Instruct: Classify Amazon reviews into positive or negative sentiment
Query: It vibrates

I just purchased the new B model and the fan in it stinks. It may pump out a lot of air, but it vibrates. I mounted it to my basement ceiling and I could feel it vibrate in my living room floor above it. I exchanged it for another one and it did the same thing so I returned it.I've seen an older model run and it didn't have this problem.I just bought a JDS 750-ER and it is much smoother and quieter. I think the overall build quality is a little better and it has a third rear filter.