Switching in an audio system with multiple playback paths

A system comprising:

• a playback path having a playback input for receiving an input signal and configured to generate at a playback path output an output signal based on the input signal, wherein:
• the playback path is configured to operate in a plurality of operational modes;
• and
• the playback path comprises an inline filter configured to filter the input signal to generate a first filtered input signal;
• and
• a control circuit configured to:
• receive a first signal from within the playback path and indicative of the input signal and the first filtered input signal;
• receive a second signal generated from the input signal externally to the playback path;
• and
• select a selected operational mode from the plurality of operational modes based on the first signal and the second signal.

A method comprising:

• receiving a first signal from within a playback path and indicative of an input signal, wherein the playback path comprises a playback input for receiving the input signal and configured to generate at a playback path output an output signal based on the input signal, and wherein the playback path is configured to operate in a plurality of operational modes;
• filtering the input signal with an inline filter integral to the playback path to generate a first filtered input signal, wherein the first signal is indicative of the first filtered input signal;
• receiving a second signal generated from the input signal externally to the playback path;
• and
• selecting a selected operational mode from the plurality of operational modes based on the first signal and the second signal.

A system comprising:

• a playback path having a playback input for receiving an input signal and configured to generate at a playback path output an output signal based on the input signal, wherein the playback path is configured to operate in a plurality of operational modes;
• and
• a control circuit configured to:
• receive a first signal from within the playback path and indicative of the input signal;
• receive a second signal generated from the input signal externally to the playback path;
• select a selected operational mode from the plurality of operational modes based on the first signal and the second signal;
• measure a difference between the first signal and the second signal when the input signal is zero, the difference indicative of noise present in the signal path;
• and
• set a threshold of the first signal for exiting a noise-gating mode of operation of the system based on the difference.

A method comprising:

• receiving a first signal from within a playback path and indicative of an input signal, wherein the playback path comprises a playback input for receiving the input signal and configured to generate at a playback path output an output signal based on the input signal, and wherein the playback path is configured to operate in a plurality of operational modes;
• receiving a second signal generated from the input signal externally to the playback path;
• selecting a selected operational mode from the plurality of operational modes based on the first signal and the second signal;
• measuring a difference between the first signal and the second signal when the input signal is zero, the difference indicative of noise present in the signal path;
• and
• setting a threshold of the first signal for exiting a noise-gating mode of operation of the system based on the difference.

A system comprising:

• a playback path having a playback input for receiving an input signal and configured to generate at a playback path output an output signal based on the input signal, wherein the playback path is configured to operate in a plurality of operational modes;
• a multi-stage output driver, the multi-stage output driver comprising an output stage that operates as a Class-D audio output stage in a first mode of the plurality of operational modes and operates as a Class-AB audio output stage in a second mode of the plurality of operational modes;
• a common feedback loop that remains constant and operative as the systems is switched between the first mode and the second mode;
• and
• a control circuit configured to:
• receive a first signal from within the playback path and indicative of the input signal;
• receive a second signal generated from the input signal externally to the playback path;
• and
• select a selected operational mode from the plurality of operational modes based on the first signal and the second signal.

A method comprising:

• receiving a first signal from within a playback path and indicative of an input signal, wherein the playback path comprises:
• a playback input for receiving the input signal and configured to generate at a playback path output an output signal based on the input signal, and wherein the playback path is configured to operate in a plurality of operational modes;
• and
• a multi-stage output driver, the multi-stage output driver comprising an output stage that operates as a Class-D audio output stage in a first mode of the plurality of operational modes and operates as a Class-AB audio output stage in a second mode of the plurality of operational modes;
• wherein a system comprising the playback path further comprises a common feedback loop that remains constant and operative as the playback path is switched between the first mode and the second mode;
• receiving a second signal generated from the input signal externally to the playback path;
• and
• selecting a selected operational mode from the plurality of operational modes based on the first signal and the second signal;