Visaton EX 60 R

I bought these Visaton EX 60 R electrodynamic exciters to experiment with them the possibility of hidden speakers in a historic building.
I am really satisfied with the results. They can be attached to different surfaces. i prefer thin wood as it resonated better than thicker ones. Different sizes give different frequency range... smaller surface area gives higher frequencies, so one can mix. When attached inside false ceiling be sure to suspend the surface emitting the sound to avoid undesired vibration noise.
When attached to vertical wall boards do consider that the nearer the board is to the wall gives more bass.
Pros: Very good solution for hidden speakers. Flexible in terms of balancing frequencies.
Cons: The surface needs to have vibration insulation from the surrounding surfaces.
Looking forward to install more of these "invisibles" :)