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The XPS panels are 1" thick x 24" x 30" (mid to Hi range unit). It is important to use XPS (Extruded PolyStyrene) panels. The balsa panels are 1/2" thick x 30" x 36" (Lo to mid range unit). Balsa panels may also be found as lightweight plywood panels used for commercial signs. The radius on all panel corners is 4" and the exciters are placed on the back, off center, based on a 2/5, 3/5 rule. So for example, the exciter on the XPS panel is located 9.6" vs 15.4" from the long sides and 12" vs 18" from the short sides. These 2 alternate positions works equally well. As explained in the sugar part of the video, counterweights should be fitted to dampen the resonance of the panels. Each panel has 4 counterweights - each weighing 1/16 of the (painted) panel weight - are placed on 2/5, 3/5 points in every small rectangle created by the position of the exciter unit. This is a bit complicated to comprehend, but watch the sugar part of the video closely, over and over until you get it. Also in the video, there is a good explanation of how and why the selected materials and panel size results in a frequency range of 130Hz-20KHz The original acoustic exciters used are : Dayton 25mm DAEX25FHE-4 (4 ea.) or as alternatives Dayton 32mm DAEX32EP-4 (4 ea.) However most likely you will have to source alternate makers units from Ebay, AliExpress, etc. Links: Dayton users guide, excellent explanation: http://www.daytonaudio.com/index.php/exciters-buyers-guide (scroll down) Living room test song used, for comparison: https://www.youtube.com/watch?v=sGsC98vR4Q4 (Thanks to GlenGlen !) Link to build step by step: http://projectgallery.parts-express.com/speaker-projects/dml-flat-pannel/ IMHO instead of using an old school bass speaker, you may experiment with a deep frequency exciter. This is the unit some readers may recognize from a gamers chair, which literally kicks ass, when grenades are thrown in the game etc. Depending on actual test results such units may be placed under a table top, on the wall, on the floor etc: https://www.ebay.com/itm/50MM-Resonanzdampfer-Alle-Resonanz-Lautsprecher-Vibration-Starke-Bass-Speaker-fs/292413284916?hash=item441530a234:g:eCQAAOSww85aer26