Recording Audio on an iPhone Using RCA Cablesby Michael Cox
In addition to its other functions, Apple's iPhone is an incredibly flexible recording device. Depending on the app you use, you can record voice notes, create DJ mixes or even multitrack musical instruments anywhere you can take your phone. If you want to connect a line-level source such as a mixer, however, you'll need outboard gear that may be as simple as a cable adapter from RCA plugs to your iPhone's headphone/mic jack or as powerful as a dedicated audio interface.
The simplest way to wire up your line-level device for iPhone recording is to use an adapter with an RCA or other connector at one end and an iPhone-compatible 3.5 mm TRRS plug at the other. The adapter plugs in to your iPhone's headphone jack and provide mono input. Some iPhone input cables, such as the AmpliTube iRig, also include a jack for monitoring your audio. For more flexibility, an interface such as the Tascam iXZ includes XLR and 1/4-inch connections as well as monitoring and level control. Many adapters use 1/4-inch plugs; an additional RCA-to-1/4-inch adapter may be necessary to connect your line-level device.
For more flexibility or to record in stereo, you'll want an interface with a Lightning or Dock connector. A number of companies make devices that allow line-level input via the iPhone's custom port, including the Blue Mikey, Line 6 Mobile In or TASCAM iXJ2. To run stereo RCA output to these devices, use a Y-adapter cable to combine the two signals into one stereo 3.5 mm mini plug. Most older devices with Dock connectors will work with newer iPhones using a Lightning Adapter.
Your method of connecting will likely depend on what you'll be recording and what app you're using. For multitrack audio, Apple created a version of GarageBand for the iPhone, and the app includes effects, loops and an on-screen keyboard just like the OS X version. Third-party recording software also abounds, such as Multitrack DAW and the free Multi Track song Recorder. The iPhone's default Voice Memos app offers single-track stereo recording for mixes or capturing live sound, but other apps like Voice Record Pro or Audio Memos offer more features.
When recording to the iPhone, use a line-level signal if possible: an amplified signal may cause distortion clipping in the recording, and a signal sent with a high level of amplification could damage the iPhone's audio circuitry. Always turn the power off to your output device before connecting it to the iPhone, and if the device has a volume control, turn it up gradually after connecting. If you use a Dock or Lightning interface and want to monitor your recording while you lay it down to avoid unwanted noise, use headphones without a built-in microphone.