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Basic Music Theory Every DJ Needs To Know

A little effort towards learning some basic music theory can tighten up your sets.
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It’s totally possible to be a competent DJ with a limited knowledge of music theory. However, a little effort towards learning some basic music theory has potential to tighten up your sets and make you a more interesting DJ.

I find that it’s really easy to get lost in the weeds when it comes to music theory. Fortunately, there’s a lot we can ignore. We really only need to focus on a handful of concepts to get the most out of our time learning theory. I’ve decided to create a straightforward guide that focuses on the core aspects you need to understand while ignoring all the rest.

In summary, we’ll cover:

  • The Chromatic Scale
  • Song Keys
  • Harmonic Mixing
  • Musical Phrasing

If you’re already tuning out then don’t worry, I’m going to make this as painless as possible!

Before we jump in, Ableton has a great beginner-friendly learning module that you can run through that helps illustrate the basics.

READ MORE: Beginner-friendly learning module.

Additionally, learning an instrument alongside your DJ practice can really help develop your music understanding. If possible, I recommend learning the keys. This will easily transfer over if you ever decide to start producing your own music. You can check out the guide below for tips on getting into keys.

READ MORE: Tips for selecting your first keyboard.

Song Keys, The Chromatic Scale, and Using Harmony

The first concept we need to wrap our heads around is the chromatic scale. This is something you’re probably familiar with. The chromatic scale consists of the twelve building blocks that are used to create everything in contemporary music. It’s easily pictured below.

These notes also directly correspond to the keys you see on the piano. The black keys are the sharp notes (shown by #) and the white keys are the regular notes. 

Why is this important?

The chromatic scale provides the building blocks that are used to form the key of the song.  If we say that a song is "in the key of G," this means that the note G sounds like the most stable “home note” (or tonic) for the song.

Among other things, the song key quickly allows you to determine which notes/scales can be used within the song. More importantly, it gives you an idea of how the song is going to sound.

Through your career as a DJ, you will come across only a limited variation on song keys. Specifically, major and minor keys of the chromatic scale. For example, you’ll find a song in the key of G minor (Gm), or D# major (just D#), or A# minor, and so on.

The key of the song will allow you to determine if the song is going to sound upbeat, or if the song will have a more serious feel. As a rule of thumb:

Major keys: happy and uplifting

Minor keys: serious and somber

There is also one corollary benefit to knowing the song key - harmony!

Have you ever heard two songs played next to each other that just seem to fit? This is probably because the two songs were in the same key. In other words, the songs harmonized well with each other.

Mixing in harmony basically comes down to the song key. Without getting too technical, there are certain keys that blend well with each other. This has been described using the Camelot System (see picture below.)


If you want to keep things simple, just mix two songs together that are in the same key. Just note, that if you stick to one key for too long your set will start to sound boring.

As you progress, try mixing using the Camelot System. Here is Harmonic Mixing’s explanation of how it works:

“To select a compatible song, choose a keycode within one "hour" of your current keycode.  If you are in 8A, you can play 7A, 8A or 9A next.  If you are in 12A, you can play 11A, 12A or 1A.  This mix will be smooth every time.

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You can also mix between inner and outer wheels if you stay in the same "hour."  For example, try mixing from 8A to 8B, and notice the change in melody as you go from Minor to Major.”

For those of you who are familiar with a little more advanced theory - the Camelot system is essentially the same as the circle-of-fifths. A fifth is a very consonant interval that will sound pleasing to the ear when mixed together. A DJ only needs to know the relationship between each keys, not how many sharps or flats a key contains. Thus, the circle-of-fifths was adapted into the Camelot system.

A word of caution: mixing between the inner and outer wheels can sometimes sound off depending on the chord structure of each song (say, going from 9A to 9B.) Make sure you still use your ears and aren’t mixing based solely on the Camelot wheel.

The Camelot System can also be used to boost the energy of your set. This is when you mix into a key that is two numbers higher on the Camelot wheel. For example, mixing from 7B (F Major) into 9B (G Minor) will provide a burst of excitement into your set.

Alternatively, you can drop 5 numbers between tracks to use the “Armin Van Buuren variation.” The power of the Camelot System is you will already know that your set will sound energetic before you even step behind the booth.

This system is used by world-class DJs like Kaskade, Dubfire, and Pete Tong. A great piece of software that helps you take advantage of harmonic mixing is Mixed In Key.  The software analyses each track for the song key, energy level, and cue points. It easily interfaces with all the main DJ software and is something that every DJ should have.

Keep in mind the Camelot system only applies when you have tonal elements in your mix-in and mix-out points. Mixing in harmony will do little if you’re mixing quick cuts in hip-hop or if your intros and outros only have percussive elements.

Mixing in harmony isn’t the only thing DJs need to understand. Another important concept involves the structure of the song itself.

How Understanding Musical Phrasing Is Going To Make Your Life Much Easier

As you’re well aware, music tempo is measured in beats. Typically, we’re going to be dealing with music that follows a 4/4 pattern. In other words, there are 4 beats per bar. The term “musical phrase” refers to a series of bars.

The amount of bars within a phrase is going to vary depending on genre and location within the song. In vocal based music, think hip-hop or pop, phrases are typically 2, 4, 8 or 16 bars long.

In electronic music, phrases generally range from 8, 16, 32 to 64 bars per phrase.

Why should we care about phrasing?

The reason DJs focus so much on phrasing is it helps you find the “1” in the track. In other words, it really helps you with your mix-in and mix-out points. The “1” refers to the first beat in any given phrase.

I like to picture electronic songs in blocks. The image below gives a good illustration of what I’m talking about. In this case, the intro would be a 4 bar phrase, the verse an 8 bar phrase, the build is 2 bar, and the drop is an 8 bar phrase.

Knowing the different phrases of the song will allow you to mix your tracks in a way that will feel natural to the listener. With practice, you will be able to mix and match different phrases of different songs (try to keep them in the same key).

The key here is to try and mix in at the start of a phrase (also called the “1”).

How will you know?

If the music was produced correctly, the producer will provide hints at when a phrase is starting or ending. This will usually involve introducing building elements, a snare that is rising in pitch for example, or adding/subtracting different track elements.

It may take some practice to gain an intuitive sense of phrasing in your genre of music. However, once you have a grasp of the basic concept, you will open the doors to a more creative style of mixing.  

The video below does a great job of explaining the concept of phrasing if you are still unsure.

Luckily, modern DJ equipment will always help out with any of the musical theory you need to know. For instance, your software should be able to pick up on the song key. Just be aware that these systems aren’t always 100% accurate. Mixed In Key will detect both the key of the song as it relates to the Camelot system, as well as the different cue points as it relates the the song phrasing.

Beatport is a great source for finding the song key of a particular song. Just type the song title in the search bar and you will be provided the key as well as the BPM of the track.

The phrasing of a track can usually be picked up by looking at the waveform within your software. Again, this may take some practice to get but it’s totally possible to pick out the different phrases of the song by paying attention to the gain levels of the waveform.

Your software, in addition to some decks, will show the bar count above the waveform. This is another easy way to get your bearings when you’re quickly scrolling through a waveform.

That sums it up for the music theory side of DJing. Although not complicated, a small amount of music theory knowledge can be very powerful. If you’ve found this useful share it with a fellow DJ, producer, or engineer!

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