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Photos and specs Adcom GFA-5500 |
manual abstract
However, make sure that the cable ends are tinned before you make the cable connections to the banana plugs. Alternatively, you can use “crimped” pins or other lugs to ensure low contact resistance at the connection to the amplifier and loudspeakers. If you prefer to use other methods of connection, unscrew the insulated head of the binding post until the hole in the binding post stud is accessible. You can then insert the bare or tinned wire, or terminal pin, through the hole. You can also use the many variety of spade lugs available by simply placing the tines of the spade lug onto the binding post stud. 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 post has 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. All loudspeakers having a nominal impedance down to 4 ohms can be connected to, and driven by the GFA-5500. The amplifier can drive these low Impedances 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 some others to even less than 2 ohms). You will not experience difficulties even with these very low impedance loads unless you demand excessively high volume levels from the system. In most applications, you can drive two or more sets of loudspeakers. You should note, however, that when loudspeakers are paralleled, the impedance presented to the amplifier is lower than the nominal impedance of each loudspeaker. In other words, if you parallel two 8 ohm sets of loudspeakers, the resultant impedance presented to the amplifier will be 4 ohms. If 8 ohm and 4 ohm loudspeakers are paralleled, the resultant impedance will be approximately 2.6 ohms. In this last situation, depending upon the lowest impedance of the nominally 4 ohm speakers, and if excessive power demands are placed on the amplifier, you may trigger the THERMAL PROTECTION on the amplifier or blow one of the EXTERNAL PROTECTION FUSES. See its respective section for more information. For convenient switching of multiple sets of speakers with impedance protection for the amplifier, you should consider the use of an ADCOM speaker selector. These are available from your local ADCOM dealer. 4 AC LINE CORD © The AC cord provides power to operate all the GFA-5500'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 of the GFA-5500. NOTE The GFA-5500'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 ensure minimal hum from the system, do not defeat the polarity ensuring 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 other outlet unless the blades can be fully inserted to prevent blade exposure AC POWER FUSE © The AC POWER FUSE protects the electronic circuits of the GFA-5500. This fuse will normally blow only if there is an overload within the GFA-5500. For continued protection of the electronic circuits it is strongly recommended that it be replaced only with a fuse of the same type and value as printed on the rear panel of the amplifier. Whenever the AC ON/OFF SWITCH on the front panel is turned on and the amplifier is energized, the POWER LED will glow. If turning on the amplifier does not cause the POWER LED to glow, this may indicate that the AC POWER FUSE is blown. Unplug the AC LINE CORD from the AC wall outlet and turn the AC ON/OFF SWITCH off and check the fuse. If the fuse is blown, replace it only with one of the same type and value as printed on the rear panel of the amplifier. If, after replacing the fuse, it blows immediately upon turning on the amplifier (POWER LED does not glow), a failed electronic component or other internal problem must be suspected. Make no further attempts at fuse replacement or operation of the amplifier. Refer the problem to competent ADCOM authorized service personnel. WARNING BEFORE ATTEMPTING TO CHECK OR REPLACE A BLOWN FUSE, BE CERTAIN TO UNPLUG THE AC LINE CORD FROM THE AC WALL OUTLET TO PREVENT POSSIBLE ELECTRICAL SHOCK. To remove a blown or suspect fuse from its holder, use only a 1/4" standard screwdriver to prevent damage to the fuse holder. Simply press lightly on the fuse holder cap and turn counterclockwise. The cap will pop out after a quarter turn. Once a new fuse has been installed in the fuse holder cap, insert it into the fuse holder body and press lightly while turning the c...