Adcom GFA-7300 User Manual

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details you can hear

GFA-7400

s,

GFA-7300

High Current

5-Channel

Power Amplifiers

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 this unit to rain or moisture.

CAUTION

RISK OF ELECTRIC SHOCK

A

DO NOT OPEN

AVIS. RISQUE DE CHOC ELECTRIQUE-NE PAS OUVRIR

The graphic symbol ot 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 gam 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 cart, stand, tripod, bracket, or table recommended by the manufacturer, or sold with the unit Any mounting of the device should follow the man ufacturer’s instructions, and should use a mounting ac cessory 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 exits from the unit

H

ATTENTION

POUR PREVENIR LES CHOCS ÉLECTRIQUES NE PAS UTILISER

CETTE FICHE POLARISÉE AVEC UN PROLONGATEUR, UNE PRISE

DE COURANT OU UNE AUTRE SORTIE DE COURANT, SAUF SI LES LAMES PEUVENT ÊTRE INSÉRÉES À FOND SANS EN LAISSER AU CUNE PARTIE A DECOUVERT

CAUTION

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

CAUTION

Any outdoor antenna must be located away from all power lines.

POWER LINES

OUTDOOR ANTENNA GROUNDING

If an outside antenna is connected to your tuner or tuner-preamplifier, be sure the antenna system is grounded so as to provide some protection against voltage surges and built-up static charges. Section 810 of the Nationai Electrical Code, ANSI/NFPA No. 70-1984, 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 4-6 feet (1 22-1 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

POWER LINES

STANDOFF INSULATORS, b

ANTENNA LEAD-IN WIRE

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 ram, 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.

TO EXTERNAL ANTENNA

POWER SERVICE GROUNDING ELECTRODE SYSTEM (e g interior metal water pipe)

BONDING JUMPER, d

OPTIONAL ANTENNA GROUNDING ELECTRODE DRIVEN 8 FEET (2 44 M) INTO THE EARTH IF REQUIRED BY LOCAL CODES SEE NEC SECTION 810-21 (f)

TERMINALS OF RADIO RECEIVER

GROUND WIRE, a.b

GROUND CLAMPS

NOTE TO CATV SYSTEM INSTALLER

This reminder is provided to call the CATV system installer’s attention to Article 820-22 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

Congratulations on your decision to purchase the GFA-7400 or GFA-7300 5-channel power amplifier. The GFA-7400 and GFA-7300 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.

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, 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.

GFA-7400 FEATURES

Precision-matched devices used throughout the signal path. 100,000 pF of power supply-filter capacitance for greater reserve capacity. Independent power supplies for each channel. Fewer gain stages improve signal reproduction accuracy. Custom toroidal power transformer provides better regulation and greater peak current capability. Independent thermal-overload and distortion LEDs for all 5 channels. High quality, gold-plated 5-way binding posts. High quality, gold-plated RCA jacks.

Large independent internal heatsinks for greater cooling capability of output devices. Convenient 12 VDC power ON/OFF triggering.

Heavy gauge, anodized aluminum front panel.

Powder-coated, baked chassis and top cover for greater durability. Cooling vents for greater efficiency and cooler operation while driving low

impedance loads.

Made in the USA

GFA-7300 FEATURES

Precision-matched devices used throughout the signal path. 47,00j0 pF of power supply-filter capacitance for greater reserve capacity.

Independent power supplies for each channel.

Fewer gain stages improve signal reproduction accuracy.

Custom toroidal power transformer provides better regulation and greater peak

current capability.

Independent thermal-overload and distortion LEDs for all 5 channels.

High quality, gold plated binding posts.

High quality, gold-plated RCA jacks. Large independent, internal heatsinks for greater cooling capability of output

devices.

Heavy gauge, anodized aluminum front panel.

Powder-coated, baked chassis and top cover for greater durability. Cooling vents for greater efficiency and cooler operation while driving low impedance loads.

INSTALLATION & HOOKUP

UNPACKING THE GFA-7500 and GFA-7300

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 full operational and mechanical testing, should ensure a product flawless in both appearance and performance. After you have unpacked the GFA-7400/7300,

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 THE CARRIER. SAVE ALL PACKING MATERIALS UNTIL THE CLAIM HAS BEEN SETTLED.

PLACING THE GFA-7400/7300

During normal home operation the internal heatsinks of the GFA-7400/7300 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-

7400/7300 should be kept away from external sources of heat such as radiators and hot-air ducts. The GFA-7400/7300 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-7400/7300.

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-7400/7300, but the free flow of air through the ventilating

slots in the amplifier may be partially obstructed.

If you observe these recommendations, the GFA-7400/7300 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-7400/7300 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-7400/7300.

NOTE! Product shown is for reference only, The GFA-7400 and GFA-7300 differ in

appearance but have the same basic configuration.

CONNECTING THE GFA-7400/7300

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:

GFA-7300 GFA-7400

RR (Right Rear) ............................... Surround Right (SR)

LR (Left Rear)................................... Surround Left (SL)

FR (Front Right)

...............................

Front Right (FR)

C (Center)......................................... Center (C)

FL (Front Left)

..................................

6

Front Left (FL)

Oinputs;

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:

Blue ................................................FL (Front Left)

Red

Green ......................................................C (Center)

White with Blue Stripe White with Red Stripe

OOutputs:

The GFA-7400/7300 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

When connecting the amplifier to the loudspeaker, it is vital to maintain proper polarity (positive to positive, negative to negative). On the GFA-7400/7300, 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 recommended that your speaker cables be terminated with “U” type spade connectors. These will give the most contact area insuring long-term reliability. The spade connector should have a maximum width of 0.57 inches and ^ p an opening width of no less than 0.25” (see diagram on right). -i—p-

.............................................

......................

..................

LR (Left Rear) / (Surround Left)

RR (Right Rear) / (Surround Right)

Nofii

FR (Front Right)

:)

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.

It is suggested that for ail the channels follow this chart for speaker lengths and wire gauges.

up to 24 feet up to 36 feet up to 58 feet

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.

....

.................................

......................................

7

AWG16

AWG14 AWG12

All loudspeakers having a nominal impedance down to 4 ohms can be connected to and

driven by the GFA-7400/7300. 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 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 to the GFA-7400/7300. 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, hometheater mode is in operation. A device such as the Adcom GFS-3, GFS-4 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.

CARING FOR YOUR GFA-7400/7300

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 cloth, slightly dampened with a very mild detergent solution or glass cleaner. DO NOT SPRAY OR

POUR LIQUIDS OF ANY KIND ON THE GFA-7400/7300.

DESCRIPTION OF UNIT

REAR PANEL

NOTE! Product shown is GFA-7400, GFA-7300 is simiiar.

O Inputs

The audio inputs for the GFA-7400/7300 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 Left, Center, Right Front, Left Rear, and Right Rear. To insure that the performance designed into the GFA-7500 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-7400/7400 for more information).

O Outputs

The GFA-7400’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 GFA-7300’s connections to the loudspeakers are basically similar; there are two

terminals for each speaker, which are colored RED for the positive (+) output and BLACK for the

negative (-) output. The high-grade gold-plated binding post terminals on the GFA-7300 are however, different. These connectors easily accept stripped bare wires or pins. To use spade lugs it is necessary to remove the black molded plastic guide block that fits over the binding posts. To remove, take out the two screws at the top and bottom of guide block. Store the guide block and screws for future use.

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-7400/7300 for more information).

o 12VDC Triggering. (GFA-7400 Only)

The GFA-7400 and GFA-7300 are very high power amplifiers 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-7400 by a 12Volt DC output jack on the rear of certain ADCOM pre-amplifiers and tuner pre

amplifiers. 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. Although 12VDC is optimal the circuit will operate from approx. 5 to

30VDC, not to exceed 250mv. Center conductor (tip) is positive (+).

O AC Fuse

The AC Fuse protects the electronic circuits of the GFA-7400/7300. This fuse, normally, will fail only if there is an overload within the GFA-7400/7300. 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-7400:

Fuse Rating For 115 volt operation...

For 230 volt operation........ 8 Amp 250 Volt

....15 Amp 250 Volt

.....

......

BUSS®

......

ABC-15/250V

......

AGC-8/250V

....

.....

Littelfuse®

....

(3AB)314015/250V

....

(3AG)312008/250V

GFA-7300:

For 115 volt operation....

For 230 volt operation....

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 on/y 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

FIRE HAZARD, AND MAY VOID THE WARRANTY.

If the Power LED ( you are using the 12VDC Triggering feature (GFA-7400 Only) 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.

Fuse Ratina

,...T8 Amp 250 Volt

....T4Amp 250 Volt

0

) does not glow, it may be an indication that the AC fuse has blown. If

.....

......

WARNING

BUSS®

......

MDL-8A/250V....

......

MDL-4A/250V....

Littelfuse®

....

(3AG) 313008/250V

....

(3AG)313004/250V

10

Fuse replacement GFA-7400:

To remove the fuse-holder cap, you will need a %” standard flat-blade screwdriver. Place the screwdriver in the recessed slot in the cap. Turn the cap Vs-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-holder. Place the screwdriver in the recessed slot, gently press in and

turn Vs-turn clockwise.

Fuse replacement GFA-7300:

To remove the fuse-holder cap, you will need a #2 Philips type screwdriver. Place the screwdriver in the recessed slot in the cap. Turn the cap 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.

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 clockwise until fully inserted, being careful not to over-tighten.

O AC Power Cord

The AC cord provides power to operate all the GFA-7400 and 7300’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-7400/7300.

The GFA-7400 and 7300’s power cord is supplied with a “polarized” AC plug as required by UL/CSA standards and the National Electrical Code. To minimize the risk of electrical shock and

to insure minimal hum from the system, do not defeat the polarity insuring feature of the plug (one wide blade and one narrow blade). To prevent electrical shock, do not use this polarized plug with an extension cord or AC outlet unless the blades can be fully inserted to prevent blade

exposure.

11

FRONT PANEL

NOTE! Product shown is the GFA-7400. The GFA-7300 is similar in appearance.

The On/Off Switch controls power to the power transformer and circuits of the GFA-

7400/7300. Whenever the GFA-7400/7300 is energized the Power LED (O) will glow. To turn

the GFA-7400/7300 on, press the push-button. It will remain in the “engaged” position while the

unit is energized. To turn the GFA-7400/7300 off, press the push-button in and release and it will move to the “disengaged” position.

o Power LED

This LED will glow whenever the On/Off Switch (O) is turned on and the GFA-7400/7300 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 (©) glows, that amplifier channel will not produce sound even though the

Power LED may still glow. When the GFA-7400/7300 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 (O) has not failed, the Power LED is out, and the Thermal Protection LED (©) 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.

12

O Thermal Protection LEDs

The GFA-7400/7300 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 thermal 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 (O) 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-7400/7300 is

an indication that the amplifier has been overdriven 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.

O 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 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 loudspeakers you are using. If, however, the Distortion Alert LEDs glow brightly or are illuminated most of the time during playback, you are overdriving 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.

13

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.

SYMPTOM

Power LED does not glow. No sound AC Fuse(0)failed.

Power LED glows, Preamp or source unit is not on. but no sound Connections in rear of amp are loose.

One channel not producing sound

Hum from all speakers at any volume Hum from all speakers (hum goes up or down with volume). Hum from the amplifier itself

AC Power Cord(O) not plugged in.

Transformer thermal protection engaged 12VDC triggering malfunctioning (GFA-7400 Only)

INPUT(O) orOUTPUT(O) connector disconnected or loose. Speaker disconnected. Internal protection engaged Ground loop (difference in ground voltages between components). Problem with source unit (CD, tape, etc.), or RCA cable connecting that source unit to the preamp. Some major appliance, dimmer, halogen or fluorescent light is creating interference.

POSSIBLE REASON

POSSIBLE SOLUTION

Plug in AC Power Cord(O) Replace AC Fuse(O). Wait until unit cools down, it will reset. Reset power switch manually Check connection of 12VDC trigger at source Make sure whole system is on. Verify all connections on rear of amp

Verify both connections on that channel

Verify connection at speaker. Bring to Dealer or Service Center If Cable TV is present (see Note 1). If Cable TV is not present (see Note 2). Try different source (tuner, tape, etc.)

and/or different RCA cable

Make sure all appliances, dimmers and suspect lights are off.

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 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 1 and 2 on next page, to troubleshoot a hum problem).

14

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 box, or VCR). If the hum is no longer present, you must insert a “75Q Ground Loop Isolator” before reconnecting the line. You should check with your Adcom Dealer to obtain one. If the “75Q 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.

15

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 which it was bought. 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 inquiries to:

ADCOM Service Corporation

11 Elkins Road East Brunswick, NJ 08816

Phone, Fax or E-mail inquiries to:

Voice: 732-390-1130 Fax: 732-390-5657 Monday through Friday 9:00AM to 5:00PM EST E-mail:

Service@adcom.com

New Location and Telephone Numbers as of Spring 1998

ADCOM Service Corporation

10 Timber Lane Marlboro, NJ 07746 USA

Voice: 732-683-2356 Fax: 732-683-2358

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-7400/7300, 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 when 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 packing was not designed to withstand

rough Parcel Post handling. FREIGHT COLLECT SHIPMENTS CAN NOT BE ACCEPTED UNDER ANY CIRCUMSTANCES.

16

GFA-7400 SPECIFICATIONS

Power Rating (To FTC Requirements)

100 watts continuous average power into 8 ohms at any frequency between 20Hz to 20kHz with all channels driven at less than 0.075% THD

150 watts continuous average power into 4 ohms at any frequency between 20Hz to 20kHz with all channels driven at less than 0.075% THD

IM Distortion (SMPTE)

1 watt to 100 watts into 8 ohms............................................................................................................................................................< 0 075%

1 watt to 150 watts into 4 ohms........................................................................................................................................................... < 0.075%

iM Distortion (CCiF, Any Combination from 4kHz to 20kHz)

100 watts into 8 ohms.............................................................................................................................................................................< 0.025%

150 watts into 4 ohms.............................................................................................................................................................................< 0.025%

THD + Noise at 100 watts into 8 ohms (Typical)

20Hz...................................................................................................................................................................................................................0.012%

1kHz................................................................................................................................................................................................................. 0.012%

10kHz................................................................................................................................................................................................................. 0.02%

20kHz................................................................................................................................................................................................................ 0.025%

THD + Noise at 150 watts Into 4 ohms (Typical)

20Hz.................................................................................................................................................................................................................. 0 025%

1kHz................................................................................................................................................................................................................. 0 025%

10kHz................................................................................................................................................................................................................0 035%

20kHz................................................................................................................................................................................................................ 0.045%

Frequency Response @ 1 Watt into 8 ohms (10Hz to 20kHz)...................................................................................................................+0, -0.25dB

Power Bandwidth (-3dB)............................................................................................................................................................................. 1.5Hz to 65kHz

Dynamic Headroom into 4 ohms................................................................................................................................................................................2.5 dB

Signal to Noise Ratio, “A” Weighted (100 watts into 8 ohms).........................................................................................................................> 1 lOdB

Gain......................................................................................................................................................................................................................................29dB

Input Sensitivity

for 1 Watt.......................................................................................................................................................................................................0.1 volts

for 100 Watts.................................................................................................................................................................................................1.0 volts

Input Impedance................................................................................................................................................................................................................50kf2

Damping Factor (20Hz to 20kHz)................................................................................................................................................................................. s 400

Rise Time (5kHz, 80V, peak-to-peak square wave, 20% to 80%)...........................................................................................................................4.5|iS

Power Consumption (Continuous, All Channels Driven)

Quiescent............................................................................................................................................................................................................ 96VA

Maximum........................................................................................................................................................................................................ 1440VA

100 watts into 8 ohms................................................................................................................................................................................ 1165VA

Power (Available in 230VAC on special order).............................................................................................................................. 115VAC - 50/60Hz

Chassis Dimensions........................................................................................................................... 5” (127mm) x 17" (432mm) x 14” (355.6mm)

Maximum Dimensions........................................................................................................................5%” (146mm) x 17" (432mm) x 15” (38lmm)

Weight.............................................................................................................................................................................................................. 42 lb. (19.1 kg)

Weight, Packed..............................................................................................................................................................................................48 lb. (22.8 kg)

All specifications are subject to change or improvement without notice. Dimensions and weights listed are approximate, actual product may vary slightly.

17

GFA-7300 SPECIFICATIONS

Power Rating (To FTC Requirements)

60 watts continuous average power into 8 ohms at any frequency between 20Hz to 20kHz with all channels driven at less than 0.075% THD 90 watts continuous average power into 4 ohms at any frequency between 20Hz to 20kHz with all channels driven at less than 0.075% THD

IM Distortion (SMPTE)

1 watt to 60 watts into 8 ohms..................................................................................................................................................................<0 07%

1 watt to 90 watts into 4 ohms..................................................................................................................................................................< 0.07%

IM Distortion (CCIF, Any Combination from 4kHz to 20kHz)

60 watts into 8 ohms.................................................................................................................................................................................. <0 025%

90 watts into 4 ohms............................................................................................................................................................................... < 0.025%

THD + Noise at 60 watts into 8 ohms (Typical)

20Hz........................................................................................................................................................................................................... 0.0075%

1kHz.................................................................................................................................................................................................................. 0.007%

10kHz.......................................................................................................................................................................................................... 0.015%

20kHz................................................................................................................................................................................................................. 0 025%

THD + Noise at 90 watts into 4 ohms (Typical)

20Hz.................................................................................................................................................................................................................. 0.015%

1kHz...................................................................................................................................................................................................................0.010%

10kHz............................................................................................................................................................................................................................. 0 022%

20kHz............................................................................................................................................................................................................................. 0 035%

Frequency Response @ 1 Watt into 8 ohms (10Hz to 20kHz)................................................................................................................. +0, -0 25dB

Power Bandwidth (-3dB)...........................................................................................................................................................................1.5Hz to 100kHz

Dynamic Headroom into 4 ohms................................................................................................................................................................................ 1.9 dB

Signal to Noise Ratio, “A” Weighted (60 watts into 8 ohms)....................................................................................................................... > 115dB

Gain................................................................................................................................................................................................................................. 29dB

Input Sensitivity

for 1 Watt........................................................................................................................................................................................................0 1 volts

for 60 Watts................................................................................................................................................................................................... 1.14 volts

Input Impedance............................................................................................................................................................................................................... 50kQ

Damping Factor (20Hz to 20kHz).......................................................................................................................................................................... > 800

Rise Time (5kHz, 90V, peak-to-peak square wave, 20% to 80%)..........................................................................................................................2 7pS

Power Consumption (Continuous, Aii Channeis Driven)

Quiescent............................................................................................................................................................................................................ 80VA

Maximum.......................................................................................................................................................................................................... 960VA

60 watts into 8 ohms...................................................................................................................................................................................... 840VA

Power (Available in 230VAC on special order)............................................................................................................................. 115VAC - 50/60Hz

Chassis Dimensions........................................................................................................................4V4” (118mm) x 17" (432mm) x 14” (355 6mm)

Maximum Dimensions.................................................................................................................... 5” (127mm) x 17" (432mm) x 14%” (375mm)

Weight.............................................................................................................................................................................................................. 351b. (15 9 kg)

Weight, Packed.............................................................................................................................................................................................. 40 lb. (18.2 kg)

All specifications are subject to change or improvement without notice. Dimensions and weights listed are approximate, actual

product may vary slightly.

18

>CCOM'

11 Elkins Road

East Brunswick, NJ 08816

USA

Tel: 732-390-1130

Fax; 732-390-5657

Web: http://www.adcom.com

New Location and Telephone Numbers as of Spring 1998

ySXXM

10 Timber Lane

Marlboro, NJ 07746

USA

Tel: 732-683-2356

Fax: 732-683-2358

98KFTD01

PRINTED IN THE USA

Adcom GFA-7300 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

OWNER’S MANUAL

TABLE OF CONTENTS

ADCOM PROTECTION PLAN (USA ONLY)

GFA-7400 FEATURES

GFA-7300 FEATURES

INSTALLATION & HOOKUP

UNPACKING THE GFA-7500 and GFA-7300

PLACING THE GFA-7400/7300

CARING FOR YOUR GFA-7400/7300

DESCRIPTION OF UNIT

Fuse replacement GFA-7400:

Fuse replacement GFA-7300:

O AC Power Cord

O Thermal Protection LEDs

O Distortion Alert LEDs

TROUBLESHOOTING

SERVICING

New Location and Telephone Numbers as of Spring 1998