Originally Posted by RTracey
So Mike, I'm curious as you seem to be a pretty knowledgeable guy about this stuff. If I understand correctly, your chair is on a wood riser, but your subs are on the slab. If true, the subs and the wood riser are not physically coupled, so how can the subs transmit a tactile response that way? I would have thought both sub and chair would have to be on the same riser, basically a wood subfloor above your slab, for that to work. Thanks.
Thanks for the compliment. Like everyone on these threads, I am still learning as I go along. The first thing that I can tell you is that the wood riser works. I have a couple of theories for why it works, but as with many things in audio, the empirical observations come first, and the explanations follow at their leisure.
First, I believe that concrete does transmit tactile energy. It just doesn't transmit it very well, or very far, compared to a wood floor. So, some proximity between the energy source (the sub) and the wood riser, could be an important factor. I also believe that direct airborne energy (the pressure wave) from a sub, and particularly from a ported sub, might conceivably excite the wood riser, under a chair, in a way that it could not with concrete.
David Gage, the creator of Marianna Subs, at Deep Sea Sound, tested the concept with several different types and thicknesses of material several years ago. You could probably do a Forum search, or contact him directly to find out more about his tests and conclusions. FWIW, I think that one reason the wood riser works so well for me is that I have a nearfield PB13, located 2' behind my listening chair, and pointed right at the back of my chair. So, I believe that I am getting both transferred vibration, from the concrete to the wood riser, but also getting the benefit of the direct pressure wave from the driver and ports. In my case the ports are at almost the same height as the surface of the 1 1/4" riser. Whether there would be quite as much additional tactile response with sealed subs, or with more distant subs, is harder to predict, but I believe there would still be some benefit at high SPL levels.