IP Library Granted Patent US 8,068,615
Granted Patent B2
US 8,068,615 · App. 11/431,063 · Granted Nov 29, 2011

Automatic transformer saturation compensation circuit

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Quick Facts
Patent No.
US 8,068,615
App. No.
11/431,063
Granted
Nov 29, 2011
Kind
B2
Abstract

A transformer saturation compensation circuit for loudspeakers in embodiments of the invention may include one or more of the following features: (a) a transformer with a primary winding and a secondary winding electrically coupled to an output, (b) a high pass filter, (c) a current dependent resistive load electrically coupled in parallel with the capacitor and electrically coupled to an input, (d) a switch located at the primary winding electrically coupled to the capacitor and the resistive load, the switch being rotatable to each of the taps, where the current dependent resistive load provides saturation compensation for different loudspeaker configurations without requiring changes to a highpass filter cutoff frequency, and (e) a resistive load electrically coupled in parallel with the current dependent resistive load and the capacitor.

Claims (23)

1. A transformer saturation compensation circuit for loudspeakers comprising: a transformer with a primary winding and a secondary winding electrically coupled to an output, a high pass filter, a current dependent resistive load electrically coupled in parallel with a capacitor and electrically coupled to an input, and a switch located at the primary winding and electrically coupled to the capacitor and the resistive load, the switch being rotatable to each of taps of the primary winding, where the current dependent resistive load provides transformer saturation compensation for different loudspeaker configurations without requiring changes to a highpass filter cutoff frequency, wherein the current dependent resistive load provides cycling intervals of saturation for the transformer.

2. The circuit of claim 1 , wherein the current dependent resistive load is at least one incandescent bulb.

3. The circuit of claim 1 , further comprising a resistive load electrically coupled in parallel with the current dependent resistive load and the capacitor.

4. The circuit of claim 1 , wherein the capacitor shunts high frequencies from the input to the primary transformer winding during transformer saturation.

5. The circuit of claim 4 , wherein the high pass filter shunts frequencies above 100 Hz to the primary transformer winding.

6. The circuit of claim 1 , wherein the switch is rotated to the selected primary winding transformer tap during the loudspeaker installation.

7. The circuit of claim 5 , wherein frequencies below 100 Hz traverse through the current dependent resistive load where the power of the frequencies below 100 Hz is dissipated by the current dependent resistive load.

8. A transformer saturation compensation circuit for loudspeakers comprising: a transformer with a primary winding having multiple taps and a secondary winding electrically coupled to an output, a high pass filter, a current dependent resistive load electrically coupled in parallel with the high pass filter and electrically coupled to an input, and a switch located at the primary winding and electrically coupled to the high pass filter and the resistive load, the switch being rotatable to each of the taps, where the current dependent resistive load provides transformer saturation compensation for different loudspeaker configurations without requiring changes to a highpass filter cutoff frequency in a transformer mode, wherein the current dependent resistive load provides cycling intervals of saturation for the transformer, the switch also being rotatable to bypass the transformer through the current dependent resistive load to the output when the loudspeaker is in an eight ohm mode.

9. The circuit of claim 8 , wherein the current dependent resistive load functions as a current limiter in the eight ohm mode.

10. The circuit of claim 9 , wherein the eight ohm mode is generally selected for a single loudspeaker on an input line from an amplifier.

11. The circuit of claim 8 , wherein the transformer mode is generally selected for multiple loudspeakers on an input line from an amplifier.

12. The circuit of claim 8 , wherein all frequencies traverse through the current resistive load when the circuit is in the transformer mode and the transformer is not saturated.

13. The circuit of claim 12 , wherein the current resistive load reduces the power at the primary transformer winding during transformer saturation and resumes normal operation when the transformer is no longer saturated.

14. A loudspeaker having a transformer saturation compensation circuit, comprising: a housing; a contact on the housing to receive an incoming audio signal; a transformer with a primary winding and a secondary winding electrically coupled to a speaker, a high pass filter, and a current dependent resistive load electrically coupled in parallel with the high pass filter and electrically coupled between the contact and the primary winding, the current dependent resistive load provides transformer saturation compensation without requiring the elimination of low frequency audio signals, wherein the current dependent resistive load provides cycling intervals of saturation for the transformer.

15. The loudspeaker of claim 14 , further comprising at least two taps on the primary transformer winding each tap being a different loudspeaker configuration based upon a power level of the incoming audio signal.

16. The loudspeaker of claim 15 , further comprising a switch located at the primary winding electrically coupled to the high pass filter and the resistive load, the switch being rotatable to each of the taps, where the current dependent resistive load provides saturation compensation for different loudspeaker configurations without requiring changes to a highpass filter cutoff frequency.

17. The loudspeaker of claim 14 , wherein the current dependent resistive load is at least one incandescent bulb.

18. The loudspeaker of claim 14 , further comprising a resistive load electrically coupled in parallel with the current dependent resistive load and the high pass filter.

19. The loudspeaker of claim 14 , wherein the high pass filter shunts high frequencies from the input to the primary transformer winding.

20. The loudspeaker of claim 19 , wherein the high pass filter shunts frequencies above 100 Hz to the primary transformer winding.

21. The circuit of claim 1 , wherein the transformer saturation compensation involves the resistor load providing cycling intervals of saturation for the transformer during periods in which low frequency content on the input results in transformer saturation.

22. The circuit of claim 8 , wherein the transformer saturation compensation involves the resistor load providing cycling intervals of saturation for the transformer during periods in which low frequency content on the input results in transformer saturation.

23. The circuit of claim 14 , wherein the transformer saturation compensation involves the resistor load providing cycling intervals of saturation for the transformer during periods in which low frequency content in the incoming audio signal results in transformer saturation.

Assignments (6)
INTELLECTUAL PROPERTY SECURITY AGREEMENT Recorded May 15, 2026
From: ELECTRO-VOICE DYNACORD LLC
To: GLAS TRUST CORPORATION LIMITED
Reel/Frame 075643/0407 →
TERMINATION AND RELEASE OF SECURITY INTEREST IN INTELLECTUAL PROPERTY RECORDED AT REEL 73363, FRAME 0729 Recorded May 4, 2026
From: GLAS TRUST CORPORATION LIMITED
To: ELECTRO-VOICE DYNACORD LLC (F/K/A BOSCH SECURITY SYSTEMS, LLC, F/K/A BOSCH SECURITY SYSTEMS, INC.)
Reel/Frame 075499/0896 →
INTELLECTUAL PROPERTY SECURITY AGREEMENT Recorded Oct 28, 2025
From: BOSCH SECURITY SYSTEMS, LLC (FKA BOSCH SECURITY SYSTEMS, INC.)
To: GLAS TRUST CORPORATION LIMITED
Reel/Frame 073363/0729 →
MERGER/NAME CHANGE Recorded Mar 9, 2010
From: TELEX COMMUNICATIONS, INC.
To: BOSCH SECURITY SYSTEMS, INC.
Reel/Frame 024052/0267 →
SECURITY INTEREST RELEASE Recorded Sep 13, 2006
From: BNY MIDWEST TRUST COMPANY; GENERAL ELECTRIC CAPITAL CORPORATION
To: TELEX COMMUNICATIONS, INC.
Reel/Frame 018917/0957 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Jul 25, 2006
From: JAKOWSKI, STEVEN J.
To: TELEX COMMUNICATIONS, INC.
Reel/Frame 017994/0337 →