Once you’ve got your guitar in Open D7 tuning, the next step is putting it to work. The 12 bar blues is the perfect vehicle — the dominant seventh sound built into your tuning gives every chord that authentic blues character.
Your 1-4-5 Positions in Open D7
Since the guitar is tuned to D dominant 7th, you’re in the key of D. Your 1-4-5 chord positions are:
D (the 1 chord): Open position or 12th fret
G (the 4 chord): 5th fret (a fourth is 5 frets up from open)
A (the 5 chord): 7th fret (a tone above the 4)
This is the same math as any open tuning — once you know where your 1-4-5 lives, you can play the slide guitar blues in that key.
The Standard 12 Bar Structure
The classic 12 bar blues breaks down like this:
Bars 1-4: D (the 1 chord) — four bars on your open position or octave
Bars 5-6: G (the 4 chord) — two bars at the 5th fret
Bars 7-8: D (the 1 chord) — back to D for two bars
Bar 9: A (the 5 chord) — one bar at the 7th fret
Bar 10: G (the 4 chord) — one bar at the 5th fret
Bar 11: D (the 1 chord) — back to D
Bar 12: Turnaround/closing riff
That’s your 12 bars: 4 + 2 + 2 + 1 + 1 + 1 + 1 = 12.
Using the Octave Position
One of the advantages of open tunings is having the octave at the 12th fret. Colin likes to move between the open position and the 12th fret during the D sections — this lets you slide up and actually use the slide, rather than just sitting on open strings.
Your D chord sounds the same at open and at the 12th fret, just an octave apart. Moving between them adds movement and lets you take advantage of what the slide does best.
The 4-5 Passing Note
When moving from the G (4 chord) to the A (5 chord), a common blues move is adding a passing note. Instead of jumping straight from the 5th fret to the 7th fret, slide through:
G (5th fret) → G# (6th fret) → A (7th fret)
That chromatic walk-up from 4 to 5 is a classic blues sound you’ll hear in countless songs.
A Simple Closing Riff
For the turnaround at bar 12, Colin uses a simple descending line on the third string:
3rd fret, 3rd string → 2nd fret → 1st fret → open 3rd string
Then hit the G-G#-A (5th-6th-7th fret) walk-up to set up the next verse. If you’re ending the song, finish on a D with a little slide flourish.
Comparing to Open D Major
If you’ve played 12 bar blues in Open D major, the positions are identical. The difference is the sound — Open D7 has that flatted seventh baked in, so every chord automatically has that blues tension. You don’t have to add anything to get the dominant seventh sound; it’s built into the tuning.
Practice Tips
Start by just getting comfortable with the chord positions. Play through the 12 bar form slowly, counting the bars out loud if you need to. Once the structure is automatic, you can start adding fills, varying your rhythm, and moving between open and octave positions.
The dominant seventh tuning does a lot of the work for you — your job is to keep good time and let that bluesy sound ring out.
Want to Play Slide Guitar? Start Here (Free)
Most people grab a slide and get frustrated within five minutes. There's a reason for that, and it's easy to correct once you know the secret!
I've put together a short series of free video lessons that will get you playing slide the right way. You'll learn the best tuning to start with (hint: it's not standard!), how to lay down a mean rhythm with your slide, and why slide guitar can actually be easier than normal guitar once you know the trick.
No spam, just guitar. Unsubscribe anytime.