302 Dual Microphone Preamplifier
Contents
1. In a nutshell here are the do s and don ts of phantom powering Verify that your microphone can be phantom powered if it is a condenser mic Ensure that your microphone s output is low impedance balanced and floating This is especially important for ribbon mics Turn the phantom power off when connecting vintage ribbon microphones Mute your monitor speakers or headphones when turning the phantom power on or off If you don t there will be a loud nasty pop Mute your monitor speakers or headphones whenever you plug in or unplug a phantom powered microphone If you don t there will be a loud nasty pop Plug in an A B powered microphone without a suitable adapter Worry about your dynamic or ribbon microphones as long as they are wired so that the output is balanced and floating Use the microphone input for line level sources especially those that are transformerless Use the microphone input with unbalanced sources Use a direct box to feed an unbalanced source into the microphone input Worry about your tube condenser mics They are compatible although they cannot be phantom powered Chapter 7 Applications Dynamic or Ribbon Microphone When using a dynamic or ribbon microphone with the Symetrix 302 use the following control and switch settings GAIN Completely counter clockwise PAD Out POLARITY Out PHANTOM POWER Out Slowly turn the GAIN control clockwise until the desired output level from the 3022. The microphone preamp shall be the Symetrix Inc model 302 Dual Microphone Preamplifier Specifications Input Output Connections Input Type Low Z Balanced Transformerless Input XLR Maximum Input Level 14 dBV with pad In Output TRS jacks Euroblock Maximum Output Level 24 dBu Balanced 10k Ohm load Power In 7 pin DIN 22 dBu Balanced 600 Ohm load Input Impedance gt 3k Ohms Physical Output Impedance 300 Ohms Balanced Size hwd 1 75 x 8 5 x 6 5 in 4 445 x 21 59 x 15 875 cm 150 Ohms Unbalanced Shipping Weight 4 5 lbs Electrical Performance Data Clip Indicators Frequency Response THD Noise red LEDs fire 3dB below clipping 20Hzto 20kHz 0 1dB 007 1kHz OdBu 600 Ohms out 01 1kHz 22dBu 600 Ohms out Signal to Noise Ratio 95 dB 50 dBV 150 Ohms in EIN lt 128 dBu 150 Ohms source 60 dB gain 22 kHz bandwidth Minimum Gain 20dB Maximum Gain 60dB 12 117V AC nominal 95 130V AC 50 to 60 Hz 230V AC nominal 165 255V AC 50Hz Power Requirements In the interest of continuous product improvement Symetrix Inc reserves the right to alter change or modify these specifications without prior notice 1998 Symetrix Inc All rights reserved Chapter 10 302 Limited Warranty Symetrix Inc expressly warrants that the product will be free from defects in material and workmanship for 18 months Symetrix s obligations under this warranty will be limited to repairing or replaci
3. ture sale delivery resale repair replace ment or use of any product will not exceed the price allocable to the product or any part thereof which gives rise to the claim In no event will Symetrix be liable for any inciden Warranty and Service expressly disclaims any IMPLIED warran ties including fitness for a particular purpose or merchantability Symetrix s warranty obligation and buyer sremedies hereunder are SOLELY and exclusively as stated herein This Symetrix product is designed and manufactured for use in professional and studio audio systems and is not intended for other usage With respect to products purchased by consumers for personal family or household use Symetrix expressly disclaims all implied warranties including but not limited to warranties of merchant ability and fitness for a particular purpose This limited warranty with all terms condi tions and disclaimers set forth herein shall extend to the original purchaser and anyone who purchases the product within the specified warranty period Symetrix does not authorize any third party including any dealer or sales representative to assume any liability or make any addi tional warranties or representation regarding this product information on behalf of Symetrix This limited warranty gives the buyer certain rights You may have additional rights provided by applicable law tal or consequential damages including but not limited to damage f
4. Chapter 3 Fast Setup Fast First Time Setup Follow these instructions to get your 302 up and running as quickly as possible The intent of this section is fast setup only Please refer to later chapters for explanation of the 302 s controls and functions 1 Set the Microphone 1 and Microphone 2 GAIN controls completely counter clockwise 2 Set the Microphone 1 and Microphone 2 PAD switches to the OUT position 3 Set the Microphone 1 and Microphone 2 POLARITY switches to the OUT position 4 Set the PHANTOM POWER switch to the OUT position unless you will be using a condenser microphone which requires phantom power 5 Connect your first microphone to the Microphone 1 XLR Input If you are using two mics connect your second microphone to the Microphone 2 XLR Input Caution Use only balanced microphones and cables 6 Connect Output 1 and Output 2 of the Symetrix 302 to the inputs of the destination device 7 Plug the 302 into an AC outlet using the external power supply the Symetrix PS 3 or PS 3E Caution Failure to connect the 302 to the proper AC mains voltage may cause fire and or internal damage 8 Turn the Microphone 1 and Microphone 2 GAIN controls slowly clockwise until you achieve the desired output level from the 302 9 Fast setup is now complete Please refer to later chapters of this user s guide or the Symetrix Customer Service Department if you have additional questions O Symetrix Front Panel Controls
5. halfway between mic level and line level Because the Symetrix 302 is designed to accept the output of the hottest condenser microphone the pickup output not the amplifier output of a guitar or bass can generally be connected to the input of the 302 through a 1 1 low impedance transformer without over loading the input of the 302 Never connect the guitar or bass directly to the mic input of the 302 The transformer connected between the guitar bass and the 302 protects the circuitry of the guitar bass from Phantom Power and it protects the 302 s Phantom Power from short circuiting The transformer also balances the unbalanced output of the guitar bass before it reaches the input of the 302 When using a guitar or bass as the input to the Symetrix 302 use the following control and switch settings GAIN Completely counter clockwise PAD Out POLARITY Out PHANTOM POWER Out Slowly turn the GAIN control clockwise until the desired output level from the 302 is achieved Engage the PAD and POLARITY switches if necessary BASS OR GUITAR LOW IMPEDANCE TRANSFORMER THE PHANTOM POWER SWITCH SHOULD BE IN THE OUT POSITION MICROPHONE 1 MICROPHONE 2 PHANTOM POWER San GAN G 4548 PAD POLARNY 15dB PAD POLARITY 302 Ps 100 E IN 180 ON DUAL MICROPHONE _ OUT ao a _ ao ao LOF PREAMPLIFIER our mur ca O o Symetrix 20 Q 2 60 a ENGAGE IF NEEDED Chapter 8 Troubleshooting T
6. is achieved If needed engage the PAD and POLARITY switches DYNAMIC OR RIBBON MICROPHONE THE 15dB PAD AND PHANTOM POWER SWITCHES SHOULD BE IN THE OUT POSITION MICROPHONE 1 GAIN uve MICROPHONE 2 GAIN a PHANTOM POWER a 15dB PAD POLARITY N se mou cur a o POLARITY ze N zo a OFF cur ane MICROPHONE PREAMPLIFIER jo O Condenser Microphone When using a condenser microphone that requires Phantom Power with the Symetrix 302 use the following control and switch settings GAIN Completely counter clockwise PAD Out POLARITY Out PHANTOMPOWER In Slowly turn the GAIN control clockwise until the desired output level from the 302 is achieved Condenser mics typically have a higher output than dynamic or ribbon mics so the final GAIN setting will typically be lower for a condenser mic than for a dynamic or ribbon mic Ifneeded engage the PAD and POLARITY switches Caution If your condenser microphone uses T system powering do not engage the Phantom Power CONDENSER MICROPHONE MICROPHONE 1 MICROPHONE 2 PHANTOM POWER GAIN mag GAIN dB 48 PAD POLARITY 15dB PAD POLARITY 02 N 180 N DUAL MICROPHONE O zur a O _ IoT mo OFF CLIP CLIP PREAMPLIFIER o ERR O y O ENGAGE IF NEEDED ENGAGE TO PROVIDE PHANTOM POWER Guitar or Bass Pickups The typical output level of guitar or bass pickups falls about
7. mated there is no guarantee that both pins 2 and 3 will make contact at exactly the same time It is possible that a damaging current could flow through the mic for a brief moment under these conditions However this is a connector problem not a problem with the mic itself or phantom power in general 2 In the past it was a common practice to ground the center tap of the mic s output transformer However this practice should be avoided in phantom powered systems The solution Locate the center tap and cut the connection between it and pin 1 ofthe XLR connector 3 Ifthe mic s output transformer has developed leakage the microphone may become noisy when phantom power is turned on Crackling sputtering or even humming noises may occur The leakage not the power is the problem The solutions are A Turn off the phantom power B Puta 1 1 low impedance transformer between the mic and the input C Getthe micrepaired The dominant remote powering system in use today is the phantom power system which is compatible with both condenser and non condenser microphones dynamics ribbons etc If your microphone s specifications sheet claims that it requires phantom power the Symetrix 302 can power it The technical requirements for operation and or compatibility are 1 The microphone must have a balanced low impedance output 2 The balanced output must be floating with respect to ground If there is a center tap it must not be grounded
8. the GAIN control counter clockwise and or engage the mic pad If the CLIP LED is still on reduce the level of signal that you are sending to the input of the 302 Make sure that you are using the correct power supply for your location The PS 3 is for locales such as the United States which use 117V AC mains power and the PS 3E is for locales such as Europe that use 230V AC mains power 11 ON C9 etrix Specifications Chapter 9 Architects and Engineers Specifications The microphone preamp shall be a high performance dual channel unit that is of a single rack space wide and one rack space high The unit shall provide two independent channels of pre amplification designed to boost nominally mic level signals to line level Each channel shall have a gain control that is continuously variable from 20dB to 60dB of gain a 15dB input pad a polarity reversal switch and an LED indicator that lights in the presence of signal peaks There shall also be a front panel pushbutton switch to engage phantom power and an LED that indicates the presence of AC power The following connections shall be available on the rear panel Each channel shall have an XLR3 mic input wired pin 1 ground pin 2 pin 3 a TRS line level output and a euroblock style removable terminal strip line level output There shall also be a mix output that provides a sum of channels 1 and 2 via a euroblock style removable terminal strip
9. 302 Dual Microphone Preamplifier Users Guide O Symetrix O etrix Table of Contents Chapter 1 Introduction Chapter 2 Operator Safety Summary Chapter 3 Fast Setup Chapter 4 Front Panel Controls Chapter 5 Rear Panel Connections Chapter 6 Using the 302 Chapter 7 Applications Chapter 8 Troubleshooting Chapter 9 Specifications Chapter 10 Warranty and Service Chapter 11 Declaration of Conformity Rev A 01 11 September 1998 Symetrix part number 53302 0A01 Subject to change without notice 1998 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 Under copyright laws no part of this manual may be reproduced or transmitted in any form or by any means electronic or mechanical including photo copying scanning recording or by any information storage and retrieval system without permission in writing from Symetrix Inc O A On BON 12 13 15 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 Congratulations on your purchase of the Symetrix 302 Dual Microphone Preamplifier The 302 is an ultra clean two channel dual mono preamp for use in
10. AS OUVRIR 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 voltage within the product s enclosure that may be of sufficient magnitude to constitute a risk of electric shock to per sons The exclamation point within an equilateral triangle is intended to alert the user of the presence of important operating and mainte nance servicing instructions in the literature accompanying the 302 1 e this manual Caution To prevent electric shock do not use the polarized plug supplied with the 302 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 Identifies information that needs extra emphasis A Note generally supplies extra information to help you to better use the 302 Note Chapter 2 Caution Identifies information that if not heeded may cause damage to the 302 or other equipment in your system Warning Identifies information tha
11. Chapter 4 MICROPHONE 1 MICROPHONE 2 PHANTOM POWER o GAIN dB GAIN dB o 40 15dB PAD POLARITY 40 15dBPAD POLARITY 302 g DUAL MICROPHONE O e O PREAMPLIFIER Front Panel CLIP LED TheCLIPLED lights when the signal reaches 3dB below clipping This LED should never be on solidly It is usually all right ifthe CLIP LED flashes occasionally on peaks in the program material If you see the CLIP LED light monitor your final signal destination to be sure that you are not creating distortion by running audio levels that are too hot GAIN control Setsthe gain ofthe preamplifier from aminimum of20dB to amaximum of60dB 15dB PAD Reduces the input signal by 15dB when the switch is setto the IN position POLARITY push button Inverts the phase of the signal being amplified when the switch is set to the IN position PHANTOM POWER Applies a positive DC voltage to pins 2 and 3 ofthe XLR input jacks when the switch is set to the IN position This provides the ability to power condenser microphones which require phantom power Caution When Phantom Power is engaged always turn your monitoring speakers and headphones completely off before connecting or disconnecting any microphones to the 302 This is to avoid a loud pop which occurs due to the sudden change in voltage on XLR pins 2 amp 3 when they are connected to or disconnected from Phantom Power Such a loud pop can result in speaker and or hearing dama
12. batteries an external power supply that is connected to the microphone by a special multiwire cable or through a standard microphone cable by phantom or T system powering Phantom powering and T system powering are incompatible systems Phantom power derives its name from its invisibility to audio signals even though the micro phone cable carries both phantom power as direct current and audio signals as alternating current Specifically the term phantom power means a positive DC voltage sent to the microphone on both audio leads through current limiting resistors which also serve to isolate the audio leads 302 etrix from one another The front panel phantom power button applies phantom power via pins 2 and 3 of the mic input XLR connectors The phantom power technique uses the two signal conductors in a standard balanced mic cable to deliver the power required by the microphone eliminating the need for internal batteries or an external power supply Because the voltage is applied equally to both sides of a floating balanced circuit no current flows through the microphone s transformer or through the microphone element itself It is often said that the sound of some dynamic microphones is affected by phantom power and that ribbon mics cannot be plugged into an input that is phantom powered For the most part these are myths that grew out of difficulties created by other problems in the mic circuit 1 When XLR connectors are
13. critical digital and analog recording situations The 302 delivers exceptional sonic performance even at extremely high input levels making it the ideal mate to the newest transformerless condenser microphone designs When compared with older mic preamps the 302 offers substantial sonic advances such as 1 Its solid stereo imaging less than 10 degree phase shift at 20kHz 2 Excellent transient handling its positive and negative slew rates are symmetrical 3 Very low noise approaching the theoreti cal limit and 4 Almost undetectable distortion 007 Variable gain inputs with 15dB pads allow the 302 to handle any input level up to 14dBV Phantom power is available at both inputs In addition both channels include a polarity switch to correct for improperly wired cables or unresolvable mic placement problems Introduction Balanced low Z line drivers are on 3 conduc tor 1 4 TRS connectors and Euroblock connectors These drivers are capable of 24dBm maximum output The output stage can also drive unbalanced lines of up to a maximum of 18dBm We recommend that you read this manual cover to cover You will find the answers to most of your questions inside However if you are in a hurry go directly to Chapter 3 Fast Setup It will get you started quickly Please feel free to contact us if you have questions comments or suggestions Phone 425 778 7728 Fax 425 778 7727 Email symetrix symetrixau
14. dio com Website www symetrixaudio com MICROPHONE 2 PHANTOM POWER MICROPHONE 1 o GAIN dB m 15dB PAD POLARITY 302 OUT ze DUAL MICROPHONE z PREAMPLIFIER ES cur GAIN dB 40 e PAD POLARITY _ a ON dur a OFF 00 05 o f Oe 20 60 O 20 O Front panel BALANCED LINE OUTPUTS O Symetrix MANUFACTURED BY SYMETRIX INC LYNNWOOD WA USA OUTPUT 2 OUTPUT 1 2 OUTPUT 1 CONNECTTO MPU or SYMETRIX PS 3 OR PS 3E POWER SUPPLY ONLY govpssoss O THIS PRODUCT CONTAINS NO USER SERVICABLE PARTS ill MICROPHONE INPUTS 8 OUTPUT 1 O INPUT 2 INPUT 1 FABRIQU AUX E U PAR SYMETRIX INC LYNNWOOD WASHINGTON R F REZ TOUTE R PARATION A UN TECHNICIEN QUALIFI Rear panel 302 O etrix 302 etrix Operator Safety Summary The information in this summary is intended for persons who operate the equipment as well as repair personnel Specific warnings and cautions are found throughout this manual wherever they may apply The notational conventions used in this manual and on the equipment itself are described in the following paragraphs Equipment Markings CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN TO REDUCE THE RISK OF FIRE OR WARNING ELECTRIC SHOCK DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE RISQUE DE CHOC ELECTRIQUE AVIS NE P
15. ge Caution Never connect an unbalanced microphone or mic cable to the input of the 302 when the Phantom Power is engaged This will short out the Phantom Power See page 8 for more Do s and Don ts of Phantom Powering Chapter 5 Rear Panel Connections o Sym etrix BALANCED LINE OUTPUTS a INPUTS MANUFACTURED BY SYMETRIX INC LYNNWOOD WA USA OUTPUT 2 OUTPUT 1 2 OUTPUT 1 POWER CONNECT TO Ee pp e o OUr INPUT SYMETRIX PS 3 OR PS 3E POWER CE a gonpssoss O THIS PRODUCT CONTAINS NO USER SERVICABLE PARTS FABRIQU AUX E U PAR SYMETRIX INC LYNNWOOD WASHINGTON R F REZ TOUTE R PARATION UN TECHNICIEN QUALIFI Rear Panel POWER INPUT 7 pin DIN receptacle Connect this to the 7 pin DIN plug of a Symetrix PS 3 or PS 3E only Connect the AC power connector ofthe PS 3 or PS 3E to an AC power source that is of the correct voltage and frequency as marked onthe PS 3 or PS 3E Note The PS 3 is a 117V AC power supply used to power a single unit The PS 3E is a 230V AC power supply used to power a single unit The PS 3 and PS 3E are Symetrix accessories available from your Symetrix dealer BALANCED LINE OUTPUTS TRS jacks 1 4 inchtip ring sleeve TRS phone jack wired Tip high Ring low and Sleeve ground Use these jacks when you need 1 4 inch balanced or unbalanced outputs Output 1 or Output 2 The nominal signal level here is 4 dBu If you need an u
16. he 302 reduce the input level at each channel by 15dB Use these pads when a very high output mic is used or when the incoming signal is so hot that the clip indicator is lighted with the gain control at minimum As previously mentioned the 302 uses gain controls not volume controls or faders It is not necessary to use the pads to reduce input levels in order to get the gain controls to operate in some theoretical best position The only best operating position for a gain control is the minimum gain that delivers the required output level In addition to their more common use in reducing input signal strength the pads can also give the user a wider gain control adjustment range for more accurate channel to channel level matching For very close level matching the resolution of the gain controls at the very lowest end of their range may be too coarse if the pads are not engaged There is a trade off here however When using the pads the apparent noise floor is higher Polarity Push buttons Both channels include a polarity push button In the normal out position signal source polarity is maintained to the outputs In the in position the wiring from the XLR connector pins 2 and 3 is reversed This allows for correction of miswired cables and for polarity match ing of various manufacturers microphones Powering for Condenser Microphones All condenser microphones require some kind of electrical power This power may be supplied by internal
17. l 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 6 YU U K Date ofissue September 1 1998 Place of issue Mountlake Terrace Washington USA Authorized signatyre Dane Butcher President Symetrix Incorporated Co O Symetrix 15 O Symetrix Symetrix Inc 6408 216th St SW Mountlake Terrace WA 98043 USA Tel 425 778 7728 Fax 425 778 7727 Website http www symetrixaudio com Email symetrix symetrixaudio com
18. nbalanced output use a tip ring sleeve phone plug for best results and connect only to the tip and sleeve Note Connecting an unbalanced cable here will result in an output level that is 6dB lower than the output level achieved using a balanced cable Euroblock connectors Low profile balanced and ground connectors typically used in contractor sound installations Use these jacks when you need Euroblock balanced outputs Output 1 Output 2 or Output 1 2 Note The signal at Output 1 2 is a combination of Output 1 and Output 2 signal with the level balance between Output and Output 2 determined by the front panel GAIN and PAD settings MICROPHONE INPUTS XLR inputs Balanced XLR input jacks for Microphone and Microphone 2 Pin ground Pin 2 Pin 3 These are mic level inputs designed to accept the balanced output from one microphone Caution When Phantom Power is engaged do not use unbalanced microphones or mic cables Caution When Phantom Power is engaged do not use switched mics which short Pin 2 and or Pin 3 to ground Caution When Phantom Power is engaged always turn down monitors headphones before connecting or disconnecting microphones O Symetrix Chapter 6 Using the 302 The Preamplifiers The 302 s ultra low noise low distortion mic preamps provide direct coupled balanced low Z inputs for optimum transient response and phase coherency The positive and negative slew rates are symme
19. ng at Symetrix s option the part or parts of the product which prove defective in material or workmanship within 18 months from date of shipment provided that the Buyer gives Symetrix prompt notice of any defect or failure and satisfactory proof thereof Products may be returned by Buyer only after a Return Authorization number RA has been obtained from Symetrix Buyer will prepay all freight charges to return the product to the Symetrix factory Symetrix reserves the right to inspect any products which may be the subject of any warranty claim before repair or replacement is carried out Symetrix may at its option require proof of the original date of purchase dated copy of original retail dealer s invoice Final determination of warranty coverage lies solely with Symetrix Products repaired under warranty will be returned freight prepaid by Symetrix via United Parcel Service surface to any location within the Continental United States At Buyer s request the shipment may be returned via airfreight at Buyer s expense Outside the Continental United States products will be returned freight collect The foregoing warranties are in lieu of all other warranties whether oral written express implied or statutory Symetrix Inc Limitation of Liability The total liability of Symetrix on any claim whether in contract tort including negli gence or otherwise arising out of con nected with or resulting from the manufac
20. or loss of 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 installa tion or removal of products or substitute facilities or supply houses 13 Servicing the 302 If you have determined that your 302 requires repair services and you live outside of the United States please contact your local Symetrix dealer or distributor for instructions 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 302 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 shipping materials If you don t have the factory packaging materials please use an oversized carton wrap the
21. roubleshooting Chart SYMPTOM PROBABLE CAUSE No output signal Check cables and connections Is a microphone connected to the 302 s input and is the 302 s output driving a line level input Check for AC power presence Make sure that your microphone and mic cable are balanced If you are using a mic or mic cable with a switch is the switch inthe on position If you are using a condenser microphone which requires Phantom Power did you turn the Phantom Power on Humor buzzin output Check your cables Ground loop check related system equipment grounding Are all systemcomponents on the same AC ground Make sure that your microphone and mic cable are balanced Distortion Check the level of the input signal on the 302 s LED display Is the CLIP light on all the time If so reduce the incoming signal level by turning the INPUT level counterclockwise Is the incoming signal already distorted Make sure that your microphone is not broken and that the mic is not distorting Noise hiss Check input signal level The input signal may be too low If so boost the incoming signal if possible or move your mic closer to the signal source Is the input signal already noisy Verify that all system compo nents are on the same AC ground Noise crackle Check for broken mics and or bad cables POWER LED noton Is the unit plugged in Is the AC outlet OK CLIP LEDonconstantly Make sure that you are feeding the 302 a mic level signal not line level Turn
22. t if ignored may be hazardous to your health or that of others CAPITALS Controls switches or other markings on the 302 s chassis Boldface Strong emphasis Power source This product is intended to operate from a power source that does not apply more than 255Vrms between the power supply conductors or between either power supply conductor and ground A protective ground connection by way of the grounding conductor in the power cord is essential for safe operation Danger from loss of ground If the protective ground connection is lost all accessible conductive parts including knobs and controls that may appear to be insulated can render an electric shock In line power supply This product receives its operating power from the Symetrix PS 3 or PS 3E power supply These are the only power supplies approved for use with the product Do not connect the product to any other in line or plug in transformer The use of other power sources may cause damage to the equipment or present a shock hazard to the operator 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 Stay out of the box To avoid personal injury or injury to others do not remove the product covers or panels Do not operate the product without the covers and panels properly installed
23. trical ensuring sonic integrity Gain Controls Clip LEDs Pads The 302 s gain controls set the gain of the preamp circuitry They operate like the trim controls found on most mixers On a mixer the trim controls set the initial amount of amplification for cach mic input The faders govern how much of the amplified signal is allowed to pass into the rest of the system Using a separate mic preamp such as the 302 assumes that somewhere downstream there will be a volume control that functions like the fader on a mixing console The 302 offers 40dB overall gain range from 20 dB to 60dB when used without the pad Including the 15dB pad the total range is 75dB with a minimum overall gain of 5dB Any mic output level is easy to match with the 302 s stepless gain control regardless if it is the 60dBV to 80dBV levels common with ribbon mics or the near line level often delivered by transformerless condenser mics Input signals as high as 14dBV can by handled by the 302 The front panel clip LEDs fire at 3dB below clipping Both source level and preamp gain are directly related to the noise floor as well as to head room at the output The key to using the 302 at its optimum performance level is to 1 Usethe maximum allowable source level 2 Use only as much gain as necessary The combination of the highest possible input levels with the lowest possible gain always results in minimum noise and maximum headroom The PAD push buttons on t
24. 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 will be COD unless you have made other arrange ments prepaid Visa or Mastercard Out of warranty Repairs Ifthe 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 Chapter 11 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 302 Dual Microphone Preamplifier 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 50081 1 Electromagnetic compatibility Generic emission standard Part 1 Residential commercial and light industry EN 50082 1 Electromagnetic compatibility Generic immunity standard Part 1 Residential commercia
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