I Sing The Vocoder Electric

From the lowest note of the bass drum to the crisp high sizzle of cymbals, the voices of the drum set have always suggested the possibility of melodic playing. And throughout the history of the instrument, many great drummers have approached the kit with an ear for melodicism. However, I've always wanted to go beyond the unspecific pitches of drums and cymbals and actually play chords and bass lines from my acoustic drum set.

My first CD, itrhymes, released in 1994, contained several solo pieces in which I triggered melodic and harmonic content from acoustic drums and pads. After years of experimentation with MIDI and triggering, I finally decided such technology was unreliable. These early attempts, which involved MIDI triggering and slicing through sequences of preprogrammed notes, were fraught with potential disaster.

Cross triggering or an accidental double stroke could easily bump a bass line out of sync with the chord structure. And I was limited and obliged to play exactly the correct number of notes in each sequence. One missed or extra stroke would throw the whole thing out of whack.

After trying many different approaches, I found a reliable and very expressive way to play harmonic material from the drum set, which I now use in live performance. My latest CD Idiot Fish features many examples in which I play bass lines from the bass drum and chord structure from the snare drum — and it doesn't stop there. Wobble basses, voices, glitch sounds — the sky's the limit — all played live from an acoustic drum set.

This technique is almost foolproof. As long as you're comfortable playing with a click, you can play as many or as few notes as you want, and the way you hit the drum will affect both the volume and timbre of the sound. The method involves the use of vocoders, and thankfully, computer technology has developed to a point where we can actually use them in a fairly effective way.

This article will teach you the process I developed and the tools I use. For purposes of demonstration I will use a simple and familiar blues form and chord structure for harmonic examples. But, of course, this is only a starting point. Basically any sound you want to initiate and mold by striking a drum can be adapted to this method.

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Vocoder MP3 Example



Everyone has heard the results of the vocoder, which is most commonly used to create a synthesized robotic voice. It's an audio processor that captures the characteristics of an audio signal, sometimes called the modulator, and applies it to a synthesized sound that is simultaneously fed into the vocoder. This second sound can be referred to as the carrier. For example, the performer says, "Hey, let's party" into a microphone while some brassy synth chords are fed into the vocoder. The result is a brassy synth robot saying, "Hey let's party."

In order to make each drum play its own unique set of sounds, you need a separate vocoder for each drum in your kit. At one time this idea was just too pricey and bulky, back when vocoders were standalone hardware units. (They also sometimes came as a component of a synthesizer.)

However, software vocoders are now available, making it possible to run multiple vocoders simultaneously on a single laptop. Ableton Live software is perfect for this process, since it makes multiple vocoders accessible and is perfectly suited for handling loops of chords, bass lines, and other sounds you'll want to use.

For our project, we will feed the sound of our snare drum and bass drum into vocoders, while inputting the audio of our desired blues chord changes and bass line. The result will be heard each time we hit the drum to which the sound has been assigned. We'll dig deeper into that later.

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First you need an audio interface to convert the sound of your drums from analog to digital. This usually connects to your computer via a USB connection, although other connections like firewire can also be used. These interfaces are priced from around $100 to thousands. I use a Focusrite Scarlet interface that has four inputs and four outputs and costs around $200. I'll use only two inputs in this example, but typically I use all four to vocode from my toms as well. It's nice to have four outputs so that two can be sent to sound reinforcement, while the other two are assigned to your headphone, where you can send a click and the audio results of your vocoding. These routing options are usually accomplished though the software of your audio interface.

In early attempts, I used clip-on microphones attached to the drums, but experienced problems with feedback and crosstalk from the other instruments and drums. Putting a noise gate on each channel helped a little, but I had to set the threshold too high to make it effective, resulting in lots of missed notes as the gate stopped quieter hits from being heard.

The solution? You might be surprised to read this, based on what I wrote about my earlier attempts, but I wound up using drum triggers. Here's the trick — I didn't use them to trigger anything. See, triggers are basically really poor microphones. They typically consist of PZM transducers, which is an acronym for "pressure zone microphone." A trigger offers far more isolation than an actual microphone, and yet still picks up characteristics of the drum. They can cost as little as $20 and as much as $100. Simply mount them on the drums, plug them in to audio inputs on your interface, and play with the input levels as you strike each drum to make sure you're getting a strong, clean signal that doesn't overload the system.

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The system described in this article can vocode any sound, but for this "blues" project I recommend a string or brassy sound for the chords and bass line (although any bass sound will be fine). These can easily be created in Ableton Live.

For this project we will need a total of four tracks. Two will be audio tracks and two will be MIDI tracks, as shown in Fig. 1. In Ableton Live, this is done either through a pull-down menu, or Windows CTRL–T/Mac CMD-T for audio tracks, and Windows CTRL-Shift-T/Mac CMD-Shift-T for MIDI tracks.

One of the MIDI tracks will be a brass synth sound and the second will be a bass sound. You can simply drag and drop synth plugins from Ableton's supplied plugins for this. Fig. 2 shows the menu on the left where we dragged the Ensemble Brass synth plugin shown at the bottom of the screen. Do the same in track two for any bass sound you like.

Now we will use a MIDI keyboard to record the chords on track one and a bass line on track two in solid whole-note values to fill the measure with an even sound. The long red lines you can see in the MIDI clip at the bottom of Fig. 3 represent the long notes of our chords.

If you choose a sound patch for the chords or bass that has a quick decay, you may want to change the envelope of that sound to get solid, sustained notes. This is important, because the sound will be heard only when you hit a drum, and you want each note to be strong whether you strike at the beginning or the end of a measure.

The track's audio output is set to "Master" by default, so you can hear what you play through the master output. So after recording your MIDI clips, set the output of these tracks to "Sends Only" (shown in the pull-down menu in Fig. 4) to mute the audio output going to the master output. The audio loop you created will continue running, but we will hear it only through the vocoders rather than the master output.

Now you have two channels with synth chords and a bass line, so it's time to set up audio tracks for the vocoders. First, set the monitor section of each audio track to "In" (Fig. 5) so you can hear the throughput of your snare and bass. Then go to the input section of each audio track and select "Ext. In" for the input from the pull-down menu shown in Fig. 6.

Follow the same process to select the input channels in which your triggers are plugged. Fig. 7 shows input 1 (track 3) as my bass drum and input 2 (track 4) as my snare. By dragging and dropping from the menu at the left side of Ableton Live, shown in Fig. 8, we will now place a noise gate plugin, vocoder plugin, and compressor plugin in each of these tracks.

The noise gate is important because even though the triggers offer more isolation than a microphone would, we still need to limit crosstalk from other nearby drums. Set up a low threshold to eliminate cross-triggering yet still allow for some sensitivity. The compressor will help control dynamics, maintain an average level in the overall mix, and control any unwanted spikes.

Assign both the carrier and audio sources using the pull-down menus in the vocoder plugin, shown in Figs. 9 and 10. First set the carrier to "External," which will feed the sound of your drums into the vocoder. Then assign the "Audio From" — in this case "Ensemble Brass" track 1 will be assigned to the snare vocoder with chords, and "Dual Osc 3 Buzz Octaves Bass" will be assigned to the bass drum vocoders with single notes, which are merely the roots of the chords.

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As long as everything's set up correctly, you should be good to go. Put on a set of headphones and hit "play" in Ableton Live. Make sure the click is on and you can hear it. Click the arrow icon next to the 1 in the Master Track on the far right to fire up both loops and start the whole "scene" (as Ableton Live calls the horizontal row of loops). In this example, we are using only scene 1. If you've done it correctly, you shouldn't hear anything after clicking on the arrow.

Now hit your snare, and — voila! — you will hear the sound of your chord pattern as well as the bass playing the low notes. Fig. 11 shows the transient spikes at the left in the noise gate created while I played the bass drum; the vocoder doing its job in the middle analyzing different bands of frequencies; and the compressor on the right keeping things in check.

You can play with adjustments in the vocoder like depth, format, attack, and release, which all will affect your results. These are just personal preferences, though, so experiment and have fun.

To view a video of me playing this exact Ableton Live file, go to drummagazine.com/vocoder. You will also find the actual Ableton Live file for download, in case you have the software and want to experiment with our "blues" project on your own. Finally, you can also check out my band Idiot Fish, which extensively uses this technique on the drums. Go to idiotfish.net for even more.