Four-Note 7th Chords: Diatonic 7th Chords. Learn to play diatonic 7th chords in C Major, Bb Major, G Major and F Major. Guitar: Gibson 2002 Les Paul R9. Lehle P-Split High Impedance Signal Splitter. Fender Pro Reverb Amps (2). D’Addario Strings. Pickboy 1 mm TF Signature. BOSS RC-1 Loop Station.