Members JonR Posted June 20, 2012 Members Posted June 20, 2012 I have a question.... How is the use of F#7 and Bm7 explained, theoretically? I've been using them since finding them in a set of blues progressions of the web, but haven't studied the "why" yet. Time to do so, I feel. Bm7 is the diatonic ii chord in A major, and F#7 is its V - ie, a "secondary dominant", labelled "V/ii" (V of ii). Jazz is full of these. As well as secondary dominants (before just about any chord), you can have "secondary supertonics" - which is a fancy name for putting the ii in front of any new (secondary) V7 you introduce. So you could precede that F#7 with C#m7b5, which is the "supertonic" (ii) of B minor. (NB: not C#m7, which is ii of B major, although that might also work. Of course, that's the iii of the key too, but if you play C#m7-F#7 it's probably going to work more like a ii-V in B.) And once you get into tritone subs for the secondary dominants.... well then your head starts exploding (but not in a bad way) .
Members JonR Posted June 20, 2012 Members Posted June 20, 2012 But the ii (Bm7) is not "in front" of the F#7....or do you mean "in front" in the same way that you disagreed with girevik when if fact you agreed ...ie after the secondary dominant? The "in front" comment was in the context of "secondary supertonics" - not the primary ii chord (Bm7). F#7 is V of Bm and is in front of it. You can put the ii of Bm in front of the F#7: C#m7b5-F#7-Bm(7). You're right about the Bm7 preceding the E7 (and then the Bb7). Same principle, but I was talking about secondary chords. To illustrate what I mean, here's an example where I'll try to add as many secondary chords as I can: Progression in key of C major: C - F - Em - Am - Dm - G7 - C Adding secondary dominants (SD): C - C7 - F - B7 - Em - E7 - Am - A7 - Dm - D7 - G7 - C Adding secondary supertonics (SS): C - Gm7-C7 - F - F#m7b5-B7 - Em - Bm7b5-E7 - Am - Em7b5-A7 - Dm - Am7-D7 - Dm7-G - C OK, that's obviously a bit excessive! (And I've put the primary supertonic back where it belongs: Dm7 before G, because that had got detached by the subs.) Adding 7ths to the diatonic chords sweetens the whole thing up, and provides some nice shared tones: Cmaj7 - Gm7-C7 - Fmaj7 - F#m7b5-B7 - Em7 - Bm7b5-E7 - Am7 - Em7b5-A7 - Dm7 - Am7-D7 - Dm7-G7 - Cmaj7 (or C6) Notice: (a) two of the SS's are diatonic to C (Bm7b5, Am7); but they're performing a double role here, as "pivot chords" (belonging to two keys at the same time). (b) where the target chord is minor, then the SS's are m7b5 chords; where the target is major, then they are m7 chords. In the original sequence, I omitted the vii chord: Bdim (Bm7b5). This chord can't have its own secondary dominant, because it can't act as a tonic (even temporarily). But it could have been inserted between F and Em, and then been replaced by B7 in the second sequence. In the SD sequence, you could omit the minors and just go for SDs all the way - effectively replacing the diatonic minors with dom7s on the same root. And you can do this in any combination of course - keeping some, replacing others. But that only works because I wrote it as a cycle of 5ths (after the F) to start with. (Omitting the diatonic minors also works well in the SS-SD sequence.) When it gets to the SS level, normally the length of the SD is halved, so 4 beats of a SD would become 2 beats of SS and 2 of SD. Eg, instead of |B7 / / / |, you'd have |F#m7b5 / B7 / |. Naturally - if you're doing this with an existing tune - all these games have to fit the melody and song structure too. When it comes to tritone subs, you can of course replace any SD with its tritone sub. When it's preceded by its own ii chord, you can normally convert that too. So if you're going to use Eb7 instead of A7 (to go to Dm), you can use Bbm7-Eb7, rather than Em7b5-Eb7. (Again, as long as it sounds right in context.) NB: with tritone subs, the preceding ii chord is usually a m7, not m7b5. (There may be a rule about when it is or isn't, I'm not sure .) I'll let you play around with changing any of those dom7s for tritone subs and see what happens....
Members JonR Posted June 21, 2012 Members Posted June 21, 2012 My pleasure. I imagine it would baffle quite a few others, while more advanced people might squint at it and say "hmm, yes but..." You're obviously a person who is at just the right level to grasp it! Here's a real world example, which - with the above knowledge - you should be able to disentangle : Charlie Parker "Blues For Alice": ||:F(maj7) - - - |Em7b5 - A7 - |Dm7 - G7 - |Cm7 - F7 - | |Bb7 - - - |Bbm7 - Eb7 - |Am7 - D7 - |Abm7 - Db7 - | |Gm7 - - - |C7 - - - |Am7 - Dm7 - |Gm7 - C7 - :|| It used to be a harmless little 12-bar blues in F and now look at it... Tips: 1. Bars 1, 5 and 9/10 are pinned to the usual blues changes. 2. Think "backcycling" - taking any target chord and stringing a cycle of 5ths sequence before it to lead on to it. 3. Otherwise: SDs, SSs, and TSs! (tritone subs).
Members Virgman Posted July 3, 2012 Members Posted July 3, 2012 Chord Substitution For Dummies Key of C for example: C-Dm-Em-F-G7-Am-BdimR--T---R---T--T---R----T R = ResolutionT = Tension Subs R's for R's and T's for T's
Members JonR Posted July 3, 2012 Members Posted July 3, 2012 Hmmm. We seem to have been responding to polishpaul purely by telepathy...
Members mosiddiqi Posted July 3, 2012 Members Posted July 3, 2012 Hmmm. We seem to have been responding to polishpaul purely by telepathy... It's unfortunate, he seems to have been upset by a lack of response to another thread of his....people often either have nothing to say or are simply too busy to respond as quickly as the thread starter might like..that's life
Members Tricky Posted July 4, 2012 Members Posted July 4, 2012 Agree it is unfortunate, as this was an interesting thread (for me anyway). Certainly lacks continuity now.
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