High vs. Low Impedance: What Pilots Should Know
In aviation, not all audio systems are created equal. There are two main types: High-Impedance and Low-Impedance, and they don’t play nicely together without the right adapter. Knowing which system your aircraft uses can save you a lot of confusion on the ramp. These systems aren’t interchangeable, and understanding the difference can help you avoid frustration—and ensure your headset works exactly as it should.
High-Impedance: The Standard in Most Civilian Aircraft
High-impedance systems are the most common type in general aviation and commercial aircraft. If you're flying a Cessna, Piper, Beechcraft, or most airliners, you're almost certainly working with a high-impedance setup.
These systems typically operate in the 300–500 ohm range and provide a DC bias voltage needed to power the microphone. Our Harmony System is built to work exclusively with high-impedance systems, as that's what the vast majority of pilots are using.
If you’re using a low-impedance headset in a high-impedance aircraft, you can usually make it work by adding a simple passive adapter.
Low-Impedance: Found in Some Helicopters and Military Aircraft
Low-impedance systems operate at around 5 ohms and don’t supply the voltage needed to power high-impedance microphones. These are typically found in military aircraft and some civilian helicopters.
If you’re trying to use a high-impedance headset (like the Harmony System) in a low-impedance aircraft, you’ll need a powered adapter that supplies the microphone with the voltage it needs to function. These adapters often include a battery pack to do the job.
Not Sure What You Have? Neither Are We.
Here’s the tricky part: There’s no visual indicator on most panels that tells you whether you’re dealing with a high- or low-impedance system. And unfortunately, we can’t confirm it for you either. If you're unsure, we always recommend checking your aircraft documentation or contacting your avionics technician for guidance.
Some aircraft—especially in military or specialized helicopter operations—may have communication panels that support both impedance types, but that’s not common.
Final Thoughts
Understanding your aircraft’s impedance system is key to getting the most out of your headset. The Harmony System is designed to plug in and perform seamlessly in high-impedance environments, which covers the vast majority of pilots. But when you step into a less conventional aircraft, it's worth double-checking before you plug in.
Whether you're flying cross-country or just doing pattern work, clear audio starts with the right connection.