my diy sway brace, installed:
this was the first sway brace i installed. even the "washers" are made of elastomers. they don't look as neat as the rubber washers i used later, but the elastomer washers still do the job of decoupling the parts from one another. the shadow behind the metal brace indicate that the brace is not in contact with the wall. similarly, the bolts are also not in contact with the sway brace, because i enlarged the brace holes and filled them with elastomer, effectively creating bushings.
i am, however, not deluded into thinking that "no contact" means isolation. an overloaded spring is as good as no spring, hence, short circuited connection. but because sway braces are not as load-bearing as ceiling hangers, i am less concerned. i plan to use perfect view's a/c support as hangers, unless a better alternative comes up.
if you have more discriminating needs, i suggest you spring for (pun intended
) industrial sway braces, or hire a pro like mikep. i only shared mine, with no intention of advocating it. diy at our own risk. i am certainly willing to live with my hack, for my non-commercial "listening room".
hope this was somewhat helpful! good luck, fellow diyers.