Bye-bye b7!

The chord diagram shows a D7 chord with its minor 7th on the 1st fret of the b-string. The spot shows a 7. Sounds reasonable, doesn't it?

But some users asked me why I just write a 7 instead of a b7, as they have seen in countless theory books and chord diagrams on other sites and apps.

Let me explain where the b7 can be found and why you don't find any b7 in Oolimo's chord diagrams.

There are three kinds of sevenths
diminished 7th - minor 7th - major 7th

The basic concept of naming intervals in scales

The basic idea of naming intervals in scales is to clearly differentiate between major and minor intervals.

In scales
with a
The 7th is
defined as
major 7th7
minor 7thb7
diminished 7thbb7

Major intervals (major 2nd, major 3rd, major 6th, major 7th) and perfect intervals (perfect 4th, perfect 5th) are written unsigned (2, 3, 4, 5, 6, 7).

The minor, diminished or augmented variants are prefixed with the according accidentals.

That's actually great and comprehensible and helps to understand the concept of pefect, major and minor, augmented and diminished intervals in scales.

Here is how 7ths are represented in chord symbols

The basic idea of naming chords is to create chord symbols that are clearly distinguishable at first glance.

In chords
with a
The 7th is
represented as
major 7thmaj7△7
minor 7th7
diminished 7thdim7○7

You may also find other variants of those chord symbols (not recommended), like e.g. MA7 or j7 for maj7.

This way of writing avoids the question, what an accidental would refer to, if a minor or diminished 7th was notated with accidentals. A Db7, would it be a D chord with a b7 or a Db chord with a 7 (which would mean a major 7th in that case)?

It's very obvious, that the different writings are likely to cause confusion.

How the 7ths appear in different music theory (jazz harmony) books

As if this wasn't confusing enough, let me confuse you even more!

Especially jazz harmony books are dealing with chords and their associated scales. I own a handful of harmony books and found out that most of them have their own way of adapting the interval names to their modern chord symbol representatives. It may work well inside each book, but looking up things in different books, on websites and apps may turn into total confusion. It's hard to believe what I found!

maj7, △7maj777M7M7
dim7, ○7dim7bb7○7bb7b7

Interval names on Oolimo

Chord diagrams and explanations on chords simply help to find and learn the components that together form the chord, named with its specific chord symbol. Knowing where each component can be found in the chord shape will enable you to modify or extend the chord easily by yourself.

For this purpose it seems to me to be the best way to display the intervals in the chord diagram the way they relate to their representatives* in the chord symbol.

Oolimo names intervals the way they are represented in modern chord symbols
in case of sevenths dim7, 7 or maj7

*) Not neccessarily exactly as they appear. For example a minor 3rd is displayed as m3 (instead of b3) in the chord diagram. It is the component, that is reflected as an "m" (or - when prefering icons) in the chord symbol. The 3 itself doesn't appear at all in the chord symbol. m (or the minus icon) stands for m3.


There are obviously no strict rules or laws, but there is a universal logic that always adapts to whatever an author has defined as convention. By modifying the interval names from 7 to M7, or bb7 to ○7, the straight road of absolute interval naming has already been left towards modern chord nomenclature.

Many users have the potential to learn a lot here, even if they didn't study music theory books before. Those would probably be just confused, if the 7th of a G7 chord was named b7 and the 7th of a Gmaj7 chord would be displayed as 7. The confusion could maybe even lead to misinterpretations like e.g. Ab7 being seen as A major chord with a minor 7th (A plus b7) or writing an Fmaj7 chord erroneously F7.

I want to shake off the yoke that the mismatch between absolute scale intervals and chord symbols imposed on us. We are basically talking about chords here and there's no need to keep naming the minor 7th "b7", as maj7, 7 and dim7 are clearly distinguishable.

The "absolute interval" naming formula "number 1 to 7, optionally prefixed by accidentals (b,#,bb)" should not be considered as irrelevant though. It is great for the basic understanding of intervals and should be learned along with the first contact with notes and scales, before even dealing with chords symbols.

"7" in chord diagrams and explanations on Oolimo
always stands for a minor 7th

P.S: Scales are also used to make you hear the chords and chord progressions when playing melodies or improvising over chords. By emphasizing certain chord tones the scales can be seen as "horizontal chords".