I am getting a buzzing sound when playing a few notes around the low "A" on a guitar. Even at a fairly low volume. At first I thought it was voice coil rub, which would not have made me happy. But when I play a note and press against the upper back panel, the buzz goes away. I think I may have drilled the holes in the back panels too large and used too small of screws, but that's what I had on hand. I'm thinking of lining the surface where the back panels meet the cleat with felt, and/or perhaps using some #8 wood screws and some Fender style "dress washers". Hopefully Home Depot will have something similar in stock so I don't have to place an order with Amplified Parts just for the dress washers and pay the shipping which would probably be more than the washers. The rest of the speaker cabinet is rock solid with the finger joints I used and the 1/2 inch baffle board.