There is a connection problem causing a "static" sound. This was most likely a problem BEFORE the speaker was shipped. Maybe the seller didn't even know it was there.
When you open the speaker you'll see if there are push clip connectors, These conections are prone to 'fretting' as they age. If one is bad, others are not far behind. As they age they also increase resistance. A weak point.
How old are the speakers? How much humidity have they been exposed to? Have they been sitting in a garage or storage warehouse?
An excellent up grade would be removing all press clips and silver solder them back on. Those cheap little tin clips are NOT good.

