Field-Coil Audio Transducer Volume Control Without Tone Loss
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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 solutions either sacrifice these overtones or introduce inferior distortions.
Innovation Solution
A system and method that modulates 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 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 system is segmented into two independent coil systems: a voice coil for generating sound pressure and a field coil for generating the magnetic field. This segmentation allows independent control of sound pressure level and magnetic field strength, enabling tone preservation at reduced volumes.
Solution Approach 2:
The magnetic field strength is made dynamically adjustable through the field coil, which can be independently controlled via a separate power supply. This dynamic adjustment allows the system to maintain optimal magnetic field conditions for tone generation while operating at lower sound pressure levels.
2Stress or pressure
If the volume is reduced to lower levels, then the sound pressure level becomes suitable for small venues, but the overtones are lost
Solution Approach 1:
By separating the voice coil and field coil functions, the system can independently adjust sound pressure level without affecting the magnetic field strength that generates overtones. This allows tone quality to be preserved even when overall volume is reduced.
Solution Approach 2:
The system changes the operating parameters by decoupling the control of sound pressure level from magnetic field strength. The field coil maintains optimal magnetic field parameters for tone generation while the voice coil operates at reduced amplitude for lower volume output.
3Ease of operation
If a preamplifier stage is used to generate distortion, then the distortion can be controlled, but only class A-type distortion is produced and the overdriven output stage distortion is lost
Solution Approach 1:
The distortion-generating function is extracted from the preamplifier stage and relocated to the output stage. The field coil system directly generates the desired overdriven output stage distortion characteristics at the point of power amplification, preserving the authentic distortion type.
4Manufacturing precision
If tube amplifier inherent distortions are maintained, then the natural tube character is preserved, but the ability to control sound pressure level independently is limited
Solution Approach 1:
The independent field coil system segments the volume control function from the tone generation function. This allows the tube amplifier to maintain its natural distortion character while the field coil provides versatile volume control across a broad range without affecting the inherent tube distortions.
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 25 dB range of sound pressure level variation while maintaining the integrity of the audio signal's spectral content.
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
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.