Very simple concept widely used in jazz ( but good for other styles). Like shown in the video, G7 and Db7 are two chords a tritone away (tritone=6 semitones) that share the same 3rd and 7th.
G7= G B D F
Db=Db F Ab B
as you see the notes B and F are common to the two chords. This means that I can also substitute the IIm chord that usually comes before it (as in a II-V-I)
I can play both
Dm7 G7 Cmaj7
Abm7 Db7 Cmaj7
Hi There! If you liked these lessons: Download all the products In This Page in exchange for a donation to support the site (minimum $10): my 4 eBooks+Mp3 examples, and 84 blues backing tracks (divided in 7 sets). A total value of $149 at full price on other sites!
Use the drop down menu if you want to donate more, it's appreciated! All products on this page are digital goods you can download instantly after a successful Paypal checkout.