What is Phantom Power?
Introduction
Phantom power—sounds a bit spooky, right? If you’re new to home recording, this term can seem confusing. But don’t worry, we’re here to help. Phantom power was actually first used in copper wire-based landline telephone systems, starting with the rotary-dial phone back in 1919.
The first widely available phantom-powered microphone was the Schoeps model CMT 20, which was released in 1964. It’s called phantom power because it sends electricity through the same cable that carries the audio signal.
So, let’s take a closer look at what phantom power is, how to use it, and how it can affect your studio setup.
What is it and how does it work?
If you’ve ever used condenser microphones in your home recording studio, you probably already know how important phantom power is. While a few condenser mics can be powered by other methods, almost all studio models rely on phantom power.
Phantom power is a way of supplying DC voltage through a balanced audio connector to power a condenser microphone. To use phantom power, you’ll need a phantom power supply to provide the correct voltage, along with a balanced XLR connector to deliver that power to your mic.
There are two things you need for phantom power: a phantom power supply and an XLR connector. Condenser microphones use active circuitry, which requires the right amount of power to operate. Plugging your condenser mic directly into an electrical outlet will destroy the microphone’s delicate circuitry and could even trip your electrical service panel.
That’s why you should always use a dedicated phantom power supply for your condenser microphone. Although “phantom power supply” might sound complicated, it’s really just like any other power supply. It includes a transformer, a rectifier, and filters. The term “phantom” is used because the power is invisible—it travels along the same cable that carries the audio signal.
Phantom Power Sources
Phantom power can come from a variety of devices. Choosing the right one that fits your content creation needs is an important decision. Here are three of the most common devices that can supply phantom power:
Audio Mixer
Audio mixers accept microphone or instrument inputs and send audio signals out via USB. They feature pre-amps, various audio controls, and often include built-in effects for live mixing. A mixer is a great choice if you plan to go busking, stream, or perform live in any situation where you need to process audio on the spot.
Audio Interface
Audio interfaces also accept microphone or instrument inputs and output the audio through USB. With simple controls like a gain knob and a phantom power button, these devices are designed for straightforward audio recording. An audio interface is ideal if you’re doing podcasts, voice-overs, home studio recordings, or any project where you’ll edit or process the audio afterward.
Phantom Power Adaptors
These devices have a single purpose: to provide phantom power to your microphone. Usually available in single or dual-channel versions, adaptors don’t have extra features or controls. This makes them affordable, compact, and easy to use. They’re perfect for anyone who just needs to power a condenser microphone and nothing else.
How Does It Work With Microphones?
Before we dive into the topic of phantom power, let’s talk about a few common types of microphones. The dynamic microphone is probably the most widely used. A dynamic microphone doesn’t need any kind of external power to operate. Another popular type of microphone is the condenser microphone.
A condenser microphone requires external DC power to work. Depending on how the microphone is designed, this power can come from a battery, bus power from a computer, or several other sources. However, the most common method is through phantom power. For phantom power to work, you must use a balanced microphone cable.
A balanced mic cable has three conductors: Pin 1 is ground, Pin 2 is audio positive, and Pin 3 is audio negative. Most microphones produce a positive voltage on Pin 2 when sound hits the diaphragm. It’s important to remember that each condenser microphone has its own power needs, and each audio input device supplies different amounts of phantom power.
You’ll need to check your device’s manual to see if it supports phantom power. On most devices, you can turn phantom power on or off with a switch, button, or software setting. You might see it labeled as “+48V” instead of “phantom power.”
Why do we need Phantom Power?
Determining whether your microphone needs phantom power is important to make sure you’re using it correctly and getting the best possible performance. If you want to learn more about phantom power and how to figure out if your mic requires it, keep reading.
Phantom power is mainly used with condenser microphones because they need electricity to convert vibrations in the air into audio signals. In the past, these microphones relied on large external power supplies to provide current for their electronics.
When FET transistors replaced vacuum tubes in audio equipment, microphones no longer needed high-voltage power supplies. Instead, engineers designed a way for the audio console itself to deliver the necessary electricity. If you’re running live sound, you probably won’t notice much of a difference if phantom power is switched on for a dynamic mic.
However, if you’re recording, you might pick up some extra hum if phantom power is on. It’s best to turn off phantom power before plugging in or unplugging a microphone. The loud pop that occurs when you do either of these things can damage your equipment—not just the microphones, but possibly your speakers as well.
Damaging Equipment by Phantom Power
Yes, phantom power can damage equipment. While dynamic microphones are unlikely to be harmed, sending phantom power to a ribbon microphone can cause permanent damage. It’s always recommended to turn off phantom power before connecting other gear, like line-in devices and monitors.
A studio setup includes microphones, outboard equipment, audio systems, instruments, and cables—all of which have different internal components and circuitry. Another type of device that can be damaged by phantom power is line-in instruments.
Line-level gear, such as keyboards, guitars, or other electronic instruments that don’t require external power to be recorded, can be at risk. Using line-level devices with phantom power turned on can fry their output electronics. The longer a preamp or line-level device is plugged into an interface that’s sending phantom power, the greater the risk of damage.
In some cases, phantom power can also harm devices with unbalanced outputs. If you’ve ever turned on phantom power while your studio monitors are active, you’ve probably heard a sharp pop sent through the audio system.
Although this “popping” sound is unlikely to cause noticeable damage to your monitors, it certainly doesn’t do them any favors. It’s the sound of a power surge being sent through the interface and out to the monitors. It’s best to make sure your monitors are turned off before activating phantom power, or at least turn their volume down so the pop isn’t sent through the system.
Conclusion
In conclusion, phantom power is a type of electrical supply used to power active digital devices. Condenser microphones need phantom power to work, while dynamic microphones do not. If you’re using a condenser microphone, make sure that phantom power is turned on for the device you’re using.
Phantom power has made life much easier for sound engineers, artists, record producers, and many other music professionals. In the past, recording low frequencies on certain instruments and vocals was nearly impossible, but thanks to this technology, it’s something most people can now do at home.
