JBL PRX515 User Manual

Also see for PRX512M: User guide User guide

Contents

27Noise or hiss heard at outputHum or Buzz that increases ordecreases when the mixer levelcontrols are moved.Hum or BuzzSpeakers feed back and howl whenthe microphone volume is turned upToo much low frequencies whenplaying back prerecorded musicNoisy Source Device Disconnect the devices that are connected toyour speaker one at a time. If the noise goesaway, the problem is with the source or theconnecting cable.Improper A/C ground or faultyequipment connect tomixer inputDisconnect or mute channels one at a time toisolate the problem. Refer to the owner’smanual of the faulty equipment fortroubleshooting help.Faulty cable between sourceequipment and mixerSubstitute a known-good cable for thesuspected faulty cable.Improper A/C grounding,ground loops• “Telescope” the audio ground by using anXLR/F to XLR/M adapter on one end.• Re-route audio cable away from AC powerand lighting cables.Excessively long unbalancedcable run• Use the balanced outputs (if available) ofyour mixer to drive your PRX speakers.• Use a “DI” (direct injection) box to convertyour unbalanced equipment output to abalanced output.Improper system gain structure Review the Owner’s Manual for your systemsetup and adjust controls as needed.• Input sensitivity (gain)Microphones are pointed intothe speakersMove the speakers to they do not point themicrophone’s pickup pattern.Equalizer settings are incorrect Locate the feedback frequency and reduce itusing the mixer EQ or an external equalizerExcessive gain Reduce the gain at the mixer and move themicrophone closer to the sound source.Recorded music withexcessive low frequenciesSwitch the EQ switch to “flat”