Tim Lerch on Reharm

[Christian Miller]

Agreed.

Can someone explain why he says the #IV m7b5 acts as a tonic??

For example in the key of G, a Dbm7b5 doesn't sound good in a II V I subbing for the tonic.

I think of Dbm7b5 => Bbm6 or Eb9 type of sound but not a tonic.

Aha my favourite sub

Usually it's used as a sub for the first I chord in a ABAC tune, often on the second repeat. For example IIRC Ted Greene uses it in this way on his recording of They Can't Take That Away. Some you might already subbing without realising - I Thought About You originally started on an F chord, not a Bm7b5, but most people play that these days.

The short answer is that it contains the root and third of the I chord and the reason it works better as a chord in this position rather than a resolving chord is that it is a great first chord for an extended turnaround. Which is how it is used in ITAY. So you can take a 1-6-2-5 for example:

C | A7 | D-7 | G7

And change to
F#-7b5 B7 | E-7 A7 | D-7 | G7

Won't work with every melody. A variation is this:

F#-7b5 F-6 | E-7 E?o7 | D-7 | Dbmaj7

Which works with a pedal C in the melody for example.

Not a big fan of theories of harmony. Chords schmords. In general, I think if you have a strong baseline and good counterpoint with the melody, the middle voices will look after themselves. And a strong baseline often has elements of stepwise motion, or perhaps a cycle 4 progression. But there's a lot of clever stuff you can do with reharmonising using maj7 chords and so on.

[Christian Miller]

Bbmin Eb7 is the backdoor progression. It happens in many tunes including Rhythm Changes.
Literally no one would say it's ii V to Ab, lol.
Tim Lerch is strawmanning here a bit I think.

I dunno we've had some on here. Also I think Mark Levine's Analysis of Just Friends (from the Jazz Piano Book IIRC) which is like this. Maybe that's what he was thinking of.

[pamosmusic]

Aha my favourite sub

Usually it's used as a sub for the first I chord in a ABAC tune, often on the second repeat. For example IIRC Ted Greene uses it in this way on his recording of They Can't Take That Away. Some you might already subbing without realising - I Thought About You originally started on an F chord, not a Bm7b5, but most people play that these days.

The short answer is that it contains the root and third of the I chord and the reason it works better as a chord in this position rather than a resolving chord is that it is a great first chord for an extended turnaround. Which is how it is used in ITAY. So you can take a 1-6-2-5 for example:

C | A7 | D-7 | G7

And change to
F#-7b5 B7 | E-7 A7 | D-7 | G7

Won't work with every melody.

Not a big fan of theories of harmony. In general, I think if you have a strong baseline and good counterpoint with the melody, chords will take care of themselves.

Common in the second pass through I Should Care, though in that case works as part of a back cycle too.