Pitch, tempo and key
This is the final instalment of music theory, I promise. We will finish off by finding out what is meant by pitch, tempo and key of a track. Although I’ve touched on pitch control on a CDJ in the past, in the video I will show it to you again and explain how it affects the tempo and key of a track.
Let’s start with the easy one. The tempo of the track is the speed of the track. When you listen to music in different genres, you’ll notice that some are slow and some are fast. Music in the same genre tend to all be at a similar tempo.
Recall from a previous tutorial that music is broken up into beats, bars and phrases. The tempo of a track is measured in the number of beats per minute, shortened down to BPM. You may have heard of hardware or software BPM counters, these simply measure the beats per minute of your track so you know the tempo it is playing at. Trance tends to be between 130-140 BPM.
Why is this important? Well, if you’re going to mix 2 tracks together there will be a point when both tracks are being played to the public at the same time. If they aren’t at the same tempo (therefore the same BPM) then the beats won’t line up nicely with each other and it will sound awful. In the video I’ll quickly show you how horrid this can sound.
In music theory, pitch represents the perceived fundamental frequency of sound. In other words, the BFG would have had a low frequency voice and hence a low-pitched voice. Somebody who has inhaled a helium balloon will have a high frequency voice and hence a high-pitched voice.
This is a complicated subject in its own right so I won’t go into too much detail. All I will say is that changing the pitch of a track changes its key. We will discuss this more when we talk about harmonic mixing in the future. For now, keep in mind that it is a good idea to have the tracks you want mixing together recorded in the same key or in keys that sound well with each other.
If you want to get a head-start in this topic, do so at the harmonic mixing guide.
Let’s put a spanner in the works
Ok, back to tempo. Whether you’re mixing CDs, vinyl or MP3s, the equipment used will have a tempo control.
Recall that I said tempo changes the speed of a track. When producing music, changing tempo means just that, changing the speed without affecting the frequency and is commonly referred to as ‘time-stretching’. To change the frequency without affecting the tempo would be ‘pitch-shifting’.
However, for some reason in DJing terminology changing the tempo actually means both pitch-shifting and time-stretching. When you slow down the tempo, not only will the track slow down but the frequency will lower as well like when a track has been slowed down to a halt (we shall do this in the video using the ‘vinyl speed adjust’ knob).
If somebody can tell me why in the DJ world this function was decided to be called tempo when it does more than change the tempo of a track, I’d love to hear it.
Until next time….
Cool, we’re all done with theory. Onto beatmatching next time. We are slowly but surely getting there.