subwoofer buzz - how to eliminate it

It's in the corner so I will move it, turn it sideways, try the simple things first.

Moving the sub out of the corner may also improved the sound of bass in your room. In his great series of videos, Art Noxon of ASC talks about the high and low pressure areas in the room: standing waves build up along wall/wall, wall/floor, and wall/ceiling intersections, corners being the most problematic. ASC even makes a bass trap for use under subs, which sounds counter-intuitive but actually isn't.

thank you all! I moved it to the side, by the wall, and already sounds better.

Bingo!

You might also consider moving sub to a less excitable location in the space.

“More rubber”? I definitely had a chuckle there.