System and method for varying low audio frequencies inversely with audio signal level

A method of providing an automatic loudness compensation circuit comprising:

• receiving an input audio signal with a full audible frequency band having a high, mid, and low range of frequencies where the low range represents a bass content;
• coupling the input audio signal to a voltage detector to produce an output voltage;
• coupling the output voltage of the voltage detector to a control circuit, the control circuit comprising a filter circuit;
• comparing a corner frequency associated with the filter circuit to the strength of the input audio signal;
• shifting the corner frequency such that the corner frequency is inversely related to the strength of the input audio signal;
• coupling an output of the filter circuit to a power amplifier for amplifying the filter circuit output;
• and
• driving an audio speaker with the amplified filter circuit output.

An automatic loudness compensation circuit including a terminal coupled to an input audio signal from an external source and a signal supply having voltage sufficient to drive an output audio speaker comprising:

• an R.M.S. detector for providing an R.M.S. voltage from the input audio signal with a full audible frequency band having a high, mid, and low range of frequencies where the low range represents a bass content;
• a control circuit including a filter circuit for adjusting a corner frequency associated with the filter circuit such that the corner frequency is inversely related to the input audio signal;
• a power amplifier for increasing the power of the output signal from the filter circuit;
• and
• a terminal for providing an amplified output signal.

An automatic loudness compensation circuit including a terminal coupled to an input audio signal from an external source and a signal supply having voltage sufficient to drive an output audio speaker comprising:

• means for detecting an R.M.S. voltage from the audio input signal with a full audible frequency band having a high, mid, and low range of frequencies where the low range represents a bass content;
• means for adjusting a corner frequency of a filter circuit such that the corner frequency is inversely related to the audio input signal;
• means for amplifying the output signal from the filter circuit;
• and
• a terminal for providing an amplified output signal.

A system for obtaining a first order bass boost compensation comprising:

• a terminal for receiving an audio input signal having a signal level;
• a level control for determining the level of the input audio signal with high, mid, and low range of frequencies where the low range represents a bass content;
• an automatic loudness compensation circuit comprising:
• a power supply voltage having voltage sufficient to drive an output audio speaker;
• an R.M.S. detector coupled to the power supply voltage for providing an R.M.S. voltage from the input audio signal;
• and
• a control circuit coupled to the R.M.S. detector comprising a filter having an associated corner frequency, the control circuit for adjusting the corner frequency such that the corner frequency is inversely related to the input audio signal to generate a low pass signal;
• a summing circuit coupled to the automatic loudness compensation circuit, the summing circuit summing the audio input signal and the low pass signal to generate an output signal;
• a power amplifier coupled to the summing circuit for increasing the power of the output signal from the summing circuit;
• and
• a terminal for providing an amplified output signal to an audio speaker.

A system for obtaining an automatic loudness compensation comprising:

• a input terminal for receiving an audio input signal having a signal level with a full audible frequency band having a high, mid, and low range of frequencies where the low range represents a bass content;
• a level control coupled to the input terminal for determining the level of the input audio signal;
• an automatic loudness compensation circuit coupled to the level control, the automatic loudness compensation circuit comprising a filter circuit for adjusting a corner frequency associated with the filter circuit such that the corner frequency is inversely related to the audio input signal, to generate a low pass signal;
• a summing circuit coupled to the automatic loudness compensation circuit, the summing circuit summing the audio input signal and the low pass signal to generate an output signal;
• a power amplifier coupled to the summing circuit for increasing the power of the output signal from the summing circuit;
• and
• an output terminal coupled to an audio speaker for providing an amplified output signal to the audio speaker.