Please help me understand this device...

[Ally007]

Hi Folks, I'm an aspiring songwriter, trying to get to grips with music theory. I recently acquired this circle of 5ths tool (see photo). I understand how it shows groups of chords that go together for songwriting purposes (eg, the group outlined in pink in my photo). But in what way is the opposite group (outlined in green) useful or significant, in relation to the I, IV, V group outlined in pink? Many thanks!

[eLawnMust]

The group ontop are diatonics & on the bottom are the tritone opposites of that group which are 6 semitones away. It's a different way of utilizing the COFs... There are many ways to view the COFs I commonly go counter-clockwise which makes it a circle of fourths so say play a CMaj7 to Fsus2 to BbMaj7 to Ebsus2 so on, so forth you then after a time come back to the beginning...

It's 'theory' which is a rational way of looking at a phenomena but not the only way & not necessarily the 'right' way depending on your intended outcome... I learned it young at organ lessons but found it much better to just jam to records & listen to what sounds good then mimic it then do my own 'take' on it & pretty much forget the COF...

[Ally007]

The group ontop are diatonics & on the bottom are the tritone opposites of that group which are 6 semitones away. It's a different way of utilizing the COFs... There are many ways to view the COFs I commonly go counter-clockwise which makes it a circle of fourths so say play a CMaj7 to Fsus2 to BbMaj7 to Ebsus2 so on, so forth you then after a time come back to the beginning...

It's 'theory' which is a rational way of looking at a phenomena but not the only way & not necessarily the 'right' way depending on your intended outcome... I learned it young at organ lessons but found it much better to just jam to records & listen to what sounds good then mimic it then do my own 'take' on it & pretty much forget the COF...

Thank you!

[Farnaby]

The group ontop are diatonics & on the bottom are the tritone opposites of that group which are 6 semitones away. It's a different way of utilizing the COFs... There are many ways to view the COFs I commonly go counter-clockwise which makes it a circle of fourths so say play a CMaj7 to Fsus2 to BbMaj7 to Ebsus2 so on, so forth you then after a time come back to the beginning...

The top group aren't any more diatonic than the other chords - that's an incorrect usage of the term diatonic. Each adjacent group of three can form a I IV V (the middle one of the three being the I). So the top 3 are no different to the bottom 3 in this respect.

I have never found any practical use for the COF, although it is a neat way to display all the keys and their key signatures as a learning aid.

[Ally007]

The group ontop are diatonics & on the bottom are the tritone opposites of that group which are 6 semitones away.

Again, thank you. I would really like to know how the tritone opposites can be useful in music composition.

[imrae]

The group ontop are diatonics & on the bottom are the tritone opposites of that group which are 6 semitones away.

Again, thank you. I would really like to know how the tritone opposites can be useful in music composition.

They are the most harmonically "distant". Jumping to them directly will sound very jarring, which is rarely but sometimes desirable. (e.g. tritones are used a lot in heavy metal)

Looking at the tool more closely, I don't think the number labels on the green section e.g. "bIII" are supposed to be related to the numbers on the pink section. On this side, we see "I" is assigned to Fm, with IV and V assigned to Bbm and Cm. The "bIII" is Ab which is the third degree of the scale (and relative major). So this part of the tool is intended for navigating a minor key. I don't think there is any special significance to this group of labels being opposite the ones for major key; it could have been a separate disc and they are just put opposite for convenience.

[Ally007]

So this part of the tool is intended for navigating a minor key. I don't think there is any special significance to this group of labels being opposite the ones for major key; it could have been a separate disc and they are just put opposite for convenience.

Ah, I see! Now it makes sense... Very much appreciated, @imrae !

[akaiguy86]

Im no expert, but I always seen it as a chart showing the forth of every key counter clockwise and the fith of every key clockwise. Also helps with detailing how many sharps and flats are in each key.