MIDITina is an English Concertina CoreMIDI control surface. MIDITina doesn't produce any sound on its own, it is for playing hardware or software VST-style MIDI synthesizers via CoreMIDI hardware interfaces connected to the dock connector or virtual MIDI instruments running on your device such as IK Multimedia SampleTank or Sonosaurus ThumbJam. The entire range may be transposed up or down up to two octaves in semitone increments using the "Transpose (semitones)" slider on the settings page. While playing, you may also optionally send real-time volume, expression, modulation, or wind controller MIDI messages by tilting the iPhone/iPod to the right or left. Here's the settings changes required for two popular synth apps: IK Multimedia SampleTank: - In Settings (touch the gear icon), enable "Background Audio" Sonosaurus ThumbJam: - In "Prefs", under "MIDI Control", in "MIDI General Options" enable "Use CoreMIDI" and "Active in Background" Other CoreMIDI compatible synth apps will have similar settings.