Wave dependent compressor

• US 5,483,600 A
• Filed: 02/14/1994
• Issued: 01/09/1996
• Est. Priority Date: 02/14/1994
• Status: Expired due to Term

• Current Assignee: Aphex, LLC
• Original Assignee: Aphex Systems, Ltd. (RØDE Microphones)
• Inventors: Werrbach, Donn
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): HARVEY, MINSUN OH
• Application Number:
  US08/196,296
• Time in Patent Office: 694 Days
• Field of Search: 381/106, 381/107, 381/108, 333/14, 455/72
• US Class Current: 381/106
• 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

Abstract

An audio compressor using interactive layered time constants to create an easy to use compressor which self adapts to the program characteristics and provides a desirable and pleasing effect over a wide range of audio program material. The audio compressor includes an adaptable filter connected between an output signal path and a control feedback signal path of a voltage control amplifier. The adaptable filter comprises a first resistor-capacitor circuit connected to the output signal path and producing a charging/discharging voltage which is more dependent on a transient peak value of the audio signals and a second resistor-capacitor circuit working under the charging/discharging voltage of the first resistor/capacitor circuit for producing a charging/discharging voltage which is more dependent on an average value of the audio signals. The second resistor-capacitor circuit is connected in series to the first resistor-capacitor circuit for providing a wave dependent control feedback signal to the control feedback signal path which feedback signal is instantaneously and continuously dependent upon both the average and the transient peak value of the audio signals.

Claims

1. A wave dependent compressor, comprising:

a. an input signal path for receiving an input signal;

b. an output signal path for rendering an output signal;

c. a voltage control amplifier connected between said input signal path and said output signal path;

d. a rectifier connected to said output signal path for producing a rectified signal which is a rectified version of said output signal of said voltage control amplifier;

e. an adaptable filter connected to said rectifier and operating with a multiplicity of interactive layered time constants, the adaptable filter comprising a one-way current device connected to said rectifier for permitting said rectifier to charge the adaptable filter but preventing said rectifier from discharging the adaptable filter;

f. said adaptable filter further comprising a first resistor-capacitor circuit connected to said one-way current device and producing a charging/discharging voltage which is more dependent on a transient peak value of said rectified signal than it is on an average value of said rectified signal;

g. said adaptable filter further comprising a second resistor-capacitor circuit to which said charging/discharging voltage of said first resistor/capacitor circuit is applied for producing a charging/discharging voltage which is more dependent on said average value of said rectified signal than it is on said transient peak value of said rectified signal, the second resistor-capacitor circuit connected in series to said first resistor-capacitor circuit for providing a wave dependent control feedback signal which is instantaneously and continuously dependent upon both said average and said transient peak value of said rectified signal; and

h. a control feedback path connected between said adaptable filter and said voltage control amplifier for supplying said wave dependent control feedback signal to said voltage control amplifier to provide instantaneous and continuous gain control adjustment;

i. whereby said wave dependent compressor operates under said multiplicity of interactive layered time constants to create a self-adaptive compression over a wide range of said input signal and therefore provides said output signal with an instantaneous and continuous gain control.

2. The invention as defined in claim 1 wherein said one-way current device of said adaptable filter includes a diode and a first resistor connected in series.

3. The invention as defined in claim 2 wherein said first resistor has a resistance of 20 KΩ

.

4. The invention as defined in claim 1 wherein said first resistor-capacitor circuit of said adaptable filter includes a first capacitor and a second resistor connected in parallel.

5. The invention as defined in claim 4 wherein said first capacitor has a capacitance of 1 μ

F.

6. The invention as defined in claim 4 wherein said second resistor has a resistance of 20 KΩ

.

7. The invention as defined in claim 4 wherein said second resistor-capacitor circuit of said adaptable filter includes a second capacitor connected in series to said first capacitor.

8. The invention as defined in claim 7 wherein said second capacitor has a capacitance of 4.7 μ

F.

9. The invention as defined in claim 7 further comprising means for adjusting the charging/discharging rate of said second resistor-capacitor circuit of said adaptable filter.

10. The invention as defined in claim 9 wherein said means for adjusting the charging/discharging rate of said second resistor-capacitor circuit of said adaptable filter includes a variable resistor connected in parallel with said second capacitor.

11. The invention as defined in claim 10 wherein said variable resistor has a resistance within a range from 100 KΩ

to 1 MΩ

.

12. The invention as defined in claim 1 wherein said second resistor-capacitor circuit of said adaptable filter is grounded.

13. In an audio compressor having a voltage control amplifier connected between an input signal path and an output signal path, the improvement of utilizing an adaptable filter comprising:

a. rectifying circuit connected to said output signal path for providing a rectified signal, the rectifying circuit including a diode and a first resistor connected in series;

b. a first resistor-capacitor circuit connected to said rectifying circuit and including a first capacitor and a second resistor connected in parallel and producing a charging/discharging voltage which is more dependent on a transient peak value of said rectified signal than it is on an average value of said rectified signal;

c. a second resistor-capacitor circuit including a second capacitor to which said charging/discharging voltage of said first resistor/capacitor circuit is applied for producing a charging/discharging voltage which is more dependent on said average value of said rectified signal than it is on said transient peak value of said rectified signal;

d. said second resistor-capacitor circuit further including a variable resistor for adjusting its charging/discharging rate;

e. said second resistor-capacitor circuit connected in series to said first resistor-capacitor circuit for providing a wave dependent control feedback signal which is instantaneously and continuously dependent upon both said average and said transient peak value of said rectified signal; and

f. a control feedback path connected between said adaptable filter and said voltage control amplifier for supplying said wave dependent control feedback signal to said voltage control amplifier to provide instantaneous and continuous gain control adjustment;

g. whereby said adaptable filter operates under said multiplicity of interactive layered time constants to create a self-adaptive compression over a wide range of said rectified signal and therefore provides said audio compressor with an instantaneous and continuous gain control.

14. The invention as defined in claim 13 further comprising a rectifier connected to said output signal path for producing a rectified signal which is a rectified version of said output signal of said voltage control amplifier.

15. The invention as defined in claim 14 wherein said first resistor has a resistance of 20 KΩ

.

16. The invention as defined in claim 13 wherein said first capacitor has a capacitance of 1 μ

F.

17. The invention as defined in claim 13 wherein said second resistor has a resistance of 20 KΩ

.

18. The invention as defined in claim 13 wherein said second capacitor has a capacitance of 4.7 μ

F.

19. The invention as defined in claim 13 wherein said variable resistor has a resistance within a range from 100 KΩ

to 1 MΩ

.

20. The invention as defined in claim 13 wherein said second resistor-capacitor circuit of said adaptable filter is grounded.

21. An adaptable filter connected between an output signal path and a control feedback signal path of a voltage control amplifier, the adaptable filter comprising:

a. a first resistor-capacitor circuit connected to said output signal path and producing a charging/discharging voltage which is more dependent on a transient peak value of an output signal of said voltage control amplifier than it is on an average value of the output signal, wherein the first resistor-capacitor circuit includes a first capacitor;

b. a second resistor-capacitor circuit to which said charging/discharging voltage of said first resistor/capacitor circuit is applied for producing a charging/discharging voltage which is more dependent on said average value of said output signal than it is on said transient peak value of said output signal, wherein the second resistor-capacitor circuit includes a second capacitor connected in series to said first capacitor; and

c. said second resistor-capacitor circuit connected in series to said first resistor-capacitor circuit for providing a wave dependent control feedback signal to said control feedback signal path which feedback signal is instantaneously and continuously dependent upon both said average and said transient peak value of said output signal;

d. whereby said adaptable filter operates under said multiplicity of interactive layered time constants to create a self-adaptive compression over a wide range of audio signals and therefore provides said voltage control amplifier with an instantaneous and continuous gain control.

22. The invention as defined in claim 21 further comprising a rectifier connected to said output signal path for producing a rectified signal which is a rectified version of said output signal of said voltage control amplifier.

23. The invention as defined in claim 22 wherein said adaptable filter further comprises a one-way current device connected to said rectifier for permitting said rectifier to charge the adaptable filter but preventing said rectifier from discharging the adaptable filter.

24. The invention as defined in claim 23 wherein said one-way current device includes a diode and a first resistor connected in series.

25. The invention as defined in claim 24 wherein said first resistor has a resistance of 20 KΩ

.

26. The invention as defined in claim 21 wherein said first resistor-capacitor circuit further includes a second resistor connected in parallel with said first capacitor.

27. The invention as defined in claim 26 wherein said first capacitor has a capacitance of 1 μ

F.

28. The invention as defined in claim 26 wherein said second resistor has a resistance of 20 KΩ

.

29. The invention as defined in claim 21 wherein said second capacitor has a capacitance of 4.7 μ

F.

30. The invention as defined in claim 21 wherein said second resistor-capacitor circuit further comprises means for adjusting its charging/discharging rate.

31. The invention as defined in claim 30 wherein said means for adjusting the charging/discharging rate of said second resistor-capacitor circuit includes a variable resistor connected in parallel with said second capacitor.

32. The invention as defined in claim 31 wherein said variable resistor has a resistance within a range from 100 KΩ

to 1 MΩ

.

33. The invention as defined in claim 21 wherein said second resistor-capacitor circuit of said adaptable filter is grounded.