How To Turn On Phantom Power

Except for the Aztec tube microphone*, every Roswell condenser mic requires "phantom power." This page shows how to turn on phantom power for popular audio interfaces.

What is Phantom Power?

Condenser microphones require external power to operate. Most microphone preamps, including the preamps built in to audio interfaces, can supply 48V to each microphone input. This power supply system is built in to practically every mic preamp on the market. It is called "phantom power."

Most audio interfaces have a single button for phantom power, whether they have one microphone input or many. That is, the phantom power supply is typically ON or OFF for every mic input on the device. Some higher-end preamp/interfaces provide individual control of phantom power for each mic input.

For some devices, phantom power can be engaged via the interface device driver on the host computer, or via the DAW. In most cases, it is easier to find the button on the hardware. The button could be labelled "Phantom Power," "48V," "+48," or anything similar. 

How To Enable Phantom Power On Popular Audio Interfaces

This table shows the location of the Phantom Power button for popular audio interfaces from Focusrite, Presonus, Mackie, UAD (Universal Audio), M-Audio, Audient, RME, and MOTU.

Brand	Model	Photo
Antelope	Zenith 2 The Zenith 2 has a red button marked "+48V" on the rear panel. When Phantom Power is on, a red LED lights up below both gain controls.
Audient	iD4 Find the "48V" button on the rear panel of the Audient id4.
Audient	iD14 Both mic inputs of the Audient iD14 have individual "48V" toggle switches.
Behringer	UM2 Find the "+48V" switch on the rear panel of the Behringer UM2.
Focusrite	Scarlett Solo The front panel of the Focusrite Scarlett Solo has a "48V" button.
Focusrite	Scarlett 2i2 The front panel of the Focusrite Scarlett 2i2 has a "48V" button.
M-Audio	M-Track Solo Find the "Phantom Power" switch on the front panel of the M-Track Solo.
M-Audio	M-Track Duo Find the "48V" switch on the front panel of the M-Track Duo.
Mackie	Big Knob The Big Knob has a "+48V" button on the top panel, top left corner.
Mackie	ProFX 6 The ProFX 6 has a phantom power button above the main meter display.
MOTU	M2 Small MOTU interfaces have a "48V" button near the Gain control.
MOTU	M4 The MOTU M4 interface has a "48V" button near the Gain control. The M4 has separate phantom power control for each microphone input. The button glows bright red (backlit) when Phantom Power is on.
Presonus	Audiobox Go The Audiobox interfaces have a clearly marked "48V" button on the front panel. The button on the Go glows blue when engaged.
Presonus	Audiobox USB96 The Audiobox interfaces have a clearly marked "48V" button on the front panel. The button on the USB96 glows red when engaged.
Presonus	Quantum ES2 The ES2 has a round "48V" button on the left side of the top panel.
RME	Babyface Pro FS The Babyface Pro has no dedicated 48V button. Press the IN button to select inputs 1 and 2. Press the SELECT button to choose channel 1, 2, or both. Press SET to activate Phantom Power for the selected channel. The orange LED(s), marked "P48," will light. If the device is not in standalone mode, presumably you would engage P48 via the RME driver or TotalMix software instead.
SSL	SSL2 The SSL2 interface has a "+48V" button for each mic channel.
UAD	Volt 1 The Volt 1 interface has a "48V" button on the front panel
UAD	Volt 2 The Volt 2 interface has a "48V" button on the front panel
UAD	Volt 176 The Volt 176 interface has a "48V" button on the front panel

*Why don't tube microphones need phantom power?

Tube microphones nearly always require much higher voltage and current than phantom power can provide; that is why tube mics nearly always have a stand-alone power supply.

As an example, the Roswell Aztec power supply has two power rails: one 6.3V rail for the tube filament, and one 120V rail for the tube plate.

Why don't dynamic microphones need phantom power?

Dynamic microphones such as the Shure SM57 and SM58 have no circuitry inside, and require no external power. All condenser microphones have circuitry inside, and do require some power source -- whether internal batteries, on a separate power supply, or "phantom power" supplied by the preamp/interface. 

Is it safe to hot-plug microphones?

We do not recommend connecting or disconnecting condenser mics from cables that are carrying phantom power. Doing this probably will not hurt the microphone, but could hurt the microphone.

The best and safest way to connect or disconnect a condenser microphone is to disable phantom power first. Then count to 10, because audio circuit power rails never turn on or off instantly. Waiting 5-10 seconds allows the stored charge in filter capacitors to dissipate. Then plug or unplug the microphone.

Tube microphones should never be connected or disconnected from a live power supply. For the Roswell Aztec, and any other tube microphone, it is safer to only connect or disconnect the microphone when the power supply is unplugged or switched off.