... sound batting and/or weighting speakers ...


Hello to all... 

Need some thoughts and/or suggestions: I am using a pair of KEF Q1s - luv the sound, so much more full than I ever expected - and the driver has such cone extension that the speaker box really vibrates. Now - I am assuming that the vibration really = the possibility of distortion ( or a smearing at higher volumes, tonal deformity, if that is different) and I am wondering if this is more controllable by:
Adding more sound batting into the enclosure (thru the bass port)
Weighting the speakers with a bag of lead shot (?) over the top of the driver/cabinet box ( the cabinet is not flat on top, so I can't use a brick or solid weight; I'm guessing the weight should be something moldable, so the lead shot in a bag is possible if I can figure a way to affix it to the cabinet...)

Thoughts? Suggestions? Alternates?
insearchofprat
Are the screws attaching the driver to the cabinet tight?

You say you love the sound of the KEF, so why try to change the sound?  Stuffing any type of dampening material inside the loudspeaker will radically change the loudspeaker's sound.  You'll be changing the internal volume which at the very least will change the bass response.  I think I understand what you are trying to do with the lead shot, but why not just wrap it alternating layers of duct tape and bubble wrap.  Either solution will only slightly mask the real issue inherent in the KEF's cabinet design.  All box loudspeakers experience cabinet vibration and it's not necessarily a bad thing.  If I were you, I would just continue to love the sound and stop worrying about the vibration.
There are three reasons enclosures dance, The cabinet is too light, the cabinet walls are not stiff enough and lastly the cabinet is not firmly fixed to the floor. #1 add mass. Put a granite slab on top of the speaker. You can get cut offs cheep at your local granite installer. #2 This one is tough. You would have to thicken the enclosure walls. At that point you may want to consider another speaker. #3 Put three spikes on the bottom of each speaker and jamb them right into the floor. This assumes your floor is reasonably solid. Good Luck.

Mike
Oh, I forgot one more solution. Get two subwoofers and take the bass away from those speakers.
I have  monitors and subs I massed load these and truly focuses the details.
i measured the dimensions went to a place that does granite countertops and picked out the granite I got Gee edges and just put a little blutac on top the granite adds a lot of mass and looks great I bought blue pearle from a Norway for $200 for the monitors, and $100 for each sub.
Just one quick point. 
 And not that this is really going to help the OP unfortunately. But it should reinforce the lesson learned.
 "There is just simply "NO", substitution for mass". You may address the effects as much as you will. But after fighting that battle enough times.
 I am sure you will come to this conclusion as well.