Master Class: Rack 'Em Up

May 1, 2008 12:00 PM, By Len Sasso

CREATIVE USES FOR LIVE'S NEW DRUM RACKS

The Drum Rack instrument is one of Ableton Live 7's most interesting new features, and its creative potential is enormous. You can build a virtual drum machine with different MIDI and audio effects for each drum sound. You can slice Live-warped or REX audio files automatically, allowing you to resequence the slices effortlessly. You can use it as a triggering device for loops and resampled Live Scenes and then use Live's other tools to manipulate those loops and Scenes. I'll start this master class with a brief account of how Drum Racks work, then cover these applications and more.

Like Live's Instrument Racks, Drum Racks house parallel chains of virtual instruments. You can place Live's built-in MIDI effects before the instrument and follow it with audio-effects plug-ins. But unlike with Instrument Racks, you do not need to set up key, Velocity, or controller zones to select the chains. Instead, you can tie chains to Drum Rack pads, which represent MIDI notes. When a pad is triggered by its associated MIDI note or by a mouse-click, it sends a note (C3 by default) to all chains tied to it. (For convenience, you can also set a chain to receive all MIDI notes directly, in which case it is not triggered by any of the pads.)

CONTROL, MIX, AND LOAD

A Drum Rack's pads are arranged in a four-by-four matrix just to the right of the rack's Macro knobs (see Fig. 1). When the rack is completely folded (Macro knobs, chains, and plug-ins suppressed), the pads remain visible. There are 128 drum pads, corresponding to the 128 MIDI Note Number range, and you use the slider to the right of the pad display to bring other pads into view. If you have a supported MIDI control surface with physical drum pads, their assignment follows the slider, so they are always mapped to the visible Drum Rack pads.

Three of Live's MIDI effects are especially useful with Drum Racks. If your control surface pads send short triggers, you may want to precede the rack with a Note Length MIDI effect to convert the triggers to fixed-length gates. (Use Time mode to create gates up to 60 seconds long.) For chains that receive all MIDI notes, use Pitch and Velocity effects at the beginning of the chain to set key and Velocity ranges. You can also transpose and perform various Velocity alterations with those plug-ins.

A Drum Rack can house up to six effects chains, and as effects chains are added, the Chain List sprouts send-level controls to the left of the volume, pan, mute, and solo controls. Those are all duplicated in a graphically more convenient foldout Session-view submixer. Each effects chain can house any number of effects or even nested Effects Racks.

Although you can plug any Live or third-party virtual instrument into a Drum Rack chain, the most common choice by far is Live's Simpler sample player. Whether you want a pad to trigger a single event (such as a drum hit, a sound effect, or an audio file slice), an imported loop, or a rendered Session-view Scene, Simpler is the simplest way to go. For that reason, dragging an audio clip from Live's browser or from a Session- or Arrangement-view track to a Drum Rack pad automatically inserts a Simpler in the chain and loads the dragged sample into it.

SCRAMBLED BEATS

Swapping slices of a REX or other sliced-format audio file is well-trod territory, especially with drum loops. It usually works better to swap similar-sounding slices, which might, for example, be found at the same beat position within different measures. Therefore, random swapping is not typically a viable option, but Drum Racks make it easy to introduce some randomness into the process.

The first step is to convert the audio file to a Drum Rack with each slice on a different pad. Live will do that automatically for any audio clip: just right-click on the clip in the browser or project to bring up its contextual menu, and select Slice To New MIDI Track. That brings up a dialog box in which you choose slicing parameters. For any format other than REX (for which Live uses the REX slices), you choose whether to slice by Live's Warp markers or some beat division. You also choose a slicing preset, and either Built-in or Built-in 0-Vel is a good choice. (With the latter, MIDI Velocity has no effect when triggering the slices.) You can create your own slicing presets by saving appropriately configured Drum Racks in the Library/Defaults/Slicing folder.

Once you have the file sliced into a Drum Rack, play each slice and mark down which ones are similar and, therefore, swappable. For each group of similar slices, Command-click (Ctrl-click in Windows) in the Drum Rack's Session-view submixer to select each chain in the group, then drag all the selected chains to an empty MIDI track or to the mixer's drop area (see Fig. 2). A new Drum Rack will be created, along with a MIDI clip containing the trigger notes for the moved slices.

To randomly swap the slices, first click-and-drag the Drum Rack pads so that the slices are contiguous. Next, double-click on the triggering MIDI clip to reveal it in the Clip view, and drag each of its notes down to the bottom row. (If you play the clip now, it will trigger only the first slice.) Now insert Live's Random MIDI effect before the Drum Rack.

The Random effect randomizes the MIDI Note Numbers of incoming notes based on five settings: Chance, Choices, Scale, Mode, and Sign. Set Choices to one less than the number of slices, Scale to 1, Mode to Rnd, and Sign to Add. Some MIDI notes played by the trigger clip will then be randomly transposed up by a number of semitones between 1 and the Choices setting. How often notes are transposed depends on the Chance setting. If you divide the number of slices into 100 and subtract the result from 100, each slice will be equally likely. For instance, if there are 10 slices, you would set Choices to 9 and Chance to 90 percent (see Web Clip 1). When you use lower Chance settings, the first slice is favored, which can be very useful.

If you have a percussion part that is particularly boring (a sequenced drum-machine loop, for example), try adding insert effects to chains playing similar slices. Although slice swapping is easiest to set up with unpitched material, it is not limited to that. Rhythm-section instruments with repetitive parts also make good fodder; just ensure that the swapped slices play the same pitch or chord.

CATCH THE GROOVE

Unlike many other sequencers, Live does not provide a way to automatically apply the groove of one audio file to another. But the aforementioned Slice To New MIDI Track feature makes it easier to do so manually, at least with short, similar files.

Suppose, for instance, that you have 1-bar bass and drum loops with different eighth-note swing feels, and that you want to conform the bass to the feel of the drum loop. Furthermore, suppose that the drum loop is not already sliced. (If it is, you won't need to use the slicing trick I'll discuss next — just proceed to matching up the slices.)

Place the drum loop on an Arrangement-view track, set Live's tempo to match, and turn on both warping and tempo master for the clip. Making the clip the tempo master lets you move the Warp markers as the file plays without hearing the effects of warping, which are irrelevant in this example. Set the Arrangement-view loop region to match the drum loop. In the Clip view, ensure that there is a Warp marker at the end of the drum loop (at the grid marker for bar 2) so that creating and moving other Warp markers won't change the overall clip length.

Set Warp markers for each of the eighth-note grid markers by double-clicking on them. (The leftmost number of a grid marker is the bar, the middle number is the beat, and the rightmost number is the 16th note within the beat. For instance, 1, 1.2, and 1.2.3 are all eighth-note markers, but 1.2.1 and 1.2.4 are not.) Move each of the Warp markers to the audible beginning of the note to which it corresponds. For a cleanly played swing-eighth drum loop, you will mostly be moving the 3-digit Warp markers to the right (see Fig. 3).

Turn tempo master off and slice the warped loop to a new MIDI track using the Warp markers. Mute the original loop and play the new MIDI track; it will sound just like the original (whereas the warped audio file will now have the swing removed).

To conform the bass to the drum loop, set its Warp markers as just described for the drum loop and also slice it to a new MIDI track. Instead of using the generated MIDI clip, copy the MIDI clip from the drum track. It's unlikely that the bass will slice as nicely into separate events as the drums. You may need to merge some of the bass loop slices and adjust the copy of the drum MIDI clip accordingly (see Web Clip 2).