Watch the 12/8 Blues online guitar lesson by Jeff McErlain from Blues Survival Guide: Rhythm Edition

The classic slow blues is almost always in 12/8 time. The bottom number in a time signature tells us the note value equaling one beat in this case an 1/8 note. The top number tells us how many of those beats are in a bar. So in 12/8 time we have twelve eighth notes in a measure. In other words, four triplets. We can count this as ONE-two-three, TWO-two-three, THREE-two-three, FOUR-two-three. Of course we are accenting the down beats in capital letters. Unclear? Listen to the ride cymbal, he is playing that very pattern.