Popping noise on output1 to line level audio

[Richard Hosch]

I have connected my M1G to my whole house audio using the line level conversion circuit described by Elk (including the optional 10uF blocking capacitor), which feeds a signal sensing override input on my WHA amplifier.

This works as expected, except… the M1G appears to be producing a quite audible and annoying pop both before and after any synthesized voice message (garage door is open, or whatever). The pre-message noise is a sort of “pop-boom” and the post-message noise is a softer pop or click.

I have swapped inputs on the amplifier, including connecting the M1G to an “always on” input that bypasses any signal sensing circuitry in the amplifier, and have verified that the noise is being generated by the M1G itself.

Any suggestions on possible remedies? Is there audio out available on the J7 header that might be useful in this situation? Would purchasing the two-way listen in module provide an audio out that might be free of this noise? Or, if there are any thoughts on the origin of this noise (how the panel is powered, grounded, configured, or anything else) I’d love to hear them. I have 16 zones of audio available to send messages and sirens to which would be quite nice, but for now I’m limited to muddled output through an Elk Echo speaker that really isn’t intelligible.

[Michael Newton]

any luck on this topic? i just connected a line level to Output 1 and am having the same “pop” noise before each audible zone or output from the M1 to the amplifier. Any suggestions would be great!

 

Thanks!

[Brad Weeks]

The J7 header connector on the M1 has line-level audio output on pin 7. And ground is pin 6.

That would connect directly to the external amp’s line level input.

Should try to keep the connection as short as possible.

You would need to make a connector to fit on J7 or buy the ELK-M1TWA just for the cable.

[Richard Hosch]

Michael, no I had not made muh headway. I did try running the audio through one of the Elk relays and creating some rules that  attempted to close the relay just after an audio message started and then open it again just after, thinking I might could complete the line out circuit after the pop had already passed. Unfortunately, not only was I not able to get a timer and delay to work as expected, but the opening and closing of the built in relay caused just as bad of a pop. I was looking into a signal sensing circuit with soft turn on and off from elliot sound products that would probably do the trick but hadn’t yet tackled the project…

 

Brad, thank you! That answers a question I had searched for quite a while but never found the answer to. I figured I’d have to buy the module to get access to a line level out on that header but really thought it was probably there somewhere. I’ll give that a shot and see if it’s a cleaner output than the standard siren/speaker out.

[Richard Hosch]

Brad,

So that worked! Audio out, and it eliminated the pops. However, it doesn’t seem like this header is affected by volume settings in the globals for voice? Do you know if there is any way to control this volume elsewhere in the settings? It seems the override input on the WHA amplifiers I have do not have a level setting for the override input, which is a minor annoyance. I can pad down the line level connection if needed but thought I’d see if you or anyone knew of a setting to affect that first.

 

Oh, and tip for anyone else that finds this thread and post needing to do this – the header is a standard size, same as used in a ton of other devices. For example, a 2 or 3 pin LED or fan header for a computer motherboard and a few seconds with a file make this connection a snap. But warning… be careful to look at the J7 pic on the Elk mainboard and count starting with pin 1 on the correct side. If you get it wrong and count from the opposite side, the results are “unpleasant” to your ears and I would bet risk damaging your equipment.

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