For anyone with a fireplace especially in an audio room.
Always chasing an improvement in soundstage size and shape but this was originally conceived to make my walk out lower level warmer. Even with the flue packed with fiber glass and the doors closed the cold air drops 3 floors where the temp falls 4 to 5 degrees. To help solve this issue I purchased a sheet of 1-inch pink Styrofoam and 1 sheet of Luan. And 2 decorative handles and some spray adhesive. I used the same cloth that covers my home-grown acoustic panels and sprayed glued the 2 panels together with the luan on the backside so the fabric could be glued and stapled to the wood. Tight snug fit, sealing the opening. The room is warmer as a result and my audio system sounds better too. The fireplace is over my right shoulder and 12 ft away on a diagonal. The center fill is now much more precise the bass has more impact and the midbass is very specific on placement. I did the same for the other 2 fireplaces with a different choice of fabric selected by my bride. More consistent air pressure in the room is probably why there is better audio performance. TomD