I wedged coins behind one corner of the tappa so that it warped outward a little bit (and removed them after a few days.) Now, that corner of the cajón delivers a nice "crack" note when you slap it. IMG_7776 Technical Details Camera: iPhone 7 Taken: January 11, 2019 Focal length: 3mm Aperture: f/1 Exposure: 1/15 second ISO: 64