Loop-Based Composition

Okay, I'll stand up and admit it. My name is Michael and I'm a loop-based composer. While some people believe that using loops to make up the majority of a piece of music is not really composition, I understand music theory and am quite comfortable working with a pencil, staff paper and the mechanics of writing music; nonetheless, I am drawn to loop composing. Webster's dictionary defines the word compose as (1) "to arrange shapes and colors into a painting" and (2) "to arrange words or objects into good order." According to the second definition, I would have to conclude that arranging loops to create a song qualifies as composition. The trick is having the ear to know what makes good musical sense, and the knowledge to manipulate the loops to achieve the results you are after. In this article, I want to take you through a hypothetical composing session and offer tips that help to get the most out of your tools. I work with Sonic Foundry's ACID software, but these tips also work if you are using Cakewalk's Sonar or other loop-based composition software.

Suppose that you are hired to compose a piece of music in a specific style for use as source music or underscore. Using loops, I've created everything from orchestral music to funk tracks. Having a large and versatile loop library will allow you to take on many different composing jobs. The first task is to determine the style. I've found it best to ask my clients for examples of music similar to what they want in their project. Then, I evaluate these examples to answer the following questions: What is the average tempo? What instruments or sounds make up the song? What is happening harmonically with the chord changes? Is there an active or a simple bass line? How is percussion used? What is the song's form? At this stage, you need to gather as much information as you can.

Fig. 1. A single bass guitar sample, starting pitch on an A, is pitch-shifted, ascending in quarter notes

Once you have a clear idea of what you need to accomplish, the next step is to

develop your content. I generally start by looking through my collection for sounds that fit the style. If you're like me, you've purchased looping CDs and have copied those loops you like best to your hard drive for easy access. These discs are often sold acidized and are therefore ready to use. You may also own audio content on CD-ROM, audio CD, or DAT tape, that may be useful but not trimmed to loop or acidized for easy use. I start with the non-acidized products. Once you know the type of source material you need for this piece, grab the CDs or DATs that make the most sense stylistically or that may contain sounds like those you noted during your listening session.

Fig. 2. Vertical lines show the software ideal time-stretching points.

Let's say you have an audio CD of bass guitar loops in the correct style. Play through the audio tracks and concentrate on those close to your planned tempo and key (a track's tempo and key are usually listed on the CD insert). When you find tracks that sound useful, extract them into an audio editor. At this stage, it is helpful to choose the chord progression you plan to use. If you are planning a verse with a simple I- to-IV chord progression, your ears will direct you to the bass guitar loops that are appropriate. It is important to note that I rarely find a stand-alone loop that is perfect for my composition. When you listen closely, you may find that a portion of a loop is all you need. Or you may find that a portion of one loop combined with a portion of another creates the part you need. If you are writing a simple bass part, you may only need a sample of a single bass note. This can be placed on any beat with your software, and the pitch can be shifted to make up the changes (figure 1.) Add additional content by performing the same procedure on material from your DAT sources or unacidized wave files on CD-ROM. If you have a DAT tape with some great Rhodes electric-piano loops on it, for example, record the loops into your audio editor.

Fig. 3. Volume envelopes in use: the blue lines seen on the kick drum (bar 11, on the "and" of three) and on the snare drum (bar 11, beat four) cause the sound to be played back a few decibels softer than the two previous hits.

Once you have placed selected content from these sources into your audio editor, start preparing the material for use in your looping software. Create your loops by combining sections or extracting individual notes. Get them to loop correctly so that the timing is perfect and the recording repeats seamlessly. Remove noises and fade them if necessary so that the end of a loop doesn't simply cut off. If you are using Sound Forge, you can acidize the loop by including the number of beats and pitch information in the files header. Sound effects (single drum hits and the like), can be set to one shot. The same can be done in ACID itself. Don't be afraid to experiment. As you build your content, be creative. For one composition, I needed a trippy, unrecognizable sound, so I took a loop of a jaw harp, ran it through a wah and other effects and came up with a completely new-sounding loop.

Next, you should load each wave file of your proposed content into your looping software to check the file's stretching properties. Changing the stretching properties and placing the stretch markers at the proper points makes a loop more useful (figure 2). At this point, you should have saved a batch of new content for the song and edited it so that it is ready for use. With this material, and your collection of stock acidized loops on your hard drive, you are ready to start assembling the song.

First, decide which section will begin the song. (It is not essential, however, that you start at the beginning of the song. It doesn't matter where you start, because moving, copying, or adding sections is never a problem in loop-based composing.) Suppose that you decide to begin with the chorus. Referring to your notes, you find that you wanted a 12-bar chorus. You've chosen the key of E major and a tempo of 108. Set the new song file accordingly. Check your notes for the instrumentation you wanted to use. A full-blown chorus, for example, might include bass, drums, Rhodes, guitar, percussion, a synth chordal pad, and sound effects.

Most musicians start constructing a track with a drum loop. You might previously have cut the exact loop you want to use, or you may be auditioning loops from your stock collection. If so, audition the loops that are closest to your tempo.

As an alternative to a loop, you could consider programming a pattern using one-shots. With this method, you take single hits of the kick and snare drums, and place them exactly where you want to make up the groove (using the "snap to" feature and pasting make this easy). Use volume envelopes to get the proper accents, because you won't want each attack played at the same volume (figure 3). The cool thing about this feature is that you can easily audition different kick and snare sounds after your pattern is built. In ACID, you simply drag the new sound from the explorer view to the track and all hits will be replaced with the new sound. The envelopes remain intact. You can build a hi-hat part in the same way or use a loop of an isolated hi-hat. I've often used a combination of one-shots and a drum loop, using the one-shots to double parts in the loop. This gives flexibility in the mix, enabling you to manipulate the loop by dropping or silencing it, allowing it to drop out for a single snare hit for example.

After settling on a drum track, continue to build your chorus by auditioning content. Next, you might audition the Rhodes loops you constructed earlier in your audio editor. Add the one you like best that works well with the drums. Next, let's say you audition the bass lines that you assembled, but find that none of them work. You could build a bass line using the single notes or small phrases that you cut earlier, or you could go to the stock loop collection on the hard drive.

One of the beauties of working with loops is that the software will play each loop you highlight in the proper tempo and key so you can instantly hear how it works against the other parts. Keep your tempo and key in mind as you make this search. Loops with a much different tempo or key may not stretch well, creating audible artifacts such as a warbling sound. When you find a bass line that would work if edited, you have plenty of options. Most looping software will allow you to erase unwanted audio and to split and slide the audio as you like. Another approach is to use volume envelopes to silence unwanted sections or to bring the audio into your audio editor.

At this point in the process, I usually feel like a conductor. I know what I want to hear as the song starts taking shape, and instead of asking the percussionist not to play the shaker on the "and of four," I just go in with the eraser tool and remove the shaker hit. Instead of asking a percussionist to change the pattern occasionally, I use three or four different shaker loops at different times. Here you need to draw on your musical sensibilities and your familiarity with the client's examples if you are to come up with a viable piece of music. Would the horn line sound better coming in on beat two? No problem, just slide it over a bit. I would caution you not to get so trapped into existing loops that you don't consider recording your own instruments. There is no need to search for the perfect guitar part if you can play it yourself.

After composing the other sections of the song and making final decisions on the song's form, go back and add drum fills, drops, and/or one-shot cymbal hits to make strong transitions between the sections.

Eventually I reach a point where I've taken the song as far as it will go in loop-based software. Next, I export each track as a wave file, and import the resulting tracks into a digital audio sequencer. This step is not necessary, of course, if your audio sequencer features looping capabilities as Cakewalk's Sonar does. Working in an audio sequencer provides much more flexibility for tracking vocals or the lead instrument, and mixing.

All of this may sound time-consuming and difficult, but with experience, loop-based composition is a very speedy process and is great when you have a deadline looming. To my ears, the sound of a loop is more convincing than that of a MIDI module. After all, the loops feature real instruments played by real musicians. Remember that your composition doesn't have to be limited by the loops you own. Sometimes loops can augment music you have written from scratch with pencil and staff paper in hand. Many composers who don't have the budget, time, studio space, or access to a string quartet or horn section can still get the musical effects they desire with loops. Compelling music can be created with loops, whether they make up the entire composition, or are used in combination with MIDI performances and real instrumental tracks. The sonic possibilities are vast.

Sidebar: Glossary of Looping Terms

acidized loop. A digital-audio recording that has its stretching properties, root note, and number of beats or tempo stored in its file header. Looping software requires this data to play back the loop correctly in the designated tempo and key. audio editor. Software designed to perform extensive edits on mono or stereo digital-audio recordings. audio sequencer. Software designed to play back multiple tracks of digital audio for tracking or mixing purposes. content. The actual digital-audio recordings that will make up a loop-based composition. drops. The muting (dropping out) of most musical elements in order to emphasize a particular lyric, hit, or transition during the construction or mixing of a tune. loop. A digital-audio recording, that is generally only a few bars in length and designed to repeat seamlessly. one shot. A digital audio recording that is played only once (not looped) and without reference to pitch. Examples of one-shots include a cymbal crash, snare drum hit, or an explosion sound effect. stretching. The positioning of markers during the acidizing process to signal the software where a likely time-stretch point will occur (usually at a major transient). After this process, when the software is time-stretching audio to match a tempo, few if any unwanted sonic artifacts are produced. volume envelope. A graphic representation of changes in volume that allows for an increase or decrease in volume. A volume envelope could be used to accent a particular beat during the construction of a pattern made up of one-shots. wave file. The standard digital-audio file format in the PC world.

Photo Caption Michael Nickolas is a guitarist and composer with national network TV credits. Visit his website at www.studionineproductions.com(Opens in a new window). His latest CD, We Got By is available at amazon.com.