Composing with a sampled library

Here's a short phrase that ends on a long, high C, held for four full beats. It's playing on a small sampled keyboard instrument. Press play and listen to that last note.

The final note fades out long before its four beats are up. Now try exactly the same notes on an organ.

The organ holds the note at full strength right to the end. Same notes, same lengths, and one phrase lands while the other trails off into a gap. A sampled instrument can only play what was recorded. The recording session decided what your phrase can do.

What's inside a sampled instrument

A sample library is a set of recordings plus a map that says which recording plays for which key and how hard. The name on the box ("Grand piano", "Concert harp") tells you the source. It doesn't tell you everything the instrument can do.

Each recording has a length. A piano note recorded for three seconds lasts three seconds; holding the key longer doesn't create more piano. Each recording was made at one pitch, so the sampler stretches it to reach the keys in between. And each was played one way: soft or hard, plucked or bowed, open or muted. Anything nobody recorded, the instrument can't do.

That's why the best composers who work with libraries spend the first few minutes just playing, getting to know the instrument the way you'd get to know a session player before writing them a part.

Get to know the instrument first

Before writing a full part, ask the instrument four questions and note the answers on a card. It takes five minutes and saves hours of fighting the library later.

• Where does it sound best? Play a slow chromatic run from the bottom to the top at one steady velocity. Notes far from a recording's original pitch get faster and brighter going up, slower and darker going down. Mark a comfortable range, a special-effect range and a range to avoid.
• What changes when I play harder? Play one note softly, medium and hard. A library with recorded dynamics switches to a different recording, so loud notes change color as well as level.
• How long does a held note last? Hold a note in the middle and at the top. Count the beats before it fades.
• What happens when I let go? Some instruments stop dead, some ring on, some play a little release sound like a damper or a breath.

Use the transpose control on the first player above to move the phrase down an octave. As it crosses below middle C you'll hear the character shift: the sampler has switched to a different recording. That's a zone boundary, and the key and velocity mapping guide is about where those boundaries go and why.

A written note is a request

A four-beat note in your MIDI tells the instrument when to let go. It doesn't make the recording any longer. On a piano or a harp, sound starts dying the instant the string is struck. On a short sample, it can be gone before the phrase arrives where it was going.

Tempo makes this worse. At a slow tempo, four beats is a long time, and a short tail leaves an obvious hole. The same phrase at a fast tempo might be fine.

You have honest choices. Rewrite the ending: repeat the C, or put something underneath that keeps the energy going. Choose an instrument that sustains, like the organ. Or decide the decay is beautiful and write around it, which is exactly what harp and piano writing has always done. Reverb can blur the gap but won't bring the note back; it gives you a room where the note used to be.

Dynamics are colors, not volume

On a well-recorded library, soft and loud are different recordings. A soft piano note isn't a quiet loud note; it's rounder and darker, with less hammer. A hard one has a bright, glassy edge.

That makes velocity a composing decision. Put a hard accent on the G in our phrase and it might jump out with a bite you didn't intend. Write it softer and use the instrument's level to set how loud the part sits in the mix. Choose the recording for its character, then set the volume for the arrangement.

Articulations are recordings too

An articulation is a way of playing: plucked or bowed, open or muted, staccato or legato. Good orchestral libraries record each one separately, and you switch between them with keyswitches, special notes below the playing range that select which set of recordings to use.

An envelope can soften a pluck's start, but it won't turn a pluck into a bow. The bow's slow bite, the string's continuing motion, the slight rasp: none of that was recorded, so none of it exists. Before writing a part that depends on a legato line or a tremolo, check that someone actually recorded it.

Write for what you found

Once you know the instrument, let it lead. If it has a gorgeous short attack, let rhythm carry the phrase. If it has a long, warm sustain, leave space for it to bloom. If the soft and hard layers are very different, use that difference for a real accent instead of crossing it by accident on every repeated note.

Rewriting a phrase to suit a library isn't admitting defeat. It's what every arranger does for a real player: you write the part that player can make sing.

Same idea, different place: the seams you're writing around are the zones and layers someone mapped. Key and velocity mapping shows the same picture from the instrument maker's side.

When it falls apart in the mix

A part can sound lovely alone and vanish under drums. Soft layers can lack the attack to cut through. A low chord on a sampled piano can muddy the bass. Long tails can blur a fast rhythm.

Before reaching for brightness and volume, try moving the part: a different register, a different voicing, a different rhythm. Lifting one inner note often reveals the melody better than turning everything up.

Make it yours

Pick a sampled instrument you like (try Maru's Sampler if you don't have one) and spend five minutes on the four questions above. Write the answers on a card: useful range, what velocity does, how long notes last, what happens on release.

Then write an eight-bar idea that only uses what the card says the instrument does well. Make the second four bars one deliberate development of the first. Save the MIDI with the card beside it. Finally, play the same notes on a plain synth. Whatever you lose (a particular decay, a soft-to-hard bloom, a register that sings) is what the library brought, and what you'll look for next time you choose one.

Quick check

1. Your sampled cello holds a whole-note chord, but it dies away after two beats at your slow tempo. More release? Release only shapes what happens after the key comes up; it can't add recording that isn't there. Check whether the library has a sustained or looped articulation, rewrite the part to re-bow the note, or choose a different instrument.
2. A library's editor has a keyswitch panel. Does that mean it has staccato, pizzicato and legato recordings? Not necessarily. The panel is the ability to switch; whether there's anything to switch to depends on what was recorded. Play each switch and listen.
3. Your accent on one note sounds harsh and out of place, even though you only nudged velocity from 100 to 110. Why? That small step probably crossed into a louder recorded layer with a sharper attack. Pull it back under the boundary and get the accent from level or timing instead.

Next steps

• Go deeper: Live performance and looping. A written part plays the same every time. What changes when you play it live and the music keeps looping under you?
• Use it: Round robins and articulations. Plan repeated notes and changes of playing style.