Adcom GFA GFA-7700 User's Manual
Contents
1. GFA 7 700 High Current 5 Channel Power Amplifier Owner s Manual THE FOLLOWING PRECAUTIONS AND SAFETY INSTRUCTIONS ARE REQUIREMENTS OF UL AND CSA SAFETY REGULATIONS Warning To reduce the risk of fire or electric shock do not expose ATTENTION this unit to rain or moisture POUR PREVENIR LES CHOCS ELECTRIQUES NE PAS UTILISER CETTE FICHE POLARISEE AVEC UN PROLONGATEUR UNE PRISE CAUTION DE COURANT OU UNE AUTRE SORTIE DE COURANT SAUF SI LES LAMES PEUVENT ETRE INSEREES A FOND SANS EN LAISSER AU RISK OF ELECTRIC SHOCK CUNE PARTIE A DECOUVERT DO NOT OPEN CAUTION AVIS RISQUE DE CHOC ELECTRIQUE NE PAS OUVRIR TO PREVENT ELECTRIC SHOCK DO NOT USE THIS POLARIZED PLUG WITH AN EXTENSION CORD RECEPTACLE OR OTHER OUTLET UN LESS THE BLADES CAN BE FULLY INSERTED TO PREVENT BLADE EXPOSURE The graphic symbol of a lightning flash with an arrow point within a triangle signifies that there is dangerous CAUTION voltage within the unit and it poses a hazard to anyone POWER LINES removing the cover to gain access to the interior of the unit Only qualified service personnel should make Any outdoor antenna must be located away from all power lines any such attempt OUTDOOR ANTENNA GROUNDING eee ou of an ee Lia aire If an outside antenna is connected to your tuner or tuner preamplifier be Oa ASA TALT E WaNS A ISET O AG COVIGE soca ts sure the antenna system is grounded so as to provide some protection necessary to refer to the ins2. into the transformer if its temperature exceeds 125 C This high temperature will seldom if ever be encountered unless the amplifier is subjected to abnormal conditions such as operation into loads of less than 3 ohms at very high listening levels etc If the AC Fuse 4 has not failed the Power LED is out and the Thermal Protection LED 9 does not glow this would indicate that the thermostat within the transformer has opened Once the temperature within the transformer decreases to a normal level the thermostat will reset itself automatically and normal operation will resume If you are to avoid continually tripping the thermostat in the transformer you must reduce the sound level demands correct the load impedance of the loudspeakers or both Distortion Alert LEDs 8 The Distortion Alert circuit is a unique ADCOM distortion detection system which reads all forms of non linear distortion such as THD IM slew induced clipping etc The Distortion Alert LEDs will light when distortion reaches approximately 1 regardless of impedance voltage current phase angle or the reactance of the loudspeakers which the amplifier is driving Sometimes when the amplifier is in use the LEDs may occasionally flicker during high volume listening particularly if you are driving low impedances This flickering is no cause for concern The LEDs are simply warning you that the amplifier is approaching its maximum power output into the particular lo
3. 8 174 625mm x 17 432mm x 14 355 6mm Weight anoeia Ee E A E EE E E E T N R OEA TEE 56 lb 25 4 kg Weight Packed cisseanunin inei an E R N O EERE A EEEE ERE 64 lb 29 1 kg 15 8551 East Anderson Drive Suite 105 Scottsdale Arizona 85255 Voice 480 607 2277 Fax 480 348 9876 www adcom com gfa7700_manual_v1
4. panel Power Switch must be left in the in on position To connect you will need a monaural mini phone plug to monaural mini phone plug cable of appropriate length not included to reach from the rear panel of the amplifier to the rear panel of the pre amplifier Contact your dealer for information on using this feature with ADCOM and other brand pre amplifiers Although 12VDC is optimal the circuit will operate from approx 5 to 30VDC Center conductor tip is positive AC Fuse 4b The AC Fuse protects the electronic circuits of the GFA 7700 Normally this fuse will fail only if there is an overload within the GFA 7700 It may however fail if the amplifier attempts to deliver very high power into very low impedance loudspeakers In either case BE SURE TO REPLACE THE AC Fuse ONLY WITH AN EXACT REPLACEMENT FUSE The proper fuse values are Fuse Rating BUSS Littlefuse For 115 volt operation 15 Amp 250 Volt AGC 5 250V ov cccscsenecevees 3AG 312005 250V For 230 volt operation 8 Amp 250 Volt AGC 37250Visccedcasedawinees 3AG 312003 250V WARNING Before attempting to replace a failed fuse be certain to unplug the AC Power Cord from the AC wall outlet to prevent possible electrical shock Replace the AC Fuse only with one identical in type and rating as printed on the rear panel DO NOT USE ANY SUBSTITUTE FUSES WITH DIFFERENT RATINGS OR VALUES Failure to observe this precaution may cause
5. when measured between one conductor and the shield With the DB 25 computer type Multichannel input connector 3 there is no need to worry about color coding or properly connecting the RCA plugs as this is done in one connector with one cable The DB 25 can easily transfer all five channels from the output of the processor unit to the input of the GFA 7700 amplifier There can be no errors with the DB 25 it is shaped so that it can only be connected in the proper direction Contact your dealer to locate a DB 25 signal cable Outputs 2 NOTE The GFA 7700 is polarity correct That is it does not invert phase from input to output Any positive signals at its inputs will appear as a positive signal at its outputs In connecting the amplifier to the loudspeaker it is vital to maintain proper polarity positive to positive negative to negative On the GFA 7700 the positive terminal is color coded RED and labeled and the negative is color coded BLACK and labeled The positive terminal on the speaker will be color coded RED or will be labeled pos positive 8 ohms or 4 ohms The negative terminal on the speaker will be color coded BLACK or will be labeled neg negative C Common G or ground It is necessary that your speaker cables be terminated with U type spade connectors These will give the most contact area insuring long term r
6. COM to ensure that your amplifier is as flawless in appearance as it is electronically The front panel is a heavy gauge high grade aluminum extrusion carefully finished and anodized for durability The chassis top cover and rear panel are heavy gauge steel that has been powder coated and baked to ensure a lasting finish If the front panel top or sides become dusty or fingerprinted they can be cleaned with a soft lint free cloth slightly dampened with a very mild detergent solution or glass cleaner DO NOT SPRAY OR POUR LIQUIDS OF ANY KIND ON THE GFA 7700 12 Troubleshooting Resolving Problems Use the chart below to solve common situations that don t require professional attention If the steps stated in POSSIBLE SOLUTION do not resolve your problem then please contact your ADCOM Dealer or call the ADCOM Customer Service Department Any problems not covered here should be brought to the attention of your ADCOM Dealer or ADCOM Customer Service Department A special note on hum When there is a low volume hum audible throughout your speakers even with the main volume turned all the way down you have a common phenomenon known as ground loop A ground loop is basically a difference in ground voltages between two or more components which are connected electrically and which creates multiple current paths where there must only be one This difference in potential creates a 60 Hz low level sound approximately a low A t
7. O QUALIFIED SERVICE PERSONNEL cable entry as practical GFA 7700 Features e Precision matched devices used throughout the signal path e 120 000 pF of power supply filter capacitance for greater reserve capacity e Independent power supplies for each channel e Fewer gain stages improve signal reproduction accuracy e Custom toroidal power transformer provides better regulation and greater peak current capability e Independent thermal overload and distortion LEDs for all 5 channels e High quality gold plated 5 way binding posts e High quality gold plated RCA jacks e Large independent internal heatsinks for greater cooling capability of output devices e Convenient 12 VDC power ON OFF triggering e Heavy gauge anodized aluminum front panel e Powder coated baked chassis and top cover for greater durability e Cooling vents for greater efficiency and cooler operation while driving low impedance loads e Standard DB 25 connector to simplify installation Table of Contents Introduction Warranty Information sseicavscecveisccusvecsdsecavvosestwdecnrbecsveberateesteeieeeteeeececes 2 Description of Unit REAP PANEL 5 ccescccersntins secon ssdwusimvennsdanesbnulsedsutesebeese sweats cesses cewaeaeusiens 5 FONE Panel cortex cents semice ctisieaitee dass aaiie owdensaah sens aE EEE SEEEN 7 Installation amp Hookup Unpacking the GFA7700 cc secsecditasdssesedveaviacdyndessdssteatea ss ween conde teats oon 9 Placement Of t
8. ain In the unlikely event damage has occurred notify your dealer immediately and request the name of the carrier so a written claim to cover shipping damages can be initiated THE RIGHT TO A CLAIM AGAINST A PUBLIC CARRIER CAN BE FORFEITED IF THE CARRIER IS NOT NOTIFIED PROMPTLY IN WRITING AND IF THE SHIPPING CARTON AND PACKING MATERIALS ARE NOT AVAILABLE FOR INSPECTION BY THE CARRIER SAVE ALL PACKING MATERIALS UNTIL THE CLAIM HAS BEEN SETTLED Placement of the GFA 7700 During normal home operation the internal heatsinks of the GFA 7700 may become warm However there are instances during high level playback into low impedances when the heatsinks will become much warmer than usual To ensure the amplifier s long term trouble free operation it is necessary to provide adequate ventilation for the heatsinks Therefore the GFA 7700 should be kept away from external sources of heat such as radiators and hot air ducts The GFA 7700 should never be placed with other heat producing components in a cabinet or enclosure lacking free air flow The top and bottom panels of the amplifier s chassis have been provided with vents to allow the necessary cooling of the internal components It is imperative that these vents are not obstructed in any way We recommend that you do not stack other components on top of the GFA 7700 Not only will heat generated by the amplifier affect the performance of equipment stacked on top of the GFA 7700 but the free flow of a
9. are being made be certain that the AC On Off Switch 6 of the amplifier is in the OFF position the AC Power Cord 5 of the amplifier is disconnected from the AC wall outlet and that all associated components are turned off center channel i l TS surround pg inputs left front speaker right front speaker listening viewing position left rear right rear speaker speaker Connecting the GFA 7700 Remember that the Left and Right designations are as you are sitting down in your listening viewing area On the rear panel the inputs and outputs are grouped in 5 bracketed sets one for each channel They are as follows RS Right Surround LS Left Surround RF Right Front C Center LF Left Front 10 Inputs 1 To preserve the correct effects be certain to connect the RCA cables to the proper RCA input connector If the cables are color coded then use this sequence for the connections BUC iicssocsesnsdstawanesss seveesecessesensneesesobiasmsineeens Left Front REG oranana ace binece AE AE ETANOA Right Front GOON E E E Center White with Blue Stripe cssssssssssssosssssossooo Left Surround White with Red Stripe ccccesceeeeeceeeees Right Surround The recommended maximum RCA cable capacitance should be less than or equal to 30pF per foot when measured between the two conductors and less than or equal to 50pF per foot
10. cs cscveservesncserssscesnnsernaeen AWG16 UP CO 72 feelers annaa AWG14 UP to 116 feet sis csvwesvicsescsedessecenecenseees AWG12 If longer runs are needed it is best to consult with your Adcom Dealer to maximize the performance of your system with your exact conditions All loudspeakers having a nominal impedance down to 4 ohms can be connected to and driven by the GFA 7700 The amplifier can drive these low impedance speakers at more than adequate power levels with no difficulty It should be noted here that many loudspeaker systems which are nominally rated at 4 ohms drop in impedance in some parts of their frequency range to as low as 2 ohms and sometimes less You will not experience difficulties even with these very low impedance loads unless you demand excessively high volumes levels from your system It is not recommended that you run additional sets of speakers on any or all of the amplifiers in the GFA 7700 in order to insure the integrity of the system If you choose to add remote speakers in another room it is strongly suggested that a switching system to disconnect the non home theater speakers be incorporated when the surround sound home theater mode is in operation A device such as the Adcom GFS 3 or GFS 6 Speaker Selector is strongly recommended A Speaker Selector enables you to maintain integrity while giving you the flexibility to add speakers throughout your house CARING FOR YOUR GFA 7700 Great care has been taken by AD
11. d the protection circuit will trip and the Thermal Protection LED for that channel will light After approximately 5 seconds the unit will attempt to reset if the short has been corrected the amplifier will resume proper operation If the short is still present the channel will cycle off again The cycling of the protection circuit will continue until the short is corrected or the amplifier power is switched off Activation of the Thermal Protection circuitry in any of the amplifiers in the GFA 7700 is an indication that the amplifier has been over driven or that the load the loudspeakers are presenting to the amplifier is unreasonably low If you wish to prevent recurrent activation of the thermal protection circuitry you must reduce the volume level demands or correct the load impedance condition which may be causing activation of this circuitry Installation amp Hookup Unpacking the GFA 7700 Before your new GFA 7700 left our factory it was carefully inspected for physical imperfections and tested for all electrical parameters as a routine part of ADCOM s systematic quality control This along with full operational and mechanical testing should ensure a product flawless in both appearance and performance After you have unpacked the GFA 7700 inspect it for physical damage Save the shipping carton and all packing material as they are intended to reduce the possibility of transportation damage should the amplifier ever need to be shipped ag
12. eliability The spade connector should have a maximum width of 0 57 inches and an opening width of no less than 0 25 see diagram on right max0S 0 25 min To properly connect the speaker cable to the binding posts turn the insulated head of the binding post clockwise until the wire or connector is firmly secured Finger pressure is sufficient and you should not use pliers or other tools which could damage or over tighten the binding post assembly The binding posts have been designed in such a way that finger pressure is all that is required to cause a pinching action among the different metal surfaces to ensure proper connection It is very important to use the correct size of wire in order to avoid unnecessary loss of amplifier power in the cable reduction of amplifier damping factor and other undesirable conditions Recommended capacitance of the speaker wire should not exceed 50pF per foot This insures high frequencies will not be rolled off 11 It is suggested that the three front channels follow this chart for speaker lengths and wire gauges UP CO 24 TeCtiss sis scscessendeavecesesecadsanereenes AWG16 UP to 36 FECL isis ssceesescssncscrssesessssonaaden AWG14 UP to 58 feet nese sccaiewseianecedeedsaaseaes sens AWG12 Generally for the two rear surround channels longer runs of cable are needed but since less program material is being transmitted through the cable longer runs are acceptable UP CO 48 FECL c
13. er Place the screwdriver in the recessed slot gently press in and turn 1 g turn clockwise AC Power Cord 5 The AC cord provides power to operate all the GFA 7700 s circuits Its plug can be connected to a standard wall outlet provided the outlet supplies a voltage compatible with the power requirements printed on the rear panel of the GFA 7700 SP 700 6 7 9 8 Front Panel On Off Switch 6 The On Off Switch controls power to the power transformer and circuits of the GFA 7700 Whenever the GFA 7700 is energized the Power LED 7 will glow To turn the GFA 7700 on press the push button It will remain in the engaged position while the unit is energized To turn the GFA 7700 off press the push button in and release and it will move to the disengaged position Power LED 7 This LED will glow whenever the On Off Switch 6 is turned on and the GFA 7700 is energized The Power LED indicates that there is AC voltage being fed to the amplifier but it does not signify that all the amplifier s circuits are in operation If for example one of the Thermal Protection LED 9 glows that amplifier channel will not produce sound even though the Power LED may still glow When the GFA 7700 is turned off the Power LED will take some time to fade out completely It may take up to 30 seconds to fully extinguish Additionally the internal power transformer is provided with a thermostat which will interrupt power
14. erence enters house All warnings on the unit and in its operating instructions should be adhered to d Use jumper wire not smaller than No 6 AWG 13 3 mm copper or the equivalent when a separate antenna grounding electrode is used See NEC All operating and use instructions should be followed Section 810 21 j Do not use this unit near water for example near a bathtub washbowl EXAMPLE OF ANTENNA GROUNDING AS PER NATIONAL ELECTRICAL CODE INSTRUCTIONS kitchen sink laundry tub in a wet basement or near a swimming pool CONTAINED IN ARTICLE 810 RADIO AND TELEVISION EQUIPMENT The unit should be installed so that its location or position does not interfere POWER LINES with its proper ventilation For example it should not be situated on a bed sofa rug or similar surface that may block the ventilation openings or placed in a built in installation such as bookcase or cabinet that may impede the flow of air through its ventilation openings SERVICE ENTRANCE CONDUCTORS STANDOFF The unit should be situated away from heat sources such as radiators heat S INSULATORS b registers stoves or other devices including amplifiers that produce heat T The unit should be connected to a power supply outlet only of the voltage MAST and frequency marked on its rear panel n SERVICE ANTENNA The power supply cord should be routed so that it is not likely to be walked ENTRANCE LEAD IN WIRE on or pinched especially near the plug convenience
15. hat appears to hum It can be caused by adding new components to your system but that does not imply there is anything electrically wrong with any new component With the advent of audio video and home theater systems the problem has become commonplace Generally the cause is the Cable TV incoming signal line This new incoming line may add an additional ground at a different potential from the AC line ground of your other equipment Symptom Possible Reason Possible Solution Power LED does not glow AC Power Cord 3 not plugged in Plug in AC Power Cord 3 No sound AC Fuse 4 blown Replace AC Fuse 4 Transformer thermal protection engaged Wait until unit cools down it will reset Power LED glows Preamp or source unit is not on Make sure whole system is on but no sound Connections in rear are loose Verify all connections on rear of amp One channel not Input 1 or Output 2 connectors Verify both sets of connections on that producing sound disconnected or loose channel Speaker disconnected Verify connection at speaker Internal protection engaged Bring to Dealer or Service Center Hum from all speakers Ground loop difference in ground If cable TV is present see Note 1 at any volume voltages between components If cable TV is not present see Note 2 Hum from all speakers Problems with source unit CD tape Try different source tuner tape etc hum goes up or etc or RCA cables connecting that and or different RCA cable d
16. he GFA 7700 c cc cscicidasiecsaieatigus ANAE REAREA 9 Quick Connection Diagram ccccccesscceseccesnccecesceeesacesssaeeessseeesaeeesaes 10 Connecting the GFA 7700 sc sscieasseeeeoecsd na dansasseeessieueesdctesesetess ens seaienees 11 Caring for your GEA 7700 mesine sn cesor nE o EEEE ESEE E EE soles 12 Troubleshooting Resolving ProDIEmS wcsses cecdendocdavertavinsdacteasd aise cdadevaceacnd steedebieddesdavesiinces 13 Service INFOMMALUION ecc 2cteded ddieeccaeed eeaSendaasadendesptaccaca see piasecccueet esa necen aes 14 SPECINCALIONS eese esain NEE EEE NE EEEE teams 15 Dolby ProLogic and Dolby Digital are registered trademarks of Dolby Laboratories Licensing Corp Introduction Congratulations on your decision to purchase the GFA 7700 5 channel power amplifier The GFA 7700 integrates very well with any other home theater system such as Dolby ProLogic or Dolby Digital You have made a wise choice that will reward you with exceptionally accurate and musical sound reproduction for years to come To realize the full potential of your new amplifier please read these operating and installation instructions thoroughly before attempting to make any connections to it ADCOM Protection Plan USA ONLY ADCOM offers the enclosed valuable Limited Warranty Please read the details on the Warranty Card carefully to understand the extent of the protection offered by the Warranty its reasonable limitations and what you should d
17. ir through the ventilating slots in the amplifier may be partially obstructed This is particularly important if your system includes low impedance loudspeakers which are difficult to drive or you will consistently demand high volume levels from the amplifier and speaker system If you observe these recommendations the GFA 7700 will perform reliably in any reasonable environment You should also pay attention to such normal considerations as protection from excessive dust and moisture Occasional vacuuming of accumulated dust on the chassis panels and around the ventilating slots should be all that is required The optimal performance of your new GFA 7700 will ultimately depend on the care with which you make the connections between the amplifier preamplifier surround sound decoder and the loudspeakers All input and output signal connections should be made only with high quality low loss low capacitance cables following the recommendations in the Inputs and Outputs section of CONNECTING THE GFA 7700 Quick Connections For those of you who are in a hurry to hook up your amplifier into your system we have included this quick connection section The wiring is straight forward and expeditious if you use the proper cables and follow this diagram exactly If you have any difficulties or questions please refer to the appropriate section of this manual for complete descriptions and instructions WARNING Whenever connections to or from the GFA 7700
18. n you call or write for a Return Authorization For warranty coverage a copy of the original proof of purchase is required If you have no original copy please contact your dealer to obtain a duplicate copy If the original shipping carton and its fillers have been lost discarded or damaged a duplicate carton may be obtained from our Service Department for a nominal charge Always ship PREPAID VIA UNITED PARCEL SERVICE UPS OR OTHER APPROVED CARRIER DO NOT SHIP VIA PARCEL POST since the packaging was not designed to withstand rough Parcel Post handling FREIGHT COLLECT SHIPMENTS CAN NOT BE ACCEPTED UNDER ANY CIRCUMSTANCES 14 GFA 7700 Specifications THD Noise into 8 ohms Typical QOHZ eieaa n tae ahantas Shem aemen E dana danteas cause sads uel EEEE ee RERED 0 006 IKA ce cttann ss asda benetcaae mses cides E E E ap E AE NE EE E EE 0 006 TOKHZ isrecnsecironnirrirenasini debenshacde badedhons EE EE E AR OE E EEEE EAE 0 02 DOK FE E E E E stawseees 0 04 Frequency Response 1 Watt into 8 ohms 10Hz to 2OKHZ cc ceeeeeeeee eee es 0 0 25dB Power Bandwidth 30B iscccseascccsssadac ins soseed san cbacascenbeeanen tee vaedsace sesntesaatecssaseee 1 5Hz to 100kHz Power Rating EIA CEA 490 A 185 Watts continuous power into 8 ohms at 1kHz at less than 1 0 THD N IM Distortion SMPTE TP Wath IMtO e OMIMSi aotan in smcee a cnc usneeee aenven ea esate te decmemeeesarosecs lt 0 05 IM Distortion CCIF An
19. o in order to obtain its benefits Be sure to verify that the serial number printed on the rear panel matches the serial number on the outer carton If any number is altered or missing you should notify us immediately in order to ensure that you have received a genuine ADCOM product which has not been opened mishandled or tampered with in any way Always retain your original sales receipt as a proof of purchase 3 O multichannel 12VDC trigger audio input Oe AC fuse 15ABC 250V Power Amplifier Powerconsumption max 1440W 120VAC 50 60 Hz Description of Unit Rear Panel Inputs 1 The audio inputs for the GFA 7700 are through high quality gold plated RCA jacks to minimize high frequency losses noise etc They will accept standard RCA type plugs one for each of the five channels Front L Left Center Front R Right Surround L Left and Surround R Right To insure that the performance designed into the GFA 7700 is preserved you should use the highest quality audio cables possible There are many cables which are color coded and specifically designed for this application Your Adcom dealer can help select the best cable for your needs See Connecting the GFA 7700 for more information Outputs 2 The GFA 7700 s connections to the loudspeakers are made through high grade 5 way gold plated binding post terminals There are two terminal
20. own with volume source unit to the preamp Hum from the amplifier itself Some major appliance dimmer halogen or Make sure all appliances dimmers and fluorescent light is creating interference suspect lights are off Note 1 Cable TV systems can sometimes contribute to ground loop problems which cause hum To determine if your cable system is the contributing factor disconnect the Cable TV incoming signal line round 750 at the wall or the first component to which the cable is connected to i e the cable box or VCR If the hum is no longer present you must insert a 750 Ground Loop Isolator before reconnecting the line You should check with your ADCOM Dealer to obtain one If the 750 Ground Loop Isolator works only partially or not at all then please read Note 2 to complete the troubleshooting procedure Note 2 Make sure that the power amplifier is at least six inches from the Preamp and or Processor Usually putting another component between them is sufficient to minimize the hum If this does not reduce the hum turn the system off and disconnect all Inputs from the amplifier If the hum still persists then your Dealer or Service Center must examine the amplifier If the hum disappears try another set of RCA cables Connect one RCA cable at a time to see if the specific cable or component is responsible If any or all cables cause the hum to appear then the preamp or processor should be evaluated for proper operation by
21. receptacles or where EQUIPMENT the cord exits from the unit ANTENNA DISCHARGE Clean unit only as recommended in its instruction manual UNIT c z TO EXTERNAL ANTENNA The power supply cord of the unit should be unplugged from the wall outlet TERMINALS OF RADIO RECEIVER when it is to be unused for a long period of time POWER SERVICE GROUNDING ELECTRODE SYSTEM GROUND WIRE a b e g interior metal water pipe Care should be taken so that objects do not fall and liquids are not spilled GROUND CLAMPS into the enclosure through any openings BONDING JUMPER d This unit should be serviced by qualified service personnel when E DEES ARCEN ASAN INTO A The power cord or the plug has been damaged or THE EARTH IF REQUIRED BY LOCAL B Objects have fallen or liquid has been spilled into the unit or CODES SEE NECSECTION 810 21 C The unit has been exposed to rain or liquids of any kind or NOTE TO CATV SYSTEM INSTALLER D The unit does not appear to operate normally or exhibits a marked change in performance or This reminder is provided to call the CATV system installer s attention to E The device has been dropped or the enclosure damaged Article 820 22 of the National Electrical Code that provides guidelines for proper grounding and in particular specifies that the cable ground shall be DO NOT ATTEMPT SERVICING OF THIS UNIT YOURSELF connected to the grounding system of the building as close to the point of REFER SERVICING T
22. s for each speaker which are colored RED for the positive output and BLACK for the negative output The binding posts will accept a variety of connector types the most secure and prevalent of these is the U type spade connectors at least 0 25 wide and maximum width of 0 57 The terminal will also accept bare wire up to AWG10 and banana type plugs single or dual See CONNECTING THE GFA 7700 for more information DB 25 Multichannel Audio Input Connector 3 Input connections may be made with the optional DB 25 computer type connector Using this type of connecting cable would override the need to use the RCA type inputs 1 This mode of connection retains the same high level of signal transfer simplifies the job significantly and insures automatic correct connections to all channels 4a 4b 5 12VDC Triggering 4a The GFA 7700 is a very high power amplifier and as such must be directly connected to the wall outlet or an appropriate surge protector or AC line conditioner It must never be connected to the switched outlets on the rear panel of a pre amplifier Usually this would mean that when you turn on off your pre amplifier you would have to turn on off your power amplifier separately We have however provided the ability to control the OFF ON function of the GFA 7700 by a 12Volt DC output jack on the rear of certain ADCOM pre amplifiers and tuner pre amplifiers When using this feature the front
23. serious damage to the amplifier circuits MAY CREATE A FIRE HAZARD AND MAY VOID THE WARRANTY If the Power LED 7 does not glow it may be an indication that the AC fuse has blown If you are using the 12VDC Triggering feature above it may be possible that there is a problem with that connection To determine if the problem is caused by a malfunction in the 12VDC system remove the small plug inserted into the 12VDC Triggering jack Press the front panel power switch to turn off the amp and immediately re press the power switch If the problem is caused by the 12VDC triggering circuit the amp will turn on and the LED will glow DO NOT attempt repair of the 12VDC system If you are not sure or the amplifier displays other symptoms please consult the RESOLVING PROBLEMS section on page 13 To remove the fuse holder cap you will need a 14 standard flat blade screwdriver Place the screwdriver in the recessed slot in the cap Turn the cap 1 g turn counter clockwise until the cap pops out towards you Grasp the cap with your fingers and pull it completely out The fuse is inserted in the back of the cap gently pull it free Since the fuse has a ceramic body you cannot visually examine the fuse element It is therefore suggested that you replace it with an identical substitute or bring the fuse to your Adcom dealer so they may check its integrity To replace the fuse insert it in the back of the fuse holder cap Place the cap into the fuse hold
24. truction manual and its d built tatic ch Section 810 of th warnings for proper operation of the unit against voltage surges and built up static charges Section 810 of the National Electrical Code ANSI NFPA No 70 1984 provides information with Do not place this unit on an unstable cart stand tripod respect to proper grounding of the mast and supporting structure grounding bracket or table The unit may fall causing serious of the lead in wire to an antenna discharge unit size of grounding injury to a child or adult and serious damage to the n location of antenna discharge unit connection to groundin unit Use only with a cart stand tripod bracket or table conductors location of antenna g S g g recommended by the manufacturer or sold with the unit Any mounting of the device should follow the man a Use No 10 AWG 5 3 mm copper No 8 AWG 8 4 mm aluminum ufacturer s instructions and should use a mounting ac No 17 AWG 1 0 mm copper clad steel or bronze wire or larger as a cessory recommended by the manufacturer ground wire electrodes and requirements for the grounding electrode Read all the safety and operating instructions before connecting or using b Secure antenna lead in and ground wires to house with stand off this unit insulators spaced from 4 6 feet 1 22 1 83 m apart c Mount antenna discharge unit as close as possible to where lead in Retain this notice and the owner s manual for future ref
25. udspeakers you are using If however the Distortion Alert LEDs glow brightly or are illuminated most of the time during playback you are over driving the amplifier and should turn down your volume control to reduce the listening level otherwise it may cause the Thermal Protection to be activated or in extreme cases damage your loudspeakers Thermal Protection LEDs 9 The GFA 7700 is provided with both a thermal protection circuit and a current overload circuit which will shut down the individual amplifier s channels if its heatsink temperature reaches 85 C or the amplifier s outputs are shorted The Thermal Protection LEDs will light when either of these protection circuits are on its respective channel has been triggered and the amplifier is inoperative The thermal protection circuitry will typically be triggered by very high power demands into impedances much lower than the amplifier is capable of driving at those levels If any amplifier channel s output through the loudspeaker s ceases abruptly and its Thermal Protection LED glows you will know that its heatsink temperature has become unacceptably high and the circuitry is protecting the amplification devices Please note that the Power LED 7 will remain on and the amplifier will still be energized Once the temperature of the heatsink s drops to a safe operating level that amplifier will automatically resume operation If the output of any channel of the amplifier becomes shorte
26. y Combination from 4kHz to 20kHz 8 ONIMS 3s its sacs sannndacsaswtacscensachcessbeacecesebdacscwnda chdetehsavecetebdaas cok ducaes oe cadacesendecnees lt 0 01 Dynamic HEAadrOOM ssi sec ccdesssccacncscecoat inner Tien E R decenaeeee 1 9 dB Signal to Noise Ratio A Weighted cee eeeceeceececceeeeeeeeeeeeeeeeeaeeneeteateneenees gt 115dB GAIN E E P A abs eaie E E A E E P E ee ans cakes cae E detainee 29dB Input Sensitivity OPT Wat E EAS E E ETA E E T I E TATS 0 1 volts for 150 WattSis oerien e ies aan aa Ea E a a EEEIEE 1 14 volts input Impedan CE isensosriore iieri rriaire T Ea EA EANET ARNS EEE Saa 50kQ Damping Factor 20Hz to 2OKHZ ccccceccecececeeeececeeeeeeeeeeeeeeeeeeeeeeeeenseeeeeeeeeeeeeees gt 800 Rise Time 5kHz 90V peak to peak square wave 20 to 80 cceceeeeeeeeneeneeeee es 2 7uS Power Consumption Continuous All Channels Driven QUIESCOEN Gs fas sesciedecncsescessaccessainsosheus oacatmessae sued sumeiecbsmes acnvaceswebseondes header EEREN 80VA MAXIMUM Siwadendscacadasdoads rieron lense Gebeschaanes ahedce E a a E En E R chen ene EnS 1440VA 150 Watts into g ONIMS isiesscrerdiieseancddcecesieasaciccwd Aetencte cedtutesssaaddeinewteaaded ERASE Eiaa 1375VA Power Available in 230VAC on special order 115VAC 50 60Hz Chassis Dimensions 0ccecececeeeeceeeeeeeees 7 3 184 15mm x 17 432mm x 15 381mm Maximum Dimensions 0ceeeeee eee ees 67
27. your Dealer or Authorized Service Center 13 Servicing ADCOM has a Technical Service Department to answer questions pertinent to the installation and operation of your unit In the event of difficulty please contact us for prompt advice Please have the following information readily at hand the unit s model and serial numbers and dealer from whom it was purchased If your problem cannot be resolved through our combined efforts we may refer you to an authorized repair agency or authorize return of the unit to our factory To aid us in directing you to a convenient service center it would be helpful if you indicate which major city is accessible to your home Please address mail inquires to Phone Fax or Email inquiries to ADCOM Service Voice 480 607 2277 8551 East Anderson Drive Suite 105 Fax 480 348 9876 Scottsdale Arizona 85255 Monday Friday United States of America 9 00 AM to 5 00 PM MST www adcom com service adcom com UNDER NO CIRCUMSTANCES SHOULD YOUR UNIT BE SHIPPED TO OUR FACTORY WITHOUT PRIOR AUTHORIZATION OR PACKED IN OTHER THAN ITS ORIGINAL CARTON AND FILLERS For fax inquires please include a return fax or voice number for the reply When calling or writing about your GFA 7700 be sure to note and refer to its serial number as well as the date of purchase and the dealer from whom it was purchased In the event the unit must be returned to our factory for service you will be instructed on the proper procedure whe
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