Easy Guide To Music Theory For DJs

Phil Morse | Founder & Tutor
Read time: 10 mins

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There are lots of reasons why as DJs, it pays for us to have a basic understanding of music theory. Understanding music theory:

  • Helps us to describe music, to talk about music to other DJs and musicians, and to understand others when they’re talking about music
  • Helps us to be able to properly use all of the tools that make working with music easy – even if it’s only understanding the keymixing features of our DJ software
  • Gives us a greater understanding of and appreciation for the music we play
  • Prepares us for if and when we want to start producing music

The good news is that language of music – beats, chords, notes, rhythm, melodies – is finite. Once you know it, you know it. Sure, you can study music theory for years, but the basics can be learned fast.

That’s what this article’s here for. By the end of this article, you’ll have learned the language that musicians use to talk about beats, rhythm, key, scales, chords, notes and melodies, and you’ll understand how all of these things fit together.

Easy Guide To Music Theory For DJs – Contents

Almost certainly, not all of this will seem relevant to you at first, and that’s natural. Remember in mathematics lessons at school when at some point you probably thought, “But why do I need to know this? When would I ever use it?”

It can be like that with music theory too.

But I guess you’re here because you know that grasping this is necessary to opening doors to work more closely with music in your future – so stick with it, and try to at least understand the concepts, even if you don’t see all the practical use for them today.

Remember you can always bookmark this article to come back to it in the future, when you need to revisit some of the concepts here that maybe don’t seem crucial to you today.

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Use a keyboard

Before we get started, a word of advice: Yes, this is all finite and learnable, but you’re going to have to get your head around some concepts that are very possibly going to be completely new to you and at first, a little baffling.

It is much easier to understand these things if you actually try them out for yourself. So I really want you to grab a keyboard of some kind, so you can play along with what I show you.

Here are a few ideas for obtaining one if you don’t have one:

  • Download a piano app for your phone or tablet – Any that features standard-looking black and white keys as found on a piano will do
  • Use any keyboard lying around your home – As long as it is laid out like a piano keyboard and plays at least three notes at once, it’ll do (it doesn’t matter what it sounds like)
  • Buy a Midi keyboard and use it with any music-making program on your laptop – Midi keyboards are a bit like DJ controllers, in that they work with software on your computer; it’s your computer that actually makes the noise. They are relatively cheap – The Nektar SE25, for instance, is under $50

Music Theory For DJs

1. Rhythm and timing

Rhythm is, of course, where it all starts for DJs. It’s also the easiest of the musical areas we are about to cover to understand. After all, as DJs we’re used to counting our beats and bars.

So here’s a recap:

Music is divided into “bars”, sometimes called “measures”, and usually there are four beats in a bar. That’s what people mean when they describe dance music as “four to the floor”.

Even types of dance music or parts of tracks that don’t have four obvious kick drum sounds in every bar still follow this pattern underneath. When you start counting “one, two, three, four, one, two, three, four…” over your music, your “one” counts will usually naturally correspond with the start of each bar – this is an instinct in all of us. Don’t think this is only something you learn as a musician, because anyone who’s ever danced to music or anticipated a big drop in a track knows it perfectly.

When a sound occurs on the first beat of a bar, we say that sound is on the “one” beat, same for “two” beat etc.

Now for our first technical term. A sound that is one bar long is called a “whole note”. “Note” is a term that can mean lots of things in music theory, but in this instance it is describing the length of the sound.

So if a whole note is a sound that is one bar long, it follows that a sound that is half a bar long is called a “half note”, a sound that is a quarter of a bar (or one beat) long is called a “quarter note”, and so on.

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2. Notes

Now let’s move on to the more common use of “note” – to describe a certain type of sound, namely a melodic sound. A note can be high or low, and the crucial thing is that it could be sung, whistled etc – it has a pitch. You can’t whistle a kick drum, but you can whistle a note. That’s the difference between a note and other types of sounds.

A good technical definition of a note is “a melodic sound made by vibrations”. If you hit a tuning fork, the note it makes is formed by the number of times a second it vibrates. The more vibrations, the higher the note. (Tuning forks normally vibrate 440 times a second, which is an A note, as it happens.)

Believe it or not, there are actually only 12 notes. That’s because as soon as the number of vibrations per second that form a note doubles or halves, you get the same note, just a higher or lower version of it. We hear the same note, but we can also tell if it’s higher or lower.

Just like in tempo there’s a strong relationship between, say, 80bpm and 160bpm (and you can successfully beatmix between the two), same with musical notes. The distance between a halving or doubling of vibrations is called an “octave”.

In Western music, there are 12 actual notes that comprise every octave, that is to say 12 notes before you get back to the note you started on, only “an octave higher” or “an octave lower”. That’s why however many keys there are on a keyboard, there are still only 12 “actual” notes to choose from. Each octave has 12 piano keys in it.

Now let’s talk about how notes are named. The naming convention relates to how they’re laid out on a piano. White notes are A, B, C, D, E, F, G, and the black notes between them all have two names – they can be named “sharp” or “flat” in relation to the nearest white note.

An example: The black note between A and B can be called A sharp (A#) or B flat (Bb), in different situations – but both refer to the same note, and you’ll always be understood no matter which one you use.

More terminology: The distance between each note is called a “semitone” or a “half step”, and the distance between every two notes is called a “tone” or “step”.

3. Key/scale

A key is a set of notes that work well together in a song, and a scale is simply those notes played sequentially, up or down. We can usually these terms interchangeably and be understood.

Try playing every single note upwards from C (the white note immediately to the left of the left-hand black key of the two black keys that are in a pair on a keyboard) until you reach the C an octave higher.

It doesn’t sound very musical, does it?

Now play only every white note from C up to the next C.

Sounds better, right?

That’s because you just played the scale of note in a musical key – a set of seven notes with a particular note as the “main” note, that just sound good together. These sets of seven notes out of twelve are a cornerstone of Western musical theory.

The scale you just played was “C major” (or just “C”). We could also say this song is in the “key of C major”.

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Most songs only have one key. A key generally only uses seven notes out of the 12 – because these combinations of seven notes just sound good together (it’s all to do with those vibrations per second again for each note, but we don’t have to go into it here).

A key is always named after its starting, or “root” note, and you can start on any note on the keyboard and still play a major scale. It just so happens that the scale of C major avoids all the black notes. (Others use progressively more black notes.)

So how do we know which notes to play, and which to leave out? The formula for a major scale is: Tone, tone, semitone, tone, tone, tone, semitone. (We often say “whole, whole, half, whole, whole, whole, half”.)

As long as you skip and play the notes in that sequence, you can play a major scale from any starting note – but again, any other than C will start to use various black notes, too. Start on D and follow the same pattern, and you play a scale in the key of “D major” (or just “D”) and so on.

The seven notes can also be referred to as, unsurprisingly, “First”, “Second”, “Third” and so on. (This numbering system is useful because it helps us to describe sequences of notes, independent of any particular any starting note.)

So playing the white notes from C up to the next C, you just played a “major” key/scale. Major keys sound “twee”, “cheerful” and “complete”.

So the other main type of key is the “minor” key. It sounds a bit more sad and even a little menacing when compared to the major key. It has a yearning, unfinished quality. (A lot of dance music is in minor keys, to convey that “on and on and on” feeling to the dancefloor that keeps people dancing.)

From the root note, a minor scale’s note spacing (again, the way it plays seven notes and leaves out the other five) is “whole, half, whole, whole, half, whole, whole”.

Again, you can start on any note and as long as you respect this, it will still be a minor key and scale. And again, we number these notes, calling them “First”, “Second”, “Third” etc up to “Seventh”.

Try it starting at C – you’ll have to include some black keys now, and you’ll hear the difference.

But here’s a curious thing: Every major key has a related, or “relative” minor key.

If you move three semitones down from the first note of a major key and play a minor scale, you’ll notice it uses exactly the same notes as the major scale – just starting from a different place.

So from C, three semitones down is A – and if you play all the white keys up from A, that is A minor. Same notes, different key, scale and feel! So A minor is the only minor scale that, like C, also avoids all the black keys.

(Tip: Songs in these two keys are likely to mix together well when DJing.)

Read this next: The Ultimate Guide To Keymixing For DJs

Why does a keyboard have black and white keys?

Is there any fundamental difference between them? The answer is no. But there are two reasons why it is this way:

  1. It helps pianists to know where they are on a keyboard (imagine all white keys in a row…)
  2. It means that you can compose in both a major key (C) and a minor key (Am) without ever using the black keys

That second point is useful to know for those of us without formal musical training, because we can program our keyboards so we only ever have to play the white keys if we want, while actually playing in any musical key, using a function called “transpose” on our sequencers and DAWs.

4. Chords

Chords are sets of notes played together. Notes used in chords in songs are nearly always chosen from the song’s key. For this training, we’ll assume all chords contain three notes – they can also contain more.

Chords set the mood at any given point in a song, and move the song forward/tell its story.

The three notes in a basic chord are called a “triad”, and you get a triad by playing a note in a scale, missing a note, playing a note, missing a note, playing a note – so you could play the First, Third and Fifth notes, or the Second, Fourth and Sixth, or Forth, Sixth and Eighth (into the next octave) from your scale, all of which would make a chord that fits.

Don’t get confused here. you “play one, miss one, play one, miss one, play one, miss one” from the notes in the scale (ie the 7 notes out of the 12 for your particular key), not the actual notes on the keyboard (ie not all 12).

There are two basic types of chords we’ll consider here, just like there are two types of keys – Major and Minor.

  • Like major keys, major chords sound “happy”. When the number of piano keys between the three notes in the scale that comprises the triad are FOUR then THREE, your chord is a major chord (for instance, the First, Third and Fifth from C in the C Major scale are C, E and G, which are four then three piano keys apart)
  • Like minor keys, minor chords sound ‘sad”. When the number of piano keys between the three notes of the triad are THREE then FOUR, your chord is a minor chord (for instance, to turn our C chord into a C Minor chord, we’d drop the middle note, E, by a semitone, to Eb)

Do major keys always use major chords?

So in a major key, are all the chords major chords? And in a minor key, are all the chords minor chords? No!

Why not? Again, remember, to make the chords that work in a key, we play one, miss one, play one, miss one, play one, where “one” refers to the seven notes of the scale. But when we do this, the actual number of piano keys between these notes will vary.

Try it on your piano:

  • In a major key, the first six chords as you move up through the notes will always be Major, Minor, Minor, Major, Major, Minor – so in C, this would be C, Dm, Em, F, G, Am. (Note that the seventh chord is called a “diminished” chord and doesn’t follow this rule – we are going to completely forget about this chord, as it is discordant, and very rarely used in the music we play)
  • In a minor scale, the six chords as you move up through the notes will always start with a Minor chord, then it’s that pesky chord we won’t use, then the third to seventh will be Major, Minor, Minor, Major, Major – so in Am, this would be Am, (not used), C, Dm, Em, F, G

Want a visual reminder of these concepts?: Grab your free download

So just one final thing to tell you about chords: Now you know the difference between major and minor chords, I can share with you a way of numbering them that also shows whether they’re major or minor chords.

Using Roman numerals, we can indicate whether the actual chord is Major on Minor by putting those Roman numerals in upper case (Major) or lower case (Minor). A Major scale’s six main chords, for instance, are written as I, ii, iii, IV, V, vi.

As with everything in this article, I’ve covered just the important basics here, and there are countless chords that build on these – in the handouts you can download for free as part of this article is a chord chart that shows you how to play not only all the major and minor chords, but that contains other common variations.

5. Melodies

We’re nearly there! We’ve got a decent understanding of rhythm, notes, keys/scales, chords… now let’s look briefly at how musicians approach the theory of melodies and melody writing.

Melodies are single note sequences played over chords. When we refer to melodies we usually refer to notes played higher than those in the accompanying chords. They’re often sung, or played on a lead instrument. They’re the bit the “postman would whistle” in any given track – the “hook”.

If melodies only use notes from the currently playing chord, they will sound great, but rather “safe”. Interesting melodies tend to be “based” around the notes in the current chord, but with variations. However, these additional notes usually are at least from the key/scale the song is played in.

These additional notes can be “hangover” notes from the previous chord, or precursors to the next chord, or following some other pattern that resolves over the length of the complete melody, but their purpose is almost always to introduce “tension”, that the listener yearns to be “resolved”. This resolution happens by the chord and melody note combination returning to the “start” at some point, usually the end of the musical section.

(And no, the notes don’t HAVE to be from the same key/scale – but if they’re not, it introduces considerably more tension, and is a much more extreme trick to pull – often used if the whole song itself is about to change key, which does happen sometimes.)

Read this next: 5 Reasons All DJs Should Learn To Produce Music

Sing a nursery rhyme!

As a simple example of tension and release in a melody we all know, let’s hum a nursery rhyme.

Hum “Baa Baa Black Sheep”. When the melody reaches the word “wool”, we’re not resolved, right? There’s tension, right? (Admittedly, it’s not edge-of-seat tension in a major key nursery rhyme, but it’s there!). If you left it there, it’d feel strangely unfinished.

That tension is “resolved” by the descending notes that follow – “yes sir, yes, sir, three bags full” – that return us by “full” to the starting note. That’s the “release”.

Tension and release is super-important in dance music, so when writing or analysing melodies and chord progressions, always be on the look out for when there is tension, and when and how it is released.

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Wow, some ride right? Yet above is all you’ll likely ever need as a DJ or DJ/producer.

I want to reiterate that you don’t need to instinctively understand all of this – you just need to know it exists, and that you can come back here to brush up when you need to.

I also want to reinforce that it is super important to try out what’s taught here – this will likely only start to make sense when you have a keyboard to test some of these things out on. I suggested ways to achieve this if you don’t own one at the start of the article.

To help all this sink in, make sure to download your free pack of musical diagrams and charts to print out and pin up next to your DJ or music gear.

Remember, from a DJ’s point of view, knowing this stuff is an advantage because it will help you to understand things like keymixing software, and those “short cut” DAW plugins that help you to write music without being a musician. Of course, should you one day want to learn to play an instrument, you’ll definitely need to know all of this.

Good luck, and please feel free to ask any questions below – we’d be more than happy to help.

Last updated 25 February, 2024

Digital DJ Lab