Introduction to using mCircle

This is an introduction to the free online software (javascript app) from mDecks: mCircle located at

mCircle was created by Ariel J Ramos using his Decoding the Circle of Vths (fifths) method to analyze and study musical structures and subsets using a graphical approach.

In this introduction we will use mCircle to find the answer to a basic question (which could then be extrapolated into a more complex one)
Q. How many Major Triads are there in the Major Scale and in which degrees of the scale are they found?
The answer should be obvious to any beginner-intermediate theory student:
A. 3 major triads –> I, IV and V

Now let’s use mCircle to find the answer.
1. Launch mCircle. The layout has 4 main areas.
The Main Structure.
The sub-structure Candidate.
The sub-structures found contained in the main structure.
A list of the main-structure’s degrees where the sub-structures were found

mcircle areas

2. In the main structure section choose Ionian from the popup labeled V1 by Name
3. In the sub-Structure Candidate section choose Major Triad from the popup labeled V2 by Name

And there’s your result: I, IV and V.
Now here’s a new question which I leave to the reader:

How many Minor Seventh Chords are there in a Dorian scale and where are they?



Decoding the Circle of Fifths Chart description

mDecks: Decoding the Circle of fifths chart
Decoding the Circle of Vths Chart

The “Decoding The Circle of Vths” Chart is laid out as a poster sized page of
18 x 24
. In high resolution PDF format.

The chart is organized in six sections:

  • The Circle and the Mode/Transposition Formula
  • Symmetry and Inversions over the circle
  • Limited-Mode Structures
  • Most Common Source Scales and their Modes
  • Secondary & Substitute Dominants
  • Small Structures. Useful subsets candidates

Every structure is graphed over the circle of 5ths with its modal vector and the
M (# modes) number for that structure. All structure of limited mode are included in the chart. Major, Melodic and Harmonic minor and their modes. Small structures such as triads and tetrads are also included.

There are endless ways to apply the concepts presented in the “Decoding the Circle of Vths” chart. From jazz improvisation and voicings to tonal and atonal music composition and theory, many exercises and studies can be designed using this graphical approach to musical structures over the circle of fifths.

The eBook. Contents:
1. A formal intruduction to the concept and nomenclature. Definitions of modal structures, normal vectors, structure transformations and more, with examples and exercises for each one.
2. A description of the “Decoding the Circle Vths” chart’s layout and how to use it when applying the concept.
3. A set of exercises and ideas on how to apply the chart and concept to Jazz improv, Voicings, Composition and Arranging.
4. A brief manual on how to use the mCircle online software.
5. An appendix with worksheets for studying and applying the concept.

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