Measuring apparatus for measuring the force factor of a dynamic loudspeaker driver

A measuring apparatus for measuring the force factor of a dynamic loudspeaker driver comprising:

• first and second terminals for connecting a dynamic loudspeaker driver to the measuring apparatus, the dynamic loudspeaker driver comprising a magnet, a membrane movably mounted with respect to the magnet, and a voice coil attached to the membrane and operatively coupled with the magnet;
• an amplifier configured to generate a voltage;
• a voltage measuring device configured to measure the voltage present at the first terminal;
• a displacement measuring device configured to measure the displacement of the membrane or voice coil with respect to the magnet;
• an electric/electronic device connected between the amplifier and the first terminal;
• the measuring apparatus being configured to operate in a first mode of operation the amplifier to generate a voltage and to operate the electric/electronic device to have a low impedance during the first mode of operation, such that the voltage generated by the amplifier is substantially present at the first terminal in order to displace the membrane with respect to the magnet, and the measuring apparatus being configured to operate the electric/electronic device to have a high impedance during a second mode of operation, such that the dynamic loudspeaker connected to the measuring apparatus moves its displaced membrane, resulting in an induced voltage generated by the dynamic loudspeaker driver and being present at the first terminal, the second mode of operation immediately following the first mode of operation;
• and
• an evaluation device configured to determine the force factor of the dynamic loudspeaker driver connected to the measuring apparatus in response to the measured displacement of the membrane and the induced voltage measured by the voltage measuring device during the second mode of operation.