Silver MemberUsername: Frank_abela
Post Number: 275
I imagine that when the whole house is vibrating, the sound in the main system room is pretty loud. I'm willing to bet that the floor boards or joists under the speakers are the same ones supporting the entertainment centre. This would account for the vibration of the centre. You don't mention the size of the room. Would it be square by any chance? If it's something like 12 feet square, then there is a strong chance you are exciting the room with a resonance frequency in both directions (laterally and lengthwise). This usually sounds like a low insistent boom when it happens.
As it's a suspended floor, it's going to be easier to excite the floor with larger amplitude than a stone floor. The speakers are large, so they're more likely to go quite deep and cause the excitation. If you used spikes under the speakers you may be able to miss the floorboards that cause the entertainment centre to vibrate, and you may also reduce the floor excitation. If you're already using spikes, you may find some benefit in placing the speakers on a concrete or slate slab, although results are variable depending on the room mode that you're hitting.
If you're not using spikes, I'd start by using them. Spikes are better for a carpet anyway since they only make a small hole where a speaker base crushes the pile of a square foot or more of carpet. If you want to move the speakers afterwards, then a stiff brush over the holes obscures them. If the pile is crushed because you weren't using spikes, then raising the pile is a real pain.