Condenser Microphone Shielded Cord Grounding
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Solution Overview
Problem
Condenser microphones connected via a microphone cord are vulnerable to electromagnetic interference from cellular phones, leading to noise issues and potential electrical shocks due to inadequate shielding and grounding configurations.
Innovation Solution
A twin-core shielded microphone cord connects the microphone capsule and output module section, with the shield wire connected to the output module's shield case and circuit board via a high-frequency choke coil, preventing electromagnetic waves from entering the circuit board and ensuring safe grounding even with a phantom power source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the shield covered wire is directly connected to the ground circuit of the circuit board, then electromagnetic shielding is improved, but electrical shock risk increases due to phantom power source voltage
Solution Approach 1:
A high-frequency choke coil is introduced as an intermediary component between the shield covered wire and the ground circuit. This choke coil has low impedance at low frequencies (allowing DC grounding) but high impedance at high frequencies (blocking electromagnetic interference). This mediator resolves the contradiction by enabling both safe electrical grounding and effective electromagnetic shielding without direct connection.
2Object-affected harmful factors
If the shield case is directly connected to ground via first grounding pin, then electromagnetic shielding is improved, but loop current path is formed causing noise
Solution Approach 1:
The high-frequency choke coil serves as an intermediary that breaks the loop current path while maintaining grounding functionality. The choke coil's high impedance at high frequencies prevents loop currents from forming through the shield case and ground connection, thereby eliminating noise while preserving electromagnetic shielding effectiveness.
3Reliability
If grounding connection is made through first grounding pin to phantom power source, then electrical shock prevention is improved, but electromagnetic shielding effectiveness is reduced
Solution Approach 1:
The high-frequency choke coil acts as a frequency-selective intermediary that presents low impedance to DC currents (enabling safe grounding of the phantom power source) while presenting high impedance to high-frequency electromagnetic interference signals. This dual characteristic resolves the contradiction by simultaneously ensuring electrical safety and maintaining electromagnetic shielding effectiveness.
Data Source
AI summary
In a condenser microphone where a microphone capsule and an output module section are connected to each other via a microphone cord, strong electromagnetic waves generated from a cellular phone or the like are positively prevented from entering the output module section through the microphone cord. The condenser microphone in which a microphone capsule 10 and an output module section 20 are connected to each other via a microphone cord 30 composed of a twin-core shield covered wire, the microphone capsule 10 including a condenser microphone unit 12 and an impedance converter 13, the output module section 20 storing, in a shield case 21, a circuit board 22 including a voice output circuit, wherein a shield covered wire 33 of the microphone cord 30 is connected to the shield case 21, and the shield covered wire 33 is also connected to a ground circuit of the circuit board 22 via a high-frequency choke coil 51.