Impedance matching circuit for driving a speaker system

• US 9,008,324 B2
• Filed: 05/15/2014
• Issued: 04/14/2015
• Est. Priority Date: 05/15/2013
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Colorado Energy Research Technologies, LLC
• Inventors: Powell, Wayne J., Boehmer, Robert D.
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): SUTHERS, DOUGLAS JOHN
• Application Number:
  US14/279,111
• Publication Number:
  US 20140341400A1
• Time in Patent Office: 334 Days
• Field of Search: 381/59, 381/58, 381/55, 381/111, 381/123
• US Class Current: 381/59
• CPC Class Codes: H03H 2001/005 Wound, ring or feed-through type inductor
• CPC Class Codes: H03H 7/38 Impedance-matching networks
• CPC Class Codes: H04R 3/12 for distributing signals to two or more loudspeakers specially adapted for hearing aids H04R25/407

Abstract

An impedance matched resonant circuit uses inductors coupling an audio source and a speaker array in order to reduce feedback reflection induced by an audio signal traveling from the audio source to the array of speakers. An RC circuit could also be coupled to the positive and negative terminals of the speaker array to reduce the slope differential of the audio signal at certain frequencies. The circuit can be packaged together in a single module with switches to activate and deactivate portions of the circuit to alter the effectiveness of the circuit depending upon need.

Claims

1. A circuit for improving efficiency of an array of speakers having a positive and negative terminal, comprising:

a first circuitry configured to couple the positive terminal of the array of speakers with an audio signal source, wherein the first circuitry comprises an inductor configured to reduce reflection of an audio signal by the array of speakers; and

a second circuitry configured to operatively interpose a capacitor and an electrically variable resistor between the positive terminal of the array of speakers and the negative terminal of the array of speakers.

2. The circuit of claim 1, wherein the inductor comprises a paramagnetic material.

3. The circuit of claim 1, wherein the inductor comprises a ferromagnetic material.

4. The circuit of claim 1, wherein the variable resistor comprises a potentiometer.

5. The circuit of claim 1, wherein the inductor has a gap that comprises at least one of a ferromagnetic and diamagnetic material.

6. The circuit of claim 1, wherein the variable resistor is controlled by a computer programmable logic controller.

7. The circuit of claim 1, wherein the capacitor is a variable capacitor.

8. The circuit of claim 7, wherein a capacitance of the variable capacitor is controlled by a computer programmable logic controller.

9. The circuit of claim 7, wherein the variable capacitor is a digitally tuned capacitor.

10. The circuit of claim 1, further comprising a third circuitry coupled to the negative terminal of the array of speakers, and further coupled to the audio signal source, wherein the third circuitry comprises a second inductor.

11. The circuit of claim 10, wherein the third circuitry comprises a switch in parallel with the second inductor.

12. The circuit of claim 1, wherein the first circuitry comprises a switch in parallel with the inductor.

13. The circuit of claim 1, wherein the second circuitry comprises a switch in series with the resistor and the capacitor.

14. An audio enhancement kit comprising:

a first circuitry comprising a first inductor configured to be coupled to a positive terminal of an array of speakers;

a second circuitry comprising a second inductor configured to be coupled to a negative terminal of the array of speakers; and

a third circuitry that couples to both the positive terminal and the negative terminal of the array of speakers, comprising a resistor and a variable capacitor.

15. The audio enhancement kit of claim 14, wherein the resistor comprises a variable resistor.

16. The audio enhancement kit of claim 15, wherein the variable resistor comprises an electronically variable resistor.

17. The audio enhancement kit of claim 14, wherein the variable capacitor comprises an electronically variable capacitor.

18. A circuit for improving efficiency of an array of speakers having a positive and negative terminal, comprising:

a first circuitry configured to couple the positive terminal of the array of speakers with an audio signal source, wherein the first circuitry comprises an inductor configured to reduce reflection of an audio signal by the array of speakers; and

a second circuitry configured to operatively interpose a variable capacitor and an electrically varied variable resistor between the positive terminal of the array of speakers and the negative terminal of the array of speakers,

wherein a capacitance of the variable capacitor is controlled by a computer programmable logic controller.

19. The circuit of claim 18, wherein the variable resistor comprises a potentiometer.

20. The circuit of claim 18, further comprising a third circuitry coupled to the negative terminal of the array of speakers, and further coupled to the audio signal source, wherein the third circuitry comprises a second inductor.

21. The circuit of claim 20, wherein the third circuitry comprises a switch in parallel with the second inductor.

22. The circuit of claim 18, wherein the first circuitry comprises a switch in parallel with the inductor.

23. The circuit of claim 18, wherein the second circuitry comprises a switch in series with the resistor and the capacitor.

24. A circuit for improving efficiency of an array of speakers having a positive and negative terminal, comprising:

a first circuitry configured to couple the positive terminal of the array of speakers with an audio signal source, wherein the first circuitry comprises an inductor configured to reduce reflection of an audio signal by the array of speakers; and

a second circuitry configured to operatively interpose a digitally tuned variable capacitor and an electrically varied variable resistor between the positive terminal of the array of speakers and the negative terminal of the array of speakers.

25. The circuit of claim 24, further comprising a third circuitry coupled to the negative terminal of the array of speakers, and further coupled to the audio signal source, wherein the third circuitry comprises a second inductor.

26. The circuit of claim 25, wherein the third circuitry comprises a switch in parallel with the second inductor.

27. The circuit of claim 24, wherein the first circuitry comprises a switch in parallel with the inductor.

28. The circuit of claim 24, wherein the second circuitry comprises a switch in series with the resistor and the capacitor.