JBL PRX815XLF Owners Manual English - Page 21

Symptom Likely Cause Improper A/C grounding, ground loops. What to do • "Telescope" the audio ground by using an XLR/F to XLR/M adapter on one end. • Re-route audio cable away from AC power and lighting cables. Hum or Buzz. Excessively long unbalanced cable run. • Use the balanced outputs (if available) of your mixer or source equipment to drive your PRX800 speakers. • Use a "DI" (direct injection) box to convert your unbalanced equipment output to a balanced output. Improper system gain structure. Review the Owner's Manual for your system setup and adjust controls as needed. • Check input sensitivity (gain). Speakers feedback and howl when the microphone volume is turned up. Microphones are pointed into the speakers. Equalizer settings are incorrect. Excessive gain. Move the speakers so they do not point to the microphone's pickup pattern. Locate the feedback frequency and reduce it using the mixer EQ or an external equalizer. Reduce the gain at the mixer and move the microphone closer to the sound source. Too much low frequencies when playing back prerecorded music. Recorded music with excessive low frequencies. Switch the SYSTEM EQ button to "Normal". Speaker is unresponsive. System error may have occurred. • Power cycle the speaker. • Perform the Factory Soft Reset, see "FACTORY RESETS" on page 19. Section 7: Connection Types 21