Adcom GFA-7700 owner manual Inputs, Outputs

Inputs (1)

To preserve the correct effects, be certain to connect the RCA cables to the proper RCA-input connector. If the cables are color coded, then use this sequence for the connections:

Blue	Left Front
Red	Right Front
Green	Center
White with Blue Stripe	Left Surround
White with Red Stripe	Right Surround

The recommended maximum RCA cable capacitance should be less than or equal to 30pF per foot when measured between the two conductors, and less than or equal to 50pF per foot when measured between one conductor and the shield.

With the DB-25 computer-type Multichannel input connector (3), there is no need to worry about color coding or properly connecting the RCA plugs, as this is done in one connector with one cable. The DB- 25 can easily transfer all five channels from the output of the processor unit to the input of the GFA- 7700 amplifier. There can be no errors with the DB-25, it is shaped so that it can only be connected in the proper direction. Contact your dealer to locate a DB-25 signal cable.

Outputs (2)

NOTE: The GFA-7700 is “polarity correct”. That is it does not invert phase from input to output. Any positive signals at its inputs will appear as a positive signal at its outputs

In connecting the amplifier to the loudspeaker, it is vital to maintain proper polarity (positive to positive, negative to negative). On the GFA-7700, the positive terminal is color coded RED and labeled “+,” and the negative is color coded BLACK and labeled “-.” The positive terminal on the speaker will be color coded RED, or will be labeled “+,” “pos,” “positive,” “8 ohms,” or “4 ohms.” The negative terminal on the speaker will be color coded BLACK, or will be labeled “-,” “neg,” negative,” “C,” “Common,” “G,” or “ground.”

It is necessary that your speaker cables be terminated with “U” type spade connectors. These will give the most contact area insuring long-term reliability. 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. Recommended capacitance of the speaker wire should not exceed 50pF per foot. This insures high frequencies will not be rolled-off.

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