I'm relatively new to music theory, I was under the impression Cmaj7 was the same as C7 so i just added a minor third above the C triad (CEG) and got CEGBb. As it turns out, C maj7 is actually a major third above the C triad - that is CEGB.

Then there's the Cminor variation, that is C Eb G, and Cminor7 C Eb G Bb. If there is a discrepancy within the chords and the 7th why is there no discrepancy between regular C and C major?


Several sevenths exist. The most used is probably C7 made up from CEGBb. It is a dominant. Next is Cmaj7. C E G B. Then Cm7. C Eb G Bb. And dont forget Cm maj7. C Eb G B. They are all in common usage but C7 is more used so has the simplest, if not most explanatory name.


The "maj" modifier is for the "7", not for the "C". "major" is never indicated for the general mode of the chord (indicated by the third step): that's the default. Only minor is indicated, with "m" or in the case of Jazz, "-".

There is really not much to be done here rather than learn all of the handful of exceptions and conventions. There is not a lot of logic behind them.

  • Also I down voted due to your last paragraph. There is logic behind the conventions as dominant 7ths were dominant hence it make sense to refer to the most popular 7th as just 7. – Dom Mar 20 '17 at 19:05

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