Passive Polyphonic Double-Coil Microphone for String Instruments
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Solution Overview
Problem
Conventional single and humbucking magnetic pickups fail to accurately capture polyphonic tones, especially in instruments with distortion, as they produce a diffuse sound and are unable to separate the sounds of each string effectively, leading to noise when multiple strings are played.
Innovation Solution
A passive polyphonic humbucker microphone design featuring pairs of coils electrically and magnetically connected, with internal and external dipole magnets, and magnetic shields to isolate the magnetic fields of each coil pair, allowing each string's vibration to be detected independently without influencing adjacent pairs, enabling clear separation of polyphonic tones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single or humbucking pickups are used, then the output signal level is sufficient, but the sounds of multiple strings cannot be separated effectively, producing diffuse sound and noise in polyphonic tones
Solution Approach 1:
The pickup is divided into multiple pairs of coils, with each pair dedicated to detecting vibrations of a specific string. This segmentation allows each string's signal to be captured independently, enabling effective separation of polyphonic tones and eliminating the diffuse sound problem of conventional pickups
Solution Approach 2:
Each coil pair is configured with specific magnetic polarity and spatial orientation tailored to its corresponding string's position and vibration characteristics. This local optimization ensures that each coil pair selectively detects its target string's vibrations while minimizing interference from adjacent strings, thereby reducing noise in polyphonic playback
2Reliability
If distortion effect is applied to enhance sustain and crunch, then the natural sound is replaced, but polyphonic chords with three or more strings produce unusable noise
Solution Approach 1:
By segmenting the pickup into multiple independent coil pairs, each handling a specific string, the system maintains clear separation of individual string signals even under distortion. This prevents the signal overlap that causes noise in conventional pickups when playing distorted chords with three or more strings
Solution Approach 2:
The magnetic shields act as intermediaries that channel and contain the magnetic flux between corresponding coil pairs and strings. This mediation ensures that magnetic field interactions remain localized and controlled, preventing cross-interference between adjacent strings during distorted polyphonic playback
3Object-generated harmful factors
If humbucking configuration with two coils in series is used, then bass and midrange sound are enriched, but external electromagnetic disturbances are cancelled, and polyphonic separation is lost
Solution Approach 1:
The humbucking configuration is segmented into multiple independent coil pairs rather than using a single merged humbucker assembly. Each pair maintains the series connection and inverted polarity for noise rejection, while the spatial separation and individual optimization of each pair enable polyphonic tone separation
Solution Approach 2:
Within each coil pair, the two coils are merged in series connection with inverted magnetic polarity to achieve electromagnetic disturbance rejection. This merging preserves the noise-cancelling benefit of humbucking while the overall segmentation into multiple pairs maintains polyphonic separation capability
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
The design allows for clear and distinct amplification of each string's tone, even in chords with multiple strings, maintaining the natural sound and preserving harmonics, while enabling the use of distortion without noise interference.
Implementation Method 1
When a metal string vibrates near the microphone, the variation in the magnetic field creates an induced current, of the same frequency as the vibrating string
Implementation Method 2
a set of magnetic shields, integral with the support, each coil being surrounded by a respective magnetic shield
Implementation Method 3
an assembly of at least one internal dipole magnet, one pole of which is in magnetic connection with the core of one coil of a pair of coils and the other pole is in magnetic connection with the core of the other coil of said pair
Data Source
Figure 1~5
AI summary
The invention relates to a passive polyphonic double-coil microphone (10) for a string musical instrument (13), including: a substrate (11); and a set of pairs of coils, wherein, for each pair of coils, the two coils are electrically mounted in series and magnetically coupled (LC) together. The microphone according to the invention is essentially characterized in that it further includes: a unit consisting of at least one internal dipole magnet (40), the poles of which are magnetically coupled to the respective core of a coil from a pair of coils; a set of magnetic shields that are rigidly connected to the substrate (11), wherein each coil is surrounded by a respective magnetic shield, and wherein, for each pair of coils, one of the coils is connected to the ground, and the other is provided to carry an output signal to an amplifier.