Compressor based dynamic bass enhancement with EQ

• US 9,380,385 B1
• Filed: 03/14/2014
• Issued: 06/28/2016
• Est. Priority Date: 11/14/2008
• Status: Active Grant

• Current Assignee: THAT Corporation
• Original Assignee: THAT Corporation
• Inventors: Skinner, Scott, Hanna, Christopher M.
• Primary Examiner(s): Edun, Muhammad N
• Application Number:
  US14/212,906
• Time in Patent Office: 837 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H03G 5/165 Equalizers; Volume or gain control in limited frequency bands
• CPC Class Codes: H03G 7/002 in untuned or low-frequency amplifiers, e.g. audio amplifiers H03G7/007, H03G7/001, H03G7/008, H03G7/02, H03G7/06 take precedence
• CPC Class Codes: H03G 9/005 of digital or coded signals
• CPC Class Codes: H03G 9/025 frequency-dependent volume compression or expansion, e.g. multiple-band systems H03G9/10, H03G9/18 take precedence
• CPC Class Codes: H04R 29/001 for loudspeakers H04R29/007 takes precedence
• CPC Class Codes: H04R 3/007 Protection circuits for transducers
• CPC Class Codes: H04R 3/14 Cross-over networks

Abstract

Systems and methods for enhancing the low frequency response of a loudspeaker for relatively low input level audio signals and protect the loudspeaker for relatively high input level audio signals make use of a crossover network configured so separate an audio input signal into at least two frequency bands including a low frequency band; and a signal compressor responsive to the energy level of the low frequency portion of an input audio signal in the low frequency band and configured to provide amplification gain on the low frequency portion of the input signal when the energy level of the low frequency portion of the input signal is relatively low. One or more peak limiters may be positioned before the summer(s), in the circuit, but after the low band compressor. The EQ unit(s) may be positioned before all processing to the L and R inputs.

Claims

1. A system for enhancing the low frequency response of a loudspeaker for relatively low input level audio signals and protecting the loudspeaker for relatively high input level audio signals, the system comprising:

a crossover network configured so as to separate each of left and right audio input signals into at least two frequency bands including a low frequency band;

a dynamic system including a low band compressor configured to produce outputs signals responsive to the energy level of the low frequency portion of input audio signals in the low frequency band of each of the left and right audio input signals, and configured to provide amplification gain on the low frequency portion of each input signal when the energy level of the low frequency portion of the input signal is relatively low so as to enhance the low frequency response of the loudspeaker, and provide attenuation of the low frequency portion of each input signal when the energy level of the low frequency portion of the input signal is relatively high so as to protect the loudspeaker from being overdriven, wherein the output signals are compressed outputs signals corresponding to the low frequency portion of each of the left and right audio input signals, respectively;

left and right equalizers configured to receive the left and right audio input signals and shape the spectral characteristics as desired for input to the dynamic system; and

left and right peak limiters, each configured to receive to the compressed output signals of the dynamic systems, respectively, and to limit the peak amplitude of the compressed output signals, respectively, and provide the compressed output signals to the signal summer.

2. A system according to claim 1, wherein each static equalizer is configured with a lower frequency limit that is below a crossover frequency of the crossover network.

3. A system according to claim 2, wherein the configurable parameters include one or more of the following:

crossover frequency and maximum allowable gain.

4. A system according to claim 2, wherein the configurable parameters include crossover frequency, maximum allowable gain, and EQ filter coefficients.

5. A system according to claim 1, wherein parameters of the system are configurable to optimize for a given speaker characteristic or listener preference.

6. A system according to claim 1 cascaded with a static EQ such that the combination produces an overall frequency response made up of both dynamic and static frequency bands.

7. A system according to claim 1, further comprising two loudspeakers for left and right channel stereo play, each being operative to receive an input signal and to produce a corresponding auditory output signal.

8. A system for enhancing the low frequency response of at least two loudspeakers for left and right channel stereo play for relatively low input level audio signals and for protecting the loudspeakers for relatively high input level audio signals, the system comprising:

a crossover network configured to receive left and right channel audio input signals and separate each into at least two frequency bands including a low frequency band; and

a signal compressor responsive to the energy level of the low frequency portion of each of the left and right audio input signals and configured to provide amplification gain on the low frequency portion of the input signal when the energy level of the low frequency portion of the input signal is relatively low so as to enhance the low frequency response of the loudspeaker, and provide attenuation of the low frequency portion of the input signal when the energy level of the low frequency portion of the input signal is relatively high so as to protect the loudspeaker from being overdriven, wherein the signal compressor is further configured to provide as output signals compressed outputs signals corresponding to the low frequency portion of each of the left and right audio input signals, respectively; and

a signal summer configured to provide a summed compressed signal representing the sum of the compressed output signals of the signal compressor of the left and right channels, the signal summer including two summing blocks for providing left and right channel summed signals as a function of the summed compressed signal and the portion of each left and right channel signal provided in each remaining frequency band; and

peak limiters configured before the two summing blocks and after the signal compressor, wherein the peak limiters are configured to receive the compressed output signals of the signal compressor of the left and right channels, respectively, and to limit the peak amplitude of the compressed output signals, respectively, and provide the compressed output signals to the signal summer.

9. A system according to claim 8, wherein the crossover network is configured to separate the audio signal into two frequency bands.

10. A system according to claim 8, wherein parameters of the system are configurable to optimize for a given speaker characteristic or listener preference.

11. A system according to claim 10, wherein the configurable parameters include one or more of crossover frequency and maximum allowable gain.

12. A system according to claim 10, wherein the configurable parameters include one or more of target level, compression ratio, attack time constant and release time constant.

13. A system according to claim 8 cascaded with a static EQ such that the combination produces an overall frequency response made up of both dynamic and static frequency bands.

14. A system according to claim 13, wherein the configurable parameters include crossover frequency, maximum allowable gain, and EQ filter coefficients.

15. A system according to claim 8, further comprising two loudspeakers for left and right channel stereo play, each being operative to receive an input signal and to produce a corresponding auditory output signal.