Qu24 Buzzing Sound (Hum?) issues

[audioNoobParticipant]

Hi all,

I am an audio noob and am volunteering to help get to the bottom of a very strange audio issue that is plaguing us. Every so often, and I can’t consistently recreate the issue our speakers will start buzzing/humming and get progressively louder. Example attached. We have a driverack in the loop and have run the feedback wizard and EQ’d our room. But this issue continues to plague us. Any ideas what this could be? Know thats not a lot of detail as I myself am not too sure what I need to be looking for, but if there is anything that comes to mind, or any specific additional details that would help with troubleshooting please do let me know. THANK YOU SO MUCH!!

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[GigaParticipant]

Sounds like 120 – 125 Hz so probably a problem in a powersupply (filtering) somewhere in the chain.

You could double check by looking at the RTA

Good luck !

Giga

[GigaParticipant]

Edit: on second thought, I’ve never encountered a double the 50-60 Hz from your wall outlet so that’s probably not it.

Have you tried disconnecting all peripherals one by one to isolate the problem ? Or, for example connect your mains to a mix output instead of LR out ?

Giga

[Mike CParticipant]

To me that sounded like feedback the way it just kind of swelled up in level.
It maybe kind of held back some do to the mentioned “feedback wizard” unit.

[audioNoobParticipant]

Thank you both @mike and @giga!

I (only based on my limited googling around) thought maybe it was a “ground loop”. Due to:

– Having multiple pieces that are on separate power plugs. Rough diagram attached.

However, looking more into it, maybe this isn’t it? If it was a ground loop I guess I would expect to hear it consistently. My issue is I *don’t* hear it consistently. When I test it, and I YELL into the mic, talk quitely, etc. its fine.

However, _sometimes_ someone will recite on it and it will do what you heard in the clip.

Which is making me think maybe it is standard feedback like you said @mike.

In which case I guess I need to somehow be here when it happens and actually see what frequency is causing that issue and EQ it?

Ps: I’ve attached pics of our setup and the settings on our QU-Pad.

THANK YOU guys again, really appreciate it all!

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[GigaParticipant]

Are the other mics open when this occurs ? If so, you should see above average signal on that input. I see you have gated your inputs, maybe somehow one of the gates opens and takes of from there. Pulling a bit of 100-125 Hz will probably help. The question is in the mains or in the monitors.

Giga

[Mike CParticipant]

Remove all the gates on the vocal mics!!! Gating a vocal mic it tricky at best with a consistent person on the mic who knows how to speak directly into the let along various people using the mics.

Going by the gate indicator you are gating them to full off……if you want to attempt vocal mic gating reduce the gate depth to about 6db and apply a longer hold and release time.

First try getting the system gain set up properly and EQ’ing the main and monitor systems before trying anymore gated vocal mics.

As mentioned when the gate or gates open the system could start feeding back as in the recording you posted.

Also I noticed that you have a few EQ cuts inplace but the EQ is in the off / bypass mode.

[Author]

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