Watch the Lydian b7 online guitar lesson by Chris Buono from Modes That Matter
Next up is a melodic minor mode and one that very much matters in playing over altered dominant chords as well as basic dom7’s. It especially works great over those bII7 chords you always see a half step above a maj7 chord. Lydian b7 is built from the 4th degree of melodic minor and it’s formula is as follows: 1 2 3 #4 5 6 b7. As the name suggests this mode is relative to the Lydian mode, which coincidentally is built from the 4th degree of its parent scale (major or Ionian). And, speaking of names this scale is also known as the Lydian Dominant mode or the overtone scale.
The non-irony is you’ll see that many other modal names are based off the major mode names. This fact makes it important you digest those formulae (including the purposefully omitted Locrian mode whose formula is 1 b2 b3 4 b5 b6 b7) so you have a heads up to a new formula before you even touch your guitar.
As for the defining tritones pair found in all melodic minor modes, in Lydian b7 you’ll find them between 1-#4 and 3-b7. Thinking back to the previous statement where it was said these tritones are a whole step apart you might be apt to challenge what you just read. Well, before you take any action dig this little tidbit. Tritones are the only interval that can invert and still be the same quality. If you invert the second pair of tritones mentioned here you’ll get b7-3 and that is a whole step below the tritone between 1-#4. Pretty sneaky, sis!