale or as indicated on the peak re sponding output meter Set the SPEECH CURVE buttons as necessary and as required by the situation The 125Hz button removes boominess and some of the proximity effect caused by close talking a single D cardioid microphone such as a Shure SM 58 without making voices sound thin The 6kHz button removes sibilance and high frequency feedback without causing telephone voice 8 Note Do not use pink noise or sine waves for setup It simply will not work the ARM circuitry will think your signal is noise Use speech or music Helpful Hints Microphone Techniques Note The ability of the expander to discriminate between wanted and unwanted signals is partially determined by mic technique Be particularly careful of high frequency sounds entering the side or rear pattern of a cardioid mic Most cardioid mics exhibit a sharply rising off axis response charac teristic at higher frequencies Check the off axis curves in the manufacturer s literature If there s only a 3dB 6dB difference between the on axis frontal response and the off axis side or rear re sponse in the 5kHz to 10 kHz region high frequency sounds will be picked up by the mic thereby possibly preventing the downward expander from reducing unwanted sounds Use the mic s directional pattern
13. LEVELER ACTIVE LED Indicates the leveling activity Ifthe LED is off then the gain of the AGC Leveler is frozen at the last setting The signal level where the gain is frozen is determined by the AUTO RELEASE LEVEL control AUTO RELEASE LEVEL Determines the level that the input signal must exceed to allow the AGC Leveler to respond Ifthe signal level is below this threshold active LED OFF then the AGC gain is frozen and the AGC allows the signal level to fall to zero This keeps the AGC Leveler from undoing fades etc Another way to understand this control is to think of it in terms of the minimum signal level required to make the AGC Leveler try to maintain the Target Output Level Once the signal falls below the AUTO RELEASE setting the AGC Leveler allows the signal to decrease When the input signal exceeds the AUTO RELEASE setting the AGC Leveler once again tries to maintain constant output level RECOVERY RATE Sets the basic recovery time Fast for speech slow for music or music speech Fast might work for music in special applications RATIO Determines the input output ratio This control instructs the 421m how aggressively you want to maintain the target output level Using a 2 1 ratio a 2dB drop in the input level results in a 1dB drop at the 421m s output With a 4 1 ratio a 4dB drop at the input is limited to a 1dB decrease at the output The 421m computes the additional make up gain needed for the ratio setting and a
14. UTO RELEASE LEVEL control in the AGC Leveler section Then use the expander s RE LEASE control to prevent expander action during short pauses General PA System Considerations In a public address system it is important to ensure that feedback cannot occur when the AGC Leveler reaches a state of maximum gain for instance when the 421m is trying to boost the volume of a very quiet voice Avoid this by talking into the mic just loud enough for the ACTIVE LED to light Ifyou hear feedback then raise the AUTO RELEASE LEVEL until the feedback dies Lower ing the RATIO will also help Remember The ACTIVE LED does not have to be on constantly while signal is present In fact depending on your circumstances you may elect to set the AUTO RELEASE LEVEL high enough to prevent the 42 1m from responding to all soft voices Stereo Link And Bypass Switching The STEREO LINK and BYPASS buttons interact In stereo mode the designated master unit takes over all functions for both units including in bypass switching If the STEREO LINK button is in the out position the 421m is in slave mode which means the 421m gets its commands via the link cable from the master unit Note Ifa421mis placed in SLAVE mode and is not connected to another 42 Im via a linking cable the unit will remain in BYPASS mode regardless of the setting of its BYPASS button If there is a master unit connected then the BYPASS button on the master determines the status of the sl
15. V or is it that TV news types have their vocal chords somewhere new and others try to use it for a snack You get the idea What this means to you is roller coaster audio levels Try the 421m It will do for a lectern or other announce microphones what no compressor has ever done before consistent audio levels with increased freedom from feedback Some hints use moderate ratios 3 1 to 4 1 unless you want a really in your face sound Use either or both of the speech filter switches The AUTO RELEASE LEVEL affects the size of the microphone s pickup circle More CCW settings expand the circle allowing the 421m to raise lower level voices more remember it won t keep them from sounding distant or off mic Higher settings restrict the pickup range of the microphone so a weak talker won t be picked up as well unless they move in on the microphone to cause the gain to readjust to their voice level In noisy environments try a higher more clockwise setting You can use the downward expander in AUTO mode to gate the mike off when idle Ensure that the TARGET OUTPUT LEVEL isn t high enough to cause feedback when the AGC Leveler has fully engaged you can force a release by quickly turning the AUTO RELEASE LEVEL control and then returning it to its former setting Live PA Have you ever mixed live sound for someone who just can t play at the right level They re usually too soft when playing rhythm and too loud when playing leads A 421m can help
16. ake additions to or improvements to its product lines without making similar upgrades to Product purchased by Buyer Symetrix does not authorize any third party including any dealer or sales representative to assume any liability effect any repairs or modifications to the Product or make any additional warranties or representation regarding the Product or Product information on behalf of Symetrix Symetrix s total liability on any claim whether in contract tort including negligence or otherwise arising out of connected with or resulting from the manufacture sale delivery resale repair replacement or use of Product will not exceed the purchase price of the Product or any part thereof which gives rise to the claim In no event will Symetrix be liable for any incidental or consequential damages including but not limited to damage for lost revenue cost of capital claims of customers for service interruptions or failure to supply and costs and expenses incurred in connection with labor overhead transportation installation or removal of products or substitute facilities or supply houses as a result of Product failure This limited warranty gives Buyer certain rights Buyer may have additional rights under applicable law N etrix Servicing the 421m If you have determined that your 421m requires repair services and you live outside of the United States please contact your local Symetrix dealer or distributor for instru
17. ave gt Symetrix etrix Applications Chapter 6 An AGC Leveler has many applications in recording studios auditoriums or theatres commercial or industrial PA systems tape duplication systems and broadcast Here follows a small sample of applications Broadcast Telephone Line Driver At sometime or another every broadcast engineer ends up having to send audio down a telephone line Of course you need to keep levels hot but if you hit the line too hard the phone company frowns It s good practice to ensure that there is a hard limit to any signal that ends up going down a phone line The 421m is well suited to the task of unobtrusive yet unyielding control of audio levels As a starting point use the SLOW recovery rate low RATIO 2 1 and a low AUTO RELEASE LEVEL Set the TARGET LEVEL control for the desired average level into the line and then dial in enough peak limiting to keep the peaks under control You may want to back the TARGET LEVEL off slightly so that you don t need as much peak limiting Peak limiters are more inaudible if you only limit occasional peaks Conference or Courtroom Recording If you re recording conferences or courtroom proceedings you are faced with the same problem at the lectern microphone i e some people speak too softly while others are too loud If possible install a separate 421m on each microphone and feed the outputs of the 421m s into the line inputs of your mixer I
18. controls as follows DOWNWARDEXPANDER THRESHOLD Bypass DOWNWARDEXPANDER RELEASE Straight up AGC LEVELER AUTO RELEASELEVEL Straight up RECOVERY RATE In RATIO 4 1 TARGET OUTPUT Straight up SPEECH CURVE 125 Hz Out SPEECH CURVE 6kHz Out Apply an input signal to the 421m Observe the input and output meters there should be activity The input meter reads the actual input signal The output meter reads the actual output signal Both meters are peak responding and are calibrated in VU 0 VU 4 dBu 1 23V RMS Set the AGC Leveler by first adjusting the TARGET OUTPUT LEVEL control for the output level required Next decrease the setting of the RATIO control until you obtain the desired amount of dynamic range reduction Speech tolerates higher ratios than music Use a higher ratio 4 1 for stronger leveling action The difference between the two meters shows what the 421m is doing Re member that a 1 1 ratio setting amounts to BYPASS for the AGC Leveler Set the RECOVERY RATE button as required by the program material starting point FAST speech SLOW music SLOW speech and music In sound reinforcement applications set the AUTO RELEASE LEVEL control to limit the pickup range of the microphone Lower more CCW settings will increase the pickup range the level setting is lower therefore the AGC Leveler will track lower level signals and higher settings will force the user to be more on mike In recording broadcast or tape duplicat
19. ctions on how to obtain service If you reside in the U S then proceed as follows Before sending anything to Symetrix contact our Customer Service Department for a return authorization RA number The telephone number is 425 778 7728 or email tech symetrixaudio com In warranty Repairs To get your 421m repaired under the terms of the warranty 1 Call us for an RA number 2 Pack the unit in its original packaging materials 3 Include your name address daytime telephone number and a brief statement of the problem 4 Write the RA number on the outside of the box 5 Ship the unit to Symetrix freight prepaid We do not accept freight collect shipments Repairs made in warranty will cost you only one way freight charges We ll prepay the return surface freight If you send us your product in substandard packaging we will charge you for factory ship ping materials If you don t have the factory packaging materials please use an oversized carton wrap the unit in a plastic bag and surround it with bubble wrap Pack the box full of Styrofoam peanuts Be sure there is enough clearance in the carton to protect the rack ears you wouldn t believe how many units are returned with bent ears We will return the unit in Symetrix packaging Of course if the repair is due to operator error parts and labor will be charged In any event if there are charges for the repair costs you will pay for the return freight All charges wil
20. e machine Using separate 421m s and separate tape tracks will help if and when someone tries to transcribe the conference Keeping things separate also helps negate the 421m s tendency to bring the telephone interface s leakage trans hybrid loss up to the same level as the caller which isn t a good idea The 421m helps by keeping the signal levels more consistent from caller to caller which is a good idea Theatre and Auditorium Cue Systems An auditorium cue system consists of a microphone s mounted in the audience area of a theatre or auditorium that feeds an amplifier that drives speakers located in the backstage areas of the hall The potential dynamic range in this application is tremendous ranging from an empty room to an audience on their feet making a plea for an encore A 421m in conjunction with close miking of the person calling the cues can work wonders keeping this sort of system under control keeping the level high enough to be audible and low enough to not be annoying The downward expander can reduce the level when the room is very quiet to eliminate electronic noise yet open up if someone speaks Post Production A 421m can be invaluable in post production How about Use the 421m when transferring location sound tapes If you keep the ratio low you Il gain consistency with a minimum loss of dynamic range Use multiple 421m s to keep variousmix elements audible Try one on FX or Foley and on dialog If yo
21. ed or replaced products will be returned freight collect THIS WARRANTY IS EXPRESSLY IN LIEU OF ALL OTHER WARRANTIES EXPRESS OR IMPLIED ARISING BY LAW OR OTHERWISE INCLUDING WITHOUT LIMITATION ANY OBLIGATIONS OF THE SELLER WITH RESPECT TO CONSEQUENTIAL DAMAGES INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR USE AND OF ALL OTHER OBLIGATIONS OR LIABILITIES ON OUR PART AND WE NEITHER ASSUME NOR AUTHORIZE ANY OTHER PERSON TO ASSUME FOR US ANY OTHER LIABILITY IN CON NECTION WITH THE SALE OF THE PRODUCT THIS WARRANTY SHALL NOT APPLY TO THIS PRODUCT OR ANY PART THERE OF WHICH HAS BEEN SUBJECT TO ACCIDENT NEGLIGENCE ALTERATION ABUSE OR MISUSE WE MAKE NO WARRANTY WHATSOEVER IN RESPECT TO ACCESSORIES OR PARTS NOT SUPPLIED BY US THE TERM ORIGINAL PURCHASER AS USED IN THIS WARRANTY SHALL BE DEEMED TO MEAN THAT PERSON OR COMPANY THAT ORIGINALLY PURCHASED THE PRODUCT This Symetrix product has been designed and manufactured for use in professional industrial systems and is not intended for other usage This warranty only applies to Buyers using the Product in professional industrial systems With respect to others including but not limited to consumers for personal family or household use Symetrix expressly disclaims all warranties including but not limited to warranties of merchantability and fitness for a particular purpose and the express warranties as otherwise provided herein Symetrix reserves the right to modify the design or m
22. eeding it a clean signal The 421m doesn t power up or doesn t respond properly Consult a qualified service technician or the Symetrix factory Note Repeated fuse blowing is a sure sign of electronic distress Unplug the unit and make arrangements for repair Warning The fuse is located internally and lethal voltages are present inside the chassis The fuse is not considered user serviceable If the fuse is blown the 421m probably needs repair 14 Chapter 9 Warranty amp Service Warranty Following are the terms and limitations of the Symetrix warranty Symetrix Inc expressly warrants to the original purchaser Buyer subject to the terms and conditions set forth below that the Product will be free from defects in material and workmanship as a result of normal commercial use for eighteen 18 months from the date of shipment Some Symetrix products contain embedded software and may also be accompanied by control software intended to be run on a personal computer Said software is specifically excluded from this warranty Symetrix s warranty obligation is limited to the repair replacement or refund at Symetrix s sole discretion of the part or parts of the Product which may thus prove defective in materials or workmanship within one year from date of purchase under normal use and which our examination discloses to our satisfaction to be thus defective provided that Buyer gives Symetrix prompt notice of its warranty claim
23. f separate 42 1m s for each mic are not an option then place a single 42 Im between the mixer output and the input of the tape recorder Foreground Music The CD changer has propelled canned music into a new era The problem of course is the wide dynamic range of CD s coupled with the fact that different CD s as mastered at diverse and unpre dictable levels Most CD s simply have too much range for foreground or background music applications The 421m helps reduce the overall dynamic range while retaining some semblance of the music s original dynamics You can link two units together for stereo if desired There s probably no need to use the downward expander in this application so turn the THRESH OLD control to the BYPASS position Set the AGC Leveler RATIO to 2 1 and use the SLOW recovery rate setting Set the AUTO RELEASE LEVEL to 9 00 0 clock or lower Experiment with the PEAK LIMITER threshold and use the PEAK LIMITER only if necessary Americans with Disabilities Act The American Disabilities Act ADA of 1990 Public Law 101 336 affects any of us who supply equipment to or operate public gathering places There are five major aspects Titles to this law all of which have staged implementation dates Title I deals with employment issues Title II deals with public services Title III deals with public accommodations and services operated by private entities Title IV deals with telecommunications and Title V deals
24. ic range of wide range wideband audio signals providing peak limiting downward expansion and bandpass limiting filters The AGC shall occupy one rack space 1U The AGC shall be capable of controlling audio signals ranging from 70 dBu to 24 dBu and reducing their range by an input output ratio ranging from 1 1 to 4 1 The input output ratio shall be adjustable via a front panel control Fast slow response speed switching shall be provided to accommodate speech and music sources A target output level control shall be provided to shift the level of the output signal over anominal 20 dB range The release time of the AGC shall be controlled by the presence of input signal and the signal sensor shall be capable of discriminating between music speech and random noise or pure tones The threshold level of the signal sensor shall be adjustable via a front panel control and the presence of signals above the threshold setting shall be indicated via a green LED The AGC shall also contain an integral peak limiter having at least a 10 1 ratio and adjustable threshold level A green LED indicator shall be provided to indicate peak limiter activity The peak limiter threshold shall determine the absolute maximum output amplitude of the AGC Leveler regardless of other conditions The AGC shall also contain an integral downward expander having a 1 2 expansion ratio with threshold and release time controls Furthermore the downward expander shall be capable of operati
25. ine Connection A sticker on the right end of the unit as viewed from the front indicates the nominal voltage setting for the unit as it left the Symetrix factory If this does not correspond to the voltage setting for your locale then do not attempt to apply power to the 421m Instead return the unit to your local Symetrix distributor for modification or replacement The 421m is shipped from the Symetrix factory with a detachable AC power cable TEC standard included Depending on the intended destination the power plug is either the US type intended for 115VAC use or the Europlug type If the power cable s plug is not right for your locale then please contact your local Symetrix distributor for the proper cable Once you have determined that the 42 1m s operating voltage matches that of your locale and you are ready to begin follow these steps 1 Plug the socket end of the power cable into the recessed AC power receptacle on the back of the 421m 2 Plug the other end of the power cable into a three hole grounded outlet or power strip Warning The421misintended to be electrically grounded It has been provided with a three wire grounding plug a plug that has a third grounding pin This plug will fit only a grounded AC outlet This is a safety feature If you are unable to insert the plug into the outlet contact a licensed electrician to replace the outlet with a properly grounded outlet Do not defeat the purpose of the gro
26. ion applications the AUTO RELEASE LEVEL control sets the minimum signal level that the AGC Leveler will track If the input signal is music with a long fade the AGC Leveler interprets the fade as a decrease in signal level and raises the gain to try to maintain the level set by the TARGET OUTPUT LEVEL control In effect the AGC Leveler un does the fade which may or may not be allowable The AUTO RELEASE LEVEL control sets how far the signal level can fall before the AGC Leveler stops trying to raise the gain More CCW set tings lower this level which may be what you want if you re trying to recreate the long piano chord heard at the end of the Beatles song A Day In The Life Set the downward expander during program pauses to minimize noise buildup by adjusting the Threshold control until the expand activity LED illuminates Set the RELEASE control for the de sired release rate Use the AUTO position of the DOWNWARD EXPANDER THRESHOLD control for situations where the input signal is noisy hum hiss or feedback In AUTO mode the expander tracks the AGC Leveler s internal auto release monitor When the AGC Leveler releases the expander begins working at the rate set by the RELEASE control If the input signal contains acoustic feedback and nothing else above the auto release hold the auto release monitor ignores it which effectively stops the feedback before it has a chance to grow into something potentially damaging Set the OUTPUT LIM
27. l be COD unless you have made other arrangements prepaid Visa or Mastercard Out of warranty Repairs If the warranty period has passed you ll be billed for all necessary parts labor packaging materials and freight charges Please remember you must call for an RA number before sending the unit to Symetrix 16 Appendix A Declaration of Conformity Declaration of Conformity We Symetrix Incorporated 6408 216th St SW Mountlake Terrace Washington USA declare under our sole responsibility that the product 421m AGC Leveler to which this declaration relates is in conformity with the following standards EN 60065 Safety requirements for mains operated electronic and related apparatus for household and similar general use EN 50082 1 Electromagnetic compatibility Generic immunity standard Part 1 Residential commercial and light industry The technical construction file is maintained at Symetrix Inc 6408 216th St SW Mountlake Terrace WA 98043 USA The authorized representative located within the European Community is World Marketing Associates P O Box 100 St Austell Cornwall PL26 6YU U K Place of issue Mountlake Terrace Washington USA Authorized signature Dane Butcher President Symetrix Incorporated Symetr N eT Symetrix Inc 6408 216th St SW Mountlake Terrace WA 98043 USA Tel 425 778 7728 Fax 425 778 7727 Website http www symetrixaudio
28. most of your questions If not please feel free to contact our Customer Service department via phone fax or e mail for answers to your questions The numbers are Telephone 425 778 7728 Fax 425 778 7727 E mail symetrix symetrixaudio com Web site www symetrixaudio com rs PE de ime Oo Em 210 O 30 60 3 o Front panel 421m AGCLEVELER 6 Symetrix roux BALANCEDIUNBALANCED LINE OUTPUT SxANceD Nea en une wPuT AC INPUT USA j 9 aD p L Lynn 001 Ton E BALANCED MICROPHONE INPUT sa EARTH SG ee eo cw q TAM 20 WATTS MAXIMUM ses 2 L Rear panel etrix Operator Safety Summary Equipment Markings CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN 1O KEUUCE IHE RISK UF FIRE UR WARNING etectric shock Do nor Expose THIS EQUIPMENT TO RAIN OR MOISTURE RISQUE DE CHOC ELECTRIQUE NE PAS OUVRIR AVI SEE OWNERS MANUAL VOIR CAHIER D INSTRUCTIONS No user serviceable parts inside Refer servicing to qualified service personnel Il ne se trouve a l interieur aucune piece pourvant entre repar e l usager S adresser a un reparateur comp tent The lightning flash with arrowhead symbol within an equilateral triangle is intended to alert the user of the presence of uninsulated dangerous volt age within the product
29. ng automatically via the signal sensor circuitry A green LED indicator shall be provided to indicate downward expander circuit activity Bandpass limiting filters shall be provided having a lowpass characteristic of 24 dB octave at 6 kHz and a highpass characteristic of 12 dB octave at 125 Hz Both filters shall be capable of being used individually or simultaneously The AGC shall provide identical peak responding input and output level meters These meters shall be capable of responding to signals ranging from 54 VU to 12 VU 50 dBu to 16 dBu An output clipping indicator shall be provided The AGC shall provide facilities for stereo coupling two units via a shielded 5 pin DIN male to male cable A front panel switch shall designate which unit is the master and which unit is the slave The line level inputs shall be active balanced bridging designs terminated with 1 4 TRS female and screw terminals The mic level input shall also be an active balanced bridging design using a three pin XLR female AES IEC standard wiring The input circuitry shall incorporate RFI filters The outputs shall be active balanced designs having equal source impedances and terminated with 3 pin XLR AES IEC standard wiring and screw terminals A separate 1 4 TRS jack shall provide an unbalanced output The balanced line level inputs shall accommodate 24 dBu signals without distortion and the balanced outputs shall be capable of delivering 23 dBm into a 600 ohm load
30. ns Determine that there really is a signal coming from the source and that it is getting to the 421m Verify cables by patching input and output connections together at the unit Check for AC power presence Check input by plugging headphones halfway into the sidechain jack and listening for input signal this verifies that the unit is receiving signal Check output by plugging headphones into output jack Check downward expander threshold setting it may be too high for the current signal level Stuckin bypass mode Check setting of the STEREO LINK button In single unit mono systems on independently operating units and on master units the switch should be in the IN position Nolimiter action Check the threshold control setting Signal levels may be too low Don t try to calibrate with sine waves Use speech or music Distortion Is the incoming signal already distorted Listen up stream from the 421m or manually place the unit in BYPASS mode to determine that you are feeding it a clean signal Buzzin the output Check input and output connector wiring Check for ground loops between interconnected system equipment Are all system components on the same AC ground Noise hiss Check input signal levels and input level control settings The input may be too low in level If so boost the signal from your console or input source Is the input signal already noisy Listen up stream from the 421m to determine if you are f
31. nse suo ZFA nel dB 0 em Harmonic Distortion lt 0 05 20 Hz to 20 kHz 4 dBm 30 kHz bandwidth Typically lt 0 01 1000 Hz 1000 Ohm Source Impedance 10k Input Impedance Tip Receive Ring Send Downward Expander Residual Noise 90 dBu 20 kHz noise bandwidth Ratio 1 2 rms responding meter Threshold 50VU bypass to 20VU Auto Threshold Speech Curve Attack Time poe Type Switch selected cutoff filters allow tailoring LF and or HF Release Time Program dependant 0 3 3 5 seconds response for speech applications depending on amount and duration E equencies LF 125 Hz 12 dB octave HF 6 kHz 24 dB octave eas 1 1 to 4 1 Input Output Metering Auto Release Threshold 70 dBu to 30 dBu Es nine LED Ber GRR 12 ER Attack Time approximately 1 ms palletes Peak Release Time Program dependant 500 ms 5 seconds pai AUK E depending on amount and duration Caprag OBO ER dE Physical E Output wo ag Sze hwo 1 72 x 19 x 6 25 inches Pe Limir Ratio 10 1 4 37 x 48 26 x 15 875 centimeters i Shipping Weight 8 Ibs 3 63kg net Threshold 15VU to 23VU bypass Attack Time 1 ms for 90 gain reduction Electrical Release Time 0 8 seconds Connector EC 3 pole Power Requirements 117V nominal 107 to 125V AC 50 to 60 Hz 10 watts 220V AC 50 Hz 10 watts Note The maximum operating ambient temperature is 25 degrees C 421m Architects and Engineers Specifications The Automatic Gain Control AGC shall be a single channel model that reduces the dynam
32. on The Symetrix 42 Im is a wide range AGC Leveler a peak limiter and a downward expander that features a microphone preamp eliminating the need for a separate outboard microphone preamp in some applications The 421m reduces the dynamic range of its input signal by the amount of its ratio setting That is if the ratio setting is 2 1 then 40 dB of input range turns into 20 dB at the output A fast peak limiter puts an absolute ceiling on the output level so you know that peaks are held to the level that you set A downward expander reduces the gain when signal levels fall too low to process reducing the noise buildup at low signal levels Speech filters allow a reduction of reduction the bandpass of the 421m to minimize feedback or amplifier power waste caused by spurious out of band signals AGC Levelers can be used anywhere that you might need to reduce the dynamic range of an audio signal over a wide range of signal levels Possible applications include tape duplication especially cassette driving telephone lines driving broadcast or STL transmitters podium or lectern micro phones paging systems unattended sound systems and music recording The 421m is listed by Underwriters Laboratories Inc UL Samples of this product have been evaluated by UL and meet the applicable UL Standards for Safety We recommend that you read this manual from cover to cover Somewhere between the confines of the two covers you should find the answers to
33. pplies it to the VCA so that the output level doesn t change with the setting of the ratio control TARGET LEVEL Sets the desired output level gt Symmetrix etrix Front panel view right o OUTPUT LIMITER SPEECH CURVE SYSTEM EL THRESHOLD Vu 125Hz 6kHz Bypass NO 9 Q 900 o O INPUT LEVEL Aw 7A STEREOLINK BYPASS 3 ao Eles Ravens Rane ous 4 UMT 54 48 42 36 30 24 18 12 6 OVU 6 12 CLIP O ss ovas GOOOGOACOCO CO 0 OCourruttever OUTPUT LIMITER La filters BYPASS button INPUT LED m eter THRESHOLD LED 125 Hz high pass 6kHz low pass OUTPUT LIMITER THRESHOLD control STEREO LINK button OUTPUT LED meter OUTPUT LIMITER THRESHOLD LED Indicates peak limiting activity OUTPUT LIMITER THRESHOLD Sets the threshold of the peak ceiling limiter This works in conjunction with the leveler s ratio and target output level controls The 421m will not allow the peak limiter to be set higher than the setting of the target output level control If you think about it it would make no sense if you allowed peaks past the target output level SPEECH CURVE FILTERS The high pass filter button on the left has a 12 dB octave rolloff and the low pass filter button on the right rolls off at 24 dB octave STEREO LINK Sets the master slave relationship between 2 units The normal setting is IN BYPASS BUTTON This control hard wire bypasses the 42 Im If STEREO LINKE
34. re paralleled The unbalanced output is paralleled from the screw terminal output The 421 wants line level signals such as those found at the output of a CD player cassette machine mixer output mixer channel insert jack etc 6 Stereo Interconnect To stereo link two 42 Im s interconnect the STEREO LINK jacks found on the rear panels of the units using a five pin DIN male to DIN male patch cord Symetrix p n 037010 This looks like a MIDI cable and a MIDI cable may actually work if all five pins are actually connected to each other Note Although the stereo interconnect cable looks like a MIDI cable it isn t There is nothing remotely resembling MIDI inside or between two 421m s If you connect either connector to a MIDI device it probably won t harm anything but it definitely won t work Decide which unit is the master and which unit is the slave using force only if absolutely neces sary and set the front panel MASTER SLAVE switches accordingly In stereo mode the slave unit s controls are disabled and only the master unit controls affect operation The following diagram shows how to stereo link two 421m s Note If there is no master unit connected via the Stereo Link connectors the slave unit any unit with it s MASTER SLAVE switch in the OUT position remains in bypass mode regardless of the setting of its bypass switch 7 Symetrix etrix Operation Chapter 5 Initial Setup Set the front panel
35. t apply more than 250V rms between the power supply conductors or between either power supply conductor and ground A protective ground connection by way of the grounding conductor 2 Chapter 2 in the power cord is essential for safe opera tion Grounding The chassis of this product is grounded through the grounding conductor of the power cord To avoid electric shock plug the power cord into a properly wired receptacle before making any connections to the product A protective ground connection by way of the grounding conductor in the power cord is essential for safe operation Do not defeat the safety purpose of the grounding plug The grounding plug has two blades and a third grounding prong The third prong is provided for your safety When the provided plug does not fit your outlet consult an electrician for replacement of the obsolete outlet Danger from Loss of Ground If the protec tive ground connection is lost all accessible conductive parts including knobs and controls that may appear to be insulated can render an electric shock Proper Power Cord Use only the power cord and connector specified for the product and your operating locale Use only a cord that is in good condition Protect the power cord from being walked on or pinched particularly at plugs convenience receptacles and the point where they exit from the apparatus Proper Fuse The user accessible fuse is a part of the IEC AC inlet connector
36. to keep unwanted sources as far off axis as possible Do every thing you can to discriminate against unwanted sounds through good mic technique The sounds picked up by an individual mic must be primarily the sound of the desired signal or the 421m s downward expander won t be able to discriminate between signal and noise Optimizing Control Settings When searching for optimum control settings here are a few rules to follow AGC LEVELER The FAST setting of the RECOVERY RATE button is best suited for speech sig nals Use the SLOW setting for musical or noisy signals or if you want the gain changes to be as unobtrusive as possible The RATIO control determines how much of the input signal s dynamic range makes it to the out put We recommend starting at 4 1 so you can clearly hear the effect and then reduce the ratio if necessary AUTO RELEASE LEVEL ARL This control determines the signal level needed to cause gain re lease in the AGC Leveler A suggested method of setting it is with no signal present increase the setting of the ARL control until the green ACTIVE LED extinguishes Then further increase the control setting slightly For musical signals use the SLOW setting of the RECOVERY RATE button Set the AUTO RE LEASELEVEL control so that the ACTIVE LED is extinguished during low level musical passages fade outs or moments of silence DOWNWARD EXPANDER When using the AUTO setting of the downward expander first set the A
37. u re creating something that will be heard in a specific environment consider using a 421m to preprocess your mix for that environment For instance suppose you re making a point of purchase video that will heard in a noisy department store over a semi ordinary television set With your mixer or an outboard EQ give the dialog a good dose of 2 5k to 5k presence boost to make it cut through the noise Then process the overall mix through the 421m with a 3 1 ratio This will keep the overall level hot but consistent and the combination of presence boosting and overall level control will make your product audible in spite of the adverse environment in which it is represented Be sure to check the previous section entitled Mixdown for additional tips and hints Chapter 7 Specifications 421m Specifications Connectors Mic Preamp Line Inputs 1 4 TRS jack and screw terminals Gain Range 15 dB to 45 dB 20k Balanced Bridging Impedance 10k Ohms Mic Input XLR female 10k Balanced Bridging Max Input Level 8 dBu Outputs XLR male screw terminals 200 Ohm Source THD Noise gain control fully clockwise 85 dBu Impedance Differentially Balanced 23 dBm maximum level Phantom Power 48V 2 TS phone Unbalanced 18 dBm maximum level CMRR gt 80 dB 10 Hz 20 kHz Bypass Relay controlled hard wire bypass in power off and bypass condiions ey R 20 to 50 kHz 4 dBm 0 1 dB 0 3 dB mi Sidechain TRS phone Unbalanced Send and Receive Pequena mespo
38. unding plug Mounting In An Equipment Rack The 421m occupies one rack space 1U in a standard equipment rack with a width of 19 48 3cm a depth of 6 5 16 8cm and a height of 1 75 4 45cm Allow at least 4 10 16cm behind the unit for the protrusion of connectors We recommend you take care not to mount the 421m next to devices that emit large electromagnetic fields such as audio power amplifiers To do so may compromise the noise performance of the 421m The 421m has been designed to conform to mechanical guidelines as described in EIA Standard RS 310 C and IEC Recommendation 297 Audio Input Connections The 421m s line input connections are via a standard 1 4 phone jack and barrier terminals The 421m s microphone input connection is an XLR female For optimum system performance we recommend that the 421m be connected to balanced signals If this is not practical in your situa tion then you may connect to unbalanced sources Audio Output Connections The 421m s audio output connections are via standard male XLR jack 1 4 phone jack and barrier terminals located on the rear panel For optimum system performance we recommend that the 421m be connected to balanced devices If this is not practical in your situation then you may connect to unbalanced devices Use any combination of the input and output connections All of the input connections are paralleled The XLR output connector and the balanced screw terminal outputs a
39. you out Connect the 421m into the mixer s channel insert jack use a relatively low RATIO setting use the expander if you need to Remember that lower ratio settings allow for more dynamics than the higher settings which means more difference between soft and loud This trick also works on microphones that are sung into and used for announcements The 421m keeps the announcements audible without the worry of forgetting to bring the fader down during a song Again use a low RATIO setting around 2 1 If you try this on a submix be careful because the large number of microphones involved makes it that much easier to push the sound system into feedback Mixdown You can use the 421m during mixdown for a number of different things For voiceover slet the 421m ride the level of the announcer while you set the basic announcer to music bed ratio or let the 421m ride the music bed while you ride the announcer s level Process background vocals with the 421m It will keep them consistently hot without making them sound squashed unless that s what you want Try using the 421m on individual instruments as a way of keeping their level more consistent without radically altering their timbre Paging Systems Just like the poor lectern mike paging systems suffer from the same ills It really doesn t matter if the audio begins life in a telephone system or if you have a dedicated paging mike Every user has their own idea of how to use the mike You can
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