Systems and methods for stabilizing a playback device

A method for controlling a playback device comprising one or more sensors, an enclosure defining an internal chamber, and an audio transducer carried by the enclosure and including an axially moveable diaphragm, a voice coil, and a suspension assembly including a composite material and operably coupling the diaphragm and the voice coil, the method comprising:

• while in an audio playback state:
• obtaining, via the one or more sensors, data indicating an axial position of a diaphragm of the playback device;
• and
• adjusting the axial position of the diaphragm based on the data indicating the axial position of the diaphragm;
• transitioning from the audio playback state to a standby state in response to an engagement trigger condition;
• and
• while in the standby state, activating a mechanical positioner to move to an engaged state to mechanically limit axial movement of the diaphragm beyond a threshold position.

A playback device comprising:

• an audio transducer comprising:
• a frame;
• a diaphragm that is axially moveable with respect to the frame;
• a voice coil configured to receive an electrical signal from an amplifier and, in response to the received electrical signal, correspondingly move the diaphragm axially inward or outward;
• and
• a negative-stiffness suspension assembly coupling the diaphragm and the voice coil, wherein the suspension assembly comprises a composite material;
• a mechanical positioner selectively moveable between (i) a disengaged state in which the positioner is spaced apart from the diaphragm and (ii) an engaged state in which the positioner mechanically limits axial movement of the diaphragm beyond a threshold position;
• and
• a control system configured to adjust the axial position of the diaphragm based at least in part on information indicating the axial position of the diaphragm while in an audio playback state, and configured to cause the mechanical positioner to move from the disengaged state to the engaged state in response to the playback device entering a standby state.