DuoBox: Fold Accordion

DuoBox turns iPhone Duo into an accordion. Hold it open like a book, with the bass buttons under one hand and the treble keys under the other, and fold the phone to work the bellows. Opening is pull and closing is push. The reeds are synthesized live on the phone, so every note follows the bellows. There are no ads and no accounts, and the full app is a single purchase, not a subscription. THE ACCORDIONS • Piano: a piano accordion keyboard, with bass and chords for F, C, G, Dm, Am and Em • Norteño: a three-row button accordion in GCF with a 12-bass. FBbEb, EAD, ADG and BbEbAb are a tap away • Diatonic: a one-row button box, where push and pull play different notes PLAYING • Eleven treble registers, including Musette and Bandoneon • An AIR button that moves the bellows silently • Room, delay and distortion, plus transpose and octave shifts • Song mode lights the next key and chord, so…