*1. Amplified signal
The plate amplifier receives a signal which is filtered on the pre-amp board to achieve correct integration. The power amplifier sends a signal to the driver.
*2. Cone excursion
As the amplified signal passes through the voice coil, the cone moves.
*3. Correction signal
A very thin sensing coil is attached to the voice coil. As the cone moves, a signal is generated. This signal is used to accurately track the movement of the cone. Effectively the sensing coil is a specialized microphone which measures the precise output of the driver.
*4. Feedback
The correction signal is fed back into the summing points of the amplifier. It is compared to the original signal and corrections are made without the use of any active circuits.
*5. Corrected signal is accurately reproduced
The driver now reproduces a signal that is corrected. The sources of distortion which plague other subwoofers are dramatically reduced.