The first moving coil cone loudspeaker, developed by Chester W. Rice and Edward W. Kellogg at General Electric Laboratory in Schenectady, New York in 1925. It is the prototype for almost all modern loudspeakers. It consists of a paper cone attached at the rim to the baffle plate with a very flexible compliant coupling, attached to a light coil of wire (voice coil) in the field of an electromagnet. In this view, the magnet appears to be pulled back so the voice coil is visible. An important part of the invention was Rice and Kellogg's characterization of the acoustic properties of the cone: to have a flat frequency response it had to have a fundamental mode of vibration below 100 Hz and be mounted in a baffle at least 2 feet square.