Interested in building your own ESL's? You MUST pick up a copy of the "Electrostatic Loudspeaker Design Cookbook" by Roger Sanders. I consider it the "Bible" for ESL's. Next get in contact with Barry Waldron (www.jps.net/eslinfo as mentioned above). He offers all of the hard to find items that you might need. These guys know what they're doing. I have built several panels now, and the preliminary results are exciting. These will be part of an ESL/TL hybrid I'm currently working on.
