Master Class: Rack 'Em Up

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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.)

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FIG. 1: In a Drum Rack, each pad corresponds to a MIDI note. Sixteen pads are visible at a time, and supported MIDI pad controllers always play the visible pads.


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.


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.

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FIG. 2: You can select and drag several chains from the submixer to the drop area to create a new Drum Rack and associated MIDI file.

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.


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.

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FIG. 3: After slicing drum and bass audio loops to new MIDI tracks, you may need to adjust the drum MIDI file to accommodate differences in the bass slices.

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).


Although you can trigger audio clips in Session-view slots directly from a MIDI keyboard, Drum Racks provide an interesting alternative. You can sequence the triggering of Drum Rack pads, whereas you must go through some convoluted MIDI routing to sequence triggering of Session-view slots. You can use Simpler's looping feature instead of warping the clip as you must do to loop its playback in a Session-view slot. On the other hand, you cannot apply real-time quantization to triggering Drum Rack pads as you can when triggering slots. Probably the biggest advantage to using a Drum Rack rather than slots for playing audio clips is that you can control multiple clips with individual effects processing from a single track.

You can drag audio clips directly to Drum Rack pads from the Live browser, Session-view slots, Arrangement-view tracks, or your computer's desktop. If you want the clips to adapt to the song tempo, ensure that warping is set up the way you want it in Live's Record/Warp/Launch preference tab. (If the clips have already been warped and analysis files have been saved, they will retain their warp settings regardless of the preferences.) Because Live sometimes guesses wrong about a clip's length and tempo, it's a good idea to check each clip before inserting it into the Drum Rack. To lock in the tempo in Session view, you need to somehow render the warped clips. You can resample the clips on a different audio track, or freeze them and then either copy the frozen clips to a new audio track or flatten their track (which is destructive).

When dealing with several clips, I prefer to consolidate them on an Arrangement-view track and slice them to a new MIDI track as in the previous example. Although it involves a bit more work, this method lets you use Drum Rack preset templates. Consolidating automatically locks in the song tempo, so you needn't worry about rendering. Before consolidating in Arrangement view, ensure that each clip starts on a bar line, and note which bar lines begin new clips or place a marker at the beginning of each clip for future reference. After consolidation, create a Warp marker at the beginning of each clip (and nowhere else) before slicing to a new MIDI track.

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FIG. 4: Map Macro knobs to control each Simpler''s Start, Loop, and Length, then assign a range of MIDI notes to those knobs to manipulate the loop from your keyboard.

Built-in 0-Vel is a viable preset template, but I prefer a different mapping of the Macro controls. You'll find my template, called “Looper,” in Web Clip 3. I use the top four Macro knobs to control each Simpler's clip-start, clip-length, loop-length, and loop-fade parameters (see Fig. 4). Notice that the Macro 2 and Macro 3 knobs have their range reversed, and that the Macro 3 knob, at its maximum value of 127, also turns looping off.

It helps to keep in mind how a Simpler's Start, Length, and Loop knobs interact. Each is calibrated in percent, but, except for the Start knob, that's a bit deceptive. The Length knob has no effect if its setting is larger than the portion of the clip after the start position. The Loop setting is in proportion to the adjusted length. For instance, if Start is 50 percent, Length is 40 percent, and Loop is 50 percent, then the portion of the clip between 50 and 90 percent plays, and the last half of that portion is the loop.

You can assign MIDI note ranges to control Live's knobs and sliders, and that's very useful here because the settings are equally divided over the note range. If, for example, you assign a range of five notes, they will set the knob to 0, 25, 50, 75, and 100 percent of its value range, respectively. For Start, Length, and Loop, a 5-note range divides the clip into quarters; a 10-note range, into eighths. On a 3-octave keyboard, I use C1 through F#2 to gate Drum Rack pads, and I use G2 through B2, C3 through E3, and F3 through A3 to control the Start, Length, and Loop Macro knobs. Reversing the range of the Length and Loop knobs makes the use of the keys more natural — higher notes always shorten.

Once you've embedded your clips in a Drum Rack, keep in mind the trick from the “Scrambled Beats” section of dragging some Drum Rack pads to new tracks to create separate racks for different kinds of material. For instance, you might want different racks for percussion (usually looping), chord instruments (looping but probably not transposable), and solo instruments (usually not looping but transposable).


Drum Racks provide a great way to turn a collection of Session-view Scenes into a real-time instrument. Each chain in the resulting Drum Rack holds another Drum Rack whose chains, in turn, hold audio clips rendered from the tracks in one Scene. Triggering a main Drum Rack's chain triggers a rendered Scene. You retain control of each Scene's mix, but as with the loops in the previous example, the tempo is locked in. You can even nest playable instruments in the main Drum Rack to create a band in a box.

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FIG. 5: Resample Live Scenes and load them into a Drum Rack for real-time sequencing.

First, create some Scenes that work well together — alternative bass, drum, and rhythm-guitar Scenes of the same length that follow the same chord changes, for instance (see Fig. 5). I often use this technique with Follow Actions on several Scene tracks to capture the Follow Actions in a new Scene. Don't overlook Live's new External Instrument, which lets you use standalone virtual instruments (if your system is set up for that) and ReWire devices such as Propellerhead Reason in your Scenes.

For each Scene track, create a new audio track and route the original track's output to it. Record-enable all the new audio tracks and ensure that their clip Slots have Clip Record buttons. Trigger each Scene and dub one pass (including any Follow Actions) to new audio clips.

Once you've recorded the dubs and saved them in the project's Samples folder, create a new MIDI track with an empty Drum Rack. Hold the Command key (Ctrl in Windows), select the clips that belong to the first Scene, and drag them to a Drum Rack's C1 pad (see Fig. 6). That pad will be relabeled Multi, its chain will contain a nested Drum Rack with a separate chain for each clip, and each of those chains will be assigned to note C1. Repeat that process, dragging the clips from the other Scenes to different pads, and you'll have each of the original Scenes triggered by a Drum Rack pad.

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FIG. 6: Drag all the resampled clips for a Scene to the same Drum Rack pad.

You can do a number of things with the main Drum Rack to make it more playable. As mentioned earlier, you can add a Note Length MIDI plug-in before each of the nested racks and set its Length knob (in Time mode) to the length of the Scene to convert triggers to gates. In order to switch between trigger and gate mode for all Scenes, map each Note Length plug-in's Device On button to a Macro knob of the main rack.

I like to map each of the nested Scene's chain-volume controls to Macro knobs of the main rack. To do that, you first need to map them to the Macro knobs of the nested racks, then map those Macro knobs to Macro knobs of the main rack. At the same time, you can create an overall volume knob by mapping each of the main rack's chain-volume controls to the same Macro knob. If you insert send effects (reverb, for instance) in the main rack, you might want to map all the send-level controls to a Macro knob as well.


You can make your Scene-playing Drum Racks self-contained instruments by adding one or more chains of virtual instruments — for example, a lead sound to play along with rhythm-section Scenes. To keep Scene triggering and playing out of each other's way, use an Instrument Rack for the virtual instrument, and use the instrument chain's key zone to avoid overlaps. If you install more than one virtual instrument chain, use the Instrument Rack's chain selector to switch instruments. To cover different instrument ranges with a small keyboard, insert a Pitch MIDI effect before the Instrument Rack.

Of course, you're not limited to triggering the dubbed Scenes manually. You can use MIDI clips to trigger them, and if you use a separate clip to trigger each Scene, you can use Follow Actions to sequence them — something you cannot do with Scenes directly in Live. Furthermore, you can use clip automation to control mixing and other parameters in the Drum and Instrument Racks.

Only clips on the Drum Rack track have envelopes for Drum Rack parameters. If you want to separate clip automation from Scene triggering, put the clips with the automation on the Drum Rack track and put the clips with the triggering notes on another MIDI track whose output is routed to the Drum Rack. Clip automation is especially effective for soloing Scene tracks and controlling the sends to dense effects such as Grain Delay and Beat Repeat that are best when used sparingly (see Web Clip 4).

Drum Racks open up a whole range of new sequencing and live-performance possibilities. Getting a Drum Rack to do what you want, especially when you're nesting Instrument and Drum Racks inside each other and using their Macro controls, can take some planning. But it's well worth the time invested, and the process gets faster as you become more familiar with Drum Racks.

Len Sasso is an associate editor of EM. For an earful, visit his Web site

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