Printable Version of Topic

Click here to view this topic in its original format

GMC Forum _ THEORY _ Intervals Journey - Chapter Iii "another Question"

Posted by: MonkeyDAthos Aug 9 2011, 08:54 PM

Hi, Gmc.
Lately have been without internet, so i decide to dedicate a bit to resume my intervals studies. but once again, i am confuse as hell.
here's the situation.

(PS: correct me if i am wrong)

Intervals:

Root
2º minor = 0,5 (one half'step from the Root)
2º major = 1 (two half'steps or one whole step from the Root)
3º minor = 1,5
3º major = 2
4º perfect = 2,5
4º Aug/5º Dim aka Tritone = 3
5º perfect = 3,5
5º Aug/6º minor = 4
6º major/7º Dim = 4,5
7º minor = 5
7º major = 5,5
Octave = 6

So far so good.
The Problem comes now.

I read, that if you expand a perfect interval by a half step, it became's a Aug Interval

and if you contract it by a half step it became' Dim.

Now for example you have a C(root) and F ( perfect fourth interval) now add a Flat on the F it become's Fb.

and the invertal change from this to this

E E
B B
G G
D 3 = D 2
A 3 A 3
E E~

Before "studying this, i would say that if you contract and perfect fourth by a half step, the interval would transform into a 3º Major nor a Dim 4. Because of the table of interval i wrote up there.
(3º major = 2
4º perfect = 2,5)

So? Hows gonna be? can you assume that 3º Major and a Dim 4º are enharmonic equivalents?
Becoming something like
3º major/ 4º Dim = 2
4º perfect = 2,5

or is there something else that, i am missing?

Same stuff confuse me, on Expansion and Contraction of Major/Minor Intervals.

For example you have a 2º Major and expand it by a half step it would or should became a Aug Second.

so i got 3 freaking name to the same interval >: o Aug Second/Major Third/ Dim Fourth.

So are they all enharmonic equivalents, changing the name. depending of the situation? or is there anything else i should know?

Posted by: dark dude Aug 9 2011, 09:46 PM

Perfect intervals -> If one fret up = Aug, if one fret down = Dim
Maj intervals -> If one fret up = Aug, if one fret down = Minor, if two frets down = Dim
Min intervals -> If one fret up = Maj, if one fret down = Dim, if two frets up = Aug

This is how I understand it, and that's out of the Musician's Institute Guitar Fretboard Workbook.

Try not to over-think it! It sounds like you understand just fine but are over-thinking

Posted by: Gabriel Leopardi Aug 9 2011, 10:04 PM

Exactly, those intervals sound the same and the name depends on the context that the notes appear.

Posted by: MonkeyDAthos Aug 9 2011, 10:05 PM

ty very much