In this section we'll look at some of the theory behind timing that is relevant to reprogramming sampled drum rhythms.

For the methods contained within this guide, there are 3 main things to consider about the timing of a drum loop:

• The length, measured in beats or bars.
  
• The speed or tempo, measured in BPM (beats per minute).
  
• The groove, mainly determined by the deliberate swing or inaccuracies in the drummer's timing.

Essentially, we want to be able to understand the drum rhythm closely enough to be able to manipulate it without any hiccups. This is one way in which my methods vary from those of other producers. To me, it's important to make an assessment on a per drum rhythm basis. In my opinion, to limit yourself to 1 simple technique is to limit yourself to work better with some samples, and not so well with others. The aim of my approach is optimum flexibility and control. That's why my methods are based on selecting different techniques, as appropriate.

The Length

At this point, we're really thinking about length in musical terms. It doesn't matter how many seconds the drum rhythm lasts. What's more important is whether it loops smoothly and how many bars it lasts. For the purpose of this guide, I'll assume that you're working with music that's made up of of 4 beats per bar. What does that mean? Well, written music can be split into equal segments called bars. A bar is sort of like the musical equivalent of a sentence. Assuming that there are 4 beats per bar, then we are dealing with bars that last 4 equal counts, '1, 2, 3, 4'.

So here is our example drum sample. Have a listen:
The example drum rhythm played 4 times
^This example consists of 1 drum rhythm that lasts 1 bar, played 4 times. Hence, the sound lasts for 4 bars (16 beats), with all it's repetitions.

Now listen to the same sample in isolation:
The example drum rhythm played just once
^This example consists of the very same drum rhythm, played 1 time. Hence the sound lasts for 1 bar (4 beats), with no repetitions.

To help get an idea of where the beats are:
The example drum rhythm played once with indicated beats
^In this example, I have added an electronic blip to indicate where the beats are positioned. You'll notice that it has nothing to do with how the drummer is playing. In music that's built on 4 beats per bar, each beat is equally spaced. Okay, to please the pedants, a human performance is rarely as accurate as a machine, and sometimes the timing of the beats can vary slightly with a non-uniform song tempo. However, on paper and in your sequencer, each beat lasts an equal portion of the bar. In this case, there are 4 beats. If you count along '1, 2, 3, 4' with the blips as it plays, you'll see what I mean.

So what is our aim, with relation to length? In the example above, our drum rhythm lasts exactly 1 bar. This is not always true of a sampled drum rhythm. Ideally what we want is for our sample to last an exact number of bars. 1 bar is simple enough, a 2 bar sample is also good, as are 4, 8, or 3 bars. 2.82 bars are not useful for the techniques I'm sharing with you. If your drum rhythm doesn't last a whole number of bars, then you need to fix it so that it does. Again, remember that this is not to do with the length in seconds, it is to do with the number of beats. If you have a sample that lasts for 5 beats, then you're going to need to chop 1 beat off to make a 1 bar loop (4 beats). If it lasts 5.3 beats, then chop off 1.3 beats - or whatever you need to make it a multiple of 4 beats.

You will notice that your audio editor allows you to play your sample in a loop, where it returns to the start of the section after each play, and plays it again and again until you stop it manually. You will know when your sample is a 1 bar loop because you'll be able to continually count in beats, '1, 2, 3, 4, 1, 2, 3, 4...', while it's looping, returning to the '1' count at the start of the sample. If you've been trying to put breakbeat patterns together without this skill in the past, my sincerest condolences go out to you.

I recommend you use the drum rhythm sample that I've provided if it's your intention to actively follow this guide, and try with your own samples later. Otherwise it might become tricky to follow in a sequential order.

The Tempo

Tempo is the musical term for speed, it's how quickly each beat occurs. Typically, tempo used to be expressed as 'moderato', 'allegro', 'presto', and a bunch of other Italian terms that aren't accurate enough for what we're doing. In our electronic age, tempo is expressed in terms of BPM (beats per minute). Be thankful, because this is perfectly practical for accurate manipulation. This is where it's very useful to know the length of a drum rhythm in seconds as well as beats. With that knowledge, we can determine the BPM, and ultimately, alter it. Hold it! Don't reach for your stop watches just yet, guys ... Our audio editing software has blessed us with the ability to just read the length of the sample in seconds straight off the screen!

Now let's go back to the example drum rhythm. Open the 1 bar sample in your audio editor (hattrixx-example-2.wav), and play it in loop mode. So what do we know about it? We know the musical length (4 beats = 1 bar), and we know the length in seconds (my audio editor reports 2 seconds). What we want to know is the BPM (how many beats there are per minute).

So here comes the maths:

We can express:
60 (the number of seconds per minute) ÷ [full length (in seconds) ÷ number of beats] = tempo in BPM

Therefore:
60 (the number of seconds per minute) ÷ length of 1 beat (in seconds) = tempo in BPM.

In our case:
60 seconds ÷ [2 seconds ÷ 4 beats] = 120 BPM.
so
60 ÷ [0.5] = 120.

This might seem a little complicated at first glance, but when we put the numbers in it starts to make sense. Stay confident even if you're no good at maths. I'm not great. It's only after years of working with these equations that I know them off by heart - I had to use reference notes for a long time! Just remember to do what's in the brackets first.

We can also express:
60 (seconds in a minute) ÷ BPM = length of 1 beat (in seconds)

Therefore:
[60 seconds ÷ BPM] * number of beats = full length (in seconds) of sample at that tempo.

In our case:
60 ÷ 120 (BPM) = 0.5 seconds per beat.
so
[60 ÷ 120] * 4 beats = 2 seconds in the full sample.

Hopefully it'll be clear to you what can be done with this knowledge. Now, in theory, you should be able to determine the BPM of a sampled drum rhythm, and change it to any BPM that you please. Don't worry if you didn't pick that up, because I'm going to be kind and supply the formulas anyway. Even if you were able to follow the above, make sure you note the following:

FORMULA FOR FINDING THE TEMPO (BPM) OF A SAMPLE:
Step 1) Find the number of seconds the loop lasts, and write down the number.
Step 2) Find the number of beats the loop lasts, and write down the number.
Step 3) Divide the number of seconds by the number of beats, and write down that number.
Step 4) Divide 60 by the result from Step 3. Voila - now you have your BPM.

FORMULA FOR FINDING WHAT LENGTH TO STRETCH (IN SECONDS) YOUR SAMPLE TO:
Step 1) Divide 60 by your destination BPM. (For example 60 ÷ 120)
Step 2) Multiply the result from Step 1 by the number of beats you have. Tada! You now have the length in seconds of your sample at your destination BPM.

That's all there is to it.

The Groove

All I will say on this subject is; be aware of groove. There was a time during my learning curve, when I thought that a drummer's groove was insignificant. WRONG. With this attitude, you will run into problem after problem. The groove is something that you should have the power to retain and manipulate at will. To appreciate the natural looseness of a breakbeat is to appreciate that the tempo of a rhythm isn't the only factor that controls the energy. This is crucial, be a step ahead of the morons with the 'faster is better' mentality.