# dom7dim=7b5?

Discussion in 'Ask Michael Dimin' started by Terry, Aug 29, 2004.

1. ### Terry

Apr 19, 2004
Is a dim, dom 7 the same as a dom 7 b5?
Thank You

2. ### jeff schmidtno longer red carded, but my butt is still sore.

Aug 27, 2004
Novato, CA
A dominant with a #4 is called Lydian Dominant. eg C7+4

But a diminished dominant is C7,b9,#9,#4. And if you add a #5 you get a diminished whole tone.

:EDIT:

okay - the first rule of bass club is - jeff isn't allowed to answer theory questions after 10pm.

sorry about that up there

Flatting the 5 on a dominant yeilds a 7b5 - but I've never heard it called diminished Dom. (don't mean oyu can't call it that) Except "Diminished" requires you to flat the 3 too. But these are just names.

in practice the good new is - if it's really the dominant function you're looking to mess around with - have at it - as long as you can smoothly resolve it to the third of the i chord you can play almost anything over the dominant. Including a b5.

3. ### Terry

Apr 19, 2004
I came across a E7 with a little dim. circle in between the E and the 7. That's where I came up w/ the ques. If the third was flat wouldn't that make it a minor 7? The dimished chords is where I stumble along

4. ### jeff schmidtno longer red carded, but my butt is still sore.

Aug 27, 2004
Novato, CA
Oh . . .

Eo7 is a straight up diminished.

You would approach it with the diminished scale.

W - H - W - H- W - H -W - H

or in your example

E - F#- G - A - Bb -C -Db -Eb-E

5. ### Terry

Apr 19, 2004
Thank You, Jeff & the mystery editor.
Terry C.

6. ### Mike Dimin

Dec 11, 1999
If there is just a little circle than it is a diminshed seven chord, which comes from the whole step/ half step scale as Jeff pointed out. The real beauty of the diminshed scale and the chords of that diminshed scale are it's total symmetry. If you look at the diminshed 7 chord carefully, you'll see that is made up of just minor thirds - E,G,Bb,Db if you go up another minor third, you start all over again with the E. Due to this symmetry the notes of the Gdim7 chord (G,Bb,Db,E), Bbdim7 (Bb,Db,E,G) and the Dbdim7 (Db,E,G,Bb) are all the same. using the whole step/ half step scale, you will find that there are only 3 diminshed seven chords in the key - in this case, the one that starts on E, the one that starts on F and the one that starts on F#. Cool -got it?

Now since the whole step/ half step scale is symmetrical there are only three of them - one that starts on E, the one that starts on F and the one that starts on F# - That is pretty cool as well

BTW, if the little cirlce between the E and 7 had a slash through it, you would have a min7(b5) chord. Diatonically, it is the 7th degree of the major scale (locrian mode) but it's practical application comes from the 6th degree of the melodic minor scale (locrian #2)

Cool stuff
Mike

7. ### Mike Dimin

Dec 11, 1999

The b5 over a dominant chord would be considered a "blue" note (as is the flat 3rd) - probably the least confusing way to think about, especially after 10pm

Mike

8. ### Terry

Apr 19, 2004
Thank you for all the good info. I like the symetry. (sp)

If I have this straight, in essence you have a 1-b3-b5-6, since the seven would be double b.? Hope that's right, otherwise it's back to the drawing board.
Terry C.

9. ### Mike Dimin

Dec 11, 1999
Terry,
bassically correct, you've got the concept, there is only one thing I want to mention - Each scale degree has to have a unique name. For example a Seventh, any seventh (diminished, minor or major) has to be seven note names away from the root. Therefore the interval of a diminished 7th is enharmonically the same as the major 6th - but the names are different. For example from the note C - a major 6th woulf be A (6 note names, C,D,E,F,G,A) while a diminshed 7 would be Bbb (seven note names)

10. ### Terry

Apr 19, 2004
Mike & Jeff, thank you for your patience & expertise. I got it now.
As a sixty year old newbie I some times get brain cramps, but you were able to cut through.
Thank You
Terry C.

11. ### Avidus

May 30, 2003
Nashville, TN
Oh . . .

Eo7 is a straight up diminished.

You would approach it with the diminished scale.

W - H - W - H- W - H -W - H

or in your example

E - F#- G - A - Bb -C -Db -Eb-E

Is there really an Eb in that diminsished scale?

Dec 11, 1999
Yes.

13. ### Avidus

May 30, 2003
Nashville, TN
oh... I always thought a diminished scale went like, well for this example anyway, E-f#-G-A-Bb-C-Db-E... I don't really get where the Eb comes in...

14. ### Mike Dimin

Dec 11, 1999
The diminished scales (half step/whole step and whole step/half step) are symmwtrical scales based on the h/w or w/h formula. Each scale is exactly the same only a half step away.

Mike