User manual JBL PB 12

[. . . ] Make certain that the AC outlet is properly grounded. Do not use an adapter plug with this product. The lightning flash with arrowhead symbol, within an equilateral triangle, is intended to alert the user to 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. The exclamation point within an equilateral triangle is intended to alert the user to the presence of important operating and maintenance (servicing) instructions in the literature accompanying the appliance. Important Safety Precautions! 11. This product should be operated only from the type of power source indicated on the marking label. [. . . ] Refer all servicing to qualified service personnel. Unplug this product from the wall outlet and refer servicing to qualified service personnel under the following conditions: a. The power-supply cord or the plug has been damaged; or b. Objects have fallen onto, or liquid has been spilled into, the product; or c. The product has been exposed to rain or water; or d. The product does not operate normally when following the operating instructions. Adjust only those controls that are covered by the operating instructions, as an improper adjustment of other controls may result in damage and will often require extensive work by a qualified technician to restore the product to its normal operation; or e. The product has been dropped or damaged in any way; or f. The product exhibits a distinct change in performance ­ this indicates a need for service. When replacement parts are required, be sure the service technician has used replacement parts specified by the manufacturer or that have the same characteristics as the original part. Unauthorized substitutions may result in fire, electric shock or other hazards. Upon completion of any service or repairs to this product, ask the service technician to perform safety checks to determine that the product is in proper operating condition. The product should be mounted to a wall or ceiling only as recommended by the manufacturer. The product should be situated away from heat sources such as radiators, heat registers, stoves, or other products (including amplifiers) that produce heat. SPEAKER PLACEMENT · As a general rule, bass response increases as a subwoofer is placed closer to a wall. Therefore, bass output is maximized when the subwoofer is placed in a corner. · It is also recommended that the subwoofer be positioned along the same wall as the front loudspeakers. Low-frequency sounds are normally omnidirectional, meaning the listener can't tell where they are generated from. However, frequencies between 75Hz ­ 150Hz can be localized, especially at higher volume levels. Positioning your subwoofer as recommended will provide the most natural soundstage and imaging from your loudspeaker system. Remember that these are just guidelines. Since every listening room is different, JBL strongly recommends experimenting with the positioning of your subwoofer to obtain the most pleasing results in your room. One technique that can help you find the ideal subwoofer location is to temporarily place the subwoofer near the main listening location. [. . . ] · Make sure that you have configured your receiver/ processor so that the subwoofer/LFE output is on. Crossover Adjustments The Crossover Frequency Control determines the highest frequency at which the subwoofer reproduces sounds. If your main speakers can comfortably reproduce some low-frequency sounds, set this control to a lower frequency setting, between 50Hz ­ 100Hz. This will concentrate the subwoofer's efforts on the ultradeep bass sounds required by today's films and music. If you are using smaller bookshelf speakers that do not extend to the lower bass frequencies, set the low-pass crossover control to a higher setting, between 120Hz ­ 150Hz. [. . . ]