Audio Transducer Field Coil Control for Low-Volume Overtones
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Solution Overview
Problem
Musicians face the challenge of preserving the desired overtones produced by overdriving amplifiers while adjusting the volume to lower levels, as existing technologies either sacrifice these overtones or fail to accurately replicate the distortions created by an overdriven amplifier.
Innovation Solution
A system and method that modulates the sound pressure output from an audio transducer by using a user-adjustable power supply to control the voltage across a separate field coil, allowing for adjustable magnetic field generation and thus volume adjustment without affecting the tonal quality of the audio signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the amplifier is overdriven to produce overtones, then the tonal quality with desired overtones is improved, but the sound pressure level becomes too loud for small venues
Solution Approach 1:
The transducer is divided into two independent coils: a voice coil for receiving audio signals and a field coil for generating adjustable magnetic fields. This segmentation allows independent control of tonal quality (via voice coil) and volume (via field coil), resolving the contradiction between maintaining overtones and reducing sound pressure level.
Solution Approach 2:
The magnetic field strength from the field coil is made dynamically adjustable through a user-controlled power supply, allowing the system to adapt the sound pressure level while preserving the tonal characteristics generated by the voice coil, thus enabling volume control without sacrificing overtones.
2Power
If commercial devices are used to simulate overtones, then the volume can be reduced, but the quality of overtones is not the same as naturally produced overtones
Solution Approach 1:
Instead of adding external simulation devices that compromise tone quality, the invention extracts the volume control function from the signal path and places it in the magnetic field generation system. The field coil's adjustable magnetic field allows volume reduction while the voice coil continues to reproduce the original audio signal with its naturally produced overtones intact.
3Ease of operation
If a preamplifier stage is used to distort heavily, then volume can be controlled, but only class A-type distortion is introduced and overdriven output stage distortions are lost
Solution Approach 1:
The adjustable magnetic field from the field coil acts as an intermediary mechanism for volume control, replacing the need for preamplifier distortion. This allows the output stage to remain in its linear operating region while still achieving volume control, thereby preserving the desired overdriven output stage distortions that would otherwise be lost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the retention of overtones at lower volumes, providing a range of sound pressure levels up to 25 dB variation without compromising the spectral content of the audio signal, effectively addressing the limitations of existing technologies.
Implementation Method 1
applying a voltage across a field coil of the transducer that is separate from the voice coil... adjusting the voltage that is applied across the field coil so as to modulate the sound pressure output from the audio transducer
Implementation Method 2
placing the audio signal across a voice coil of the transducer
Data Source
AI summary
A system and method for modulating the sound pressure that is output from an audio transducer is disclosed. In one embodiment, the method includes receiving an audio signal and placing the audio signal across a voice coil of the transducer. In addition, a voltage is applied across a field coil of the transducer, the field coil being separate from the voice coil. And the voltage that is applied across the field coil is adjusted so as to modulate the sound pressure output from the audio transducer.