System and method of reducing power consumption for audio playback

A method of operating an audio system, comprising:

• amplifying a first analog audio signal to generate a second analog audio signal;
• supplying power to cause the amplification of the first analog audio signal;
• adjustably generating a volume level signal indicative of a volume level determined for second analog audio signal;
• and
• controlling an amount of the power, wherein the power to cause the amplification being differently modulated depending on whether the volume level signal is above or below a predetermined threshold.

An apparatus, comprising:

• means for amplifying a first analog audio signal to generate a second analog audio signal;
• means for supplying power to the amplification means;
• means for adjustably generating a volume level signal indicative of a volume level for the second analog audio signal;
• and
• means for controlling an amount of power delivered by the power supply means, wherein the power to the amplification means being differently modulated depending on whether the volume level signal is above or below a predetermined threshold.

An audio system, comprising:

• an audio amplifier adapted to amplify a first analog audio signal to generate a second analog audio signal;
• a power supply adapted to supply power to the audio amplifier;
• a detection module adapted to sample a digital signal used to generate the first analog audio signal, the detection module further adapted to generate a characteristic indicating signal determined from an envelope of the first analog audio signal;
• and
• a control module adapted to control an amount of power delivered by the power supply, wherein the power to the audio amplifier being differently modulated depending on whether the volume level signal is above or below a predetermined threshold.

A method of operating an audio system, comprising:

• amplifying a first analog audio signal to generate a second analog audio signal;
• supplying power to cause the amplification of the first analog audio signal;
• sampling a digital signal used to generate the first analog audio signal to generate a characteristic indicating signal indicating an envelope related to the first analog audio signal;
• and
• controlling an amount of the power, wherein the power to cause the amplification being differently modulated depending on whether the characteristic indicating signal is above or below a predetermined threshold.

An apparatus, comprising:

• means for amplifying a first analog audio signal to generate a second analog audio signal;
• means for supplying power to the amplification means;
• means for generating a signal indicative of a characteristic related to the first analog audio signal;
• means for sampling a digital signal used to generate the first analog audio signal to generate a characteristic indicating signal indicating an envelope related to the first analog audio signal;
• and
• means for controlling an amount of power delivered by the power supply means, wherein the power to the means for amplifying being differently modulated depending on whether the characteristic indicating signal is above or below a predetermined threshold.

An audio system, comprising:

• a digital companding module adapted to receive a first digital audio signal, and generate a second digital audio signal being a product of the first digital audio signal and a digital gain parameter GD;
• a digital-to-analog (DAC) converter adapted to generate a first analog audio signal derived from the second digital audio signal;
• an analog companding module adapted to receive the first analog audio signal, and generate a second analog audio signal being a product of the first analog audio signal and an analog gain parameter GA;
• an adaptive power supply adapted to supply power to the DAC or the power amplifier;
• and
• a controller adapted to adjust the power supply, adjust the digital gain parameter GD and the analog gain parameter GA in response to a characteristic of the first digital audio signal, wherein the power being differently modulated depending on whether a volume level for the second analog audio signal is above or below a predetermined threshold.