Music Amplifier Clipping Control Using Current-Based Threshold Shaping

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Solution Overview

Problem

Existing electronic musical instruments face issues with speaker protection, as high-level attack sounds can cause distortion and potential permanent damage due to clipping, which existing technologies fail to address effectively.

Innovation Solution

A dynamic clip value control mechanism is implemented using a sound source LSI to adjust the clip value based on current consumption, gradually decreasing or increasing the clip threshold according to predefined tables, thereby preventing distortion and protecting the speaker.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If clipping is applied to protect the speaker, then speaker protection is improved, but sound quality deteriorates due to distortion

Engineering Contradiction:
Improvespeaker protectionVSAvoidsound distortion
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent implements dynamic clip value adjustment where the clipping threshold is not fixed but changes over time based on the speaker's current consumption state. The clip value is gradually increased from an initial low value to a final high value, allowing the system to adaptively balance protection needs with sound quality preservation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the clipping parameter (clip value) dynamically during operation. By transitioning the clip value from an initial state to a final state based on current consumption thresholds, the system optimizes the balance between speaker protection and maintaining audio fidelity.

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If high-level attack sounds are allowed, then sound quality is improved, but speaker damage risk increases

Engineering Contradiction:
Improvesound qualityVSAvoidspeaker damage risk
Core Design Contradiction:
Object-generated harmful factorsVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary clipping action with an initial low clip value that gradually increases. This preliminary dynamic clipping prevents peak distortion while allowing the speaker to handle high-level attack sounds safely by controlling the clip value evolution over time rather than applying immediate full clipping.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses feedback from current consumption monitoring to dynamically adjust the clip value. The system continuously monitors speaker current consumption and adjusts the clipping threshold accordingly, creating a closed-loop control that balances sound quality and speaker protection in real-time.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4290508B1Clipping control for music amplifier
Publication Date: 2025.12.10 CASIO COMPUTER CO LTD
  • EP4290508B1 patent drawingFigure 1
  • EP4290508B1 patent drawingFigure 2A~2B
  • EP4290508B1 patent drawingFigure 3A

AI summary

An electronic device includes: an amplifier configured to amplify an input signal and output an output signal obtained by shaping the amplified input signal; and at least one processor. The at least one processor is configured to: obtain a value indicating power supplied to the amplifier, control the amplifier in a first pattern such that a clip value for the output signal decreases, when detecting that the value is larger than a reference potential and that the value becomes larger than a first threshold larger than a second threshold from a state of being smaller than the second threshold; and control the amplifier in a second pattern such that the clip value for the output signal increases, when detecting that the value is larger than the reference potential and that the value becomes smaller than the second threshold from a state of being larger than the first threshold.