User manual JBL J820MBK

[. . . ] 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. In the case of the J50, do not place the speaker closer than 3 inches (75mm) to the wall behind it if possible. For the best stereo imaging, we recommend that the systems be placed so that the high frequency transducers are positioned approximately at ear level of a seated listener. [. . . ] For each channel, the red terminal on all loudspeakers should be connected to the red or (+) speaker connection terminal on the receiver or amplifier, 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. 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. 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 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. Left Speaker Red Blk. 3 +L+R Amplifier/Receiver 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 4 J SERIES LOUDSPEAKERS 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. Consult the owner's manual of the amp/receiver for clarification. No sound at all or very faint sound from both speakers 1. Amp/receiver tape monitor button pushed in while using CD, FM or phono inputs. 2. Wrong speaker switch, "A" or "B" speaker output. Sound source (CD, cassette deck, turntable) not turned on, not activated, not hooked up or not selected on amp/receiver front panel. POWER HANDLING Thanks to their high efficiency, the JBL J Series Loudspeakers will produce reasonable volume levels in a room of moderate size with very little amplifier power. [. . . ] Do not return products to the JBL factory without prior authorization. GENERAL CARE The grille is held in place by pins near the edges. To remove the grille, grasp it by both top and bottom edges and pull gently. To replace grille, re-position it carefully and press gently at the corners. Do not push on the center area of the grille. NOTE: The J50 grille is nonremovable. [. . . ]