In the world of electret condenser microphones (ECMs), the internal amplifier component—typically either a JFET or a MOSFET—plays a vital role in shaping key performance characteristics such as signal-to-noise ratio (SNR), dynamic range, and stability.
Over the years, JFETs have been widely adopted for their simplicity, low noise, and resistance to static damage. MOSFETs, on the other hand, offer extremely high input impedance and excellent linearity in theory, but come with trade-offs in ESD sensitivity and manufacturing complexity.
Our Exploration of a MOSFET-Based ECM
We previously introduced Model AS-B2573UML-808, a 25mm-diameter ECM featuring a MOSFET amplifier. It was our first attempt at leveraging MOSFET advantages—particularly targeting high-SNR applications where clean signal pickup is essential.
The model performed well in specific test scenarios, offering:
- SNR: 80 dB (typical)
- Max SPL: 110 dB
- Sensitivity: -33 ±2 dB
- Wide operating voltage range: 1.0–10V
However, during extended use in actual product integration and feedback from manufacturers, several practical challenges emerged:
- ESD vulnerability during soldering and handling
- Less consistent batch-to-batch performance in varying humidity conditions
- Higher component cost and longer qualification cycles
- Additional static protection needed at the board level
Returning to JFET—But Stronger
Based on this experience, we redesigned the product with an optimized JFET-based architecture, resulting in the launch of Model AS-B2583UML32-23861.
Though it uses a JFET, this is not simply a step back—it’s a step forward in performance and reliability, with targeted improvements to meet high-end professional demands.
Key Features of AS-B2583UML32-23861:
- SNR: 83 dB (typical)
- Max SPL: 120 dB
- Sensitivity: -32 ±2 dB
- THD: ≤1%
- Operating Voltage: 1.0V – 10.0V
- Output Impedance: ≤2 kΩ
- Unidirectional pickup pattern
- Sturdy 25mm copper-nickel-zinc alloy housing for EMI shielding and acoustic stability
Application Scenarios for 25mm ECMs
Large-diameter ECMs like these are not designed for mobile or miniature electronics. Instead, they are optimized for:
- Conference system microphones
- Broadcast and interview equipment
- Lecterns and podium microphones
- Professional audio recorders
- Stage or suspended microphone arrays
- Industrial communication terminals
In these environments, long-term stability, rugged construction, and consistent acoustic performance are more important than theoretical peak specs.
JFET vs MOSFET: A Practical Summary
| Feature | JFET | MOSFET |
|---|---|---|
| Input impedance | High | Very high |
| Noise performance | Excellent | Potentially higher |
| ESD resistance | Good | Weak – needs protection |
| Batch consistency | Stable | Variable (depends on handling) |
| Manufacturing cost | Lower | Higher |
Performance Grounded in Experience
While MOSFET remains an interesting option for small-signal amplification, in real-world ECM applications—especially for large, professional-grade microphone elements—JFET continues to deliver superior overall value.
With AS-B2583UML32-23861, we’ve refined the design for modern audio demands without sacrificing robustness or long-term reliability.
Learn more about our new 25mm cardioid ECM model here: ECM-B2583UML32-23861 Product Page .
Contact us to request samples, technical drawings, or explore OEM/ODM cooperation.
