Multichannel Audio Amplifier Limiting for Shared Power Supply Overload
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Solution Overview
Problem
In multichannel audio systems, existing power supply protection mechanisms often lead to unnecessary power limitations and audible distortion due to the dynamic nature of audio signals, failing to optimize power utilization across channels and risking switch-off during power peaks.
Innovation Solution
A method and device that adjust gain and clipping levels for each amplifier channel based on the power supply's energy reserve, using attenuation and clipping functions to ensure power supply, ensuring power utilization and minimize audible artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dynamic range compressor or limiter is used to limit the RMS level of the audio signal, then the power supply is protected from overload and switch-off is avoided, but audible distortion increases and the full output power capability of the system is not exploited
Solution Approach 1:
The patent applies dynamics by making the gain and clipping levels time-variable based on the measured power supply voltage. The attenuation function dynamically adjusts the audio signal level in real-time according to the power supply's energy reserve, allowing the system to exploit full output power capability when available while preventing overload conditions. This dynamic adaptation resolves the contradiction by enabling high power output without causing audible distortion or switch-off.
Solution Approach 2:
The patent implements feedback by continuously measuring the power supply voltage and using this information to adjust the gain and clipping levels of the audio signal. The control system forms a closed loop where the power supply state directly influences the signal processing parameters, allowing the system to respond to actual power availability and prevent distortion while maximizing output power capability.
2Power
If the gain is increased to maximize output power, then the full output power capability of the system is exploited, but the power supply may become overloaded and switch-off may occur
Solution Approach 1:
The system dynamically adjusts the gain based on the measured power supply voltage, allowing maximum gain when the power supply has sufficient energy reserve and reducing gain when the voltage indicates approaching overload conditions. This dynamic gain control enables the system to maximize output power capability while continuously adapting to prevent power supply overload and switch-off.
Solution Approach 2:
The patent applies preliminary action by proactively adjusting the gain and clipping levels based on the current power supply voltage before overload conditions occur. By monitoring the power supply state and preemptively reducing signal levels when voltage drops indicate approaching capacity limits, the system prevents overload and switch-off while maximizing power output during safe operating conditions.
3Reliability
If independent limiters are applied to each audio channel, then each channel is protected individually, but the multichannel advantage of a shared power supply is not obtained and power utilization is not optimized
Solution Approach 1:
The patent merges the protection function across all audio channels by using a single power supply voltage measurement to control the gain and clipping levels of all channels simultaneously. This unified approach allows the system to optimize power utilization across the entire multichannel system while maintaining protection, as the shared power supply state is reflected in the signal processing parameters for all channels, enabling efficient use of the common power resource.
Data Source
AI summary
A method for use in an audio system including a plurality of amplifier channels of corresponding audio channels. Each of the amplifier channels receives a respective input audio signal and is powered by a same power supply. The method comprises: obtaining a value of an indicator, wherein the indicator is representative of an energy reserve of the power supply; for each of the amplifier channels, determining a gain to be applied by an attenuation function to the respective input audio signal and a clipping level to be applied by a clipping function to the output of the attenuation function; wherein the gain decreases over time when the value of the indicator is below a threshold and the gain increases over time up to a maximum value when the value of the indicator is above the threshold, wherein the threshold is representative of a nominal energy level at which the power supply is in nominal operation; wherein the clipping level is determined as a monotonic function of the value the indicator.