key change on the fly

[medblues]

I had read somewhere that a quick way to change keys is to reach the V7 of the new key by lowering one note of a diminished 7 chord. I can do this and it makes sense. I forgot, however, what the usual ways of getting to the target diminished 7 chords are. Thanks in advance.

[Nikkorico_03]

It's quite simple actually.

So let's say you want to change keys to the key of Bb. By using your example, you want to reach the V7 of Bb, which would be F7. So what you want to do is find a diminished 7th chord a HALF STEP up from the root, so you want to find an F#dim7 chord. Then, find where the F# is in the chord, and lower it, and you will get an F7 chord.

F#dim7 = F# A C Eb
Lower the root and you get...
F7 = F A C Eb

[medblues]

Thanks but you misunderstood my question: How do you get to F#dim7 ? What are some usual progression(s) going into the desired dim7 chord ? I just want to learn some popular ways of doing it.

[Nikkorico_03]

Ah I did misunderstand, your question was in the last sentence! Sorry about that. Not sure if this helps either, but whenever I see a dom7b9, for example a C7b9, I play a C# dim7, Edim7, Gdim7, or Bbdim7 up and down minor thirds, giving you an easy way to move the melody note up to a higher register.

[matt.guitarteacher]

Originally Posted by medblues

Thanks but you misunderstood my question: How do you get to F#dim7 ? What are some usual progression(s) going into the desired dim7 chord ? I just want to learn some popular ways of doing it.

I thought that this trick was about using the F#dim7 as the transition chord, when the b9 (F#) resolves down to F that gives you a strong sense of the new key. Playing a few positions of the diminished shape and then resolving the last one sounds nice.

XX7878 XX4545 XX1212 XX1221 X13231

I've never really done anything with this. That's just what I would get from what you're describing in the original post.

[fep]

Originally Posted by medblues

I had read somewhere that a quick way to change keys is to reach the V7 of the new key by lowering one note of a diminished 7 chord. I can do this and it makes sense. I forgot, however, what the usual ways of getting to the target diminished 7 chords are. Thanks in advance.

In a minor key the viidim7 is a diatonic chord, lots of ways to go there and then to another key, you can pretty much jump to the dim7 chord from any other diatonic chord in that key and it sounds fine (imo)...

Here's some using your idea to modulate to other keys.

Am7 G#dim7 Bb7 Ebmaj7

Am7 Dm7 G#dim7 E7 Amaj7 (not a change of tonal center but a change of mode)

Am7 Dm7 G#dim7 E7 F#m7 (deceptive cadence)

Am7 Em7 G#dim7 C#7 F#maj7

[timscarey]

The fully diminished 7 chord.....

IMO 90% of the time it occurs between...

1 and 2.... CM7 - C#dim - Dm7

2 and 3.... Dm7 - D#dim - Em7

4 and 5..... FM7 - F#dim - G7

5 and 6..... G7 - G#dim - Am7

Really, its a secondary dominant with the 3rd in the bass. The music teacher in me is saying "learn what a secondary dominant is and your question will be answered" the guitarist in me is saying "learn blackbird : )

As far as using it to modulate to other keys....

Your first sentence in the OP was right on, go to the five of the new key before arriving. The diminished 7th chord is really just a dominant 7th with the third in the bass.

Adim7 = F7 with A (the third) in the bass.... At least in the context you are referring too.

Good luck!

[medblues]

Very helpful answers ! Thanks folks !