Creative Side‑chaining Effects

Ableton Live Tips & Techniques

Published in SOS June 2011
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Technique : Ableton Live Notes

Creative side‑chaining effects in Ableton Live.

Craig Hitchings

A side‑chained Gate with drums as the input source will enable you to chop short bursts of silence into any audio signal.A side‑chained Gate with drums as the input source will enable you to chop short bursts of silence into any audio signal.

Len Sasso covered the many applications of side‑chain compression in these very pages back in August 2010. However, regular Live users may also have noticed that the Auto Filter and Gate plug‑ins feature side‑chaining options. These can be applied to help lock parts together or to create rhythmic effects. This month I'll be showing you two ways to further exploit side‑chaining, and demonstrating how to employ Live's Vocoder to radically alter the texture of a drum track, which is another interesting way of using one part to affect another.

Please Shut The Gate

Let's start off simple. Open a new project and create an audio and a MIDI channel within the Session View. I'm using a drum loop taken from KJ Sawka's Mad Beatz Live Pack, which is available as a free download from Ableton's web site: www.ableton.com/pages/2009/kj_sawka_mad_beatz. I've put the 'Drum and Bass 160 White Kit 04.alc' loop into the first slot, renamed the channel 'Drums' and ramped the project tempo up to 160 bpm.

On the MIDI channel, I'm using Ableton's Analog synth, although you can use any instrument you like, or even a sample, so long as you can generate a sustained sound. I double‑clicked the first clip slot and manually drew in a single note on C1 over one bar. Within Analog itself, I activated Osc2, set its Shape to square and increased the Amp's Sustain to 1.00. Playing this back sounded utterly hideous, but engaging the filter, reducing the cutoff to around 275Hz and bringing up the resonance to 50 percent took off some of the harshness.

A basic detuned sawtooth sound created in Ableton's Analog synth.A basic detuned sawtooth sound created in Ableton's Analog synth.Now to add some rhythmic spice... Load a Gate after the synth and open its side‑chaining facilities by clicking the small triangle symbol in the Device Title Bar. Activate the Side‑chain button and the synth will, thankfully, be silenced momentarily! In the Audio From menu, choose 'Drums', and things will begin to take shape. Now the synth will only sound when the input from the Drums channel exceeds the Threshold, which you can adjust to taste, catching every single element of the drum loop or only the very loudest hits, for example, depending on how busy you want the synth part to be. Another key parameter is Hold, which can be used in conjunction with the Release knob to adjust how long the gate is held open, creating anything from short bleeps to long blasts. The Attack dial adjusts the time it takes for the gate to open after the side‑chain input has exceeded the Threshold — try using high Attack settings to create offbeat stabs that land between the main drum hits. Note that in the example shown in the screen above, I've modulated the filter cutoff with LFO1 to create some more interesting changes in the sound. With the synth locked to the drums, you can always create some great rhythmic variations by cutting up the drum loop itself.

Breaking The Mould

Side‑chained band‑pass filters are great for generating rhythmic layers of sound.Side‑chained band‑pass filters are great for generating rhythmic layers of sound.

Now let's take a look at a way of using the Auto Filter's side‑chaining functions. Sticking with the theme of locking parts together, I've used a breakbeat to completely alter the character of a fairly static pad sound. I placed another KJ Sawka audio loop, 'Drum and Bass 160 Whitekit 02.alc', into a fresh slot within a new project and again raised the tempo to 160 bpm to match that of the break.

For the pad, I decided to use a very basic approximation of the detuned sawtooth sound that's often used in drum & bass. I loaded an Analog synth on a MIDI channel and created a clip that plays the note C1 over two bars. To get this sound, you can either copy the settings shown in the screen to the left or create a similar pad in any other two‑oscillator synth, remembering to use two sawtooth waves (one of which should be detuned by around 15‑30 cents) and turning the main amp's sustain to its maximum setting to create a wall of rumbling sound. I've used a low‑pass filter with the cutoff set at 5kHz and dropped the second oscillator by an octave, to create a much more bass‑heavy tone.

Pushing The Envelope

Very short Attack and Release settings (far right) ensure that the Auto Filter's cutoff Frequency reacts quickly.Very short Attack and Release settings (far right) ensure that the Auto Filter's cutoff Frequency reacts quickly.

Now let's add an Auto Filter to further shape the pad. Again, you'll need to open the side‑chaining options, so engage the Side‑chain button and select the drum break in the 'Audio From' menu. The Auto Filter reacts in a more dynamic way than the Gate, by constantly adjusting the cutoff frequency of the filter in relation to the level of the side‑chain input. However, you won't hear any difference until you adjust the Envelope Amount control, which dictates how much the cutoff frequency will move. Set this at 127 to get an idea of how it works.

With positive Envelope Amount values, the cutoff Frequency will increase in proportion to the volume envelope of the side‑chain input signal. A negative setting will do the opposite, reducing the cutoff Frequency from its starting point. Naturally, the Attack and Release dials dictate how quickly the filter cutoff adjusts to the input signal. You should experiment with the Filter Types to create dramatic filter patterns. I opted for a band‑pass filter, with a cutoff Frequency of 70Hz, Envelope Amount at 70 and fairly quick Attack/Release settings, as in the screen at the top of the page. This turns the pad into a bubbling undercurrent of sub-bass that pulses with the breakbeat to emphasise the main hits.

Finally, I duplicated the synth channel to add another subtle layer of higher frequency content. For this, I set the cutoff frequency to maximum and reduced the Attack and Release settings drastically. I also opted to use a negative Envelope Amount setting to bring the cutoff Frequency down on the break's loudest hits, then reduced the channel volume to taste, as in the screen below. Of course, once you've created some filter movement on your own pad sounds, you can always deactivate the channel from which you're taking your side‑chain input. This will create a silent trigger, the side‑chain input not being heard during playback.

Speech Therapy

The frequencies of the filter bank in Live's Vocoder are shifted down by three octaves, using the Formant knob, for a warmer tone.The frequencies of the filter bank in Live's Vocoder are shifted down by three octaves, using the Formant knob, for a warmer tone.

Now for my favourite trick: using Live's Vocoder on a drum track with a synth as the Carrier signal. This bizarrely sounds more like a highly dynamic synth than it does drums, and can be employed to generate synth parts that mirror your drum tracks in very creative ways. To achieve this type of sound, I recommend setting up two identical audio channels with the same break loaded into adjacent slots, so that you can simultaneously play back the original break along with your new drums/synth hybrid. This time, I use the much more spacious KJ Sawka 'Dubstep 70 Brabeat 03.alc' break.

Create a new MIDI track and load up a synth of your choosing. Once again, I've gone for Analog, making sure that the Amp's Sustain is turned up to maximum to give me a prolonged tone, but feel free to use whatever sustained sound you want. In the MIDI clip, I programmed a C-major chord across four bars, with the root at C1. Returning to the first drum channel, I loaded up a Vocoder, changed the Carrier to 'External' and selected 'Analog' in the 'Audio From' menu. Playing this back drastically changes the texture of the drum track. Of course you'll need to adjust the Gate Threshold to catch the drum hits just right, and it's also worth enabling the Enhance button, which will result in a harmonically richer tone.

Now it's simply a matter of tweaking the Vocoder until you have the perfect tone for your particular track. Reducing the number of Bands will lend a more lo‑fi edge to your new instrument and lowering the Filter Bandwidth will thin out the sound, for example. At the same time, the Formant dial can be used to fundamentally alter the overall tone by shifting the frequencies of the filter bank by up to three octaves, as you can see in the screen at the bottom of the page. If you want you hybrid instrument to be less 'stabby', try compressing the drum track to reduce its dynamic range (note that, after doing this, you'll have to readjust the Vocoder's Gate Threshold).

Don't forget that in all the examples I've covered above, you can also use single drum hits as your source, so that a synth only follows the rhythm and volume of the hi‑hats, for instance. And remember that, as always, the key is to experiment until you find that fresh sound that can help inspire the rest of your track.    .


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