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7350APM Sub Power Hum Issue

jasonstam, modified 3 Months ago.

7350APM Sub Power Hum Issue

Youngling Posts: 1 Join Date: 9/6/20 Recent Posts

I purchased a 7350APM sub with a pair of 8330's and the GLM kit about 6 months ago. I recently noticed an audible "power hum" coming from the control panel of the 7350 sub. I can hear it from 8 feet away at the other end of the room. To me this seems very loud for a studio sub, I would expect it to be near silent. I've tried switching power cables, and also tried running it through a power conditioner, with no change in the sound. I moved recently, and the sub has behaved the same at two separate locations. I've also tried disconnecting the digital cables, and all XLR cables, it does not change the behaviour.
 

Before I lug this thing back to the store where I bought I'd just like to ask, is this normal?

Here is a link to a video of the humming sound. https://www.youtube.com/watch?v=-WQrzpHL524

Thanks for any help.

lukester, modified 3 Months ago.

RE: 7350APM Sub Power Hum Issue

Jedi Master Posts: 287 Join Date: 4/22/10 Recent Posts

No, it's not normal, sounds like transformer hum to me.
Usually this indicates a little bit of DC in the AC power in you home.
But since you already moved and it's a bit unlikely that you have DC in both homes, I'm fresh out of ideas.
Returning it & trying it in the shop or in yet another flat would be my suggestions.
 

Here's a dedicated DC filter, get one if the hum disapperas in the shop or wherever you test next:
https://www.atlhifi.com/shop/fully-assembled-devices/dc-blocker-trap-filter-assembled-in-case/

Fun fact: newer Genelecs like 8330 have a DC filter built in, don't know if the subs have them too now.