#1
It was Autumn Leaves, and this part of the progression came up: G7 - F#m7b5. People (even I) agreed that it was a V - I with the F#m7b5 subbing for the C. I don't even remember why. Isn't the point of a TT sub that the two chords share the same tritone? How does that work when Fm7b5's tritone is F# - C and C doesn't even have a tritone?

Link, if anyone wants it https://www.ultimate-guitar.com/forum/showthread.php?t=640716

Thanks
#2
Tritone sub is often used for chromatic bass movement.


G - F#. I wouldn't tritone sub if I didn't have something like that as a result.
#4
Garghgle.


I really wish I could find my Jazz Theory Book in moments like these. He has a full chapter on subs.


I'm not really sure why it subs like that, but I believe that half dim chords are in the dominant "area" which is why you can sub it.


Originally tritone subs would have been between two dominants, one three tones above the other. durrrr.


I don't know if I'm helping much but maybe the rambling might enlighten you and you can enlighten me.

I played those btw, sounds like sex.


Edit: I asked Mark for some back up.
#5
I was going to explain this but I can't really give a reason to, it just 'resolves'. I guess it's because the tritone resolves and that's resolving eh.

-----
-3-1- Down
-4-4- Stays
-3-2- Down
-----
-3-3- Stays

Above is a standard G7 - Cmaj7 progression (with C inverted for ease of showing) where we see the tritone resolving by moving down (which is the most common way in jazz progressions to start with. Later on you add more melody lines to chords)


-----
-3-1- Down
-4-2- Down
-3-2- Down
-----
-3-2- Down


G7 - F#m7b5. Tritone also moves down, resolves. Still creates new tension because F#m7b5 is just another tension filled chord, but at least the G7 is resolved.

So, the tritone from the B and F notes is gone so we're home free.

Edit: Basically, a dominant chord always wants to resolve up 2.5 tones (like G-C) or down half a tone (G-F#). This can be anything, it could resolve to minor, major, m7b5 (even tho those start new tension and progressions), other dominant chord (also new tension) and even dim chords (more tension gaaah).
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#7
that, to me looks like a III - II in e minor, for the second chord in a minor scale is always a 7b5
#8
If you want more head explosions, I guess the post of cas will be sufficient and will probably clear up a bit of this context. Even though it's only about subbing the V chord in ii-V-I progressions, I think you'll manage to get the idea if you combine it with what I just said.

https://www.ultimate-guitar.com/forum/showthread.php?t=372950
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#9
Thanks, guys. Confusius, I've heard of vii chords replacing the Vs, but not the Is.

I just whipped out a theory book and found this (along with my draft for the MT Quiz I was supposed to make lol):

Tonic family: I, IIImi, and VImi
Subdominant family: IV and IImi
Dominant family: V and VII°

From: Harmony and Theory: A Comprehensive Source for All Musicians - Keith Wyatt and Carl Schroeder.

EDIT: I remember trying to read that thread before, Mark. My head indeed exploded. I guess I'll try again though
#11
Tonic family
1 3 5 7
C E G B    <- Cmaj7


1 b3 5 b7
A C  E G   <- Am7


1 b3 5 b7  <- Em7
E G  B D


Combine them and we see a lot of the same notes:

A C E G
  C E G B 
    E G B D



Subdominant family
1 3 5 7
F A C E    <- Fmaj7


1 b3 5 b7
D F  A C   <- Dm7


Combined:

  F A C E
D F A C



Dominant family
1 3 5 b7
G B D F    <- G7


1 b3 b5 b7
B D  F  A  <- Bm7b5

Combined again:

G B D F
  B D F A



Gah I don't even know why I'm doing this I'll just stop Will still post this halfassed post because otherwise it would go to waste. Something about similarities in notes in the different chord families but meh.


Ninjaedit saved by john
John says:
Just write 'they have similar notes, thus similar functions' or something, and mention 'example, look at bm7b5, it's just a rootless G9' or something standard like that
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Last edited by elvenkindje at Jul 11, 2008,
#12
Quote by brando
Tonic family: I, IIImi, and VImi
Subdominant family: IV and IImi
Dominant family: V and VII°

Does it say why iii is part of the tonic family? I think of it as part of the dominant family, as it is the v of vi
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