Here’s a few audio examples of 12 bar blues progressions (Key of A) with and without dominant 7th chords. I intentionally kept the tempo, strumming, drums, and bass the same in each of these examples… it’s only the chord voicings that are different. Give them a listen and hear the difference for yourself!
Both examples below are played at 120bpm, and loop for approximately 5 minutes. You are free to strum along, or even practice any licks or riffs over these! But if nothing else, just listen and train your ear on hearing that difference.
This is played with major chords all the way through, without any use of 7th chords. To me, this one feels like it’s sitting up straight, with its shirt tucked in and hair properly combed. A bit more formal, down the middle, and what-you-see-is-what-you-get.
Same major chords as above, but each one has an additional note added to make it a dominant 7th chord. Compared to the other track, this one oozes with a bit more edge, swagger, intrigue, and mystery. I find there’s simply a bit more texture to things, thanks to the dominant 7th chords. This is the color we’re going to encounter time and again with blues-flavored music.
Again, neither of these is right or wrong. Think of dominant 7th chords as a spice you might use while cooking. Sometimes, you may not want that 7th chord sound. But far more often than not, when playing the blues, you’ll want to embrace the use of dominant 7th chords.
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