The “Lydian b7” scale is the 4th mode of the Melodic Minor Scale. Its name aptly describes what it is and what it sounds like. The Lydian Mode is of course the 4th mode of the Major Scale whereas the Lydian b7 Scale is the 4th mode of the Melodic Minor Scale. As you know, the Major Scale and the Melodic Minor Scale differ by one note. Lydian and Lydian b7 also differ by one note. In this case, the Lydian b7 Mode will have a flatted 7th (min7) and the Lydian Mode will have a major seventh (maj7).
The Lydian Mode will be used over a Maj7 type chords whereas the Lydian b7 Mode will be used over Dom7 type chords. When we think “Lydian” we thing of #11 and this is true in the case of both modes. The Lydian Mode suggest Ma7(#11) whereas the Lydian b7 Mode suggest Dom7(#11).
If you are already comfortable with the Lydian Mode, visualizing the Lydian b7 Mode as a Lydian Mode with flatted 7th is a good approach.
Here is the “C” Lydian b7 Mode.
The C Lydian b7 Mode is the 4th Mode of the G Melodic Minor Scale. G Melodic Minor is its parent scale. As we can see from the example below, they share the exact same notes.
There are numerous possibilities as to where this mode can be used. We will look at some of the most common places the Lydian b7 Mode can be applied. Our first example is for a IV Dominant chord. This is a very common chord found in many standards and jazz originals including: “If You Could See Me Now” and “The Days of Wine and Roses.”
Ex. 1 Imaj7 – IV7 – Imaj7
In the example below, we have a Bb Major Scale for our I chord, an Eb Lydian b7 Mode for the IV Dominant chord and then back to Bb Major Scale. The Eb Lydian b7 Mode is the 4th Mode of the Bb Melodic Minor Scale. The C# note in the 4th bar is a chromatic passing tone and not part of either mode.
Another common place to use the Lydian b7 Mode is over a bVII Dominant chord. (bVII7)
Ex. 2 Imaj7 – bVII7 – Imaj7
In the example below we have Bb Major Scale for our I chord, an Ab Lydian b7 Mode for our Ab7 chord and we resolve back to our I chord using Bb Major Scale once again. The Ab Lydian b7 Mode is the 4th mode of the Eb Melodic Minor Scale.
Ex. 3 Imaj7 – II7 – II – V – I
Another nice place to use the Lydian b7 Mode is on a II Dominant chord. (II7) In the example below, we have G Major Scale for the I chord, an A Lydian b7 Mode for the II Dominant chord and then Dorian, Mixolydian (part of the 10 note scale) and Major Scale for the final II – V – I progression. The A Lydian b7 Mode is the 4th mode of the E Melodic Minor Scale.