[. . . ] To prevent fire, do not cover the ventilation of the apparatus with newspapers, table-cloths, curtains, etc. To prevent fire or shock hazard, do not place objects filled with liquids, such as vases, on the apparatus. Do not install the appliance in a confined space, such as a bookcase or built-in cabinet. [. . . ] If you have any questions or problems concerning your subwoofer that is not covered in this manual, please consult your nearest Sony dealer. Since the human ear cannot detect the direction and position where the bass sound being reproduced by a subwoofer (below 200 Hz) comes from, you can install the subwoofer wherever you like in your room. To obtain a better bass reproduction, we recommend you to install the subwoofer on a solid floor where the resonance is unlikely to occur. You can obtain a sufficient heavy bass reproduction from a single subwoofer. However if you use a couple of the subwoofers, you can obtain an even more effective heavy bass reproduction. Always install the subwoofer vertically, keeping a few centimeters away from the wall. If the subwoofer is installed in the center of a room, the bass could be extremely weakened. If this happened, move the subwoofer away from the center of a room or eliminate the cause of the standing wave, by installing a bookshelf on the wall, etc. You are cautioned that any changes or modification not expressly approved in this manual could void your authority to operate this equipment. Use of this appliance with some systems may present a shock or fire hazard. Do not use with any units which have the following marking located near output. When using the double (A + B) sets of speakers, make sure that you select the "A + B" position with your amplifier. note When you are using SPEAKER A terminals only (front speaker only) or when the power of the amplifier is turned off, turn down the volume or turn off the power of the subwoofer otherwise, hum noise may be heard. Connecting to an amplifier with a special jack for a subwoofer If your amplifier has a special jack for a subwoofer (like a MONO OUT jack, MIX OUT jack, SUBWOOFER jack or SUPER WOOFER jack), connect the LINE IN jack of the subwoofer to one of those jacks using the supplied audio connecting cord. Connect the MONO OUT jack of your amplifier to the LINE IN jack of the subwoofer with the supplied audio connecting cord. If the output level of your amplifier is not large enough, the sound may not be loud enough. When using two or more subwoofers (H) (SA-W3800/SA-W3000 only) Connect the MONO OUT jack of your amplifier to the LINE IN jack of this subwoofer. Then, use the supplied audio connecting cord to connect the LINE OUT jack of this subwoofer to the LINE IN jack of another subwoofer. [. . . ] â· Set the CUT OFF FREQ as high as possible when playing back the Dolby digital. The contacts between the plugs of the connecting cords and the corresponding jacks have not been made properly. POWER OUTPUT AND TOTAL HARMONIC DISTORTION: With 6 ohm loads, from 28 Â 200 Hz; rated 60 W, minimum RMS power, with no more than 1 % total harmonic distortion from 250 milliwatts to rated output. [. . . ]