Watch the Blues for Symmy 2 online guitar lesson by Chris Buono from Juiced Blues
Blues for Symmy is drenched with offspring from a, shall we say, parental symmetrical diminished scale. Just like real life parents, the scale itself never actually comes out to play, but its brood is running amuck throughout the solo as well as the upcoming comping foray. For the solo, the symmetrical diminished scale propagates dim7 arpeggios, but before we open that can of worms, let's breakdown the scale itself.
For some this may be your first encounter with a scale whose sum total is not five or seven notes, as the symmetrical diminished scale contains eight notes making it octatonic as opposed to penta- or heptatonic. Starting from the root D the scale is as follows: D Eb F F# G#/Ab A B C D. Defining the scale by formula you'll see you have the following scale degree ingredients: 1 b2/b9 b3/#9 3 #4/b5/#11 5 6 b7. Taking a closer look you'll notice there's a pattern of steps here. Starting from the root it goes: half step, whole step, half step, whole step, etc. This is where the alternative name for this scale--half-whole scale--originates and it is this attribute that makes the scale symmetrical. The pattern of steps continues throughout and recycles at the root. Looking at the Scale Vision section below the Solo and Arpeggio Vision in the Power Tab and PDF charts you should notice the symmetry here is m3rds. Meaning, every m3rd (1-1/2 steps) the two fingerings listed repeat themselves. Another way to see it is the first of the two opposing fingerings moves in m3rds while the second does the same starting a half step higher than the first one. Sound confusing? Just play them and you'll see it immediately.
Conducting further exploration into the note forest of degrees and enharmonics you should see, you guessed it, a dom7 chord in the form of a D7 (D-F#-A-C). Like the lydian dominant scale, this is what makes the symmetrical diminished scale work in a blues setting (though there's more to it as you'll soon see) as well as serving as a significant tools for jazzers wanting to spice up their lines over altered 7th chords. That natural 6th is real nice too as it's very cool to start blues-based lines on that degree whether you're blowin' a major-, minor- or hybrid-based lick. Take those particulars and combine that with the collection of outside tones such as the b9 and b5 and you got a formidable tool. Sounds like a plan, right? Not for us--we're squeezing the fruit a little harder for the juicy juice.
There's other arpeggios lurking within this scale, namely the dim7 arp starting at the root. See it? Its spelled D F Ab B (remember B is enharmonic of Cb, which is the bb7 required to make this arpeggio truly a dim7 form as opposed to a half diminished or min7b5 arp). THAT'S where we're going, folks. Pitted against grainy sounding dom7 chords we get an edgy major vs. minor vibe that's bolstered by the upcoming clever harmonization of the symmetrical diminished scale. In regards to the Ddim7 over the D7 this is what you get: D (root), F (#9, it's also a b3rd and therein lies the major vs. minor thing as well as the forever-cool 7#9 sound), Ab (b5), and C (b7). And wait, it gets better. Contained within the dim7 arp is the sweet sounding interval of a 6th. It can be found between every chord tone combination: D-B (Cb), F-D, Ab-F, and Cb (B)-Ab (G#). Just check out the lick in bar 2 that starts on the upbeat of beat 3 for an example. The resultant dichotomy of nasty and sugary that resides in this arpeggio set in this scenario makes this a very cool option. And, we're not done yet. The Ddim7 arpeggio you'll be coaxing your tonally schizophrenic ideas from can easily be moved every three frets because of it's--lemme hear ya say it!--SYMMETRICAL!! With that in mind, remember that every note in the arpeggio can be a root. So while you have a Ddim7 arpeggio you also have one rooted from F, Ab, and B as well as any applicable enharmonic equivalents. To add to the euphoria, that same arpeggio need not be permutated to fit over the IV chord as it will work over the G7 just fine. Examining the notes you see over the G7 the chord tones are now a 5th (D), b7th (F), b9th (Ab), and 3rd (B). This affords you a hip and cohesive way to play to flow your lines over the change while at the same time inject some much sought-after tension without every leaving a vertical area of the neck! For the V chord (A7) the Ddim7 arpeggio is moved up a half step to Adim7. If you're staring at that last sentence thinking I'm losing my edge, remember: dim7 arps are symmetrical making every note a root. So moving a Ddim7 arpeggio a half step is of course an Ebdim7, but it's also a F#dim7, Cdim7 and the aforementioned Adim7. Rest assured, all is well. By doing this you set up another gritty minor over major vibe for the A7 with the Adim7 chord tones acting in the same capacity as Ddim7 over D7. And, good thing--it's the turnaround!