System and method for control of off-instrument effects

An electric guitar comprising:

• an instrument body;
• an output jack in the instrument body;
• a control bar socket extending into a top face of the instrument body;
• and
• a sensor circuit in the instrument body, the sensor circuit comprising a sensor chip configured to output a control signal based on a magnetic field;
• a control bar that has a user portion and an end portion connected to and extending transversely from the user portion, the end portion configured to be received in the control bar socket and rotatable about an axis of rotation;
• a permanent magnet on the end portion of the control bar, wherein the permanent magnet has a magnetic field;
• and
• a sensor circuit that includes a sensor chip positioned sufficiently close to the permanent magnet when the control bar is installed in the control bar socket, the sensor circuit configured to detect a change in the magnetic field resulting from rotating the control bar, wherein the sensor circuit is configured to output a control signal based on a position of the permanent magnet relative to the sensor chip.

A tailpiece assembly for a stringed instrument, the assembly comprising:

• a control bar with an end portion and a user portion;
• a tailpiece defining a socket constructed to receive the end portion of the control bar such that the control bar is rotatable about the end portion when the end portion of the control bar is installed in the socket;
• a magnet on the end portion of the control bar, the magnet defining a magnetic field, wherein rotating the control bar rotates the magnet;
• a sensor chip adjacent the socket, the sensor chip configured to output a control signal based on a change in the magnetic field, wherein when the end portion of the control bar is installed in the socket, the sensor chip is spaced from the magnet by a gap sufficiently small to enable the sensor chip to detect a change in the magnetic field as a result of rotating the end portion of the control bar;
• a sensor circuit coupled to the sensor chip and configured to output a control signal that can be modulated by rotating the control bar about the end portion;
• a power supply coupled to the sensor circuit;
• and
• an output for the control signal.

A retrofit kit for a guitar configured to output an audio signal, the retrofit kit comprising:

• a mounting plate;
• a control bar with an end portion including a permanent magnet defining a magnetic field;
• a socket mounted to the mounting plate, the socket sized and configured to receive the end portion of the control bar such that the control bar is rotatable about the end portion, the socket including a sensor chip configured to detect a change in the magnetic field as a result of rotating the end portion in the socket;
• a sensor circuit coupled to the sensor chip, the sensor circuit configured to output a control signal based on a position of the permanent magnet relative to the sensor chip;
• and
• a means for outputting the control signal separately from the audio signal of the guitar, the means for outputting the control signal electrically coupled to the sensor circuit.