DIY Super Big Ear Amp Soldering Practice Electrical Engineering KitNOTE: Speaker Headphones not included. Listen through walls, hear conversations across the room. Add a parabolic reflector and hear blocks away. The Big Ear can be hidden about anywhere. Makes an ultra sensitive intercom. Can also be used as a 1. 5W AMP. We supply a mini electret mike in the kit. Assembly with a soldering iron is required (solder and soldering iron are not included). Power requirement 6 to 12v DC. Size: 1. 75" x 1".