Many audio exciters have a circular voice coil with adhesive mounting. They say that you can just press the exciter against the panel to attach it. For the DAEX25SHF-4, I had problems with that. You can see that the exciter sags due to gravity, and the sound is low and distorted. I suppose this is due to the voice coil rubbing against the magnet. If I lift the exciter with my hand, to remove the sag, the sound is clear and loud. I have searched the internet for a discussion of this , and I have only found one post in a forum. It's kind of funny to me because the compliance of the suspension between the voice coil and the magnet is in the specification, Cms, but if you add a structure to support the magnet, you have changed that compliance. I also have not seen this addressed in any of the academic papers where they develop models of a DML speaker. Any comments on this would be appreciated. Thanks.