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HarmonyStop.com is the official distributor of the MusicSimple PowerWheel™ and Powerwheel Pro™

The Music Theory PowerWheel™ and the PowerWheel Pro.™ are the most comprehensive single-page music theory tools available today. They are small enough to slip into your notebook, yet powerful enough to get you through your music theory college classes.

A unique circular slide rule design for musical information, the PowerWheel™ is a powerful companion to, and reinforces any music theory book, class, or teaching method. It references diatonic harmony and can be used by beginners and advanced musicians. Specifically designed for college music classes, it is an exceptional tool for music analysis and provides a solid base from which to expand music writing, playing and understanding.

The PowerWheel™ is designed to easily reference all diatonic harmony and lay out any key's entire diatonic structure by simply dialing in a key's tonic. It also allows for quick transpositions from any key to any other key and gives quick references to modally borrowed chords.

The Powerwheel Pro™ is an advanced version of the PowerWheel™. It does everything the PowerWheel™ does and more... it includes chromatic as well as diatonic harmony. Reference chords beyond the 7th extension to include the 9th, 11th, and 13th extensions along with common alterations to those chords based on their chord quality. Instantly reference suspended and augmented chords and the neapolitan bII and three versions of the augmented sixth chords. The Powerwheel Pro™ also can refernce 32 of the most popular modes and scales.

“Classical, Jazz, Blues, Rock... if it’s musical, the PowerWheel™ helps you understand it.”

The PowerWheel™ and PowerWheel Pro™ allow for quick calculation and referencing of the notes and the scale degrees of any key, major or minor, its chords, the notes that make up each chord, circle of fifths progression, scales and easy transpositions to any other key, and more... The PowerWheel Pro™ also allows for calculating modes in any key and chords beyond the 7th extension to include the 9th, 11th and 13th chord extensions.

The PowerWheel™ and PowerWheel Pro™ place the rather vast spectrum of diatonic and chromatic harmony at your fingertips in a uniquely visual way.