Humming like a wheel bearing... but bearings seem OK?

[Wagon Wagon]

In need of a little advice/troubleshooting here... got a humming sound that starts at around 35mph and gets louder the faster I go. Sounds JUST like a wheel bearing going out. However... I can't pinpoint the sound to any specific corner of the car. The sound doesn't change when going around corners. Both front wheel bearings have been replaced in the last 2000 miles. The rears are original. I checked all four just to be thorough- no wobbling or excess play at any wheel.

Scratching my head on this one... anyone have any advice on what I should check?

Car is an 09 Impreza 2.5i, 95k miles, manual trans.

Edited May 28, 2019 by Wagon Wagon

[GeneralDisorder]

They won't have play. We check them with a stethoscope while driving it on the lift. Checking for play is not valid when they are at the humming stage. This means they are still tight. When they get loose they won't make that noise anymore - they will just eventually fall off. 

GD

[CNY_Dave]

Typically they will get to the very very very loud stage before falling off.

It's the oddball one that falls off early that gets you!

I have had some very loud ones that I needed to find with the stethoscope.

I had mine up in the air on 4 jackstands, wheels off, idling in drive.

[moosens]

Steve ! Been ages man ! Good to see you still around. Good luck with things. Cheers! 

[subnz]

If its not the wheel bearings,   it could be the carrier bearing (if there is one ) on the rear drive shaft.