What is impedance in audio? Are you confused about all the different terminology you’re stumbling across as you expand your audio knowledge? It can be frustrating to finally learn what something means, but then there are different levels, different types, and each one has its own set of rules.
Take impedance, for example; there’s measured, input, output, balanced, matched, and terminating. It’s enough to make you want to close the browser window and stop reading. We get it.
That’s why we’ve taken the things you need to learn and broken them down into straightforward, easy to understand explanations, no more frustration, no more getting lost. Follow along, and let’s learn about impedance today.
What is Impedance in Audio?
Before answering what is impedance in audio, you need to understand that an audio signal is a form of alternating current (AC). When dealing with analog sound equipment, the audio signal that goes in or out of the system is a level of AC voltage and current.
In audio devices, impedance is the measure of the resistance of a circuit to alternating current (audio signal). It’s measured in Ohms.
The “Z” symbol represents impedance. All audio equipment that receives an input and has an output will have impedance measurements, namely input, and output impedances. More on that later.
Impedance When Connecting Audio Devices Such as Mixers and Microphones.
When electric current travels through a conductor from one device to another, you would want to have a higher impedance at the input and a low impedance at the output.
For instance, if you connect a microphone to a mixer, your microphone has an impedance of less than 200 Ohms. The input impedance of the XLR balanced connector of a mixer or preamp is between 1500 – 3000 Ohms. This ensures an excellent current flow between the two devices.
Impedance When Connecting Speakers and Amplifiers
When you buy audio equipment, you’ll sometimes notice that the equipment, such as speakers and amplifiers, have an impedance rating measured in Ohms. What this is telling you is the resistance that the speaker presents to the amplifier.
A lower speaker impedance means that there will be more power flowing from the amplifier. In contrast, a higher impedance speaker will have less power flowing from the amplifier. Mismatching the impedance between amplifiers and speakers can result in damages to the equipment. This is why correctly matching speakers and amplifiers is so important.
What is Input Impedance?
If your equipment receives an audio signal, it has input impedance. It recognizes the signal coming from the other piece of equipment. Where connected, it “sees” the output impedance from the other device. As the signal passes from one place to another, it’s called a load (load impedance).
What is Output Impedance?
If your equipment outputs an audio signal, it has an output impedance. When it sends a signal to the input impedance of the other device, the goal is for it to be balanced. You’ll also hear this referred to as equal or matched impedance.
Here’s an important piece of info, based on the distances that the signal has to travel. If there is a long distance for the sound to travel, you’ll want to be sure that your cables also match the impedance of the equipment.
What is Impedance Matching in Audio?
Impedance matching in audio equipment means that the output impedance from one device must be the same as the input impedance of the device that is connecting to. This ensures a good signal transfer between devices.
Think of kids on a playground. When everybody gets along, things run smoothly. It’s the same thing when you’re trying to work with audio. When everything works together, life is easier.
Back in the day when audio equipment had vacuum tubes, impedance matching was crucial to ensure a good signal transfer between the different audio devices, especially in long cable runs. But in modern audio equipment, this is not a problem.
Is It Necessary to Match Impedances in Audio Systems?
Impedance matching has gotten easier over the years as audio equipment has advanced, and new components became available. Years prior, the way you needed to match equipment was different. The equipment itself was more sensitive to how things were connected. The industry has uncomplicated matters, which we’re all grateful for as you’re getting started.
The way your audio used to be hooked up, there was more power-driven to all the audio pieces, and impedance mismatched caused problems. Today, input impedances are higher, thanks to solid-state devices like integrated circuits and transistors.
With modern audio devices having a high enough input impedance, matching isn’t as critical as it used to be.
Takeaways:
When it comes to impedance, the important thing to remember is that it measures the resistance of a circuit to the incoming signal. Your input receives the signal, while your output feeds the signal. Impedance “Z” is measured in ohms.
It’s also important that your input impedance is high, and the output impedance is low when connecting audio devices such as mixers, effect, microphones, instruments, etc. Today’s equipment makes it easier than in the past thanks to solid-state devices.