Mathematics and DJing

By Bjornsane on Sunday, 11 April 2010, 13:30. Viewed 909 times.

DJing and math? I bet most of you got a bit scared when your read that. To be honest: I ain't bad at math, yet I even got a bit scared. Math and DJing seem to hold no connection... Or do they?

Before we start

Let me tell you beforehand, this might seem odd to those who do not have a lot of experience with DJing. Yet it could seriously help you out in your beatmatching -that is setting up the next track for mixing- because there is a mathematical approach to that.

Although, I would suggest you learn to DJ using "your ears" before even attempting to understand this. It's supposed to deepen your knowledge on DJing and mixing. Not some kind of shortcut to learn to make good mixes. There's no shortcut.

Math meets Music

I DJ using house- and techno music, which have BPMs around 124 up to 134. This is where the math kicks in. Lets say that most music was recorded using computers and thus be recorded at a whole number. Say, 124 or 125. That means, if I'd like to increase the BPM of a track that's 124 beats per minute, unconciously you do: 100/124 = 0,806. That means that every 0,806% would increase that tracks speed with exactly 1 BPM, or decrease it with exactly 1. That's for 124.

If you apply that to 126; 100/126 = 0,793%. It's kind of logical to think that a faster track would need less increase to increase its speed. Compare it to a car. A car driving at 50 km/h needs a bigger percentage of speed increase to reach 100 km/h, than a car driving 80 km/h. Makes sense?

Example:

So if you would like both tracks, one with a starting speed of 124 and the other of 126, to play at 128. The following applies:

This is the basic for beatmixing, that applies to the style of music I play. I'm not saying that you should calculate the speeds all the time—neither am I doing that. But I just know that I need to work in steps of .8% to find the correct speeds. 
It gives me a rough estimate on how fast tracks would be. It also gives me pointers on wether the track would be running too fast or too slow, since you cannot adjust the speeds that precise. The fine mixing is an entire different science, involving your ears. But thinking of it mathematically, it's not that hard to pull off or, at the very basic; understand.

Perhaps it could work for you, if you have trouble getting your mixes right, to calculate some basic steps for the music you play. Lets say for Hiphop, running at an average of 90 bpm, you'd need to increase with 1,11% to add just 1 BPM. It's handy to know these facts when you're mixing. 
Especially when you're nervous and afraid that you can't pull it off for a crowd.