... 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
Some boxes are square, some are rectangle, some are trapezoidal, some have extremely thick baffles, some are designed to resonate (harbeth) some are made out of mdf, others hdf, others carbon fiber, some have ports, others do not. Some boxes are incredibly well braced (look at ls50’s), some have curved front baffles, some have narrow front baffles, some speakers are designed to work well with wide front baffles, some use special glue to hold them together (dynaudio), some are lock mitered.
Shoot, there are even differences with regards to the construction of cardboard boxes!
With regards to the original post and the original question, I’ve asked the same question before and was informed bracing, and cross bracing, the inside of the cabinet will yield the best results to combat the problem which you describe!  
Douglas makes a good point in that your time, money and effort might be better spent moving up in speakers.  If you like the Kef q1’s, look for some kef xq1’s or anything in the kef xq series.  I’ve had 2 pairs of xq(‘s and they are lovely speakers. Coincentric design with a super tweeter pulled straight from their reference series , curved boxes to reduce internal standing waves, and extremely well braced inside.

I sold my last pair of xq5’s for $600...
the reality is the OP can do both.

I think it was 1985 when i built a cabinet within a cabinet and air core crossover for a KEF 104 a/b customer all wired with Fulton....ran rings around the factory 104....... but not the Cantata...

OP have any appetite to do both ????? upgrade and tweak ?
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