atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Security, Alarms and Paging Hum on Valcom horns

System with several Valcom horns connected to a V-2001-A page control.
With the music source playing, everything sounds fine. With the music source turned off, then a very annoying hum is heard on one run of speakers. There are only two horns on this cable run.

I have tried to isolate the problem by swapping out the page control and a horn, one at a time. Seems like I'm chasing my tail in circles. Did get one good quiet with the horn connected directly to the page control. I'm thinking I might have two problems: a bad horn and a bad cable.

I'm not an expert in paging/audio by any means. Just trying the elimination method, unless someone has a magic trick to try

Thanks
Jim

Yoda try a ground on one side of the music input.
I have used this a lot on Valcom systems.
Juno

Check that the cable doesn't go near any fluorescent lights too. I've heard buzzing when a service loop was right on top of a ballast.

Check the connections at the speakers. There might be just enough corrosion to unbalance the pair yet still pass audio.

While you are at the speaker, never hurts to quickly throw a know good speaker moving on the leg from the controller out.

It is time consuming but isolation will lead to a permanent solution.