Avoid asphalt products - not only are they much less effective, they have an unacceptably high failure rate.
Weight is a very important factor. Visco elasticity improves performance significantly, but that effect also corresponds to weight. Liquids need to be applied as thickly as mats to have the same benefit. At the same thickness, they weigh almost the same.
The only way to reduce weight is to use less, but there are plenty of ways to get where you want to get and still minimize the mass you add. Rattles are caused by to hard objects vibrating against each other. Find the source and use foam tape, silicone caulk and/or expanding foam to imobilize those hard objects.
Vibration dampers like Dynamat Xtreme, etc. will reduce rattles by reducing the transmission of vibrations. Use them where resonance is a significant problem. You will also get good results by stiffening/bracing the worst areas by fabricating your own solution using tubing mesh and the like.
I'm a strong believer in using closed cell foams everywhere you deaden, for all but pure SPL setups. These add a lot to the total deadening effort and add almost no mass.
Weight is a very important factor. Visco elasticity improves performance significantly, but that effect also corresponds to weight. Liquids need to be applied as thickly as mats to have the same benefit. At the same thickness, they weigh almost the same.
The only way to reduce weight is to use less, but there are plenty of ways to get where you want to get and still minimize the mass you add. Rattles are caused by to hard objects vibrating against each other. Find the source and use foam tape, silicone caulk and/or expanding foam to imobilize those hard objects.
Vibration dampers like Dynamat Xtreme, etc. will reduce rattles by reducing the transmission of vibrations. Use them where resonance is a significant problem. You will also get good results by stiffening/bracing the worst areas by fabricating your own solution using tubing mesh and the like.
I'm a strong believer in using closed cell foams everywhere you deaden, for all but pure SPL setups. These add a lot to the total deadening effort and add almost no mass.
