Phantom power is extremely useful for powering condenser microphones, but will it damage a guitar? If you have a global phantom power switch on your audio interface or mixer, is it possible to connect both microphones and guitar simultaneously without damaging the guitar?

Here’s a short and concise answer:

Phantom power cannot damage a guitar, given that you’re using a 1/4″ TS guitar cable. Most audio interfaces with combo jacks will only supply phantom power to XLR cables, which means guitars will not get phantom power at all. Furthermore, if you’re using a DI box for your guitar, the DI box will block phantom power to anything connected to its input. In other words, your guitar is safe.

Additionally, here’s a free tool to help you determine if your guitar may get damaged by phantom power:

Now it’s time to take a deeper dive into the topic! Let’s look at how phantom power can damage a guitar and what we can do to prevent it.

Can phantom power damage a guitar?

Audio interface design

The first reason why phantom power cannot damage a guitar is the way an audio interface is designed. A modern audio interface or mixer is designed with recording multiple inputs simultaneously in mind. This means that they have prepared countermeasures for situations where you plug in a guitar when phantom power is engaged.

Most audio interfaces and mixers only supply phantom power down an XLR connection. That includes combo jacks, which is an input that accepts both XLR and 1/4″ connectors. When an XLR cable is plugged in, it will provide phantom power (+48V) to power the microphones, but when you use a 1/4″ TS guitar cable, it won’t supply the electricity.

This makes it extremely convenient and safe for the user. You don’t have to worry about your guitar getting damaged by phantom power, because the audio interface or mixer won’t supply the phantom power in the first place.

However, this is only true if you follow the standard practices of using a 1/4″ TS guitar cable to connect your acoustic-electric or electric guitar. If you’re currently using an XLR cable to connect your guitar (which you shouldn’t), you should switch to using the standard 1/4″ TS guitar cable immediately.

Difference between XLR and 1/4″ TS guitar cable

If you’re a beginner, you may not know the difference between using an XLR cable and a standard 1/4″ guitar cable. But knowing the difference is crucial, and will benefit you greatly down the line.

The main difference is an XLR cable is a balanced cable while a 1/4″ TS guitar cable is an unbalanced cable. This means that an XLR cable is designed in such a way that it has the ability to eliminate electronic interference introduced during the transmission.

Electronic interference is a kind of noise added to the audio signal by surrounding electronic devices. The longer the cable, the more interference you may get.

This is the main reason why you will see most professional microphones use XLR cables. Because mic signals are small and electronic interference can really ruin the audio quality, it is essential that microphones use XLR cables.

For guitars, however, using an unbalanced 1/4″ TS guitar cable is perfectly fine most of the time. This is because guitar signals are loud enough that even if a bit of electronic interference is introduced, it will not affect the audio signal much. The distance from the guitar to an amp or DI box is usually pretty short, and also helps to minimize the amount of electronic interference.

Now, after understanding the difference between a balanced XLR cable and an unbalanced guitar cable, here’s an important concept to understand:

Phantom power will only work properly with balanced cables!

That right, with an unbalanced cable, the 48 volts of the phantom power have a high chance of damaging your gear, including microphones and guitars. That’s why most modern audio interfaces and mixers will only supply phantom power when a balanced cable is plugged in.

DI Box protection

As a safety measure, DI boxes will not pass phantom power to gears connected to their input. Similar to audio interface and mixer designers, DI boxes are also designed to prevent your gear from getting damaged by phantom power.

Hence, if you connect your guitar to a DI box, and that DI box is connected to an audio interface or mixer with phantom power engaged, rest assured, your guitar is perfectly safe.

Why do you get a loud “pop” when plugging in the guitar?

If you have phantom power engaged while plugging in your guitar, you may get a loud “pop”. It may give you a scare, but don’t worry, it will not damage your guitar. However, as you probably know by now, that’s not a good way to do things.

To avoid the loud burst of noise, there are 2 ways:

• Turn off phantom power when plugging in or unplugging your guitar.
• Turn down the volume fader when plugging in or unplugging your guitar.

If possible, I personally would recommend turning off the phantom power. But that is sometimes not possible, in the case where you only have a global phantom power switch on the audio interface or mixer. In that case, turn down the volume fader, so that you don’t get the loud noise.

What gear can be damaged by phantom power?

Most modern gears are designed to detect and reject phantom power if they do not require it. This includes dynamic microphones using XLR cables, and different kinds of instruments using unbalanced 1/4″ cables to connect to your audio interface or mixer.

However, if you have a vintage ribbon microphone, you need to be extremely careful. Even though most modern ribbon microphones are protected from phantom power if they don’t need it, a vintage ribbon microphone that has a center-tapped output transformer may get damaged!

If you do happen to have vintage ribbon microphones, here are the 2 recommended ways to go about it:

• Do not use a vintage ribbon microphone in a recording studio that uses phantom power.
• Modify the vintage ribbon microphone so that it is protected from phantom power.

The reason for the above choices is that vintage ribbon microphones can get damaged very easily if phantom power is supplied to them, and they too use XLR cables. Even if you do remember it, someone else using your studio may accidentally plug the expensive vintage ribbon microphone into your audio interface with phantom power engaged. So be aware of that before it’s too late.