Adcom GFA-7605 AV receiver
Contents
1. 5 146mm x 17 432mm x 15 381mm Weight sister eit e A seh Re ST ao 42 lbs 19 1kg Weight Packed orr a A e ie eet nal tae lie Bee ceil cp ee eee ee 48 lbs 22 8kg GFA 7607 SPECIFICATIONS Power Rating To ElA CEA 490 A Requirements 125 Watts continuous average power per channel into 8 ohms at any frequency between 20Hz and 20kHz with all channels driven at less than 1 00 THD 175 Watts continuous average power per channel into 4 ohms at any frequency between 20Hz and 20khz with all channels driven at less than 1 00 THD IM Distortion SMPTE 1 watt to 125 watts into 8 OMMS 1 ce eee eee eee eee eee teen eens lt 0 075 1 watt to 175 watts into 4 OMMS iaa EE ee rro lt 0 075 IM Distortion CCIF Any Combination from 4kHz to 20kHz 125 Watts IMto 8 ohms wade a Cae ER an anse tape ote en lt 0 025 175 Watts into 4 ONMS a thie eaters A BAe Md ace areal SRE lt 0 025 THD Noise at 125 watts into 8 Ohms Typical LOA PS DO A ON ai saea tad ia Gel alts 0 012 Za E OS A o a aloe Se abana Game iis aaah okt ie 0 012 LOZA A ES O IDE AS 0 02 LORA A AO E Ns 0 02 THD Noise at 175 watts into 4 Ohms Typical DO E a e alta 0 030 DA O EPR ES EN RN 0 026 LOZA A dl Sue 6e IE NT D fae ae ae he A 0 060 ZO A A A E a ap mond ain web aes 0 060 Frequency Response 1 Watt into 8 Ohms 10HZ t0 20KH2 nope Rh A en Sen 0eme E ee pe ak GH Ee eel 0 0 25dB Power2. ADCOM OWNER S MANUAL GFA 7605 Multichannel High Current Power Amplifiers WELCOME Dear fellow ADCOM product owner Welcome to the ADCOM family For more than twenty years ADCOM products have delivered excellent performance and value for customers around the world Our products are designed by our experienced and demanding engineering team built to the highest standards in our factory and sold and serviced through dealers custom installers and other retailers whose primary goal is your complete satisfaction We know you are anxious to hear your new amplifier in action but please take a few minutes to read this owner s manual before connecting the amplifier to your system Because ADCOM amplifiers can output tremendous power it is particularly important that you connect your amplifier to your pre amplifier and speakers while the amplifier is unplugged and your other equipment is turned off This will protect the amplifier and other equipment from potential short circuits from crossed interconnect or speaker wires while you are working on the connections In addition it is important that you allow for adequate ventilation around your amplifier and other equipment since excessive heat buildup can shorten the life of any electronic product including the amplifier Once you have correctly connected your pre amplifier and speakers to your new amplifier you should be able to enjoy many trouble free years of performance We conduc
3. Anderson Drive Suite 105 Scottsdale Arizona 85255 Voice 480 607 2277 Fax 480 348 9876 http www adcom com GFA7605_07_manual_v1
4. THE GFA 7605 7607 6 CONNECTING THE GFA 7605 7607 7 OPERATION FRONT AND REAR PANEL DIAGRAMS 8 DESCRIPTION OF UNIT REAR PANEL 9 10 DESCRIPTION OF UNIT FRONT PANEL 10 11 CONNECTIONS DIAGRAM oooooooooommmmomo 11 TROUBLESHOOTING RESOLVING PROBLEMS sis os 12 CARING FOR YOUR GFA 7605 7607 13 SERVICE INFORMATION 43e darnos idas 13 GFA 7605 SPECIFICATIONS hit stone cana 14 GFA 7607 SPECIFICATIONS esse ses 15 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 this unit to rain or moisture CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN The graphic symbol of a lightning flash with an arrow point within a triangle signifies that there is dangerous voltage within the unit and it poses a hazard to anyone removing the cover to gain access to the interior of the unit Only qualified service personnel should make any such attempt The graphic symbol of an exclamation point within an equilateral triangle warns a user of the device that it is necessary to refer to the instruction manual and its warnings for proper operation of the unit Do not place this unit on an unstable cart stand tripod bracket or table The unit may fall causing serious injury to a child or adult and serious damage to the unit Use only with a c
5. 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 and 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 holder Place the screwdriver in the recessed slot gently press in and turn 1 8 turn clockwise 5 AC Power Cord The AC cord provides power to operate all the GFA 7605 7607 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 7605 7607 DESCRIPTION OF UNIT FRONT PANEL 6 On Off Switch The On Off Switch controls power to the power transformer and circuits of the GFA 7605 7607 Whenever the GFA 7605 7607 is energized the Power LED 7 will glow To turn the GFA 7605 7607 on press the push button It will remain in the engaged position while the unit is energized To turn the GFA 7605 7607 off press the push button in and release and it will move to the disengaged position 7 Power LED This LED will glow whenever the On Off Switch 6 is turned on and the GFA 7605 7607 is energized The Power LED indicates that there is AC voltage being fed to the amplifier but it does not sign
6. multichannel power amplifier The GFA 7605 and GFA 7607 have been designed to be high performance and musically accurate in a configuration specifically designed to integrate with any home theater processor You have made a wise choice that will reward you for years to come with exceptionally accurate and musical sound reproduction To realize the full potential of your new amplifier and before making any connections to it please read these operating and installation instructions thoroughly UNPACKING THE GFA 7605 7607 Before your new ADCOM amplifier 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 lull operational and mechanical testing should ensure a product flawless in both appearance and performance After you have unpacked the GFA 7605 07 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 again 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 TH
7. 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 7 channels e High quality gold plated binding posts e High quality gold plated RCA jacks e Large independent internal heatsinks for greater cooling capability of output devices 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 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 do 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 or if the ADCOM Warranty Card is not included in the carton 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 INTRODUCTION Congratulations on your decision to purchase the GFA 7605 or GFA 7607
8. the antenna system is grounded so as to provide some protection against voltage surges and built up static charges Section 810 of the National Electrical Code ANSI NFPA No 701984 provides information with respect to proper grounding of the mast and supporting structure grounding of the lead in wire to an antenna discharge unit size of grounding conductors location of antenna discharge unit connection to grounding electrodes and requirements for the grounding electrode a Use No 10 AWG 5 3 mm copper No 8 AWG 8 4 mm aluminum No 17 AWG 1 0 mm copper clad steel or bronze wire or larger as a ground wire b Secure antenna lead in and ground wires to house with stand off insulators spaced from 46 feet 1 221 83 m apart c Mount antenna discharge unit as close as possible to where lead in enters house 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 Section 810 21 j EXAMPLE OF ANTENNA GROUNDING AS PER NATIONAL ELECTRICAL CODE INSTRUCTIONS CONTAINED IN ARTICLE 810 RADIO AND TELEVISION EQUIPMENT service entrance conductors x standoff y insulators b antenna 77 lead in wire service entrance 4 antenna discharge unit c to external antenna terminals of radio rq power service grounding electrode system e g interior metal water pipe bonding jumper Se OpEtonal antenna groundind e
9. Bandwidth 3dB 1 0 0 ccc cece ee eee eee ee eee eee eee eee eee 1 5Hz to 65kHz Dynamic Headroom Into 4 Ohms 4 444444882 2 0dB Signal to Noise Ratio A Weighted 125watts into g ohm cios Gi eee ee Meee ed SA a el eue ook Rae en ae cet oe gt 118dB A O RR 29dB Input Sensitivity fOr Watt 0 A he elt ne Da ead 0 1 volts POR AZ5 WALtS sx id ds rd da 1 1 volts Input impedances 0 iii rs e beh Se ahd aes 2 48k ohms Damping Factor ZOH to 2OKH Zs oc 8a Pa ha AS GS Joe bee at A awe Reta e gt 467 Rise Time 5kHz 120V peak to peak square wave 20 to 80 6 0uS Power Consumption Continuous All Channels Driven QUIESCON E corae anre AO nde Be ath Bbc aa eh ne A Se Oe a A be die ance On WH as at 132VA MAXIMUM Li hte See aaa a Rate AA a ae baie A ARENA AY A aa ee Nee basa 1934VA 100 Watts into 8 OhMS 2 2 32244 ee ci dre ee 4 g de dre ee ee huh ELERE PETERA 1851VA General Power available in 230V by special order 115VAC 50 60Hz Chassis Dimension 5 127mm x 17 432mm x 14 355 6mm Maximum Dimensions 5 146mm x 17 432mm x 15 381mm Weight cos wat A o A a ie 48 lbs 21 8kg Weight Packed 00000 A at A E ds 56 lbs 25 4kg ADCOM A division of Klein Technology Group LLC 8551 East
10. E CARRIER SAVE ALL PACKING MATERIALS UNTIL THE CLAIM HAS BEEN SETTLED INSTALLING THE GFA 7605 7607 During normal home operation the internal heatsinks of the GFA 7605 7607 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 7605 7607 should be kept away from external sources of heat such as radiators and hot air ducts The GFA 7605 7607 should never be placed with other heat producing components in a cabinet or enclosure lacking free air flow The top and bottom panel 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 7605 7607 This is particularly important if your system includes low impedance loudspeakers which are difficult to drive or if you will consistently demand high volume levels from the amplifier and speaker system Not only will heat generated by the amplifier affect the performance of equipment stacked on top of the GFA 7605 7607 but the free flow of air through the ventilating slots in the amplifier may be partially obstructed If you observe these recommendations the GFA 7605 7607 will perform
11. 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 SYMPTOM POSSIBLE REASON POSSIBLE SOLUTION Power LED does not AC Power Cord s not plugged in Plug in AC Power Cord s glow No sound AC Fuse s failed Replace AC Fuse s Transformer thermal protection engaged Wait until unit cools down It will reset I2V DC triggering malfunctioning Reset power switch manually Check connection of 12V DC trigger at source Power LED glows Preamp or source unit is not on Make sure whole system is on but no sound Connections in rear of amp are loose Verify all connections on rear of amp One channel not INPUT s or OUTPUT s connector Verify both connections on that channel producing sound disconnected or loose Speaker disconnected Verify connection at speaker Internal protection engaged Bring to Dealer or Service Center Hum from all speakers Ground loop difference in ground voltages If Cable TV is present see Note 1 at any volume between components If Cable TV is not present see Note 2 Hum from all speakers Problem with source unit CD tape etc Try different source tuner tape etc hum goes up or or RCA cable connecting that source unit and or different RCA cable down with volume to the preamp Hu
12. OUT PRIOR AUTHORIZATION OR PACKED IN OTHER THAN ITS ORIGINAL CARTON AND FILLERS 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 packing was not designed to withstand rough Parcel Post handling FREIGHT COLLECT SHIPMENTS WILL NOT BE ACCEPTED UNDER ANY CIRCUMSTANCES 13 GFA 7605 SPECIFICATIONS Power Rating To ElA CEA 490 A Requirements 125 Watts continuous average power per channel into 8 ohms at any frequency between 20Hz and 20kHz with all channels driven at less than 1 00 THD 175 Watts continuous average power per channel into 4 ohms at any frequency between 20Hz and 20khz with all channels driven at less than 1 00 THD IM Distortion SMPTE 1 watt to 125 watts into 8 OMMS 1 ce eee eee eee eee eee teen eens lt 0 075 1 watt to 175 watts into 4ohms 44444 lt 0 075 IM Distortion CCIF Any Combination from 4kHz to 20kHz 125 Watts into 8 OMS 3 wen IA A a tape oat een lt 0 025 175 Watts into 4 ONMS a the eaten AA Ae act EEAS lt 0 025 THD Noise at 125 watts into 8 Ohms Typical DOTA PS DO ON N tad ia Qed ales 0 012 Za E OS A o a aloe Se abana Game iis aaah okt ie 0 012 LOZA A ES O IDE AS 0 02 LORA A AO E N
13. art stand tripod bracket or table recommended by the manufacturer or sold with the unit Any mounting of the device should follow the manufacturer s instructions and should use a mounting accessory recommended by the manufacturer Read all the safety and operating instructions before connecting or using this unit Retain this notice and the owner s manual for future reference All warnings on the unit and in its operating instructions should be adhered to All operating and use instructions should be followed Do not use this unit near water For example near a bathtub washbowl kitchen sink laundry tub in a wet basement or near a swimming pool The unit should be installed so that its location or position does not interfere 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 The unit should be situated away from heat sources such as radiators heat registers stoves or other devices including amplifiers that produce heat The unit should be connected to a power supply outlet only of the voltage and frequency marked on its rear panel The power supply cord should be routed so that it is not likely to be walked on or pinched especially near the plug convenience receptacles or where the cord exit
14. 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 6 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 one specific cable is responsible If any or all cables cause the hum to appear then the preamp or processor should be evaluated for proper operation by your Dealer or Authorized Service Center 12 CARING FOR YOUR GFA 7605 7607 Great care has been taken by ADCOM 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 clot
15. ed 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 7605 7607 by a l2V DC output jack on the rear of certain ADCOM pre amplifiers and tuner preamplifiers When using this feature the front 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 4 AC Fuse The AC Fuse protects the electronic circuits of the GFA 7605 7607 This fuse normally will fail only if there is an overload within the GFA 7605 7607 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 GFA 7605 for 120 volt operation Fuse Rating 13 Amp GFA 7605 for 230 volt operation Fuse Rating 6 5 Amp GFA 7607 for 120 volt operation Fuse Rating 15 Amp GFA 7607
16. for 230 volt operation Fuse Rating 8 Amp 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 serious damage to the amplifier circuits may create a hazard fire 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 12V DC Triggering feature it may be possible that there is a problem with that connection To determine if the problem is caused by a malfunction in the 12V DC system remove the small plug inserted into the 12V DC 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 12V DC triggering circuit the amp will turn on and the LED will glow DO NOT attempt repair of the 12V DC system If you are not sure or the amplifier displays other symptoms please consult the RESOLVING PROBLEMS section on page 12 Fuse replacement To remove the fuse holder cap you will need a 1 4 standard flat blade screwdriver Place the screwdriver in the recessed slot in the cap Turn the cap 1 8 turn counter clockwise until the cap pops out towards you Grasp the cap with your fingers
17. h slightly dampened with a very mild detergent solution or glass cleaner Do not spray or pour liquids of any kind directly onto the GFA 7605 7607 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 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 inquires to ADCOM Service Voice 480 607 2277 8551 East Anderson Drive Suite 105 Fax 480 348 9876 Scottsdale Arizona 85255 USA Monday through Friday 9 00 AM to 5 00 PM MST Email service adcom com For Fax inquires please include a return Fax number for the reply When calling or writing about your GFA 7605 7607 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 any communications to us please include a daytime phone number where we may reach you In the event the unit must be returned to our factory for service you will be instructed on the proper procedure when you call or write for a Return Authorization UNDER NO CIRCUMSTANCES SHOULD YOUR UNIT BE SHIPPED TO OUR FACTORY WITH
18. ies 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 to the GFA 7605 7607 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 good sonic integrity while giving you the flexibility to add speakers throughout your house It is suggested that for all the channels follow this chart for speaker lengths and wire gauges 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 up to 24 feet AWGI6 up to 36 feet AWGI4 up to 58 feet AWGI2 1 3 4 GFA 7607 REAR PANEL LF C__RF_RS RB input oO input oO output output SD TA sos sos 7 lt A Lay Lay Model GFA 7607 Power Amplifier Powerconsumption max XXXXW AC fuse 12VDC trigger 15ABC 250V o DM 120VAC 50 60 Hz oe 2 5 GFA 7607 FRONT PANEL 227607 6 7 8 9 1 Input Jacks 6 On Off Switch 2 Output Binding Posts 7 Po
19. ify that all the amplifier s circuits are in operation If for example one of the Thermal Protection LEDs 9 glows that amplifier channel will not produce sound even though the Power LED may still glow When the GFA 7605 7607 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 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 tripping the thermostat in the transformer continually you must reduce the sound level demands correct the load impedance of the loudspeakers or both 8 Thermal Protection LEDs The GFA 7605 7607 are provided with a thermal protection circuit which will shut down the individual amplifiers if its heatsink temperature reaches 85 C The Thermal Protection LEDs will light whenever the the
20. lectrode driven 8 feet the earth if required by NOTE TO CATV SYSTEM INSTALLER This reminder is provided to call the CATV system installer s attention to Article 82022 of the National Electrical Code that provides guidelines for proper grounding and in particular specifies that the cable ground shall be connected to the grounding system of the building as close to the point of cable entry as practical GFA 7605 FEATURES e Precision matched devices used throughout the signal path e 100 000 pF of power supply filter capacitance to optimize transient response 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 12V DC 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 GFA 7607 FEATURES e Precision matched devices used throughout the signal path e 140 000 pF of power supply filter capacitance to optimize transient response e Independent
21. m from the amplifier Some major appliance dimmer halogen or Make sure all appliances dimmers and itself fluorescent light is creating interference suspect lights are off Aspecial 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 a 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 potentials creates a 60Hz low level sound approximately a low A that seems to hum hence the name 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 to the AC line ground of your other equipment refer to Note and 2 to troubleshoot a hum problem 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 75Q at the wall or the first component the cable is connected to i e the cable
22. ng term reliability The spade connector should have a maximum width of 0 57 inches and an opening width of no less than 0 25 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 Sound audio engineering practice suggests the use of at least AWG16 stranded copper cable Recommended capacitance of the speaker wire should not exceed 50pF per foot This insures high frequencies will not be rolled off All loudspeakers having a nominal impedance down to 4 ohms can be connected to and driven by the GFA 7605 7607 The amplifier can drive these low impedance speakers at more than adequate power levels with no difficulty It should be noted 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 difficult
23. 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 7605 7607 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 7605 7607 CONNECTING THE GFA 7605 7607 When connecting the amplifier to the loudspeaker it is vital to maintain proper polarity positive to positive negative to negative On the GFA 7605 7607 the positive terminal is color coded RED and labeled and the negative is color ee 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 ee e neg negative C Common G or ground It is recommended that your speaker cables be terminated with U type spade connectors These will give the most contact area insuring lo
24. rmal protection circuit in 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 Activation of the Thermal Protection circuitry in any of the amplifiers in the GFA 7605 7607 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 9 Distortion Alert LEDs 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 appro
25. s 0 02 THD Noise at 175 watts into 4 Ohms Typical DO E a e alta 0 030 DA O EPR ES EN RN 0 026 LOZA A dl Sue 6e IE NT D fae ae ae he A 0 060 ZO A A A E a ap mond ain web aes 0 060 Frequency Response 1 Watt into 8 Ohms 10HZ t0 20KH2 52 52 eek he Seen A SRS od EEE a a GeV ee 0 0 25dB Power Bandwidth 3d B 0 cece ee ee eee ee ee eee ee ee ee eee en eeee 1 5Hz to 65kHz Dynamic Headroom Into 4 Ohms 2 00 dB Signal to Noise Ratio A Weighted 125 watts into g ohm cional a en ae et ee gt 117dB A O RN RR 29dB Input Sensitivity fOr Watt aaa a a os 0 1 volts LOL Watts di id is rd s are 1 1 volts Input impedances iii rd e a bas 48k ohms Damping Factor ZOH O 2OKH Zi oc te a Jo bee aa AR ned d Sane ede ae ah e gt 498 Rise Time 5kHz 120V peak to peak square wave 20 to 80 6 0uS Power Consumption Continuous All Channels Driven QUIESCENT sis Biker ie ve HERA A E AS AME Be CUED ES hd A A wd ORE BRS 116VA MAXIMUM z sarera See aaa a Rate AAA aca eee bas A AEE RIAA A UA et Neale bas aa 1500VA 100 Watts into 8 OhMS 2 2 22444 eect eee eee ee AEEA hnd he MGS eee ee 1380VA General Power available in 230VAC by special order 115VAC 50 60Hz Chassis Dimension 5 127mm x 17 432mm x 14 355 6mm Maximum Dimensions
26. s from the unit Clean unit only as recommended in its instruction manual The power supply cord of the unit should be unplugged from the wall outlet when it is to be unused for a long period of time Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through any openings This unit should be serviced by qualified service personnel when A The power cord or the plug has been damaged or B Objects have fallen or liquid has been spilled into the unit or C The unit has been exposed to rain or liquids of any kind or D The unit does not appear to operate normally or exhibits a marked change in performance or E The device has been dropped or the enclosure damaged DO NOT ATTEMPT SERVICING OF THIS UNIT YOURSELF REFER SERVICING TO QUALIFIED SERVICE PERSONNEL ATTENTION POUR PREVENIR LES CHOCS ELECTRIQUES NE PAS UTILISER CETTE FICHE POLARISEE AVEC UN PROLONGATEUR UNE PRISE CE COURANT OU UNE AUTRE SORTIE CE COURANT SAUF SI LES LAMES PEUVENT ETRE INSEREES A FOND SANS EN LAISSER AUCUNE PARTIE A DECOUVERT CAUTION TO PREVENT ELECTRIC SHOCK DO NOT USE THIS POLARIZED PLUG WITH AN EXTENSION CORD RECEPTACLE OR OTHER OUTLET UNLESS THE BLADES CAN BE FULLY INSERTED TO PREVENT BLADE EXPOSURE CAUTION POWER LINES Any outdoor antenna must be located away from all power lines OUTDOOR ANTENNA GROUNDING If an outside antenna is connected to your tuner or tuner preamplifier be sure
27. t a thorough quality and performance test on each and every amplifier we build in our factory prior to shipment In the rare case of a defect that may occur after shipment we stand behind our amplifiers with a five year parts and labor warranty To register for this warranty please complete and mail the enclosed warranty card back to ADCOM Also please keep a copy of your sales receipt with the owner s manual so you may provide proof of eligibility for the warranty should the need arise We know you will be very happy with the sound and performance of your new amplifier We hope you will also consider other ADCOM products such as our line of pre amplifiers and DVD and CD players In addition we design and manufacture complementary products such as line conditioners surge suppressors and speaker selectors Please visit our web site www adcom com to learn more about our complete line of stereo home theater and distributed audio video products On behalf of all of us at ADCOM want to thank you for your selection of our product for your home or business entertainment system Sincerely A ds Man Douglas Klein President ADCOM TABLE OF CONTENTS WELCOME ontario des 2 SAFETY INFORMATION 4 DESCRIPTION OF UNIT GFA 605 FEATURES cerca atar este 5 GPA 7 007 FEATURES conca 5 WARRANTY INFORMATION 5 INSTALLATION amp HOOKUP UNPACKING THE GFA 7605 7607 6 INSTALLING
28. wer LED 3 12V DC Trigger 8 Thermal Protection LEDs 4 AC Fuse 9 Distortion Alert LEDs 5 AC Power Cord DESCRIPTION OF UNIT REAR PANEL 1 Inputs The audio inputs for the GFA 7605 and GFA 7607 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 channels To insure that the performance designed into the amplifier 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 7605 7607 for more information 2 Outputs The GFA 7605 s and GFA 7607 s connections to the loudspeakers are made through high grade 5 way gold plated binding post terminals There are two terminals 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 7605 7607 for more information 3 12V DC Trigger The GFA 7605 and GFA 7607 are very high power amplifiers and as such must be directly connect
29. ximately 1 regardless of impedance voltage 10 current phase angle or the reactance of the loudspeakers WARNING which the amplifier is driving Sometimes when the WHENEVER CONNECTIONS TO OR FROM THE GFA 7605 GFA 7607 ARE BEING i Ai MADE BE CERTAIN THAT THE AC ON OFF during high volume listening particularly if you are driving SWITCH OF THE AMPLIFIER IS IN THE low impedances This flickering is no cause for concern OFF POSITION THE AC CORD OF THE The LEDs are simply warning you that the amplifier is AMPLIFIER IS DISCONNECTED FROM THE AC approaching its maximum power output into the particular WALL OUTLET AND THAT ALL ASSOCIATED A COMPONENTS ARE OFF loudspeakers 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 amplifier is in use the LEDs may occasionally flicker Right Front Center D Left Front LB LS input JO input JO O AC fu 12VDC trigger 15ABC 250V D Right Back _ Left Surround Right Surround Left Back RESOLVING PROBLEMS Use the chart below to solve common situations that don t require professional attention
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