User manual ADCOM GFA-6000

[. . . ] · Large independent, internal heatsinks for greater cooling capability of output devices. · Powder-coated, baked chassis and top cover for greater durability. · Cooling vents for greater efficiency and cooler operation while driving low impedance loads. · Standard DB-25 connector to simplify installation Table of Contents Introduction Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] The Power LED indicates that there is AC voltage being fed to the amplifier, but it does not signify that all the amplifier's circuits are in operation. If, for example, one of the Thermal Protection LED (9) glows, that amplifier channel will not produce sound even though the Power LED may still glow. When the GFA-7700 is turned off, the Power LED will take some time to fade out completely. 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 continually tripping the thermostat in the transformer, you must reduce the sound level demands, correct the load impedance of the loudspeakers, or both. 7 Distortion Alert LEDs (8) The Distortion Alert circuit is a unique ADCOM distortion detection system which reads all forms of nonlinear 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. The LEDs are simply warning you that the amplifier is approaching its maximum power output into the particular loudspeakers you are using. With the DB-25 computer-type Multichannel input connector (3), there is no need to worry about color coding or properly connecting the RCA plugs, as this is done in one connector with one cable. The DB25 can easily transfer all five channels from the output of the processor unit to the input of the GFA7700 amplifier. There can be no errors with the DB-25, it is shaped so that it can only be connected in the proper direction. Contact your dealer to locate a DB-25 signal cable. Outputs (2) NOTE: The GFA-7700 is "polarity correct". Any positive signals at its inputs will appear as a positive signal at its outputs In connecting the amplifier to the loudspeaker, it is vital to maintain proper polarity (positive to positive, negative to negative). On the GFA-7700, the positive terminal is color coded RED and labeled "+, " and the negative is color coded BLACK and labeled "-. " The positive terminal on the speaker will be color coded RED, or will be labeled "+, " "pos, " "positive, " "8 ohms, " or "4 ohms. " The negative terminal on the speaker will be color coded BLACK, or will be labeled "-, " "neg, " negative, " "C, " "Common, " "G, " or "ground. " It is necessary that your speaker cables be terminated with "U" type spade connectors. The spade connector should have a maximum width of 0. 57 inches and an opening width of no less than 0. 25". (see diagram on right) 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. [. . . ] For fax inquires, please include a return fax or voice number for the reply. When calling or writing about your GFA-7700, be sure to note and refer to its serial number as well as the date of purchase and the dealer from whom it was purchased. In the event the unit must be returned to our factory for service, you will be instructed on the proper procedure when you call or write for a Return Authorization. For warranty coverage, a copy of the original proof of purchase is required. [. . . ]