[. . . ] JBL500, JBL800, JBL900, JBL Center simple setup guide thank you for choosing JBL. [. . . ] Wiring "out of phase" results in thin sound, weak bass and a poor stereo image. RIGHT LEFT ­ + ­ + ­+ ­+ Speaker Outputs Troubleshooting If there is no sound from any of the speakers, check the following: · Receiver/amplifier is on and a source is playing. If there is no sound coming from one speaker, check the following: · Check the "Balance" control on your receiver/amplifier. · Check all wires and connections between receiver/ amplifier and speakers. If the system plays at low volumes but shuts off as volume is increased, check the following: · Check all wires and connections between receiver/ amplifier and speakers. · If more than one pair of main speakers is being used, check the minimum impedance requirements of your receiver/amplifier. If there is low bass output, check the following: · Make sure the polarities (+ and ­) of the left and right "Speaker Inputs" are connected properly. [. . . ] 234794 © S A Harman International Company 5 Steen Michaelsen JBL Europe A/S Birkerød. [. . . ]