Regarding the cracked concrete baffle. The chicken's way out (easy and little danger) is to smear concrete caulk on the inside to stop the airflow. Then dribble thin epoxy or cyanoacrylate into the crack from the front and either finish the show face or not to cosmetic taste.
Like ultra-low impedance, I judge the concrete baffle to be an inadequate solution. It was changed to a stone x polyester substitute, which required considerable ventilation of fumes - the joys of manufacturing. I've mentioned my preference for the Hydrostone solution that ended up in Hales counterparts.
Like ultra-low impedance, I judge the concrete baffle to be an inadequate solution. It was changed to a stone x polyester substitute, which required considerable ventilation of fumes - the joys of manufacturing. I've mentioned my preference for the Hydrostone solution that ended up in Hales counterparts.