How to connect an electric guitar or bass to a Mac with an audio interface

Connect an electric guitar or bass to your Mac, check the signal, and set up sound in a digital audio workstation (DAW) or Fretlore. On macOS, Core Audio handles audio devices; ASIO isn't used here.

What you'll need

• An electric guitar or bass.
• A USB audio interface with an INST/Hi-Z instrument input, compatible with your version of macOS.
• An instrument cable with two 6.35 mm TS plugs and a USB cable for the interface.
• Wired headphones, with a stereo adapter if needed.

An audio interface, also called an external sound card, sends your instrument's signal to the Mac and plays sound through your headphones. You don't need a physical guitar amp to play with software processing: an amp simulator in the app takes its place.

Examples include the Focusrite Scarlett Solo/2i2, Audient iD4/iD14, MOTU M2, Universal Audio Volt 1/2, Arturia MiniFuse 1/2, and other interfaces in this class. Before connecting, check the manufacturer's website for support for your model and generation, macOS version, and Mac processor.

Connect the interface to your Mac

1. Turn down your headphones and speakers. Set the instrument input's Gain to its minimum.
2. macOS already includes Core Audio. Compatible class-compliant USB interfaces work without a separate audio driver installation: connecting the device is usually enough. Check the manufacturer's website for support for your model and macOS version; additional software may be needed for its specific features.
3. Connect the interface to your Mac with a USB cable that supports data transfer. If your Mac only has USB-C ports, use a suitable cable or USB adapter. Connect a separate power supply if the device requires one.

Look for instructions and downloads under Support or Downloads on the manufacturer's website.

Connect your instrument

Hold the plug by its body and insert one end of the cable fully into the guitar or bass output jack. Turn up the volume on your instrument.

Plug the other end into an Instrument / INST / Hi-Z input. If there's a LINE/INST switch, select INST. On an XLR/jack combo input, the plug goes into the center opening; the input itself must support instrument mode.

Line Out, Monitor Out, and Phones are outputs. 48V phantom power isn't needed for a standard guitar connection.

Connect your headphones

Set the level and check the sound

1. Play your loudest notes or chords while gradually raising the Gain for the connected input. Watch the level indicator and avoid overloading the input.
2. If the interface has Direct Monitor, turn it on. On models with an Input/Playback balance, turn the control toward Input.
3. Gradually raise the headphone volume. You should hear your instrument.

Gain controls the incoming signal level; headphone volume controls how loud you hear it. Direct monitoring helps you check the connection without an app. If your interface doesn't support it, continue with the app setup.

Check macOS playback (optional)

This checks ordinary playback through the interface. You can skip this step.

Open the Apple menu, then System Settings, Sound, and Output. Select your audio interface.

If your interface has an Input/Playback balance, turn it toward Playback/Host/DAW and play a familiar recording. You should hear it through the headphones connected to the interface. You may need to adjust the volume on the interface itself.

Choosing a macOS output doesn't replace selecting the device in your DAW or Fretlore: configure the app separately. See Apple's guide to choosing an output.

Set up your DAW

A DAW is a music application for recording and processing sound. First, we'll select the audio interface, then assign the instrument input to an audio track and check the signal. We'll use Logic Pro as the example; menu names and control locations will differ in other DAWs.

In Logic Pro, open the Logic Pro menu, then Settings and Audio. In older versions, Settings is called Preferences.

On the Devices tab, make sure Core Audio is enabled. Select your interface in Input Device and Output Device, then click Apply if the button is available.

I/O Buffer Size is on the same tab. If the sound noticeably lags behind your picking, reduce the buffer: for example, try 128 samples if available. If you hear crackling or dropouts, or see a system overload alert, increase it. On an older Mac, finding a stable setting matters more than reaching the smallest number. See Apple's guide to latency in Logic Pro.

The interface's preamp and converters affect noise, headroom, and signal fidelity. Responsiveness also depends on the buffer, sample rate, computer, and processing load from effects. An expensive interface alone doesn't guarantee low latency across the whole system.

Now create an audio track for the instrument. In Logic Pro:

1. Open an empty project and click + above the track list. In the new-track dialog, choose Audio, then Mic or Line. Expand Details if the settings are hidden.
2. In Audio Input, select your interface's individual mono input: for example, Input 1 if the cable is plugged into the first jack. A stereo pair of inputs 1 and 2 assigns them to the left and right channels, so a guitar connected to just one input will be heard in one ear. Selecting the individual mono input lets you hear it in both.
3. In Audio Output, choose Stereo Output. In some versions, the main output is labeled Output 1 + 2. Check your interface's name below the input and output fields.
4. Click Create to make the track. We'll turn on monitoring next; you don't need to start recording.

In the new track's header, turn on Input Monitoring using the I button. Play a few notes: the level meter should respond, and you should hear the instrument in your headphones. The interface's Gain sets the input level; the track fader and headphone volume control adjust your listening volume.

Input monitoring alone doesn't add an amp or effects. For a guitar amp sound in Logic Pro, click an empty Audio FX slot on the track's channel strip, open Amps and Pedals, and choose the built-in Amp Designer. You can start with a preset amp model. For bass, choose a suitable bass amp. See Apple's Amp Designer reference for more detail.

Connect in Fretlore

Fretlore is our game for real electric guitar and bass. It recognizes the notes you play and uses them in gameplay. You can slow down songs and exercises, repeat sections, and work through them with feedback on notes and timing.

Amps, effects, and cabinets are built into the game. You can play through a ready-made signal chain or build your own. The default settings are designed for a quick start: connect your instrument, check the signal, and play.

On Mac, Fretlore uses Core Audio. Open CONNECTION from the main menu. If the interface and input are already selected correctly and the meter responds when you play, there's no need to change the settings.

1. Select your audio interface and the input your instrument is plugged into.
2. Play a few notes and check the signal level. If the signal is too weak or overloaded, adjust the interface's Gain.
3. If the sound noticeably lags, reduce the buffer size; increase it for crackling or dropouts.
4. Save your settings.

If macOS requests microphone access, allow it for the game. If the USB cable is accidentally disconnected, reconnect the interface and select the device and input again if needed.

Fretlore is in development: the Connection screen and settings may change.

If something isn't working

• The Mac doesn't detect the interface — check that the USB cable supports data transfer, along with the adapter and power supply; check the manufacturer's support for your macOS version.
• The interface is detected, but the app receives no signal — check Microphone permission, the selected input device and channel, INST/Hi-Z mode, and instrument volume.
• There's a signal but no sound — check Output in the app, headphone volume, the adapter, and input monitoring. If the interface has an Input/Playback balance, check its position.
• Sound in one ear or doubled sound — check mono input selection, panning, and the plug. Turn off Direct Monitor when listening through the app.
• Crackling or dropouts — check for input overload and increase the buffer if the input level is fine. Reduce the effects load and close unnecessary apps.

After playing, turn down the volume before disconnecting. Unplug the cable from an instrument with active electronics to avoid draining its battery.