Coded Beats

One of the most exciting and disrupting technical developments in modern music was the invention of samplers. These were boxes that allowed you to record any sound into them and then manipulate and play back those sounds in many interesting ways. For example, you could take an old record, find a drum solo (or break), record it into your sampler and then play it back on repeat at half-speed to provide the foundation for your latest beats. This is how early hip-hop music was born and today it’s almost impossible to find electronic music that doesn’t incorporate samples of some kind. Using samples is a really great way of easily introducing new and interesting elements into your live coded performances.

So where can you get a sampler? Well you already have one - it’s your Raspberry Pi! The built-in live coding app Sonic Pi has an extremely powerful sampler built into its core. Let’s play with it!

The Amen Break

One of the most classic and recognisable drum break samples is called the Amen Break. It was first performed in 1969 in the song “Amen Brother” by the Winstons as part of a drum break. However, it was when it was discovered by early hip-hop musicians in the 80s and used in samplers that it started being heavily used in a wide variety of other styles such as drum and bass, breakbeat, hardcore techno and breakcore.

I’m sure you’re excited to hear that it’s also built right into Sonic Pi. Clear up a buffer and throw in the following code:

sample :loop_amen

Hit Run and boom! You’re listening to one of the most influential drum breaks in the history of dance music. However, this sample wasn’t famous for being played as a one-shot, it was built for being looped.

Beat Stretching

Let’s loop the Amen Break by using our old friend the live_loop introduced in this tutorial last month:

live_loop :amen_break do
  sample :loop_amen
  sleep 2
end

OK, so it is looping, but there’s an annoying pause every time round. That is because we asked it to sleep for 2 beats and with the default BPM of 60 the :loop_amen sample only lasts for 1.753 beats. We therefore have a silence of 2 - 1.753 = 0.247 beats. Even though it’s short, it’s still noticeable.

To fix this issue we can use the beat_stretch: opt to ask Sonic Pi to stretch (or shrink) the sample to match the specified number of beats.

Sonic Pi’s sample and synth fns give you a lot of control via optional parameters such as amp:, cutoff: and release:. However, the term optional parameter is a real mouthful so we just call them opts to keep things nice and simple.

live_loop :amen_break do
  sample :loop_amen, beat_stretch: 2
  sleep 2
end  

Now we’re dancing! Although, perhaps we want to speed it up or slow it down to suit the mood.

Playing with Time

OK, so what if we want to change styles to old school hip hop or breakcore? One simple way of doing this is to play with time - or in other words mess with the tempo. This is super easy in Sonic Pi - just throw in a use_bpm into your live loop:

live_loop :amen_break do
  use_bpm 30
  sample :loop_amen, beat_stretch: 2
  sleep 2
end 

Whilst you’re rapping over those slow beats, notice that we’re still sleeping for 2 and our BPM is 30, yet everything is in time. The beat_stretch opt works with the current BPM to make sure everything just works.

Now, here’s the fun part. Whilst the loop is still live, change the 30 in the use_bpm 30 line to 50. Woah, everything just got faster yet kept in time! Try going faster - up to 80, to 120, now go crazy and punch in 200!

Filtering

Now we can live loop samples, let’s look at some of the most fun opts provided by the sample synth. First up is cutoff: which controls the cutoff filter of the sampler. By default this is disabled but you can easily turn it on:

live_loop :amen_break do
  use_bpm 50
  sample :loop_amen, beat_stretch: 2, cutoff: 70
  sleep 2
end  

Go ahead and change the cutoff: opt. For example, increase it to 100, hit Run and wait for the loop to cycle round to hear the change in the sound. Notice that low values like 50 sound mellow and bassy and high values like 100 and 120 are more full-sounding and raspy. This is because the cutoff: opt will chop out the high frequency parts of the sound just like a lawn-mower chops off the top of the grass. The cutoff: opt is like the length setting - determining how much grass is left over.

Slicing

Another great tool to play with is the slicer FX. This will chop (slice) the sound up. Wrap the sample line with the FX code like this:

live_loop :amen_break do
  use_bpm 50
  with_fx :slicer, phase: 0.25, wave: 0, mix: 1 do
    sample :loop_amen, beat_stretch: 2, cutoff: 100
  end
  sleep 2
end

Notice how the sound bounces up and down a little more. (You can hear the original sound without the FX by changing the mix: opt to 0.) Now, try playing around with the phase: opt. This is the rate (in beats) of the slicing effect. A smaller value like 0.125 will slice faster and larger values like 0.5 will slice more slowly. Notice that successively halving or doubling the phase: opts val tends to always sound good. Finally, change the wave: opt to one of 0, 1, or 2 and hear how it changes the sound. These are the various wave shapes. 0 is a saw wave, (hard in, fade out) 1 is a square wave (hard in, hard out) and 2 is a triangle wave (fade in, fade out).

Bringing it all together

Finally, let’s go back in time and revisit the early Bristol drum and bass scene with this month’s example. Don’t worry too much about what all this means, just type it in, hit Run, then start live coding it by changing opt numbers and see where you can take it. Please do share what you create! See you next time…

use_bpm 100

live_loop :amen_break do
  p = [0.125, 0.25, 0.5].choose
  with_fx :slicer, phase: p, wave: 0, mix: rrand(0.7, 1) do
    r = [1, 1, 1, -1].choose
    sample :loop_amen, beat_stretch: 2, rate: r, amp: 2
  end
  sleep 2
end

live_loop :bass_drum do
  sample :bd_haus, cutoff: 70, amp: 1.5
  sleep 0.5
end

live_loop :landing do
  bass_line = (knit :e1, 3, [:c1, :c2].choose, 1)
  with_fx :slicer, phase: [0.25, 0.5].choose, invert_wave: 1, wave: 0 do
    s = synth :square, note: bass_line.tick, sustain: 4, cutoff: 60
    control s, cutoff_slide: 4, cutoff: 120
  end
  sleep 4
end