QUESTION:
"I know a bit about the different kinds of scales that make different musical moods, like how Carlos Santana always plays in a certain kind of scale and how it makes him sound more like himself instead of other guitarists. I was wondering if there's a way to figure out what scale they use by listening to them. Also I was wondering about switching minor scales and major scales within a blues tune, I know that Clapton does this a lot, but is there a certain place in the progression where it's best to do this without sounding like you went to the wrong note?"

EDLY ANSWERS:
Here comes the short answer to only some of your questions. First, if you practice (and even better, actively train) your ear, you can definitely identify a solo or melody's source scale(s). Put this together with some knowledge of theory, and you can do it in your sleep. My very favorite ear-training program is called Listen (sorry, Mac only) and is available from http://www.edly.com.

As for switching scales within a blues tune, either the minor or major pentatonic scale will sound good over the I and V chord, whereas you might want to be careful of the natural 3rd degree of the major pentatonic scale over the IV chord. (The minor pentatonic will work great though.) For example, in C, the major pentatonic is C D E G A C (and the minor pentatonic is C Eb F G Bb C). The E note will rub in a way that you may not like against the F (IV) chord: F A C (or F A C Eb, if it's F7). Sound confusing? Sorry 'bout that; this is a quicker answer than it would ideally be.

Here's a looser answer: Part of what makes the blues sound like the blues is the way the notes of the melody rub up against the notes of the harmony. If they rub in a way that you're used to hearing in bluesy contexts, it will sound bluesy. If it's a rub of a different color, then it may well just sound wrong.

There are your yin and yang answers, each incomplete. Like yin and yang, put them together, and you may have a whole...

Edly - Author and publisher of
"Edly's Music Theory for Practical People"
"Edly Paints the Ivories Blue"
http://www.edly.com/

What is music theory, anyway? You hear so much about it, but does anybody really know what it is? Edly does! Scales? Chords? Keys? Ear-training? Modes? Toads? If you need help connecting the musical dots or playing musical works, send your best (or dumbest) questions to Edly: edly@edly.com

Edly, one of earth's leading music theory experts, will field the responses.

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