In short
Plug the microphone into input 1, set the gain so loud speech stays below the clip light, and use phantom power only for condenser microphones. Choose the interface in System Settings › Sound › Input and in your call app. Use direct monitoring to hear yourself without delay.
To use an audio interface for video calls on a Mac, plug your XLR microphone into input 1, set the interface's gain so your loudest speech stays clear of the clip light, and turn on phantom power only if the microphone is a condenser. Then choose the interface under System Settings › Sound › Input, and choose it again in your call app. If you want to hear yourself, use the interface's direct monitoring rather than the call app.
The part that trips people up is channels: an interface usually presents two or more inputs, and a call app expects one voice. This guide covers gain, phantom power, monitoring and channels, and how to test.
Set up an audio interface for calls
- Connect the interface to the Mac with its USB cable. Most class-compliant interfaces need no driver; if yours has one, install it from the maker first.
- Plug the microphone into input 1. Many apps listen to the first input, or to the first two as a stereo pair.
- Set phantom power. Turn on 48V only for a condenser microphone that needs it. Dynamic microphones do not.
- Set the gain. Speak as loudly as you will on the call and turn the input's gain up until the level light shows healthy signal, then back it off so it never reaches the clip or red light.
- Choose the interface in macOS. Open System Settings › Sound, choose Input, and select the interface. Choose it under Output too if your headphones are plugged into it.
- Leave Input volume at the top, or disabled. With many interfaces the hardware gain is the control that matters; if macOS offers Input volume, leave it high and set the level on the interface.
- Choose it in the call app. In Zoom, Teams or Meet, select the interface as microphone and, if you listen through it, as speaker.
- Test. Use the call app's microphone test, or record yourself. Listen for your voice in both ears and no distortion on loud words.
Gain: the setting that matters most
An interface amplifies a microphone's small signal to a usable level. Too little gain and you are quiet and noisy; too much and loud syllables clip, which sounds harsh and cannot be fixed afterwards.
- Set gain with your loudest normal speech, not a quiet test phrase.
- Leave headroom. Call apps and recognisers can raise a quiet signal; nothing can repair a clipped one.
- Once set, leave it. Changing gain in the middle of a call makes your level jump.
Phantom power
Condenser microphones need power, usually 48V phantom power supplied through the XLR cable. Dynamic microphones do not need it. The microphone's documentation says which it is. Some interfaces switch phantom power for all inputs at once. Follow the interface maker's instructions about turning it on and off.
Direct monitoring
Hearing yourself in headphones helps you judge your level and stops you speaking too loudly. There are two ways:
- Direct monitoring on the interface sends the microphone straight to its headphone socket, with no delay. The call does not see it.
- Monitoring through software goes through the Mac and back, and adds a small delay that many people find distracting.
For calls, use direct monitoring, or none. Do not turn on "hear yourself" features in the call app on top.
Channels: what the call app hears
An interface with two inputs usually appears to macOS as one device with two input channels. A call app wants one voice. What happens depends on the app:
- It takes channel 1, and a microphone on input 2 is silent.
- It takes channels 1 and 2 as stereo, and your voice is only on the left. Some apps then play you in one ear on the other side.
- It mixes them, which works for one microphone and adds noise from an empty input.
What to do:
- Use input 1 for a single microphone.
- Look for a mono option in the call app's audio settings, or in the interface's own software, which can send one microphone to both channels.
- Check the format in Audio MIDI Setup: select the interface to see its input channels and sample rate.
Sample rate
48 kHz is a common rate for video and calls. You can set it in Audio MIDI Setup by selecting the interface. If you combine the interface with another device in an aggregate device, Apple says all devices should use the same sample rate; creating an aggregate or multi-output device covers that.
Common problems
| Symptom | Likely cause | Fix |
|---|---|---|
| Silence on the call | Microphone on input 2, or phantom power off for a condenser | Move it to input 1; turn on 48V if it needs it |
| Voice in one ear only on the other side | Stereo input with the microphone on one channel | Mono option in the app or interface software |
| Harsh, crackly loud words | Gain too high | Turn gain down until the clip light stays off |
| Quiet and hissy | Gain too low | Turn gain up; get closer to the microphone |
| You hear yourself twice | Direct monitoring and software monitoring both on | Turn one off |
| The call hears the room | Microphone too far away | Move it closer; see using a USB microphone for calls for placement |
Recording calls through an interface
A recorder that captures your side records whatever the Mac's selected input delivers, channels included, so the channel question applies to it as well.
Notey records the input selected in System Settings › Sound as your side of the meeting. We have not confirmed how it handles every multi-channel interface, so test yours once before a call that matters:
- Select the interface as the Mac's input.
- Press Start in Notey and speak for ten seconds.
- Check the You meter on the floating button moves, then stop and play the recording back.
If your side is silent, move the microphone to input 1 or use the interface's mono option, and test again. Setting up your Mac's audio for calls covers the rest of the setup, and choosing the right microphone on a Mac covers call apps that pick a different input.
Frequently asked questions
Why does Zoom only hear me in one ear with my audio interface?
The interface presents a stereo input and your microphone is only on one channel. Look in the call app's audio settings for an option to treat the input as mono or to choose the channel. If there is none, plug the microphone into the input the app uses.
Do I need phantom power for my microphone?
Condenser microphones usually need 48V phantom power; dynamic microphones do not. The microphone's documentation says which it is. Turn phantom power off before connecting or disconnecting a microphone if the interface's instructions say so.
What is direct monitoring on an audio interface?
It sends your microphone straight to the interface's headphone output, so you hear yourself with no delay. The call app does not see it, and the other people do not hear it twice.
What sample rate should I use for calls?
48 kHz is a common choice for video and calls. Set it in Audio MIDI Setup, and use the same rate for every device you combine.
Is an audio interface better than a USB microphone for calls?
Not by itself. An interface lets you use XLR microphones and gives you hardware gain and monitoring. A good USB microphone close to your mouth can sound just as clear on a call.