Music Industry College

As triads, yes, all these chords belong in the key of Bb major. But as dominant 7th chords, only F7 (chord V7) occurs naturally in the key of Bb major. The dominant Bb7 (chord I) and Eb7 (chord IV) don’t fit into normal major harmony but they sound good anyway. It’s typical of the blues/Rock’n’Roll sound to have coloured chords. ................
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