Has anyone tried QuietCar for reducing vibration?

What works great is "Great Stuff" spray insulating foam sealant that they sell in hardware stores, Home Depot, Lowes, etc.

If expands and fills in all the cracks and crevises (don't use too much)! It can also be trimmed if you go too far.

Just wear gloves. It is very sticky and will have to wear off your skin.

i would not use that at all. depending on your speaker design. i dont know what you mean by vibration but if you are talknin about the knuckle rap on the speakers and can hear a sound change as you move up and downd the speakers that is normal and can be determined in the design. changing the cabinent resonance may not be the best thing to do. get a good pair of brass cones under them and see if this improves all the things you mentioned like tighter bass, it should. also correct speaker setup is about 80-90% of speaker problems. utilize the room correct and sitting position can make those speakers sound like you never heard them before. depending how old they are just see if drivers need a little tightening. only about 1/16 to a 1/8 turn, as to much tighness can effect the sound of the drivers if you have cone drivers as well as not stripping the screw.usually this needs to be done only once or twice depending how much you use them and how loud as well

BILL L

I had a knowledgable friend put whatever that black gunk they use to seal windshields with is called onto the metal frames of the woofers in my bass modules of my speaker system. Thought it made a slight improvement in bass clarity. He did the same to my midrange drivers in my satellites, but I couldn't tell the effect because we made a number of additional changes to the crossovers and internal wiring at the same time. We've done the same inside the chassis of my crossovers. While I think it can only help with components to reduce vibrations anywhere you can, I'm not sure it always helps to damp internal vibrations in a speaker enclosure, as it could be that the designer was taking them into account in voicing the speakers. What you're proposing will likely change the sound of the speaker; whether that change is for the better is not going to be clear until you try it, so maybe you'd be well advised to do something that can be undone if you try it (or contact the designer/manufacturer to get their thoughts).

I've used dyna mat which is a heavy rubber like mat that the kids put in the trunks and door panels of their boob boom cars to try and control the rattles. Put it under the shelf for my CD and Phono. Actual effect?? don't know, never did an A-B test but it probably didn't hurt any.