M82 User Guide_1 - Studio Technologies, Inc.
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1. 775V with no reference to load im pedance This takes into account today s audio scene where signals have a low source impedance and a high input impedance The dBu designation is be coming the standard for the professional audio industry 10dBV Outputs Note that a user monitoring by means of a level meter e g a VU meter one of the Model 82 s outputs might expect to see a 14dB drop when changing from the 4 to the 10 DIP switch position In fact the output level will drop by only 11 78dB This is because the output level is not only switching between 4 and 10 but it s changing from a dBu to a dBV reference as well As 10dBV is the same as 7 78dBu the expected 14dB drop never occurs Model 82 User Guide Studio Technologies Inc Studiclook Specifications Audio Input 1 stereo Type electronically balanced direct coupled Input Compatibility can be connected to balanced or unbalanced signals Impedance 24k ohms Nominal Input Level 12dBV to 6dBu Input Level Control 15 turn trim potentiometers allow calibration over 12dBV to 6dBu input range Maximum Input Level 27dBu Common Mode Rejection 90dB 2 DC and 60Hz 85dB 20kHz 60dB 400kHz typical Audio Outputs 4 stereo Type electronically balanced direct coupled intended to drive loads of 600 ohms or greater can be connected balanced or unbalanced Nominal Output Level 10dBV or 4dBu each output individually2. Disconnect the 1kHz signal and con nect the normal audio source Output Level Selection Each of the four stereo line level outputs is individually configurable for a 10dBV or 4dBu nominal output level Four DIP type switches located on the right side of the front panel are used to set the output levels The legend on the switches corre spond to the output channel numbers A switch that is set to its up position config ures its associated output channel for 10dBV A switch set to its down position configures the output for 4dBu A small screw driver may be of assistance when setting the switches Operation Now that you ve installed and configured the system you re ready to go You should find operation very easy as there is nothing to do on a day to day basis For peace of mind the ExactCal LEDs will give you a visual indication whenever audio signals are present on the Model 82 s input Model 82 User Guide Studio Technologies Inc The LEDs labeled Lo will light whenever an input signal is within the range of 18dB below and 0 5dB above the nominal oper ating level The LEDs labeled Hi will light any time an input signal is greater than 0 5dB below the nominal operating level This sounds a bit confusing but isn t really so hard to understand As an example if you have a nominal 4 signal con nected to the Model 82 s line input and the ExactCal section has been used to calibrate the input the Lo LEDs w
3. stereo input offers superior common mode signal rejection To achieve optimal audio performance the ExactCal calibra tion section matches the installation specific nominal input level with the Model 82 s internal gain structure Two 15 turn trim potentiometers and four LEDs allow fast precise calibration Unlike other distribution amplifiers the Model 82 en sures that excellent audio performance can be achieved with little or no hassle Four Stereo Outputs The Model 82 contains four independent stereo output sections For compatibility with a range of facilities each output section can be separately configured for a 10dBV or 4dBu nominal output level Each output features an electronically balanced circuit capable of driving bal anced or unbalanced loads And unlike some output circuits operating a Model 82 output in an unbalanced configuration does not cause a change in the nominal output level Short circuit resistant the rugged output circuits can drive full signal levels into 600 ohm or greater loads The Model 82 s architecture precludes the need for individual output level trim poten tiometers With the input signal calibrated using the ExactCal section the four stereo outputs use 1 tolerance components Issue 1 January 2000 Page 7 Studio to provide precise 10dBV or 4dBu outputs Audio Performance The Model 82 is the result of exacting circuit design combined with the latest state of the
4. switch configurable Maximum Output Level Balanced 27dBu into 10k ohms 26dBu into 600 ohms Maximum Output Level Unbalanced 21dBu into 10k ohms 20dBu into 600 ohms Output Impedance 50 ohms Frequency Response 10Hz 70kHz 0 0 5dB down 1dB 90kHz Distortion THD N 0 004 measured at 4dBu input 4dBu output 20Hz 20kHz S N Ratio 92dB 20Hz 20kHz ref 4dBu on input and output Crosstalk 86dB 1kHz ref 4dBu on input and output Model 82 User Guide Studio Technologies Inc LED Indicators 5 1 power present 4 input level calibration Fusing 1 Type 5 x 20mm time lag Littelfuse 218 series or equivalent Rating 0 400A for 100 and 120V mains power 0 200A for 220 240V mains power Connectors Audio Input 2 3 pin XLR type female Audio Output 8 3 pin XLR type male AC Mains standard 3 blade plug meets IEC 320 specifications AC Mains Requirement 100 120 220 240V x 1096 factory configured 50 60Hz 100 120V 0 4A maximum 220 240V 0 2A maximum Dimensions Overall 19 00 inches wide 48 3cm 1 72 inches high 4 4cm 6 65 inches deep 16 9cm Mounting One space in a standard 19 inch type rack Weight 7 0 pounds 3 2kg Specifications and information contained in this User Guide subject to change without notice Issue 1 January 2000 Page 13 Studio This page intentionally left blank Issue 1 January 2000 Model 82 User Guide Page 14 Studi
5. St o Model 82 Stereo Analog Audio Distribution Amplifier User Guide Issue 1 January 2000 This User Guide is applicable for serial numbers Model 82 M82 00151 and later Copyright 2000 by Studio Technologies Inc all rights reserved 5520 West Touhy Avenue Skokie Illinois 60077 U S A Telephone 847 676 9177 Fax 847 982 0747 www studio tech com 50205 100 Issue 1 Studio Toob Table of Contents CDS 5 inyigere Wreri o q ep UU 7 What This User Guide Covers 7 System Overview 2 7 System Features rotis evel eee 7 InstallatiOEl ode Pago e 8 GODIIQUEAETOLD o b dt ebbe idt tes 10 vo o ei SR Ree SM rua ob Ras TOU 11 Troubleshooting mt EP 11 Technical NOIBS uidi ronis eo abd on mua ec 12 SDSCIIICallOrSs a 13 Block Diagram Model 82 User Guide Issue 1 January 2000 Studio Technologies Inc Page 3 Studio This page intentionally left blank Issue 1 January 2000 Model 82 User Guide Page 4 Studio Technologies Inc Studiclook Foreword am pleased to present the Model 82 Stereo Analog Audio Distribution Amplifier As president of Studio Technologies take a very personal approach when designing products Getting older 43 as of this writing has increased my appreciation of the more subtle things in
6. art components Like all Studio Technologies products the Model 82 has survived tough listening evalua tions by industry professionals These veterans have the ears to guide us in achieving the right performance The outcome is a product that achieves sonic excellence Design Philosophy Most audio distribution amplifiers contain a level trim adjustment on each output After careful study Studio Technologies concluded that these adjustments con fused and often interfered with the process of getting maximum audio performance After checking with person nel in the field it became clear that what Model 82 Front Panel EXACTCAL RIGHT ee E Power Left and Input level present LED right input trim controls calibration LEDs Model 82 Back Panel is desired in virtually every distribution amplifier applications are multiple audio outputs all operating at a standard refer ence level By implementing the ExactCal system the Model 82 s internal operating level can be easily calibrated to match that of the input signal Once this input level matching is accomplished the four stereo outputs can be individually configured for 10dBV or 4dBu nominal operating level In conclusion output trim pots are not included on the Model 82 for the simple reason that better audio perfor mance can be achieved without them Installation In this section you will be installing the Model 82 in an equipment rack Audio input a
7. ecessary to change the unit s operating voltage it must be performed only at the factory or by an authorized service technician The Model 82 uses an IEC standard con nector to mate with the AC mains cord The wire colors in the AC mains cord should conform to the internationally recognized CEE color code and must be wired accordingly Connection Wire Color Neutral N Light Blue Line L Brown Protective Earth E Green Yellow Safety Warning The Model 82 does not contain an AC mains disconnect switch As such the mains cord plug serves as the disconnection device Safety consideration requires that the plug and associated outlet be easily accessible to allow rapid discon nection of mains power should it prove necessary As soon as mains power is connected the Model 82 s power present LED will light The unit is now ready for years of trusty service Issue 1 January 2000 Page 10 Configuration Input Level Calibration With the ExactCal calibration section it s simple to match the nominal level of the input signal with the Model 82 s internal circuitry Two 15 turn trim potentiometers along with four LEDs form the ExactCal section One trim pot is associated with the left input the other with the right Two LEDs labeled Lo Hi are associated with each input They are provided as an aid to calibration as well as serving as signal present indicators The following is a step by step procedure for us
8. ectors are used to interface with the Model 82 s outputs Prepare the mating connectors females so that pin 2 is signal high or hot pin 3 is low or cold and pin 1 is shield To connect to an unbalanced load connect pin 2 as signal high or hot and pins 1 and 3 as signal low shield For optimal unbalanced operation it is impor tant to connect pins 1 and 3 together directly on the connector that mates with the Model 82 and not on the other end of the cable Note that while the Model 82 s electroni cally balanced output circuits are capable of driving loads of 600 ohms or greater the output level will drop slightly as the load impedance approaches 600 ohms A 0 5dB difference in output level can be expected as the load impedance changes from 10k ohms to 600 ohms AC Mains Power The Model 82 is internally configured to operate from either 100 120 or 220 240V Issue 1 January 2000 Page 9 Studio 50 60Hz In most cases units shipped to North America are factory selected for 120V operation Units bound for Japan are selected for 100V while our friends down under and in Europe receive units set for 220 240V Before connecting the Model 82 to AC mains power check that it is config ured to match the local mains voltage Look on the back panel adjacent to the power entry connector for the configured voltage s Note that an incorrect configu ration could seriously damage the unit Should it be n
9. eo line level input It is electronically balanced and compatible with balanced or unbal anced signals that have a nominal level range of 12 dBV to 6dBu The ExactCal section allows precise level calibration with the connected input signal The configuration section of this guide pro vides details on using the trim pots It is anticipated that in most cases a stereo signal will be connected to the input The Model 82 can also be used as a 1 input 8 output monaural distribution amplifier or as a dual 1 input 4 output monaural distribution amplifier Two 3 pin female XLR type connectors are used to interface with the input source Prepare the mating connectors males so that pin 2 is signal high or hot pin 3 is Model 82 User Guide Studio Technologies Inc low or cold and pin 1 is shield With an unbalanced source connect pin 2 to high or hot and pins 1 and 3 to shield If connecting to an unbalanced source in this manner results in hum or noise try connecting pin 2 to high or hot and pin 3 to shield leave pin 1 unterminated Audio Outputs The Model 82 contains four independent stereo line level outputs The outputs are electronically balanced and capable of driving balanced or unbalanced loads of 600 ohm or greater The outputs can be individually configured for a nominal output level of 10dBV or 4dBu so you can connect to all line level inputs with no hassle Eight 3 pin male XLR type conn
10. ill light whenever the signal is between 14 4 5dBu the Hi LEDs will light whenever the signal exceeds 3 5dBu The four outputs are fully independent You can patch reconnect or even short out an interconnecting cable without effecting the other outputs Using the front panel DIP switches you can change the output level of any or all of the outputs whenever you wish Remember that if you change the input source you may need to use the ExactCal section to recalibrate the input Refer to the configuration section of this guide for details Troubleshooting If you re having problems getting the Model 82 up and running this section can help If you haven t read the other sections of this guide you should do so before proceeding If the Model 82 Doesn t Work At AII A source of AC mains power must be connected to the Model 82 Depending on the version you have purchased 100 120 or 220 240Vac 50 60Hz is required Con firm what mains voltage is required by Issue 1 January 2000 Page 11 Studio observing the selection boxes to the left of the AC mains connector on the back panel Whenever mains power is con nected the front panel power present LED should light If the LED is not lit confirm that AC mains power is active hot and that the cord is securely mated with the connector on the Model 82 s back panel For safety in the event of a major internal failure or the connection of incorrect AC ma
11. ing the ExactCal section to match an input signal to the Model 82 s circuitry e Set the trim pots to their fully counter clockwise position Remember the trim pots are 15 turn type so you may have to rotate them up to 15 times before reaching their fully counter clockwise position Supply a 1kHz sine wave to both the left and right inputs Set the level of the source to be precisely the nominal operating level If for example the output of a console is connected to the input of the Model 82 the console output should be adjusted so that the meters read OdB or 100 If the output of the console is a 4 type then setting the console s left and right output levels to nominal should find the console output levels to be exactly 4dBu Slowly turn the trim pot associated with the left input in the clockwise direction As you increase the level watch the LEDs associated with the left channel Model 82 User Guide Studio Technologies Inc Studiclook The LED labeled Lo will light first then both LEDs will light then only the LED labeled Hi will light The correct setting is where both LEDs light their brightest Careful adjustment is required as the window where both LEDs light is somewhat less than 1dB Repeat the above procedure for the trim pot and LEDs associated with the right input When the configuration is correct both LEDs associated with the right channel input will be lit to their brightest
12. ins voltage the Model 82 contains a fuse inside its cabinet The fuse will open blow if the failure of an internal compo nent causes excessive current to be drawn from the internal power supply The fuse will also open should 220 240Vac be connected to a Model 82 that is config ured for 100 or 120Vac operation The fuse is intended to be replaced only by a competent service technician This person will have the training to safely access the guts of the Model 82 and identify where a problem is located Incorrect Output Levels You must correctly set the input trim pots so that the four stereo outputs can provide precise 10dBV or 4dBu nominal output levels These trim pots are used to match the nominal level of the audio input signal with the Model 82 s internal circuitry Refer to the Configuration section of this guide for detailed instructions Technical Notes Definition of Level dBu Whenever possible Studio Technologies has opted to use the dBu designation as it seems to be quite rational Using dBm was fine when all audio line outputs were terminated with 600 ohm loads In this way Issue 1 January 2000 Page 12 it was easy to say that OdBm is 1 milliwatt dissipated in the known load i e OdBm across 600 ohms will measure 0 775 In contemporary situations an output is rarely terminated with 600 ohms generally 10k ohms or higher The dBu designation is better because it refers to dB referenced to 0
13. life be they a part of nature or the nuances contained in a well designed piece of electronic equipment Do the technical and operational aspects of a product work together to feel right A Studio Technologies design is ready to go only when am completely satisfied Many fine people worked toward making the Model 82 happen Mitch Budniak ace consulting engineer designed many of the circuits Jim Cunningham con tributed to the analog design Carrie Loving provided engineering support Al Lux designed the printed circuit board Fred Roeck performed the mechanical design Joe Urbanczyk coordinated the safety testing and agency approvals Please contact me with your questions comments and suggestions can be reached by voice at 847 676 9177 fax at 847 982 0747 or via the Internet www studio tech com Sincerely Gordon K Kapes President Model 82 User Guide Issue 1 January 2000 Studio Technologies Inc Page 5 Studio This page intentionally left blank Issue 1 January 2000 Model 82 User Guide Page 6 Studio Technologies Inc Ste to Introduction The Model 82 Stereo Analog Audio Distribution Amplifier was developed by Studio Technologies as part of its Studio Tools group of audio support products The Model 82 is designed to work in a large variety of applications Specific applications include audio production duplication broadcast and sound rein forcement All Model 82 functio
14. ns meet or exceed the performance of the most expensive high end audio equipment What This User Guide Covers This User Guide is designed to assist you when installing configuring and using the Model 82 Stereo Analog Audio Distribution Amplifier System Overview The Model 82 from Studio Technologies Inc is a distribution amplifier that truly meets the needs of the real world The stereo input is intended to connect to virtually any line level audio source The ExactCal input calibration section allows optimal audio performance to be achieved over a nominal input level range of 12dBV to 6dBu The four stereo outputs meet exacting professional stan dards Capable of driving balanced or unbalanced loads each output can drive 26dBu into 600 ohms Using front panel switches each stereo output can be individually configured for a nominal output level of 10dBV or 4dBu The front panel trim potentiometers and LEDs make calibration and use simple The AC mains input power is factory configured for 100 120 or 220 240V 50 60Hz operation Components and Model 82 User Guide Studio Technologies Inc construction standards make the Model 82 suitable for continuous operation even for on air broadcast applications System Features One Stereo Input The differential input circuitry is compat ible with balanced or unbalanced signals having a nominal level range of 12dBV to 6dBu Using laser trimmed components the
15. o Technologies Inc DIFFERENTIAL DIFFERENTIAL LINE RECEIVER BUFFER BUFFER LINE DRIVER LEFT 2 t 21 13 78 OR 21 2 LEFT XLR F 3 gt 3 XLR M LEFT 21 LINE OUTPUT 1 1 LINE INPUT d 2 TRIMe 12dBV TO 68 1048 OR 4dBu RIGHT RIGHT XLR F 3 l 32 XLR M RIGHT 1 TRIM 1 d gm C eoe OUTPUT LEVELees any INPUT CALIBRATION Sy METER Ons LEFT CIRCUITRY FOR OUTPUTS 2 4 IDENTICAL TO OUTPUT 1 ded INPUT CALIBRATION Sy vor RIGHT POWERe R AC MAINS UV FACTORY CONFIGURABLE POWER D FOR 100 120 OR 220 240V SUPPLY aK 50 60Hz OPERATION i 8280 A STUDIO TECHNOLOGIES INC MODEL 82 STEREO ANALOG AUDIO DISTRIBUTION AMPLIFIER LOCATED ON BACK PANEL LOCATED ON FRONT PANEL BLOCK DIAGRAM DIPCSTYLE SWITCH LOCATED ON FRONT PANEL NOMINAL LEVEL IN dBu DRAWING NO DATE PAGE 50909 10 13 99 01 or 01
16. udio output and AC mains power connections will be made MODEL 82 STEREO ANALOG AUDIO DISTRIBUTION AMPLIFIER 10dBV or 4dBU output level configuration switches AC MAINS INPUT OUTPUT 4 OUTPUT 3 MODEL 82 STEREO ANALOG AUDIO DISTRIBUTION AMPLIFIER e e e CAUTION TO PREVENT ELECTRICAL SHOCK DO NOT REMOVE COVER OR BACK M RTS T y NEL e R L e R e L e R e L e R e L e R e L OUTPUT 2 OUTPUT 1 INPUT wave nusa AC mains connection Issue 1 January 2000 Page 8 Stereo line level outputs inputs Stereo line level Model 82 User Guide Studio Technologies Inc Studiclook System Components The shipping carton contains a Model 82 User Guide and warranty card Units destined for North America are shipped with an AC mains cord Your dealer or distributor will provide an AC mains cord for non North American destinations Mounting the Model 82 The Model 82 requires one space ina standard 19 inch 48 3cm equipment rack It is desirable to locate the Model 82 to allow easy access to both the front and the back panels The back panel contains the input and output connectors The front panel is used to access the calibration controls and output level switches The front panel also contains four LED level indicators The Model 82 is secured to the equipment rack using two mounting screws per side Audio Input The Model 82 provides one ster
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