? SMD Magnetic Buzzer Selection Guide: Top Sound vs. Side Sound & Center Hole vs. Offset Hole
When designing compact electronic devices, the buzzer's acoustic path and hole placement directly impact sound quality, assembly feasibility, and user experience. This guide breaks down four key structural variants and showcases real product specs to help engineers make informed decisions.
⚡ Top Sound vs. Side Sound — Acoustic Path & Design Impact
| Dimension | Top Sound | Side Sound |
|---|---|---|
| Sound Direction | Perpendicular to PCB, upward through housing | Parallel to PCB, radiates from device side |
| Housing Requirement | Must reserve sound window on top surface | Side opening sufficient; top can remain sealed |
| PCB Cutout | Usually no special PCB cutout needed | Requires precise side cutout (deviation >0.3mm causes >5dB SPL loss) |
| SPL Attenuation | Higher attenuation through housing | ~4.2dB lower attenuation (measured, advantage in slim devices) |
| Thickness Limit | Suitable for devices with adequate height | Ideal for ultra-slim designs (e.g., 0.8mm PCB + 0.5mm cutout) |
Center Hole vs. Offset Hole — Layout Flexibility
| Dimension | Center Hole | Offset Hole |
|---|---|---|
| Hole Position | At geometric center, symmetric structure | Off-center, asymmetric structure |
| PCB Layout | Center-occupied; symmetric trace routing required | Flexible positioning to clear cameras, sensors, tall components |
| Sound Directivity | Uniform sound field, no directional bias | Slight directional bias; negligible for alert tones |
| Typical Use | General-purpose, no special clearance needs | Drone camera modules, compact wearables, multi-sensor devices |
Product Parameter Comparison
| No. | Parameter | MLT-4020H Top Sound |
MLT-9032-16R Side Sound |
MLT-5020H Center Hole |
MLT-5020 Offset Hole |
|---|---|---|---|---|---|
| 1 | Rated Voltage | 3.0V | 3.6V | 3.0V | 3.0V |
| 2 | Operating Voltage | 2~4V | 2.5~4.5V | 2~4V | 2~4V |
| 3 | SPL @ 10cm | ≥65dB | ≥80dB | ≥80dB | ≥80dB |
| 4 | Operating Current | ≤80mA | ≤100mA | ≤100mA | ≤100mA |
| 5 | Resonant Frequency | 4000±300Hz | 2700±300Hz | 4000±300Hz | 4000±300Hz |
| 6 | Coil Resistance | 12±3Ω | 16±3Ω | 12±3Ω | 12±3Ω |
| 7 | Storage Temp. | -30~+80℃ | -40~+85℃ | -30~+80℃ | -30~+80℃ |
| 8 | Dimension | 4.0×4.0×H2.0mm | 9.0×9.0×H3.2mm | 5.0×5.0×H2.0mm | 5.0×5.0×H2.0mm |
Key Takeaways
- Acoustic path first: Top sound for direct outward projection; side sound for sealed or slim housings.
- Hole position matters: Center hole for symmetric, clean layouts; offset hole when center space is contested.
- Size vs. SPL trade-off: The 4×4mm MLT-4020H sacrifices ~15dB SPL for extreme miniaturization — ideal for space-constrained designs where moderate alert volume suffices.
- Temperature resilience: MLT-9032-16R stands out with -40~+85℃ storage range, making it the go-to for harsh environments.