Dock Connector Audio I/O

Several options exist for getting audio signal into and out of iPhone OS devices via the dock connector. However, not all accessories are compatible with all iPhone OS devices. So, we put together this compatibility chart, based on our own tests with SignalScope/Pro and SignalSuite.

Dock Audio Accessory Compatibility

These devices were chosen for their ability to accept stereo audio input from external sources. Some dock connector devices simply feature built-in microphones, which are of limited use for test and measurement applications. It’s also important to remember that the iPhone OS automatically selects the current route for input audio signals (built-in mic, headset, dock connector, etc).

iPhone iPhone 3G iPod touch iPod touch 2G
Alesis ProTrack In/Out(1,2) In/Out(2) Out(3) In/Out(2)
Belkin TuneTalk Stereo In(1) In In(3,4) In
Griffin iTalk Pro (5) In(5) In(5) In(3,4,5) In(5)
MacAlly iVoice Pro In/Out In/Out In/Out In/Out
Tunewear Stereo Sound Recorder In(1) In In(3,4) In
  1. Even when using the dock connector for input, if the receiver or built-in speaker is the current output device on the original iPhone, the sample rate will be limited to 8 kHz (for input and output). Connecting headphones, or an adapter cable, like a stereo mini-plug to RCA adapter, will cause the headphone output to be selected and push the sample rate back up to 48 kHz.
  2. In SignalScope Pro (or SignalScope) the Alesis ProTrack appears as an input only device, so output signals are not routed to the ProTrack’s headphone out connector. The ProTrack’s headphone output does work with SignalSuite.
  3. Using a dock connector input with the original (1st generation) iPod touch appears to require that something be plugged into the headphone jack, unless the dock connector device also supports audio output (like the Macally iVoice Pro, which, ironically, is one of the few devices that is narrow enough to allow you to simultaneously plug your headphones into the bottom of the iPod).
  4. When using the original iPod touch with standard dock connector input devices, like the TuneTalk or the Tunewear device, a dock extender, like the SendStation device, will be required in order to also plug in headphones. You need to be sure your dock extender supports audio (some do not).
  5. The Griffin iTalk Pro that we tested did not work consistently–sometimes it wouldn’t be selected for input by the device. For now, the iTalk Pro is not recommended.

Frequency response measurements of these devices can be found here.