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Author Topic: Random Intermittent Noise in Sound System  (Read 3335 times)

Frank Koenig

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Re: Random Intermittent Noise in Sound System
« Reply #10 on: December 30, 2017, 12:32:25 pm »

Do you have access to a simple recording device that has a long run time and a line input? Something like a Zoom handheld recorder. If so then start inserting it at various points throughout the signal chain and just leave it running. Note the time you hit record and then get the operators to record the time the noise occurs. With a decent size card and the lowest recording quality it'll do you should only be hitting record once a day. If it's not happened that day, delete the file and start again tomorrow.

This will do 2 things - it'll give you a recording of the issue if it's there, which might be useful for analysis. More importantly though, if the sound occurs and the recorder doesn't pick it up then you know it's getting in to a system component sometime after that point.

This, exactly. And you can use an audio editor, such as Audacity, to scan quickly through the recordings to look for noise events. Beats sitting there listening for hours. Good luck. -F
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Tim McCulloch

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Re: Random Intermittent Noise in Sound System
« Reply #11 on: December 30, 2017, 01:39:58 pm »

Maybe....maybe not, while maybe great in radio operation many will have no clue about the kind of system and equipment in John's system.


As for the noise you described, that is kind of how I would describe cell phone interference.
If that is the case check for open mic lines, bad mic cables, mic cables or wall plates with the shell tied to pin 1. Lot's of place for RF ingress in a system like you have, assuming it is an RF ingress problem.
What are your wireless mic frequencies.

The old "GSM" interference noise... that was my thought, too.

Question for the OP - does this noise happen with the system on but with nobody near microphones or the console?  If not, I'm guessing GSM "polling".  The control channel will use maximum RF to see what tower(s) respond, analyze the RF signal strength and data integrity for each tower and then connect to one of them.  The proximity of a GSM cell phone (T-Mobile, ATT, Cricket, others that use ATT/TMobile towers) to microphones, poorly shielded mic cables or even sitting next to the console is usually the culprit.
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Dave Pluke

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Re: Random Intermittent Noise in Sound System
« Reply #12 on: December 30, 2017, 01:46:29 pm »

That wireless in the simple  system...what band? Is it off/muted when not in use?

I've had Sennheiser receivers make noise when the transmitter was out of range and the receiver was searching for it.  Have learned to turn those units off when not in use.

Dave
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Art Welter

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Re: Random Intermittent Noise in Sound System
« Reply #13 on: December 30, 2017, 02:14:43 pm »

To my knowledge it has not occurred on Sunday Services for church. I have been working at the Kroc Center for two years working almost every Sunday (just missed one Sunday for vacation) and I have never heard the noise.
John,

Was the Record Out cord terminated when the noise occurred?

That cord looks like it could be an accident waiting to happen that you have missed out on for two years.

Art
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Keith Finch

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Re: Random Intermittent Noise in Sound System
« Reply #14 on: December 30, 2017, 06:02:17 pm »

The Description "rewinding/giggling chipmunky type of sound " is similar to a Video Conferencing audio problem I recently encountered. In the Audio DSP the Echo Cancellation had been router incorrectly. This allowed the Far End audio to break through during near end transmission low level times. It could be that the designer used a template from another job to speed things up on the Nexia DSP.
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John K. Harris

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Re: Random Intermittent Noise in Sound System
« Reply #15 on: January 05, 2018, 11:39:59 pm »

https://www.youtube.com/watch?v=3OII3oeWruA
Listen at about 15 seconds in. Does it sound like that?

Hey Kevin, thanks for this but unfortunately it does not sound like this. I know what the GSM interference sounds like and it is definitely not that. But thank you for your effort.
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John K. Harris

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Re: Random Intermittent Noise in Sound System
« Reply #16 on: January 05, 2018, 11:45:15 pm »

John,

Was the Record Out cord terminated when the noise occurred?

That cord looks like it could be an accident waiting to happen that you have missed out on for two years.

Art

Hey Art, thank you for reminding me that I have to update my system schematic. Unfortunately that is not in the system anymore. Originally it was used as audio output from the EAW processor then going to the input for our old camera. Since we got a new camera that has XLR inputs I have then switched the cables to XLR cables and removed that 3.5mm cable from the system.
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John K. Harris

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Re: Random Intermittent Noise in Sound System
« Reply #17 on: January 06, 2018, 12:21:48 am »

That wireless in the simple  system...what band? Is it off/muted when not in use?  Often, so-called simple systems are always live.  What you describe sounds like LTE. T-Mobile started activating 600 MHz in Hawaii last summer..... 

If that (or other) wireless are in the 600 bands, start by physically disconnecting that wireless and see if the problem stops. Disconnect it instead of turning it off so other helpful people don't turn it back on for you...

Ed Walters

Hi Ed!

Unfortunately the wireless system is in the 600MHz range. But I can definitely say that is another problem of it's own especially with lab pack dropouts.

But back to the first problem when these rentals occur there is only like a few wireless channels that are on during these events. At max maybe like four channels for most events, though some events have used of like 16 wireless channels but never had that "giggling sound". Almost every Sunday we use more than 8 wireless channels for our church services(we have two), but I have never heard it during church services.

On a side note to everyone, we used to have a Yamaha LS9-32 with a Whirlwind Digital Snake here and that sound occurred when we had that board too. Now we have the Presonus RM32/64 with a Presonus CS18ai and still have that sound.

As for the times of when that sound happens is entirely random, there have been some events that took place in the evening and that noise has happened, then other events throughout the day and the noise happens.
There has been events that were here all day and into the night but that sound/noise did not occur.

But I think adding a recorder to the system might help and that is a great idea, so thank you for that suggestion.

Also looking into the Nexia DSP might be another option, though to be honest I am not certified to work with the Nexia software. I could learn and figure it out pretty quickly but I wouldn't want to accidentally do something without knowing how to troubleshoot it. I guess I could say this about the Crestron system as well, as that I am not certified to use the Crestron software.
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Mike Caldwell

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Re: Random Intermittent Noise in Sound System
« Reply #18 on: January 06, 2018, 11:26:35 am »


Also looking into the Nexia DSP might be another option, though to be honest I am not certified to work with the Nexia software. I could learn and figure it out pretty quickly but I wouldn't want to accidentally do something without knowing how to troubleshoot it. I guess I could say this about the Crestron system as well, as that I am not certified to use the Crestron software.

Actually looking into the Nexia DSP to watch the input and output metering coule be helpfull in narrowing down were the noise is coming from, watching for a spike in the levels and noting where it showed up at.

Assuming of course the installer connected the metering function blocks to the inputs and outputs!!

You can download the software from the Bi-Amp website.

To get into the Nexia you would need to know it's IP address and if needed any passwords. Getting to the live view layout from there is not to tough, in live view you can open up processing blocks and change levels, EQ, Ect.....so be careful!! Look for the input output blocks generally on the left and right of the layout page, you should see bunch of lines "wires" going to a meter block as well as lines connecting to the various processing blocks.

As for the Crestron unit you pretty much need to be a certified Crestron programmer to have the software to really get into their equipment.
« Last Edit: January 07, 2018, 07:51:38 am by Mike Caldwell »
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Magnus Högkvist

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Re: Random Intermittent Noise in Sound System
« Reply #19 on: January 06, 2018, 11:36:20 am »

On a side note to everyone, we used to have a Yamaha LS9-32 with a Whirlwind Digital Snake here and that sound occurred when we had that board too. Now we have the Presonus RM32/64 with a Presonus CS18ai and still have that sound.

Do You still use the same Whirlwind cable?
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