User manual NAD 912

[. . . ] The line outputs are buffered, so that a low impedance or short circuit placed across it will not affect the signal at the input. If the 912 is being used to amplify a remote pair of speakers, connect the system's preamplifier to the 912's inputs, then run a pair of cables from the 912's outputs to the inputs of the main stereo amplifier. Since its power transformer generates a magnetic hum field of moderate strength, a turntable (especially one with a moving-coil pickup cartridge) should not be located near the amplifier. Do not obstruct the air outlet grilles on the top or bottom covers, and do not place the amplifier on a rug or other soft surface. [. . . ] Many stereo systems have so much voltage gain that the speakers (or your ears) are over-driven at any volume-control setting higher than 11 or 12 o'clock. As a result you are confined to using only the lower half of the volume control's range, where adjustments are imprecise and where channel-balance errors tend to be greater. If all input-level controls are reduced, you can turn up your preamplifier's volume control, making effective use of most of its range. (Suggestion: adjust the input level controls so that your preferred maximum sound levels usually occur at about 2 or 3 o'clock on the volume control. ) As an added benefit, this procedure suppresses any noise produced by the preamp's high-level circuitry (e. Any residual hum or hiss that does not go away when the Volume is turned down). Small errors in channel balance can dramatically degrade the apparent "depth" and "air" of the stereo image. Such balance errors may be due to normal production-line differences in speaker sensitivity, differences in the acoustic environment around the two speakers, and slightly different distances from your chair to each speaker. You can use the input-level controls to correct these fixed balance errors, freeing your preamplifier's balance control to correct balance errors in recordings. Ideally the "phantom" central image should seem to be floating in mid-air midway between the left and right speakers. If it is located off-center, closer to one speaker, turn down the inputlevel control for that channel slightly in order to recenter the phantom mono image. Plug the AC line cord into a nearby wall outlet that provides the correct AC power line voltage, or into a switched convenience outlet on your preamp. Before making connections to the amplifier, make sure the POWER is switched OFF. Connect the signal cable from the preamplifier, surround decoder or other signal source to the inputs. If you want to use the 912 as a single 90-watt amplifier instead of a stereo 30 W/ch amp, see BRIDGING (Refer to item 6). This amplifier is equipped with special high-current binding-post speaker terminals to handle the highest peak power levels that may occur in the "bridged" Connections may be made in either of two ways. ] (1) Strip off a half-inch (1 cm) of insulation from each speaker wire. Unscrew the knob, insert the bare wire into the opening at the base of the binding post, and tighten the knob until it grasps the wire securely. Check to be sure that no loose strand of wire is touching the chassis or an adjacent terminal. (2) Install banana plugs on your speaker wires, and plug them into the end of each binding post. [. . . ] When an amplifier is driven beyond its specified power output it normally produces "hard clipping" of the signal with harsh distortion and power-supply buzz as the output transistors saturate. Cet appareil peut être posé sur n'importe quelle surface robuste, à condition qu'elle soit plane et horizontale. Om 912 används för att driva ett par extra högtalare till en stereoanläggning, skall förförstärkaren kopplas till ingången på NAD 912, dra sedan ett par kablar från linjeutgången på 912 till linjeingången på systemets huvudförstärkare. Koppla högtalarens positiva (+) terminal till CH 1+ och den negativa (-) terminalen till CH 2+, det vill säga förstärkarens två positiva terminaler. [. . . ]