Loops and releases

Below is a recording of a held instrument with a loop region marked by the L handles. Press play: the sampler plays from the start into the loop and then repeats the loop for as long as you like. Now drag the loop handles closer and closer together.

A long loop sounds like the note carrying on, maybe with a faint pulse each time it comes round. A very short one stops sounding like the instrument at all: it buzzes, with a pitch of its own. Where do you think that pitch comes from?

It comes from the loop itself. A loop 100 samples long at 48,000 samples per second repeats 480 times a second, and 480 repetitions a second is a note, between A♯4 and B4. A loop isn't neutral. Repeat anything fast enough and the repetition becomes part of the sound.

Why we loop at all

A recording has a length; a held key doesn't. Looping is how a sampler fills the gap: when the playhead reaches the end of the loop region, it jumps back to the start and keeps going until you let go.

In the 1980s, looping wasn't optional. Early samplers like the Fairlight CMI and E-mu Emulator had very little memory, so every sound was a short recording with a loop, and that tight, slightly frozen sustain is part of the sound of the decade's records. Today we have memory to spare, and we loop because we want an organ or a pad to sustain as long as a player holds the chord.

Same idea, different place: a plucked-string synth is a very short loop fed a burst of noise, and the loop's length becomes the string's pitch. It's the buzz you just made, used on purpose. See Physical modeling.

Find a steady place

A recorded note has a beginning, a middle and an end. Loop the middle. The attack should play once, at the start; if it's inside the loop, the note restrikes over and over like a stuck key.

Listen to the middle before setting any points. Is it really steady? A singer's vibrato, the beating of an organ's chorus, a slowly breathing bow: each has its own cycle. If your loop cuts across that cycle, you'll hear a hiccup every time it wraps. Sometimes the fix is a longer loop that holds a whole number of wobbles.

Two zeros don't make a smooth join

The classic advice is to put loop points at zero crossings, where the wave passes through zero, so there's no jump in level at the join. It helps. It isn't enough.

The level matches, but the direction doesn't: the wave was heading down and suddenly heads up. That corner is a tiny jolt every time the loop comes round. Look for loop points where the wave is going the same way at both ends, and where the tone and loudness match too.

Crossfades blend the join

A loop crossfade overlaps the end of the loop with the start, fading one out as the other fades in. Instead of a hard jump, you get a short blend.

During a crossfade's overlap, two slightly different moments play together. If they're out of phase or a little different in pitch, the blend sounds hollow or wobbly, and you hear it every time round. Start with a short crossfade, listen over many repeats (a problem that's invisible on one pass gets loud on the tenth), and lengthen it only if the seam still stands out.

Looping a decay changes the instrument

A piano note fades from the moment the hammer lands. Loop a chunk of it and the fade stops: the note hangs at one level forever, more like an organ than a piano. That might be a beautiful new instrument, but it isn't a longer piano.

And if there's no loop at all, the note ends when the recording ends. A longer Release setting can't help: release only fades what's still playing, and after the recording runs out there's nothing left to fade. For a long natural decay you need a longer recording.

Letting go is a musical moment

How a note ends is as much a part of an instrument as how it starts. Lift your foot off a piano's sustain pedal and you hear the dampers settle. A singer's note ends with a breath. A string player lifts the bow.

There are two ways to make that moment:

• An envelope release fades whatever is playing. It's smooth and simple, and it's what most instruments use.
• A release sample is a separate recording that plays when you let go: the damper thump, the breath, the bow lifting. It can make an instrument feel startlingly real, and it can sound wrong if it's louder than the quiet note it follows.

Choose the release by the music, not just the instrument's name. A fast part needs short releases so notes don't smear; a slow pad wants long ones.

Drums don't loop

A drum hit should play to the end even if your finger only taps the pad. That's a one-shot: it ignores the note ending and plays the whole recording. One-shots and loops are opposite promises, so a sound is one or the other. If a drum hit cuts off early, check it's set to one-shot before making every MIDI note longer.

Make it yours

Take a sustained recording of your own: a held organ chord, a bowed note, your voice on "ooh". Keep the raw file and work on a copy.

Find a steady stretch after the attack and set loop points where the wave heads the same direction at both ends. In Maru's Sampler you enter loop points as numbers (in frames), so find them in a waveform editor first; at 48 kHz, 48,000 frames is one second. Then listen to a short note, a long hold and a few quick repeats. Write down whether the join clicks, pulses or changes tone, and set a release that ends notes cleanly before the next one.

Save the loop points, crossfade and release with the instrument. You've turned a few seconds of recording into a note that lasts as long as the music needs.

Quick check

1. Your organ loop is 100 frames long at 48 kHz and adds a strange buzz. Why? It repeats 480 times a second, which is a pitch in its own right. Make the loop much longer, over a steady stretch, so the repetition is too slow to hear as a tone.
2. Both loop points are exactly on zero crossings, but there's still a tick. What else could it be? The wave is heading in opposite directions at the two ends, or the tone and level differ. Match the direction, or add a short crossfade.
3. Your piano sample stops dead after two seconds, so you set Release to five seconds. Does the note last longer? No. Release only shapes sound that's still playing after you let go; the recording has already ended. Use a longer recording, or a loop if a frozen sustain suits the part.

Next steps

• Go deeper: Round robins and articulations. Sustained notes now sound real. But hit the same drum pad twice and it sounds like a machine.
• Use it: Preparing samples. Keep the steady stretch and clean attack your loop depends on.