User manual JBL J900MVBK

[. . . ] The magnetic shielding prevents stray magnetic fields from creating any interference or distortion of the video picture. PLACEMENT Bookshelf Models: For the best stereo reproduction, the two loudspeaker systems should be an equal distance from your listening position and separated so that the angle between them, at the listening position, is between 40 and 60 degrees (see Fig. For example, if your listening position is 8 to 12 feet (2. 5m to 4m) from each speaker, the two systems should be about 8 feet (2. 5m) apart. Placing the loudspeakers in corners or against a wall will result in the strongest (not necessarily the most accurate) bass. Except for the J50, all J Series speakers have their ports in the front so you can place the rear of the speaker up against a wall. [. . . ] For each channel, the red terminal on all loudspeakers should be connected to the red or (+) speaker connection terminal on the receiver or amplifier, Left Speaker Red Blk. (+) (­) and the black to black or (­) speaker connection terminal (see Fig. Connecting the loudspeakers in this manner ensures that they will be in phase; that is, work together rather than in opposition. This is very important when connecting several speakers together in a Dolby Pro-Logic AV application. Connecting the loudspeakers out of phase will not damage them, but will result in less bass and poor imaging. When connecting the J Center or other J Series speakers to a Dolby Pro-Logic AV receiver, refer to the instructions accompanying your AV component for use of the "test tone" to properly balance the sound output from each speaker. The use of the "test tone" and the controls on your AV receiver will enable you to correctly balance the level (volume) of sound coming from each speaker in your Dolby Pro-Logic application. Hooking Up Multiple Sets of Speakers If your receiver has two complete sets of speaker terminals ("A" and "B"), it's possible to hook up an additional pair of speakers for simultaneous sound in another room. However, some speakers may not be usable as a second pair if you want to play two sets at once. Before hooking up another set of speakers besides your J Series loudspeakers, check the following: 1. Your amplifier's minimum load impedance. Right Speaker Red Blk. The nominal impedance of the second set of speakers. Both of these specifications are expressed in ohms and both can be found in the owner's manuals which came with your speakers and amp/receiver. The receiver's minimum load impedance is determined by whether or not 4 J SERIES LOUDSPEAKERS power ratings are given for 4 ohms. This is because two sets of 8 ohm speakers will present a 4 ohm load to the receiver. The J speaker, when combined with an 8 ohm speaker, produces an impedance sufficiently close to 4 ohms. For example, the following entry in an amplifier owner's manual. . POWER: A)100 watts RMS into 8 ohms, both channels driven, 20-20kHz with less than 0. 02%THD B) 160 watts RMS into 4 ohms, both channels driven, 20-20kHz with less than 0. 02% THD. specific loudspeaker model. Please see the specification section for details. Following these guidelines will provide virtually distortion-free sound reproduction and long loudspeaker life. TROUBLESHOOTING The vast majority of new speaker "malfunctions" end up being traced to connections or switch settings. To avoid packing up correctly functioning speakers and sending them off, only to find that they're not really at fault, check the following tips first, before requesting service. Part B indicates that the amplifier can handle 4-ohm combined impedances created by two sets of speakers. If only an 8-ohm rating is given, the amp/receiver may or may not be designed to handle 4-ohm combined ratings. [. . . ] The rear panels are removable to allow service personnel access to the driver components if needed. The loudspeaker cabinet may be cleaned with a slightly damp cloth. To remove dust from the grille cloth, use a vacuum with a brush attachment. Spots may be removed with a commercial spot remover. Do not use any cleaners or solvents on the speaker drivers themselves. SERVICE Should your loudspeaker ever need service, return it to the JBL dealer from whom it was purchased. [. . . ]