Hybrid controller for mid-range mid-power audio application

Area of Science:

• Electrical Engineering
• Audio Engineering
• Acoustics

Background:

• Coil-type loudspeakers suffer from compromised audio quality due to complex impedance profiles, disrupting linear phase behavior.
• Switch-mode amplifiers, while energy-efficient, introduce non-linearity and finite internal impedance, further degrading audio reproduction.
• The loudspeaker's impedance significantly affects the driving current and force, impacting audio fidelity.

Purpose of the Study:

• To investigate the impact of loudspeaker impedance on driving current and force.
• To propose a Hybrid controller-amplifier for enhanced proportionality between audio reference and driving force.
• To maintain loudspeaker damping while improving audio reproduction accuracy.

Main Methods:

• Developed a Hybrid amplifier combining a sliding mode controlled amplifier (SMCA) and a linear controller.
• Exhaustively modeled the input-output behavior of the SMCA.
• Created a best-fit approximation of the loudspeaker impedance for controller design.
• Fabricated an 8W prototype covering 500 Hz to 20 kHz.

Main Results:

• The proposed Hybrid amplifier demonstrated improved proportionality between the audio reference and the loudspeaker driving force.
• Experimental results in both time and frequency domains validated the performance enhancements.
• The design successfully addressed the non-linearity and impedance issues affecting audio quality.

Conclusions:

• The Hybrid controller-amplifier effectively enhances audio quality in coil-type loudspeakers.
• The proposed design offers a solution for improving audio reproduction accuracy without compromising loudspeaker damping.
• This approach provides a pathway for better integration of efficient switch-mode amplifiers in high-fidelity audio systems.