10 Scales You can Play Over A Dominant 7 Chord

When you're improvising, it's good to have options. The Dominant 7 chord and especially a partial voicing ( 1 3 b7 ) is probably the most versatile of any chord type when it comes to the amount of scale options you have for melodic variation. Luckily, this chord crops up in a lot of musical styles that lean towards improv: blues, jazz and funk are all heavy on Dom 7 chords.

Here's a range of possibilities to add some spice to these chords. I'll sound the scale then play a small example using the scale so you get an idea of how it sounds. All examples are played over this partial voicing with no fifth. 

I've put them in a rough order of the 'inside' scales first and progress to a more 'outside' sound at the end. Some of these scales (well, two) rely on the 5th being altered (hence the partial voicing with no 5th in the examples). I've also marked what chord extensions are applicable to the scale. All examples are in C.

Major Pentatonic

Scale: 1 2 3 5 6

The most simple major sounding scale and very versatile! There isn't a b7 in the scale but it will sound great over any regular Dominant chord type with no altered extensions. Great for blues, soul and country phrases.

Works Over Chord Tones (Extensions): 1, 3, 5, b7  (9, 11, 13)

Mixolydian

Scale: 1 2 3 4 5 6 b7

The parent scale of the Dominant chord. The Mixolydian is the fifth mode of the Major scale. The 1 3 5 b7 of the scale make a Dom 7 chord (the V chord of the harmonized Major scale).  

Works Over Chord Tones (Extensions): 1, 3, 5, b7  (9, 11, 13)

Dominant Pentatonic 

Scale: 1 3 4 5 b7

This is sometimes called the 'Indian' Pentatonic as it's used in some traditional Indian music forms. It has a nice open, melodic sound and works well over any straight Dominant chord type.  

Works Over Chord Tones (Extensions): 1, 3, 5, b7  (9, 11, 13)

Major Blues

Scale: 1 2 b3 3 5 6 b7

Essentially a bluesy version of the Major Pentatonic. It has a passing tone (b3) between the 2nd and 3rd which adds a nice Chromatic flavor. You can also add the Major 6th to the scale too for more depth which I've done in the example. Pretty much the bedrock of Country guitar!

Works Over Chord Tones (Extensions): 1, 3, 5, b7  (9, 11, 13)

Lydian Dominant

Scale: 1 2 3 #4 5 6 b7

You could think of this as the Mixolydian scale with a raised 4th. The Lydian Dominant scale is actually the 4th mode of the Melodic Minor scale. Works great over a 7(#11) chord. Made famous as the sound of the Simpsons theme! Has a slightly weird off kilter sound that's good for adding some light outside flavor. Play this off the root of a IV chord in a blues for an instantly jazzy sound. 

Works Over Chord Tones (Extensions): 1, 3, 5, b7  (9, #11, 13)

Mixolydian b6

Scale: 1 2 3 4 5 b6 b7

Again you could think of this as the Mixolydian scale with a flat 6th. This scale is actually the 5th mode of the Melodic Minor scale. Has a very melancholy sound which is great for emotive melodic lines. Radiohead used this scale to great effect in their track 'Airbag' off OK Computer.

Works Over Chord Tones (Extensions): 1, 3, 5, b7  (#5, 9, 11, b13)

Phrygian Dominant

Scale: 1 b2 3 4 5 b6 b7

The 5th mode of Harmonic Minor. Has a kind Middle Eastern flavor to it. Very popular with neo-classical shredders. Contains a Diminished arpeggio a semitone above the root. Works well over a V chord in a blues too! 

Works Over Chord Tones (Extensions): 1, 3, 5, b7  (b9, 11, b13)

Half/Whole Diminished

Scale: 1 b2 b3 3 #4 5 6 b7

This scale is a widely used tool for creating an outside sound in jazz and blues. Has a quite dark tonality even though it has all the Major Dominant chord tones. Great for building tension.  

Works Over Chord Tones (Extensions): 1, 3, 5, b7  (b9, #9, #11, 13) 

Whole Tone

Scale: 1 2 3 #4 #5 b7

The Whole Tone or  Augmented scale will work fine over the partial voicing but the 5th is an issue here which needs to be flattened or raised. Has a spooky falling down the rabbit hole sound!? :)  

Works Over Chord Tones (Extensions): 1, 3, #4, b7  (9, #11, b13)

Super Locrian

Scale: 1 b2 b3 b4 b5 b6 b7

The Super Locrian or Altered  scale is about as outside as you could get but still works over the partial voicing. All the scale tones are flattened. Usually used as a passing scale before a IV Chord in Blues (over a Tritone substitution of the I chord). Probably best not to stay on it too long over a vamp though! 

Works really well over a 7(#9) or Hendrix Chord. 

Works Over Chord Tones (Extensions): 1, 3, b5, b7  (b9, #9, #11, b13)

Conclusion

The best way to experiment with these is to set up a jam track that uses a one chord vamp using this partial voicing. It gives you a bit more freedom to throw in some of the stranger ones and have fun with it. Most guitarist normally comp with this three note group anyway. Taking the 5th out doesn't actually do any harm as the 3, b7 are doing all the heavy lifting when it comes to the 'Dominant' sound.

Pick a scale and improvise with it. Pay attention to what notes sound 'in' or 'out'. Alternate between a simple inside Blues phrase and a more outside phrase with one of the later scales. You'll soon find some things that you like… or not!

All these scale contain arpeggios too which are another get tool for improvising. There's plenty of information online to help study how to harmonize these scales. It's a great theory workout!