Pat Maddox discovered a random DJ explaining dance music structure with his son's Legos:
A music theory PhD explains it using metrical analysis:
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The video promotes a DJ training site; the book's fucking fantastic, but don't bother unless you can read music. The training site includes a personable but not very informative video on harmonic mixing; the book assumes you already know the circle of fifths inside and out.
In my Godless Communist coaching program, one of my clients wanted to know more about producing electronic dance music, and I spent some time teaching him. His initial question was how much theory you have to know to make dance music. It's an interesting question.
A recent Reddit IAMA thread featured a classical musician explaining that he practices 4 to 6 hours a day, and a music school refugee commiserated:
Nobody thinks of DJs practicing their asses off and working hard studying theory. The typical DJ image is very different.
It's important to keep in mind, however, that metal guitarists have a similar wild image, and yet they spend a lot of their time idolizing Beethoven. And of course there are plenty of women in dance music who literally occupy more elevated positions than the one in this picture. Always take sensationalistic images with a grain of salt.
I don't go out a lot these days, but when I did, two of the best DJs I knew personally were both very well versed in music theory. One (a woman) had spent years in music school and held a degree in piano. It's difficult to tell with famous DJs, but I do know (for instance) that Sasha has employees who catalog his new music, when it arrives, by key signature. (I think I got that from How To DJ Right.) It's very easy to say this much with absolute certainty: to make good electronic music, you need to understand key signatures, chord progressions, the fundamentals of harmony, and basic drum patterns.
Whether you need any more than that is a judgement call. Given the ready availability of excellent sample libraries, you could probably skate through a lot of production without going extremely deep into music theory, and the areas of theory that you do need will vary by genre. If you want to make trance, experience with harmonic counterpoint will help you. If you want to make jazzy drum and bass, you'll need to understand jazz chords. Neither harmony or chords matter a great deal in techno, however, although of course they don't hurt, but by the same token, the intricate attention to meter and rhythm which is essential to techno might not help you at all in trance.
Something else complicates the question: engineering. You absolutely need some engineering theory, enough to understand analog synths, sidechain compression, frequency ranges, high-pass filters, low-pass filters, how to set up a sampler patch, sound design, etc. When the whole world becomes obsessed with the latest bassline, you need to understand how to make the patch on your favorite synth, if only just to contextualize the fascination.
In fact, this is why I use Propellerhead Reason. Reason models analog synths and a variety of other studio equipment. There's not much distance between learning Reason and learning the equipment that Reason models, but there's much, much less overhead. Many people don't take Reason seriously as a tool (although other people have made chart-topping records with it), but what's fantastic about it is that the energy and time you invest in learning Reason mostly doubles as investment in other studio gear as well.
It's also why my @djgoatboy account on Twitter, where I upload a new beat every day, might get a bit boring to listen to from time to time. It's mostly there to get me to practice every day, and on most days it's the dance music equivalent of practicing scales.
Anyway, if you want to learn more about producing dance music, you should sign up for my coaching program before prices go up, or just stay tuned, because I think I'm going to have more to say on the subject soon.