Type: piezoceramic + condenser microphone
The Polytone system utilizes a piezo bridge transducer in combination with a condenser microphone. The bridge transducer mounts in the treble wing of the bridge under the ‘G’ string, much like the ‘Underwood’. It is a square-shaped piece of wood with the piezo inside. The mike is mounted in the center of the treble-side ƒ-hole, and is a square-shaped wooden unit with a red-button attached, called the “feedback eliminator”. It disconnects the mike from the sound to reduce the feedback. The unit does not have panning capabilities, so there is no control over the mix of mike and transducer.