304 Headphone Amplifier User`s Guide
Contents
1. Red LED indicates power on PASS THRU LINE INPUTS THAU B THRU A INPUT B INPUT A y Rear Panel 7 pin DIN Connector Connect the 7 pin DIN plug end of a Symetrix PS 3 115 VAC or PS 3E 230 VAC here Connect the AC power connector end of the PS 3 or PS 3E to an AC power source that is of the correct voltage and frequency as marked on the PS 3 or PS 3E TRS jack connected in parallel with Input A jack Use this jack to connect to other 304 s or other audio equipment TRS jack connected in parallel with Input B jack Use this jack to connect to other 304 s or other audio equipment Input A Left channel Input B Right channel 3 conductor 1 4 jack for line level balanced or unbalanced input signals Tip high Ring low Sleeve ground 3 conductor 1 4 jack for line level balanced or unbalanced input signals Tip high Ring low Sleeve ground Using the 304 User s Guide Impedance Sensitivity Loudness Loudness is directly related to the impedance and sensitivity of the headphones Impedance determines how much power the headphones will draw while sensitivity indicates how much of the electrical signal delivered to the headphones is converted into sound Because low impedance headphones draw more power from the amplifier they will sound louder at the same control settings than high impedance headphones Also headphones of higher sensitivit2. Place of issue Lynnwood Washington USA Authorized signature FO FE MP erence EA E A E A wet nteamniees 7 pin DIN pee PHYSICAL SIZE NWO iinsiccnacisavcrderatienersepradiensevnn atndiienahedeinenbaies Y2 rack unit 1 75 x 8 5 x 6 5 in 4 445 x 21 59 x 15 875 cm SMIDDING WEIN i concidinascentidieindanseansndddediuattiainmesndaeeannmnss 4 5 lbs Dane Butcher President Symetrix Incorporated ELECTRICAL Power Requirements115 VAC nominal 95 to 130 VAC 50 to 60 Hz 230 VAC nominal 207 to 253 VAC 50 Hz 6408 216th Street SW Mountlake Terrace WA 98043 USA Symetrix T 1 425 778 28 F 4 1 425 778 7727 www SymetrixAudio com 10 The Vision Behind the Sound 304 Headphone Amplifier Warranty and Service The Symetrix Limited Warranty Symetrix Inc expressly warrants that the product will be free from defects in material and workmanship for eighteen 18 months from the date the product is shipped from the factory Symetrix s obligations under this warranty will be limited to repairing or replacing at Symetrix s option the part or parts of the product which prove defective in material or workmanship within eighteen 18 months from the date the product is shipped from the factory 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 wi
3. to qualified service personnel Servicing is required when the apparatus has been damaged in any way Such as power supply cord or plug cord is damaged liquid has been spilled or objects have fallen into the apparatus the apparatus has been exposed to rain or moisture does not operate normally or has been dropped CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN TO REDUCE THE RISK OF FIRE OR WARN l NG ELECTRIC SHOCK DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE RISQUE DE CHOC ELECTRIQUE AVIS NE PAS 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 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 accompanying the product i e this Quick Start Guide CAUTION To prevent electric shock do not use the polarized plug supplied with the unit with any extension cord receptacl
4. to the Y cable s inout Connect each of your balanced loads to the tip ring sleeve output connectors The tip connection is hot Block Diagram User s Guide HEAD x PHONE LEVEL 1 HEADPHONE OUTPUT 1 EMI LINE Q FILTER HEAD x INPUT A CIRCUITRY V PHONE LEVEL 2 HEADPHONE 5 MODE OUTPUT 2 PASS MONO STEREO INPUT V THRU A O y LEVEL e I4 HEAD i V PHONE EMI LEVEL 3 LINE a HEADPHONE INPUT B o CIRCUITRY OUTPUT 3 V PASS v THRU B O HEAD i V PHONE o LEVEL 4 HEADPHONE OUTPUT 4 Z 6408 216th Street SW Mountlake Terrace WA 98043 USA 3 O Symetrix T 1 425 778 7728 F 1 425 778 7727 www SymetrixAudio com The Vision Behind the Sound 304 Headphone Amplifier Troubleshooting Troubleshooting Chart Symptom No output Hum or buzz in output Distortion Noise hiss No LED display NOTES Probable Cause Check cables and connections Are inputs driven by outputs and outputs driving inputs Verify cables source and load Check for AC power presence Check input and output connector wiring Ground loop check related system equipment grounding Are all system components on the same AC ground Check input signal Is it too hot or is it already distorted Check the output loading Is something else clipping Check input signal levels The 304 is intended to operate at or near line lev
5. 304 Headphone Amplifier User s Guide 9 Symetrix uh lhl In lih The Vision Behind the Sound ha DPn E r Safety User s Guide 6408 216th Street SW Mountlake Terrace WA 98043 USA Symetrix T 1 425 778 7728 F 1 425 778 7727 www SymetrixAudio com 2 The Vision Behind the Sound 304 Headphone Amplifier Safety What Ships in the Box e A 304 hardware unit e One PS 3 115 VAC PS 3E 230 VAC power supply e This User s Guide If you have questions beyond the scope of this Quick Start Guide or the help module contact our Customer Support Group in the following ways Tel 1 425 778 7728 8 00 am to 4 30 pm Monday through Friday Pacific Time Web http www SymetrixAudio com This device complies with part 15 of the FCC Rules Operation is subject to the following two conditions 1 This device may not cause harmful interference and 2 this device must accept any interference received including interference that may cause undesired operation This Class B Digital apparatus meets all requirements of the Canadian Interference Causing Equipment Regulations Cet appariel numerique de la classe B respecte toutes les Exigences du Reglement sur le materiel brouilleur du Canada Important Safety Instructions Read these instructions Keep these instructions Heed all warnings Follow all instructions Do not use this apparatus near water This apparatus shall not be
6. 6408 216th Street SW Mountlake Terrace WA 98043 USA T 1 425 778 7728 F 1 425 778 7727 www SymetrixAudio com Symetrix The Vision Behind the Sound 304 Headphone Amplifier Applications The 304 can be used in the following applications Please note that this list is far from comprehensive and your imagination may create new uses that we haven t listed here Project Studio Broadcast Live Sound House of Worship Balanced Line Driver Let the 304 expand your mixer s headphone capacity You can drive it viaa tio ring sleeve to dual tip sleeve cable from your mixer s headphone jack or from one or two of your mixer s aux sends If you only use one aux send then press the stereo mono switch to route the signal to both channels Use the 304 to drive the guest headphones in your studio Does your console have an anemic headphone amplifier Does your console have an anemic headphone amplifier Create assistive listening stations at several pews Drive the 304 with a mixture of the sound reinforcement signal and a room microphone No this isn t as sophisticated as one of the RF or infrared systems but it doesn t cost like they do either Here s how to use the 304 as a one in four out balanced line amplifier Make a Y cable so that you can drive both inputs in parallel Wire the plug for the right channel input so that it is reverse polarity from the left channel input Connect your source
7. at your Symetrix product 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 Return Authorization At the Symetrix factory Symetrix will perform in warranty or out of warranty service on any product it has manufactured for a period of three 8 years from date of discontinued manufacture Before sending anything to Symetrix please contact our Customer Service Department for a Return Authorization RA number The telephone number is 1 425 778 7728 Additionally support is available via the web site http support SymetrixAudio com In warranty Repairs To get your Symetrix product repaired under the terms of the warranty iF Call us for an RA number have the serial number shipping and contact information and description of the problem ready 2 Pack the unit in its original packaging materials ca 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 Just do these five things and repairs made in warranty will cost you only one way freight charges We ll pay the return freight If you don t have the factory packaging materials we recommend using an oversize box Wrap the unit i
8. ctor 1 4 inch plugs are inserted The outputs are 1 4 inch stereo connectors Go Set the individual level controls to minimum max ccw rotation Set the master level control to the halfway position 12 noon Set the stereo mono switch as appropriate With the source signal active adjust the individual level controls for comfortable listening levels Warning The 304 is capable of driving many headphones past the threshold of pain This can also result in hearing damage For your own hearing health monitor at the lowest SPL that you can use and still get the job done 6408 216th Street SW Mountlake Terrace WA 98043 USA T 1 425 778 7728 F 1 425 778 7727 www SymetrixAudio com Symetrix The Vision Behind the Sound 304 Headphone Amplifier Front Rear Panel Overview INPUT LEVEI A a anp Aaa y MODE F F ow AMPLIFIER QUTPUT 1 HEADPHONE OUT HEADPHONE LEVEL LEVEL LEVEL 3 LEVEL 4 l LEVEL 1 OUTPUT 2 OUTPUTS OUTPUTA i ai ti iy Front Panel Input Level Sets the input signal strength Fully counterclockwise no signal Fully clockwise input signals are boosted by 20 dB Mono Stereo Headphone Outputs Combines stereo or two mono input signals into one mono output signal fed equally to both left and right head phone outputs 1 4 stereo jacks for headphones The minimum impedance is 8 Ohms see Table 1 for combined headphone imped ances
9. e or other outlet unless the prongs can be fully inserted Power Source This Symetrix hardware uses a switching power supply that automatically adjusts to the applied voltage Ensure that your AC mains voltage is somewhere between 100 240 VAC 50 60 Hz Use only the power cord and connector specified for the product and your operating locale A protective ground connection by way of the grounding conductor in the power cord is essential for safe operation The appliance inlet and coupler shall remain readily operable once the apparatus has been installed User Serviceable Parts There are no user serviceable parts inside this Symetrix product In case of failure customers inside the U S should refer all servicing to the Symetrix factory Customers outside the U S should refer all servicing to an authorized Symetrix distributor Distributor contact information is available online at htto www SymetrixAudio com First Time Setup User s Guide Introduction The Symetrix 304 Headphone Amplifier is a 1 in 4 out amplifier designed to drive multiple headphones of any impedance Symetrix proprietary high voltage drive technology gives the 304 the ability to drive high impedance headphones with the equivalent output voltage of a much larger power amplifier yet provides more than ample current for low impedance phones The four stereo outputs automatically adjust output power to match the load impedance Controls prov
10. el 4dBu is nominal Make sure that the signal you are feeding to the 304 is a line level signal not mic level Make sure that all systems components are on the same AC ground Check gain settings on upstream equipment The system gain structure should be such that the 304 receives 4dBu nominal signal Is the input signal already noisy Is the unit plugged in Is the AC outlet OK Specs Declaration of Conformity User s Guide Architects and Engineers Specifications The headphone amplifier shall have a single stereo input and four stereo outputs Each output shall have its own amplifier and volume control An overall volume control master shall also be provided There shall be an overall stereo mono switch All inputs are balanced bridging inputs Outputs shall be suitable for driving headphones in the range of 8 Ohms to 2000 Ohms The output source impedance shall be 100 Ohms The headphone amplifier shall be capable of delivering 35 volts peak to peak into a 2000 Ohm load or greater The unit shall be capable of operating by means of a Symetrix PS 3 or PS 3E external power supply connected to 115 VAC nominal 95 to 130 VAC 50 60 Hz or 230 VAC nominal 207 to 253 VAC 50 Hz where applicable The unit shall be a Symetrix Inc model 304 Headphone Amplifier Specifications Declaration of Conformity We Symetrix Incorporated 6408 216th St SW Mountlake Terrace INPUT OUTPUT Washington USA declare under our sole respons
11. exposed to dripping or splashing and no objects filled with liquids such as vases shall be placed on the apparatus Clean only with dry cloth Do not block any ventilation openings Install only in accordance with the manufacturer s instructions Do not install near any heat sources such as radiators heat registers stoves or other apparatus including amplifiers that produce heat This apparatus shall be connected to a mains socket outlet with a protective earthing connection Do not defeat the safety purpose of the polarized or grounding type plug A polarized plug has two blades with one wider than the other A grounding type plug has two blades and a third grounding prong The wide blade or the third prong are provided for your safety If the provided plug does not fit into your outlet consult an electrician for replacement of the obsolete outlet Protect the power cord from being walked on or pinched particularly at plugs convenience receptacles and the point where they exit from the apparatus Only use attachments accessories specified by the manufacturer Use only with the cart stand tripod bracket or table specified by the manufacturer or sold with the apparatus VA When a cart is used use caution when moving the cart apparatus combination to avoid injury from tip over Unplug this apparatus during lightning storms or when unused for long periods of time Refer all servicing
12. ibility that the MEUL TWO Ce scsnubensesbnnssieeunguares Bridging Balanced or Unbalanced 304 Hea ees Amplifier Maximum Input Level 18 dBu Balanced to which this declaration relates is in conformity with the following standards Maximum Output Level 21 dBm 600 Ohm load EN 60065 gt 6 VRMS 200 Ohm load Safety requirements for mains operated electronic and related apparatus for household and similar general use Inout Impedance 20k Ohms Balanced 10k Ohms Unbalanced EN 50081 1 Qu tput PAD SG AICS ssassn 100 Ohms Electromagnetic compatibility Generic emission standard Part 1 Residential commercial and light industry Performance Data EN 50082 1 Electromagnetic compatibility Generic immunity standard Frequency Response 20 Hz to 20 kHz 0 1 dB Part ie Becidedtiol commareaicend lant manst THD NOISC ce ceceecceeseeseeaeeaees 01 1kHz 0 dBm 600 Ohms The technical construction file is maintained at Symetrix Inc 02 1kHz 20 dBm 600 Ohms 6408 216th St SW Signal to NOISE RatiO ccccccseseeseeecseeeeeeeesneeeseeetseeeneneees 95 dB MOI Henge UA cnet A The authorized representative located within the European Community MaximuM GA acca sesvetin ocnea nites dudesnnedt ocdaasiueseecendendacetendeaas 25 dB iS World Marketing Associates CONNECTIONS P O Box 100 IG cee EEE AE E E T E ET A E E 1 4 TRS St Austell Cornwall PL26 6YU U K Date of issue October 31 1998 C a E peas dag tae eae a suena euaascies 1 4 TRS
13. ided are input level output level for each individual amplifier and a stereo mono switch The Stereo Mono switch allows the amplifier to be used several ways As a normal stereo amplifier with four outputs the left and right inouts are used for stereo signals which feed the left and right outputs Switching to mono Fast First Time Setup Wiring To install the 304 Plug the PS 3 power supply s DIN connector into the 304 Plug the PS 3 into a suitable source of AC power Refer to the labelling on the PS 3 to determine what is suitable Connect your source to the 304 s tip ring sleeve input jacks The inputs are balanced They will work with either balanced or unbalanced sources Connect your headphones to the four output jacks The 304 can handle headphone impedances ranging from 8 Ohms to over 2000 Ohms 60 Ohm headphones are optimal they get the loudest It is not necessary for each set of headphones to be the same although it might help if they were with a stereo input provides a quick check of the mono compatibility of a stereo mix For that matter you may want to monitor in mono As amono amplifier one signal fed to either input will feed both outputs Also in mono mode when two different mono signals are fed to the left and right inputs they will be mixed to feed both the left and right outputs The inputs are electronically balanced but will operate normally in an unbalanced configuration when 2 condu
14. l 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 additional 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 Note Some Symetrix products contain embedded software and may also be accompanied by control software intended to be run ona personal computer Said software is specifically excluded from this warranty Limitation of Liability The total liability of Symetrix 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 any product will not exceed the price allocatable to 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 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 installation or removal of products substitute facilities or supply houses Servicing Your Symetrix Product If you have determined th
15. ll 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 via United Parcel Service by Symetrix to any location within the Continental United States 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 expressly disclaims any IMPLIED warranties including fitness for a particular purpose or merchantability Symetrix s warranty obligation and buyer s remedies hereunder are SOLELY and exclusively as stated herein This Symetrix product is designed and manufactured for use in orofessional 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 merchantability and fitness for a particular purpose This limited warranty with all terms conditions and disclaimers set forth herein shal
16. mance or use of these products Under copyright laws no part of this brochure 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 The following are either Trademarks or Registered Trademarks of Symetrix Inc Symetrix SymNet SymNet Designer SymLink and CobraLink Windows is a Registered Trademark of Microsoft Inc Other product names mentioned herein may be trademarks and or registered trademarks of other companies and are property of their respective owners 6408 216th Street SW Mountlake Terrace WA 98043 USA T 1 425 778 7728 F 1 425 778 7727 www SymetrixAudio com
17. n a plastic bag surround it with bubble wrap and place it in the box surrounded by Styrofoam peanuts Be sure there is enough clearance in the box to protect the rack ears We won t return the unit in anything but Symetrix packaging for which we will have to charge you If the problem is due to operator misuse or error you will have to pay for both parts and labor In any event if there are charges for the repair you will pay for the return freight All charges will 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 11 Symetrix The Vision Behind the Sound ltem No 53 0001 304 Headphone Amplifier User s Guide 2009 Symetrix Inc All rights reserved Printed in the United States of America The information in this document 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 purposes only and constitutes neither an endorsement nor a recommendation Symetrix assumes no responsibility with regard to the perfor
18. y will sound louder than those of lower sensitivity Check the manufacturer s spec sheet for impedance and sensitivity information Proprietary high voltage driver technology allows the 304 to drive even high impedance headphones to maximum levels because the amplifiers are capable of very high output voltage swing However to get a loudness equivalent to that of low impedance headphones the controls will have to be set to higher settings when using high impedance headphones This is normal If low and high impedance headphones are combined on the same channel the low impedance headphones will be much louder As a result when a combination of high impedance and low impedance headphones is used only those of like impedance should be used on the same channel This allows each listener to properly adjust loudness without regard to the impedance and sensitivity of the other head phones It s ok to mix impedances on the same amplifier it s just not optimum You won t hurt anything Maximum Amplifier Load The minimum operating impedance or maximum load for each output of the 304 is 8 Ohms Use as many pairs of headphones as desired as long as the total combined impedance per output does not fall below 8 Ohms Table 1 shows how many headphones of various impedances may be used with each output of the 304 Table 1 Combined Impedance Values approx 8 Impedance of Headphones Maximum Number Channel ee ee
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