Send Audio and MIDI Between iPhone, iPad and Mac With Just the Charging Cable
On a Mac, combine your audio interface and your iPad or iPhone into an aggregate device in Audio MIDI Setup, then select that device in your DAW and set the iPad as a MIDI hardware output, so the charging cable carries audio to the computer and MIDI to the device.
Key points
- The charging cable can charge the device, send its audio to the Mac and receive MIDI, so no audio cables are needed.
- Create an aggregate device in Audio MIDI Setup that combines your audio interface with the iPad or iPhone.
- In REAPER, select the aggregate device, use a block size of 128 and enable the iPad as a MIDI output in low latency mode.
- Set the MIDI track's hardware output to the iPad and record the iPad's stereo channels on an audio track.
- An iPhone in airplane mode can serve as a backup sound source for live gigs.
This explainer shows music producers and keyboard players how to use an iPad or iPhone as a sound module for their computer. The only cable is the charging cable. Jason Zac demonstrates it on a Mac with REAPER, but the same idea works in Logic, Pro Tools, Cubase or most other DAWs. On a PC it is possible with third-party apps, while on macOS everything is built in.
Why not use audio cables?
The old method uses an adapter from the device's USB-C or Lightning port to a TRS jack, then a Y cable into two inputs of your audio interface. You need stereo, because most virtual instruments sound best with separate left and right channels, and mono can sound worse than the iPad itself.
This causes two problems:
- It uses up two interface channels. On a small two-input interface, you would have nothing left for vocals or guitar.
- Phone and tablet outputs are not built for professional sound. You may need a DI box to match impedances.
The charging cable avoids both problems. It powers the device, sends its audio to the Mac and carries MIDI from the Mac to the device.
Step 1: Connect and charge
Plug the iPad or iPhone into the Mac with a good-quality charging cable. Make sure the device is charged and ready.
Step 2: Create an aggregate device on the Mac
- Open Audio MIDI Setup. Press Command+1 to show Audio Devices. You do not need MIDI Studio (Command+2) for this.
- Your iPad or iPhone appears greyed out until you enable it. Enable it.
- Click the + button and choose Create Aggregate Device.
- Tick your audio interface and your iPad. The aggregate device now has your interface's inputs plus two more. In the video, an interface with 24 inputs becomes 26.
- Rename the new inputs, for example iPad L and iPad R, so they are easy to find in your DAW.
- Give the aggregate device a clear name.
Step 3: Set up REAPER
Audio
Open Preferences (Command+comma) and go to Audio, then Device. Select your aggregate device. Set the requested block size to 128 to keep latency low, then click Apply.
MIDI
Keyboards that are already connected by USB with their drivers installed will show as MIDI inputs. Jason Zac uses a Roland RD-88 and a Yamaha CK88.
Under MIDI outputs, find Apple Inc. iPad. Double-click it and tick both of these:
- Enable output to this device.
- Open device in low latency mode, so you hear notes the moment you play them.
Step 4: Build the tracks
- Create a MIDI track, for example Keyboard MIDI. Record-arm it and set its input to your controller or to all MIDI inputs.
- Create an audio track, for example iPad Audio. Arm it and set its input to the stereo pair of iPad channels.
- Playing an app directly on the iPad screen now records straight into REAPER.
- Open the MIDI track's routing and set its MIDI hardware output to Apple Inc. iPad.
- Your keyboard now plays the iPad app.
- In the demo, on a simple Mac Mini, there is no audible latency.
You can also load a normal virtual instrument on the same MIDI track and blend it with the iPad sound. To speed things up, save the whole setup as a track preset.
Using an iPhone as a live backup
An iPhone works the same way. This is handy as a fail-safe at concerts if your laptop or MIDI rig fails. Put the phone in airplane mode and keep it connected.
To switch from iPad to iPhone:
- Tick the iPhone in the aggregate device.
- Change the MIDI hardware output to Apple Inc. iPhone.
- Point the audio track's input at the iPhone channels.
How to practise this
Start with the iPad alone. First record a part played on its screen. Then add MIDI from your keyboard. Try different apps, such as GarageBand, Jordantron, GeoShred or Pianoteq, and listen for latency before you rely on the setup live.
Questions about this lesson
Do I need an audio interface input to record my iPad?
No. With an aggregate device, the iPad's audio arrives over the charging cable as two extra inputs, so your interface's own inputs stay free for vocals or guitar.
How do I play iPad apps from my MIDI keyboard?
In your DAW, enable the iPad as a MIDI output. Then set the MIDI track's hardware output to Apple Inc. iPad, and the app will respond to your keyboard.
Is there noticeable latency?
In the demonstration on a basic Mac Mini there was no audible latency. A block size of 128 and low latency mode for the MIDI output help keep it low.
Does this only work in REAPER?
No. The aggregate device is set up in macOS, so the same approach works in most DAWs, although the menu names will differ.
Practise it
- DAW MentorExplore REAPER lessons, scripts and guided help for recording and production.
- All free music apps40 practice tools for harmony, rhythm, ear training and more.
Related lessons
- How to Set Up REAPER (DAW): Preferences, Project Settings, Audio Devices and MIDITo set up REAPER, install it with the SWS extension, choose your audio interface and enable your MIDI controller, set project and peak-file paths, turn on timestamped auto-backups, copy imported media into the project folder, and set the project to 48 kHz with 24-bit WAV recordings.