User manual NAD 218

[. . . ] Note to CATV system installer: This reminder is provided to call the CATV installer's attention to Article 820-40 of the NEC , which provides guidelines for proper grounding and, in particular, specifies that the cable should be connected to the grounding system of the building, as close to the point of cable entry as practical. The lightning flash with arrowhead, within an equilateral triangle is intended to alert the user of the presence of uninsulated "dangerous voltage" within the product's enclosure; that may be of sufficient magnitude to constitute a risk of electric shock to persons. Peak power levels that may occur in the "bridged" mode or with low-impedance speakers. At moments when the amplifier is producing maximum power, voltages of nearly 100V may be present on the speaker terminals, so the terminals are protected by hinged plastic safety covers. [. . . ] If the speakers cannot easily be set face-to-face, then phasing must rely on the "polarity" of the connecting wires. The speaker terminals on the amplifier are identified as red (+) and black (-) in each channel. The terminals at the rear of the speakers are also marked for polarity, either via red and black connectors or by labels: "+", 1, or 8 ohms for positive, "-", 0, or G for negative. The red (+) terminal on the amplifier should be connected to the red (positive) terminal of the speaker, in each channel. To facilitate this, the two conductors comprising the speaker wire in each channel are different, either in the color of the wire itself (copper vs. silver) or in the presence of a small ridge or rib pattern on the insulation of one conductor. Use this pattern to establish consistent wiring to both speakers of a stereo pair. thus if you connect the copper colored wire (or ribbed insulation) to the (+) amplifier terminal in the Left channel , do the same in the Right channel. At the other end of the wire, if you connect the copper colored wire (or the ribbed insulation) to the red or positive terminal on the left-channel speaker, do the same at the right-channel speaker. If your preamplifier has balanced XLR outputs, connect a three-conductor cable from your left-channel preamp output to the left-channel XLR input on the 218 THX, and set the BALANCE switch to BAL. If your audio dealer does not have the appropriate cables, purchase balanced "microphone" cables from a shop that sells professional recording equipment. The end of the cable that has a "male" XLR plug (with three metal pins) should be connected to the 218 THX amplifier. The end of the cable that has a "female" XLR socket (with three holes) should be connected to your preamp. An XLR plug is "keyed" so that it fits into the socket only one way. If there is a set-screw in the barrel of the plug, align it with the top of the connector. Push the plug fully into the XLR socket until it latches in place. The three pins of an XLR-type ("Cannon") connector are numbered. Pin 1 is the chassis earth (ground), to which the shield of a balanced-wire cable is connected. The XLR socket has a latching feature that prevents the connector from being pulled out by accident. Before disconnecting an input cable, turn off the Power. Use one hand to press the latching tab above the XLR socket while using the other hand to pull the XLR plug out. Make connections to the right-channel input in the same way that you did for the left channel. [. . . ] This mode is activated briefly during turn-on and turn-off, to protect the speakers from low-frequency thumps. Times the Protection mode may be activated by severe overheating, short-circuited speaker wiring, or an internal fault. if the Status light continues to glow red , switch the Power OFF. When the output stage cools, relays will automatically re-connect the speakers, and normal operation can be resumed. [. . . ]