What is a transient shaper?

Transient shaping in plain English

Every drum hit has two parts. First comes the transient, a burst a few milliseconds long where the stick meets the skin, and after it comes the body of the drum, its ring and the sound of the room dying away. A transient shaper gives you a volume control for each part: Attack for the front, Sustain for everything after it.

Turn the attack up and the drum hits harder at the front, as if the player had dug in. Turn the sustain down and each hit stops sooner, so the kit sounds closer and drier, like it was recorded in a smaller room. Both controls go either side of 0 dB, and with both at zero the sound comes out exactly as it went in.

The big difference from a compressor is that a transient shaper has no threshold. A compressor only acts on what's louder than a level you set, so a soft ghost note on the snare slips past while the backbeat gets turned down. A transient shaper listens for how quickly the level changes, and a soft hit rises just as quickly as a hard one, so they get the same treatment. You'll see these called transient designers too, after SPL's hardware Transient Designer, and sometimes envelope shapers.

How does a transient shaper find the hits?

It follows the level of the sound twice, at two speeds. One follower is fast and jumps up the instant a hit arrives, while the other is slow and takes around 20 milliseconds to catch up. For the first few milliseconds of every hit the fast one is well ahead of the slow one, and that gap tells the shaper it's hearing a transient. The bigger the gap, the more of your attack setting it applies.

Sustain is found from the other end. The shaper remembers the last peak and lets that memory fade over about a quarter of a second, so once the current level has fallen well below it, the shaper knows it's in the tail. In the lab, the attack setting is fully applied when the fast follower is 10 dB ahead of the slow one, and the sustain setting is fully applied once the level is 9 dB under the last peak.

Every one of those comparisons is between two readings of the same sound. A hit at −30 dBFS and a hit at −6 dBFS open the same gap between the two followers, because the gap is measured in decibels, so they get the same boost, which is how a transient shaper can bring the ghost notes up along with the backbeat. Most transient shapers work on this idea, though the follower speeds differ from one to the next and some plug-ins let you set them.

Reading the lab

The wide screen at the top shows the whole loop. The pale shape is the sound as it was and the pink shape is what comes out. Under it, the amber gain lane has 0 dB along its centre line, so above the line the shaper is turning the sound up and below it turning it down, by as much as 12 dB either way. Hover over any point, or press and drag on a phone, to read the exact figure.

The Envelope screen is the one to watch while you learn. It zooms in on a quarter of a second around the loudest hit and shows how the shaper has split it: the pink area is what it counts as attack and the teal area what it counts as sustain. The amber line on top is the gain your two settings produce from that split, so turning Attack up raises the amber line over the pink area and leaves the rest alone. The screen beside it shows the same quarter-second before and after.

The Right now panel measures the loop after every change. It tells you how far the loudest peak has moved, the crest factor before and after, and how much the average level has changed. Press A/B to switch the shaper off. The lab turns the original up or down to the same loudness as the shaped version when you do, so the only thing that changes between the two is the shape of the hits.

The drum and percussion loops come from Wonky Percussion, a Sounds Like You pack, and the guitar and vocal are free CC0 recordings. You can also upload a file, or press Record and play something for eight seconds, and it loops through the lab instead. Nothing leaves your device.

The attack control

Attack sets how far the front of each hit is turned up or down, in decibels. At +6 dB, the first 10 to 20 milliseconds of every hit come out up to 6 dB louder, and 6 dB roughly doubles the height of the transient in the waveform. That's where the click of a kick and the crack of a snare live, so boosting it helps a drum cut through a busy mix without turning the whole drum up.

Negative values do the opposite and push a sound back. They're useful on a loop that's too spiky, on overheads where the stick hits on the cymbals poke out, and on a strummed guitar with too much pick noise.

Say your snare peaks at −10 dBFS. With the attack at +6 dB it now peaks at around −4 dBFS, while its body is left alone, so its average level rises by much less than its peaks. On the lab's drum loop, +6 dB of attack raises the peaks by 5.7 dB and the average level by 2.9 dB. Boosting the attack raises your peaks by up to the full amount you dial in, and that eats into your headroom. The drum loop in the lab already peaks just under 0 dBFS, so at +6 dB its loudest hits would be nearly 5 dB over the top in a DAW, and anything that reaches your master at that level clips.

So after a big attack boost, either turn the track down or let a clipper or a limiter catch the new peaks. Push it much further and the front stops sounding like a harder hit and starts to sound like a click laid over the drum. Step 3 in the lab takes it to +12 dB so you can hear that happen.

The sustain control

Sustain turns up or down everything after the transient: the ring of the shell, the wash of a cymbal, the room the drums were recorded in and any reverb already printed on the sample. Some plug-ins call it release, which does the same job.

Cutting it is the more common move. With Sustain at −9 dB, the drum loop's peaks drop by less than a decibel but its average level falls by about 2 dB, because so much of a drum loop's energy sits in those tails. The hits stop sooner and leave gaps, and a reverb you add afterwards gets those gaps to itself. On a sampled loop with a roomy sound you can't get rid of any other way, this is usually the quickest fix.

Boosting the sustain does the reverse: the room comes forward and the drums ring for longer, which can give a dry, clicky sample some body. It also raises whatever else is in the tails, including hiss and the other drums leaking into a close mic. At +9 dB in the lab, the loop's average level rises by about 3.5 dB and its peaks by less than 3 dB, so it gets louder without getting any punchier.

Drum settings often move the two controls in opposite directions. Attack up with sustain down gives a tight, forward sound; attack down with sustain up gives a softer, roomier one. On the drum loop, +6 dB of attack with −6 dB of sustain raises the peaks by 5.3 dB and the crest factor from 18.6 to 22.2 dB, which is the shaper making the loop spikier on purpose.

Transient shaper vs compressor

A compressor can shape transients too. Give it a slow attack of 20 or 30 ms and the front of each hit gets through before the compressor clamps down on the body, which is one of the standard ways to add punch; the attack and release lesson goes through it. The difference is the threshold. A compressor only reacts to hits that cross it, and it turns those down by more the further over they go.

In the figure, three copies of the same hit play 12 dB apart. The transient shaper adds 9 dB to the front of all three. With its threshold at −18 dB, the compressor takes about 6 dB off the loudest hit and leaves the other two almost exactly as they were.

That makes them good at different jobs. Reach for a compressor when the level jumps around and you want it more even, and for a transient shaper when the level is fine and you want to change the shape of every hit. A compressor also only ever turns the sound down, so the punch you get from one comes from turning the body down and then bringing the whole sound back up with makeup gain. A transient shaper can turn the front up directly.

An expander or a noise gate can shorten tails as well, but like a compressor each one decides by level, so quiet hits lose more than loud ones. For a side-by-side with the other tools that change the front of a sound, see clipper vs limiter vs transient shaper.

Using a transient shaper on drums, guitar and bass

Kick

A few decibels of attack brings the beater click forward, which is the part of a kick you hear on phone speakers and laptops that can't reproduce the low end. Cutting the sustain shortens the boom so it doesn't smear into the bass line, and the kick and bass lesson covers the rest of that relationship.

Snare and toms

Attack on a snare gives it more crack without making the whole drum louder. Toms tend to ring on long after they're hit, and cutting their sustain by 4 to 8 dB tightens them while keeping the natural fade. A gate does a similar job by cutting the tail off once it falls under a threshold, so it can chop the end off a soft fill; the shaper turns every tail down by the same amount, which is harder to hear working.

Room mics and overheads

Boosting the sustain on a room mic makes the room sound bigger without adding any artificial reverb. On overheads, a little negative attack takes the sharpest edge off the stick hits on the cymbals.

Drum loops and samples

This is where producers who work with samples use it most. One shaper on a full loop treats the kick, snare and hats as one sound, so a sustain cut dries the whole loop out and a small attack boost brings it forward. It's the quickest way to make a loop from one pack sit with drums from another, because it changes how long the hits ring without needing separate tracks.

Acoustic guitar and piano

Negative attack softens the pick noise at the front of each strum and lets a busy guitar part sit back. Positive attack does the opposite and makes strumming sound more percussive, which suits a sparse arrangement where the guitar is doing the rhythm. The same goes for piano, where the attack control changes how hard the hammers sound.

Bass

On picked or slapped bass, a few decibels of attack gives every note a clearer start, which helps it read under a full mix. Be gentler on sub bass and 808s. A big attack boost on a low sine adds a click, and the sustain control changes how long each note lasts, which can throw off the groove.

Starting settings for common sounds

These are places to begin. Move one control at a time and judge it at matched loudness.

How to use a transient shaper, step by step

1. Check the peaks firstIf the track already peaks near 0 dBFS, turn it down by about as much as you plan to boost the attack. The gain staging lesson explains why that's easier to do now than later.
2. Exaggerate one controlSet Attack to +6 dB or more, past where you'd want it, so you can hear exactly which part of the sound it's changing.
3. Bring it back downLower it until the hit sounds clearer but the front still sounds like part of the drum. If you can hear a separate click, it's too high.
4. Set the sustain while listening to the gapsCut it until the ring and room between hits are where you want them. Boost it only if the sound is too dry or too short.
5. Match the level and compareUse the shaper's output control to make it as loud as the bypassed version, then switch it off and on.
6. Check it in the mixA boost that sounds sharp with the drums soloed often sits right once the bass and vocal are playing, and a subtle one can disappear. Make the final call with everything playing.

Before or after compression?

If you use both on the same drum, put the transient shaper after the compressor. A compressor with a fast attack placed after a shaper sees the boosted transients as louder peaks and turns them straight back down, undoing the work you just did. After the compressor, the shaper has the final say on the shape of each hit.

Put any clipper or limiter after the shaper, because an attack boost raises your peaks and something has to catch them. That pairing is common on a drum bus: the shaper adds snap and a clipper shaves off the tallest of the new peaks, leaving drums that are louder at the same peak level and still punchy. The guide to making drums hit harder puts that chain together, and effect order covers the rest of the chain.

Transient shapers in your DAW

You probably already have one. Logic Pro's is called Enveloper, with separate gain and time controls for the attack and the release. FL Studio's is Transient Processor. In Ableton Live, the Transients knob in Drum Buss does a one-knob version of the job on everything above 100 Hz. Kilohearts Transient Shaper is free as part of Kilohearts Essentials, so it's an option in any DAW that loads plug-ins.

SPL's hardware Transient Designer has the same Attack and Sustain pair as the lab, and a lot of plug-ins copy that two-knob layout. Some add a speed or sensitivity control for the followers, a mix knob for blending the shaped sound with the original, or a clipper on the output to catch the peaks a boost creates.

Common transient shaping mistakes

Clipping the boosted peaks

Six decibels of attack means peaks up to 6 dB higher. If the track was already close to 0 dBFS, the shaper has just pushed it over, and if it reaches your output like that, the crackle you hear is clipping that has nothing to do with the shaper's sound. Turn the input down or put a clipper or limiter after it.

Judging it by volume

Both controls can make a sound louder, and louder almost always wins a quick comparison. Match the levels before you decide, with the A/B in the lab or the plug-in's output gain in your DAW.

Raising the noise with the sustain

Everything in the gaps between hits comes up with a sustain boost, so hiss, hum, amp buzz and bleed from other instruments all get louder. If a sustain boost suddenly makes a recording sound noisy, that noise was there already and the shaper found it.

Putting it across a whole mix

On a full mix the shaper finds transients in everything at once: the drums, but also vocal consonants and guitar picking. A dB or two can liven up a flat mix. Much more than that and everything sounds spiky, so shape the drums on their own track or bus before you reach for the mix bus.

Shaping drums that were already shaped

Many drum samples were compressed or clipped when they were made. Put a big attack boost on top of one and you often get a click and nothing else, so make small moves on samples; if 2 dB doesn't help, the sample probably doesn't need it.

Train your ears

The quiz under the lab hides the controls and matches the levels, and every round uses 9 dB of boost or cut. The first four rounds ask whether the attack is boosted or cut, so listen to the very front of each hit; the last four ask the same about the sustain, so listen to the gaps. Start on the drum loop, then try it on percussion, where the hits are shorter. Your best score is saved in your browser.

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