SO YOU WANNA MAKE A LOOP...

The scoop on making loops, in 10 easy steps
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By Craig Anderton
Your drummer just came up with the rhythm pattern of a lifetime, or your guitarist played a rhythm guitar hook so infectious you’re about to soak the studio in Lysol. And you want to use these grooves throughout a song, while cutting some great vocals on top.

There’s something about a loop that isn’t the same as the part played over and over again . . . and vice-versa. Sometimes you want to maintain the human variations that occur from measure to measure, but sometimes you want consistent, hypnotic repetition. When it’s the latter, here’s an easy way to create a loop from start to finish. We’ll use a rhythm guitar figure as an example.

1. CHOOSE YOUR PITCH WISELY
If you need to play in a specific key, fine. But if you plan to use the loop in other keys, remember that pitch transposition is harder to do than time stretching; transposing much past three semitones can lead to a very unnatural sound. One solution is to record the loop in two or more keys.

For example, when recording loops for my AdrenaLinn Guitars sample CD, I played each loop in the key of E (to cover the range DG) and also B (for G#C#). Therefore, it’s possible to reach any key without having to transpose by more than three semitones.

There were a few cases where it simply wasn’t possible to obtain the same chord voicing in the two keys. So, I cheated and used a DSP-based time stretching program (Prosoniq Time Factory) to transpose the pitch, then created a loop from the transposed version.

2. PLAY AGAINST A CONSISTENT TIMING TRACK
It’s easy just to “grab” part of a track from a multitrack recording. But if you’re creating a loop from scratch, playing against a rhythm track generally gives a better feel. I also add a bass part in E and B (muting whichever is appropriate) so I can play against a melody as well. Just make sure you can change the track’s tempo (e.g., a MIDI rhythm driving a virtual drum machine) because you want to . . .

3. RECORD AT A SLOWER TEMPO
Acidized or REX format files sound better when sped up than slowed down,

because it’s easier to remove audio than try to fill in the gaps caused by lengthening audio.

Set the tempo for the right feel, and practice until you nail the part. But before hitting record, slow the tempo down, typically to 100 BPM (if the tempo was below 100 BPM, leave it as is). You may also find it easier to play the part more precisely at the slower tempo.

Typically, an Acidized or REX loop can stretch (if properly sliced and edited) over a range of about –15% to +60% or higher. So, a 100 BPM loop will be viable from about 85 BPM to over 160 BPM. For really downtempo material, consider cutting at 80 BPM instead.

4. SWING OR NO SWING?
Swing, which adds a syncopated quality to a rhythm, alters the duration of note pairs. (For example, with 50% swing, the first sixteenth-note of a pair and the second sixteenth-note have the same duration; with 57% swing, the first sixteenth-note’s duration will equal 57% of an eighth-note, while the second sixteenth-note will equal 43% of an eighth-note.)

If a loop wants to swing, let it. Unless it has a huge swing percentage, it will usually play okay against something recorded without swing. Loops recorded without swing will work with a greater range of material, but they won’t have that cool feel only swing can provide.

5. HOW MANY MEASURES?
Although many loops are one measure long, I think two-measure loops “breathe” better: The first measure is tension, the second is release.

Four-measure loops work well when the sound needs to evolve over time. Eight- or sixteen-measure loops are more like “construction kits,” which you seldom use in their entirety, but from which you instead extract pieces.

It’s easy with any looping-oriented program to shorten a long loop. So if you create a four-measure loop that builds over four measures but want to build over eight measures instead, split the loop in the middle, repeat the first two measures twice (to provide the first four measures), then play the full four-measure loop to complete the eight-measure figure.

6. TRIM TIME
After deciding on the optimum length, zero in on the best candidates for looping. Say you’re recording rhythm guitar.

Solo the track, and listen to the entire rhythm guitar part. Mark off regions (based on the number of measures you want to use) that would make the best loops.

After locating the best one, cut the beginning and end to the beat. With loops played by a “real human,” the beginning likely won’t land exactly on the beat and neither will the end. Find the loop beginning, zoom in, and place it at the exact beginning of the measure (assuming there’s no rest before the first note kicks in). Snap the cursor to the measure beginning and do a split or cut. Similarly, trim the end so the loop falls exactly on a measure boundary, and cut there as well. You now have a precisely cut loop.

7. HOW ABOUT SOME “QUANTIZATION”?
Now scan the loop for transients and see if they line up properly with note divisions. Small timing differences are not a problem and, if done musically (e.g., a snare on a loop’s last beat hits just a shade late), will enhance the loop.

But if a note is objectionably late or early, isolate it by splitting at the beginning and end, then sliding the attack into place.

Moving a late note ahead in time will open a gap between the note you moved and the next note. If this creates a problem, you could:

• Add a slight fade to the first note so it glides more elegantly into the gap.
• Copy a portion of the first note’s decay, and crossfade it with the note end to cover the gap.

If the note was early and you shifted it later, then there will be a gap after the previous note, and the end of the note you moved might overlap the next note. If the gap is noticeable, deal with it as described above. As to the end, either:

• Shorten it so it butts up against the beginning of the next note.
• Crossfade it with the next note’s beginning.

If you’ve edited the loop, it’s not a contiguous file any more but a collection of various bits. To make it one file again, bounce the region containing the loop to another track, bounce into the same “clip,” or export it and bring it back into the project.

8. WHAT ABOUT PROCESSING?
A “dry” loop is the most flexible — if you throw on some reverb, then the stretching process has to deal with that too. Cut a dry loop instead, and add reverb once the loop is in a track in your host.

If an effect is an integral part of the loop, such as tempo-synced delay, embed the effect in the file if you want a “plug and play” loop. Otherwise, add the effect during playback.

Some people “master” their loops with heavy compression so the loops really “jump out,” or add extra brightness so the loop “pops.” But when you record other tracks (vocals, piano, etc.) then master the song, if you want to squash the dynamics a bit, then the loop dynamics will be super-squashed, and if you add a bit of brightness, the loop will shatter glass.

I often add a little EQ to trim response anomalies, and just enough limiting to tame any rogue peaks. Loops fit better in the track that way, and are more workable when it’s time to mix and master. You can always add processing; it’s more difficult to remove it.

9. YOU HAVE THE FILE, NOW ACIDIZE THE LOOP
You now have an ideal candidate for looping. To acidize it, bring it into Sonar or Acid. Either program will make an educated guess about how best to loop it, and will do a decent job. You can then optimize the loop markers for the best stretching over the widest range (see the article on optimizing loops on page 34).

10. . . . OR MAYBE YOU WANT A REX FILE

If you want to create a REX file, import the loop into ReCycle. Again, the article on optimizing loops on page 34 includes information on how to tweak the markers that determine where the “slices” fall for the best possible stretching.

If you followed the above directions and optimized the loop, it should work with a variety of material over a wide range of tempos, and fit perfectly into a song . . . that’s what it’s all about.

Tips

• If there’s a level shift between the loop start and end when you cut a loop to the desired number of measures, you may hear a click when the loop repeats. To correct for this, add a very short (3 ms) fade at the loop start and end.

• When playing against a rhythm track, it’s best to create one using MIDI. That makes it easy to change tempo, as well as quantize parts or add swing.

• ReCycle, Sonar, and Acid — the main programs capable of creating slice-based loops from raw files — accept AIFF or WAV format data.

• When creating an acidized loop, don’t forget to enter the root key for pitched loops. This allows the loop to follow key changes in the host program. For percussive parts, specify no root key so that only the duration, not the pitch, changes.

• Sometimes it’s worth cutting and pasting different pieces from your various performances to create the ultimate loop. If you plan to cut and paste bits and pieces of a performance to create a loop, you may need to add fades to those sections that don’t end on a zero crossing. When you bounce or export these clips prior to creating a loop, the fades will become part of the file.

• If you plan to normalize a loop, do so before trimming it to length or adding any fades.