Should you switch phantom power off if it isn't needed?

David Mellor

David Mellor is CEO and Course Director of Audio Masterclass. David has designed courses in audio education and training since 1986 and is the publisher and principal writer of Record-Producer.com.

Monday September 23, 2019
FREE EBOOK DOWNLOAD ►

When phantom power was first invented, it was designed so that any mic that didn't need it wouldn't be affected by it. So why do we now worry about switching it off?

Here's a quote from the user guide for the Focusrite Forte audio interface...

If you are using a capacitor (condenser) microphone, click the 48V button to supply phantom power to the mic. Don't turn this on if you're using any other type of mic.

I suspect the reason for saying 'don't turn this on...' is that a user might have an overly-delicate microphone that doesn't require phantom power. Because of the microphone's inadequate design it is damaged, then the user wrongly blames Focusrite! So if Focusrite tells users to switch the phantom power off, then their complaints department can sleep soundly at night. (Although I can't imagine Focusrite gets enough complaints to warrant having a whole department for them!)

Go back a few years when microphones were built for professional studios, broadcast and live sound. They found their way into home studios too. But mics had to be professional in sound quality and also design and build quality, otherwise they simply wouldn't do their job.

It would be standard practice therefore to leave phantom power switched on all the time. Capacitor mics would use it. Other mics would ignore it. Mixing consoles would be designed such that phantom power was all-on or all-off. And everything worked fine!

Ribbon microphones are delicate flowers

Where we come into problems with phantom power is with ribbon microphones. Ribbon microphones come from an era of audio even before phantom power was invented. But they have had a resurgence in popularity of late because they have an interesting sound quality. They are however quite delicate.

A well-designed ribbon microphone shouldn't care about phantom power any more than a normal dynamic mic. However, any condition that puts 48 volts across the ribbon will blow the mic, or potentially severely damage it.

This is very unlikely to happen when mics are connected with XLR cables, unless there is a damaged or incorrectly-wired cable. It is much more of a risk where a mic is connected through a patchbay, but this is less commonly done in home recording studios than in professional studios.

There is a useful guide to this problem at Royer Labs' website. It says clearly that, "Royer ribbon microphones are not usually affected by the presence of phantom power." However they go on to give good reasons why you should take care.

In practice

In practice, if microphones are properly designed then there should be no difficulty with phantom power. In fact I would go so far as to say that, in this day and age, if a microphone had a problem with phantom power, then it shouldn't be considered adequate for professional use.

But to a certain extent it is inevitable that we have to accept things as they are, so I propose three alternative courses of action...

1. Only use microphones that are OK with phantom power, and simply leave it on all of the time, like they do in broadcast studios.

2. Make it your habit to switch phantom power on for capacitor microphones that need it, and switch it off immediately after use.

3. Avoid ribbon mics. But that would mean denying yourself their special tone colour. As an alternative, you might consider buying a dedicated ribbon mic preamp.

Like, follow, and comment on this article at Facebook, Twitter, Reddit, Instagram or the social network of your choice.

Come on the Audio Masterclass Pro Home Studio MiniCourse - 60 great hints and tips to get your home recording studio MOVING

It's FREE!

Get It Now >>

An interesting microphone setup for violinist Nigel Kennedy

Are you compressing too much? Here's how to tell...

If setting the gain correctly is so important, why don't mic preamplifiers have meters?

The Internet goes analogue!

How to choose an audio interface

Audio left-right test. Does it matter?

Electric guitar - compress before the amp, or after?

What is comb filtering? What does it sound like?

NEW: Audio crossfades come to Final Cut Pro X 10.4.9!

What is the difference between EQ and filters? *With Audio*

What difference will a preamp make to your recording?

Watch our video on linear phase filters and frequency response with the FabFilter Pro Q 2

Read our post on linear phase filters and frequency response with the Fabfilter Pro Q 2

Harmonic distortion with the Soundtoys Decapitator

What's the best height for studio monitors? Answer - Not too low!

What is the Red Book standard? Do I need to use it? Why?

Will floating point change the way we record?

Mixing: What is the 'Pedalboard Exception'?

The difference between mic level and line level

The problem with parallel compression that you didn't know you had. What it sounds like and how to fix it.

Compressing a snare drum to even out the level

What does parallel compression on vocals sound like?

How to automate tracks that have parallel compression

Why mono is better than stereo for recording vocals and dialogue