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.