Hey Friend,

When we last saw F#°, he was but a lowly VII° chord in the key of G major. In E minor, he has advanced to be the II° , second only to E minor herself!

Not that this has any bearing on the sound or how you would necessarily use a diminished chord, but just gotta share a little love (or the diminished chords might start feeling bad. Can't have them getting cranky!). 

Diminished chords are the result of taking a minor chord and then flatting the fifth note. In the case of F#°, we start with an F# minor chord, from the key of F# minor. The scale is:

Take the 1 3 5 notes (F#, A and C#), which gives you F#m. Take it one step further and flatten the fifth note (C#) to C. Voila! F#°.

While you aren't going to find diminished chords in Rock very often, they do play an important part in the harmonic structure of the key progressions, so even though they can be a pain to play, you should at least try them out.

You never know what sound will spark something in your head and give you a flash of inspiration  For example, as I mess around with the diminished shape on the second, third and fourth strings (looks like an open D major shape), I figured out that if you play the major version of the previous chord in the progression, it creates a very cool transition riff.

For example, here in the key of E minor, the Im is Em, and the II° is F#°. Play that chord change.

Now alter the Em chord and make it E, and then play the F#dim. That to me is a much more usable progression. What do you think?

Alright, here are the exercise files for your enjoyment:

Like I said, you don't have to worry about these showing up in songs you want to play, but they are handy, even if it's only to train your fingers for chord changes. That alone is worth doing the work - making smooth chord changes is something you need to get good at, so practice these chords and give your fingers a good workout. Rock on!

Peace~

Dave