How to Record a Keyboard into Your iPhone
Before anything else, one question decides how you record a keyboard into an iPhone: does your keyboard make its own sound, or is it a MIDI controller? A sound-making keyboard, like a stage piano or a workstation, you record through its outputs. A MIDI controller makes no sound of its own, so there is nothing to record as audio from it directly. Here is how to handle both.
Does it make sound, or send notes?
If your keyboard produces sound, a digital piano, an arranger, a workstation, you record it through its line or headphone output into a class-compliant interface, or over one cable if it has its own USB audio.
If it is a MIDI controller, it produces no audio at all. It only sends note data to make something else play, so you record the sound of whatever it is driving, not the controller.
The distinction that trips people up
A sound-making keyboard has speakers or a headphone jack and plays notes on its own. A MIDI controller is silent by itself, it is a set of keys that tells a synth or an app what to play. Over USB, a controller sends MIDI, which is note information, not audio.
So you cannot record audio straight out of a MIDI controller, because there is no audio there. This is the single most common point of confusion, and knowing which type you have makes everything else obvious.
Recording a sound-making keyboard
Take the keyboard's line outputs, or its headphone output in a pinch, into the line inputs of a class-compliant interface, then connect the interface to the phone. Set the interface to line level, and record both left and right if the keyboard has stereo outputs, since pianos and many patches are stereo.
If your keyboard has its own class-compliant USB audio, even simpler, connect it straight to the phone with one cable and skip the interface.
Recording a MIDI controller's sound
With a controller, the audio comes from whatever it plays. Point the controller at a hardware synth or an instrument app, and record that sound source. The controller sends the notes, the synth or app makes the sound, and you record the sound.
So the recording setup is really about the instrument the controller is driving, not the controller itself. Record that instrument as you would any synth.
Where Reel fits
Reel records the audio from a sound-making keyboard through an interface or its USB audio, in clean 32-bit float and in stereo, so a piano keeps its width. For a MIDI controller, you record the synth or app it drives, and Reel captures that just the same.
See how Reel works
A quick look at recording into Reel.
Frequently Asked Questions
Can you record a keyboard on an iPhone?
Yes, if it makes its own sound. Record its line or headphone output into a class-compliant interface, or connect it over USB if it has its own USB audio. A MIDI controller makes no sound, so there is no audio to record from it directly.
What is the difference between a keyboard and a MIDI controller?
A sound-making keyboard plays notes on its own and has audio outputs. A MIDI controller is silent, it only sends note data over USB to make a synth or app play. You can record a sound-making keyboard's audio, but not a controller's, since a controller produces none.
Can you record a MIDI keyboard as audio?
Not directly, because a MIDI controller sends note data, not audio. To record audio you point it at a hardware synth or an instrument app and record that sound source. The controller supplies the notes, the instrument supplies the sound.
How do I connect a digital piano to my iPhone?
Run its line or headphone output into a class-compliant interface set to line level, then the interface into the phone, recording in stereo. If the piano has its own class-compliant USB audio, connect it directly with a single cable.
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Author
Tug
Founder of 24bit Studio and the developer of Reel, a portable 4-track recorder for iPhone.