Patent ID: 6975741
Filing Date: 2005-12-13
Classification: H04R

Abstract:
1. An electroacoustic transducer comprising: a transducer axis; a membrane capable of oscillation parallel to the transducer axis; a magnet system comprising an outer magnet system part and an inner magnet system part said outer and inner magnet system parts enclosing an air gap limited by a cylindrical boundary surface of the outer magnet system part and a cylindrical boundary surface of the inner magnet system part, said magnet system having at least one passage for enabling communication between a rear chamber volume, situated directly to the rear of the membrane, and an additional rear chamber volume lying remote from the rear of the membrane and parallel to the direction of the transducer axis; a moving coil configuration connected to the membrane and having a hollow cylindrical coil carrier and a moving coil of hollow cylindrical shape connected to the hollow cylindrical coil carrier, said moving coil being retained so as to lie at least substantially in the air gap, and being adjustable in relation to the magnet system; and guide means for guiding the moving coil configuration in a direction parallel to the transducer axis upon adjustment of the moving coil in relation to the magnet system, wherein the moving coil configuration has a cylindrical boundary surface in an area lying opposite the cylindrical boundary surface of the outer magnet system part, and the cylindrical boundary surface of the outer magnet system part and the cylindrical boundary surface of the moving coil configuration are arranged to be mutually coaxial and delimit a cylindrical gap which is acoustically impermeable above a lower limit frequency of, at most, 100 Hz.