User manual JBL MR308 II

[. . . ] Placing the loudspeakers in corners or against a wall will result in the strongest (not necessarily the most accurate) bass. Except for the M5, all MR 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 M5, 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. 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 MR 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 MR 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 MR Center or other MR 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 Part B indicates that the amplifier can handle 4-ohm combined impedances created by two sets of speakers. 4 MR SERIES LOUDSPEAKERS 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. 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 MR Series Loudspeakers will produce reasonable volume levels in a room of moderate size with very little amplifier power. However, using a small amplifier to obtain the desired volume listening levels may lead to overdriving the amplifier. This will generate high distortion levels and may cause damage to your loudspeaker. [. . . ] Do not push on the center area of the grille. NOTE: The M5 grille is nonremovable. Do not attempt to pry the grille from the cabinet as this will void your warranty. 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. [. . . ]