Bass loudspeaker drive unit - uses diaphragm suspension of negligible stiffness and PID controller to compensate for diaphragm deflection

摘要

The loudspeaker comprises a diaphragm, voice coil and magnet system. The centring mounting of the diaphragm has high compliance and the deflection of the diaphragm is compensated for using a process similar to that used in industrial line drawing recorders. The controlling low frequency represents the control input which is compared with a signal proportional to the diaphragm position, e.g. from a displacement pick-up (S1). A proportional-integral-differential (PID) controller receives the control input for driving the voice coil and diaphragm until the signal proportional to the diaphragm position momentarily corresponds to the controlling low frequency signal and the control deviation is fully compensated. ADVANTAGE - Avoids mass-spring resonance of diaphragm, linearity errors and creep effects.