Background Buzz During Voice Message Broadcast

[Douglas Burke]

My Elk M1 Gold has two M1KP2 LCD keypads and associated SP12F speakers all set up to provide voice messages when arming, disarming, etc.  For the past decade and a half there has been only a slight barely noticeable hissing (more like low white noise) in the background when these voice messages were broadcast (not problematic), yet as of a couple of weeks ago we now hear a very noticeable buzzing in the background on broadcast, in both speakers.

I haven’t made any changes whatsoever to my system for perhaps half a year and this buzzing is noticeably the same on both speakers.

Anyone have any ideas on what could be causing this?

[Brad Weeks]

Are the speaker wires ran in close proximity to 120/220 VAC lines? Disconnect the existing speakers and connect one directly to the OUTPUT 1 and test. The system could have taken a slight surge which may have damaged the onboard amplifier.

[Douglas Burke]

Hi Brad, it took a while and a very long afternoon, and here’s what I got.

• As far as I know, neither of the speaker wires run near a 120/220 VAC line.  I also had made no wiring changes anywhere within at least several months prior to the start of this buzzing.
• I disconnected both speaker wires and connected them one at a time to OUTPUT 1 and tested.  The buzzing was present in each test.
• I also noticed that the M1 panel itself is now buzzing…I had never noticed that before.  Listening closer, I further head a distinct buzzing coming from the TRG-1640. Thus, I tried some additional tests.
• I unplugged the TRG-1640 from power.  Testing the speakers on battery power, they were no longer buzzing.  Indeed, they sounded exactly as they were supposed to.  Further, the panel no longer buzzed.
• I disconnected the TRG-1640 from the panel, and plugged it into 120 VAC.  There was still a buzzing, yet significantly reduced from when also connected to the panel.  I’d call it more of a “hum”.
• I reconnected the TRG-1640 to the panel, and through the use of a long extension cord, connected it to a completely separate 120 VAC outlet (on an entirely different circuit breaker).  The distinct buzzing in the speakers, the panel and the TRG-1640 were still present.
• One last thing I noticed in all this testing was that with the TRG-1640 connected to the panel, after I plug it into 120 VAC I initially, for a few seconds, hear only the significantly reduced buzzing (the hum) in the TRG-1640.  It’s only after a few seconds does that hum increase to a more distinct buzz, and at the same time the panel starts buzzing about the same volume.

Could my problem be in the TRG-1640 perhaps?  Could it just be so old that it’s now causing the buzzing in both the panel and on the speakers?

[Douglas Burke]

I replaced the TRG-1640 with a brand new one.  Same buzzing in both places.  I guess I have to live with it.

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