The Hohner MIDI SqueezeBox is a 31-button three-row diatonic Button Accordion CoreMIDI control surface for the iPad.

Inspired by the iconic Hohner Corona II, the app uses the standard GCF (Sol) button layout popular for Tex-Mex, Norteño, Tejano, Conjunto, Vallenato, and similar styles of button accordion.

The app doesn't produce any sound on it own, it is designed for playing hardware and software VST-style MIDI synthesizers via a CoreMIDI compatible interface connected to the dock connector or virtual MIDI instruments like IK Multimedia SampleTank® for iOS or Sonosaurus ThumbJam running on your iPad.

Please visit the app support website to see some amazing live demo videos and for the settings you will need to enable in the synth app you are using to have it work with the control surface.

Touch the buttons with the fingers on your right hand to play. Buttons highlight when playing.

Multiple buttons may be pressed at the same time to make chords.

This style of accordion plays different notes depending on whether you are pushing or pulling on the bellows.

Touch the anywhere in the bellows image at the top of the screen for PUSH notes, lift your finger for PULL notes.

The PUSH/PULL indicator shows the current bellows direction. Also, the sides of the bellows light up tracking the bellows motion

You may slide your fingers between the buttons.

Touch the MIDI connector icon at the upper left corner to show the MIDI controls.

Using the controls, you may set the overall instrument MIDI volume, MIDI modulation, MIDI channel (1-8), key attack velocity playing style (fixed or variable), velocity min/max, and transposition (+/- 12 semitones).

Both fixed and variable velocity modes are provided to allow for expressive playback. In the variable velocity modes, the X or Y touch position within the bellows sets the velocity for the notes being played. The range for the velocity is set using the Min and Max Velocity sliders.

For fixed velocity, the Max Velocity slider value is used.

You may also set the Max Velocity to less than the Min Velocity to reverse the direction for velocity mapping in the bellows touch areas.

The app is based on the standard GCF tuning. Other common tunings can be achieved by setting the transposition control.

For example, for FBbEb (Fa) tuning, set a -2 semitone transposition. For EAD (Mi) tuning, set a -3 semitone transposition.

Touch the '?' icon to show the base layout note names for each button (without transposition).

Touch the '!' icon at the top center to send an "All Notes Off" message to silence any "stuck" notes should they ever occur.

Touch the 'i' icon to show the instructions page.

All settings are saved when the app exits.

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.