Focal 25A4 Buzzing Until Bass Kicks In, wtf? (Video included)

[RandomUsername3192 10+ year member]

I have a 10" Focal 25A4 in a custom enclosure. Subwoofer has worked fine with no issues since install in April. Purchased and installed at authorized Focal dealers along with a full audio setup.

Just last week, I heard a strange buzzing noise, which I attributed to some panel in my car due to the very cold temperature. After a while, the buzzing stopped. I did some experimenting- it wasn't a cold/warm up issue, but the buzzing stops when I turn my music up. It's coming from the sub.

I can have no source on at all, and the sub buzzes. The moment any bass kicks in, it stops and plays normal. So every morning I turn it up, get the buzzing to stop, then turn back down. I can even mute it and the buzzing is gone.

I have changed nothing in my setup except adding velcro to the enclosure as extra security. Never touched any wiring or removed the sub.

I emailed my installer, but he's knee deep in remote start installs because our winter season is here. So I figured I'd ask for your opinions.

Video of the sound is below:

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