A microphone capsule, also known as a mic head, mic element, or microphone, is an electroacoustic transducer that converts sound signals into electrical signals. It functions opposite to a speaker (which converts electrical signals into sound).
In a sound system, microphones serve as the input devices (for capturing sound), while speakers act as the output devices (for delivering sound).
Is There Polarity in a Microphone Capsule?
Yes, microphone capsules do have polarity. There are positive (+) and negative (–) terminals. So, how do we distinguish between them?
How to Identify the Positive and Negative Terminals?
Here are some common methods used in the industry (based on our 22 years of microphone manufacturing experience):
Visual Inspection of Solder Pads:
- The simplest way is to examine the two solder pads on the PCB of the mic capsule (see reference image below).
- (Insert image: "Mic positive-negative terminal solder pad reference")
- If a solder pad is isolated, it is usually the positive (+) terminal.
- If a solder pad is connected to the metal case or shell, it is the negative (–) terminal.
PCB Markings:
- Many microphone manufacturers print polarity marks directly on the capsule PCB (such as "+" and "–" symbols).
- (Insert image: "Polarity marking on microphone capsule")
Continuity Test with a Multimeter:
- Use a multimeter to test which terminal is connected to the capsule shell. The terminal that shows continuity with the shell is the negative (–) terminal.
How to Test Microphone Capsule Using a Multimeter
Electret condenser microphones are the most common type. Here's how to perform a basic test:
- Measure Resistance: Most ECMs have an internal resistance around 2kΩ. You can test it directly with a digital multimeter.
- When you blow air or tap the mic lightly, the resistance will change, indicating the capsule is working.
- Digital Multimeter Test: Connect the red probe to the positive terminal and black probe to the negative terminal (usually grounded). A typical reading is ~2kΩ. When you blow into the mic or tap it, the value should vary by at least 500Ω-greater change indicates better sensitivity.
- Analog Multimeter Test: Select the correct resistance range. Connect black probe to the negative and red probe to the positive. You will see similar behavior as in the digital test.
Note:
These basic tests can help you judge mic capsule sensitivity and working status. However, they cannot determine parameters such as distortion or noise level. For more advanced testing, specialized audio testing equipment is required.
Need Professional Testing or Customization?
Our microphone engineers can provide you with complete acoustic-electrical solutions and technical support. Feel free to contact us for customized mic capsule designs, testing, and consultation.
