PA System "BUZZ"

[Marvin]

I have a P.A, system @ my shop that I can not get the constant "BUZZ" to STOP.I've tried speakers-a NEW Amplifier-tried disconnecting one phone @ a time & still nothing stops the "BUZZ" PLEASE Help! If I turn the BUZZ down low so i can't hear the BUZZ - I can't hear a page through through the PA speaker.

[Guest]

this can be a numer of things , ok with no input is the buzzing still there??

[Guest]

Lots of faults can cause buzz, but no ground or poor or corroded ground connections on shields is a common cause. Inspect the unit carefully to be sure that the shield of all shielded cables is properly grounded where intended without corrosion at the connection. Usually the shield should be grounded at only one end to avoid the creation of "ground loops," where currents circulate around the system via both hard chassis grounds and cable shields. Additionally, any metal cases or plastic cases with a black or silver coating on the inside surface should be grounded via a screw or spring clip.

Another very dominant cause of buzz in audio electronics is SCR-type lighting dimmers or other power control electronics in the vicinity or on the same circuit. If you have any dimmers in the vicinity of the buzzing audio electronics, try either or both turning off the circuit containing the dimmer or chopper control or turning the dimmer to max and listen for a change in amplitude or spectrum of the buzz. If you find any interaction, either eliminate the dimmer function or replace the SCR/Triac dimmer with an autotransformer dimmer. Such autotransformer dimmers are more expensive and bulky than chopper dimmers, but they do not create fast rise-time waveforms that lead to buzz in nearby electronics.

Good luck

awright