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make music now Gating FX masterclass

060 | COMPUTER MUSIC MARCH 2006 TUTORIAL

GatingYou may think you know all there is to know about gating,but there’s more to this effect than meets the ear…

So far in this series we’ve focused

on processing effects that you

know you may not fully

understand, but that you use regularly

nonetheless. This month we’re doing

the opposite – we’re covering a type of

processor you probably think you fully

understand, but that you don’t often use

very much. That’s right, we’re talking

about the humble gate.

Like compressors, gates fall into the

category of dynamics processors, as

they’re triggered by the strength of a

signal and are used to affect that

signal’s volume. At its most basic level,

a gate reads an incoming signal and,

unless that signal exceeds a certain

volume, stops it from passing through. In

the dark ages of analogue, when just

about every stage of the recording

process added hum and hiss, and

everything was recorded to either analogue or digital tape, the only real

way to stop all this noise drowning out

the sound of your music was to use a

gate. This would prevent unwanted

noise when no notes or other desired

sounds were playing, reducing the

cumulative noise level. And because

you can’t normally hear hiss and hum

when there are other sounds going on,

this was usually enough to get rid of all

the perceived noise.

OK, we know what you’re thinking – why should you care about any of this?

The near-universal adoption of DAWs

means that any analogue interference is

a thing of the past, and when you do

need to get rid of unwanted background

noise, there are any number of

intelligent noise-removal plug-ins that

can learn the sound of said noise and

remove it from the signal. Even if you

don’t have one of those, computer-

based editing enables you to silence all

of the sections in between the words,

notes or other sounds that you actually

want on your tracks.

Well, let us just set you straight right

now – there’s a whole world of gating

possibility out there still, both creative

and practical. First, the practical…

Gateway to heaven Yes, it’s true that digital editing enables

you to strip out unwanted audio (such

as hi-hat spill in your snare drumchannel), but this isn't the simplest

process in the world. Some sequencers

will do it for you, but you still have to set

the threshold, just as you would with a

gate. And as this is an offline,

destructive process it can be a bit hit

and miss, and often impossible to undo.

So why not just use a gate? You can

even employ more sophisticated gates,

which give you a greater degree of

control and enable you to reduce the

amount of reduction rather than justhaving the gate entirely open or closed.

They also allow for more creative

envelope shaping, all of which makes

for subtle and ‘organic’ noise reduction.

Because an open gate spits out the

same signal it receives, there’s no risk

of damaging the desired sound, which

can happen with noise-reduction plug-

ins. So,

not only

can gates

(whether

digital or

analogue)

be quicker

to set up

than many

of the

more

advanced

DSP processes, but they can actually do

a better (and safer) job.

And then there’s the creative aspect. Just as compressors can be used to

enhance different signals and solve

various problems, so too can gates be

used to alter the characteristics of a

sound and even to selectively play

patterns by utilising a sidechain input.

But before we have a look at these

techniques, we first need to familiarise

ourselves with the front-panel GUI of a

modern gate plug-in, and what better

than Logic’s trusty Noise Gate, which

offers up as many parameters as you’reever likely to find on one… cm

On the DVDTUTORIAL FILES

The loops used in the walkthroughs can be foundin the Tutorial files folder

5 Using a gate gives you more flexibility than a

noise reduction plug-in such as this

1 We love logic's Noise Gate plug-in

ADVANCEDEFFECTS

PART 5

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Q&A focus

make music nowGating FX masterclass

01 THRESHOLD It helps if you

think of the noise gate asbeing naturally closed (on a

metaphorical spring). It takes a certainamount of noise pressure to push thegate open, and the threshold is where

you set the spring’s strength. Set it toolow (ie, a low level of sound) and yourisk letting all of the sound push

through, but set it too high and youcould lose some of the sound, as thesome of it’s not s trong enough to get

through. The result will be snippets of sound and loud clicks and pops as thegate repeatedly opens and slams shut.

02 REDUCTION This is where

you set the amount of gainreduction applied to any

signal that falls below the threshold (or how closed the gate really is, if you

prefer our metaphor). When set to full, the reduction ensures total silence whenever the signal drops below the threshold. You might think full reductionsounds just the ticket, but in mostpractical cases it’s a little too extremeand results in a very noticeable andunnatural opening and closing sound(although it can be useful for creatingeffects). Another useful side-effect of having, for example, only -30dBreduction rather than the full cut, is that

the reaction time of the gate will be faster – particularly on analogue or realistic analogue modelling gates. Why?

Well, quite simply, it takes time for the

gate to open, and the further it has toopen, the longer it will take, sosometimes you can actually achievepunchier attacks when going from aquiet signal to a loud one than fromsilence to loud.

03 HYSTERESIS Whensignals hover around the

threshold you cansometimes experience ‘chattering’ (littlesnippets of sound slipping through as

the gate opens and closes very quickly),and this is particularly true with very fastattack and release times. Hysteresisis a process whereby the threshold for

the gate closing again is a few dBslower than the threshold for the gateopening, so that once open, the gategives fluctuating signals the benefit of

the doubt, thus vastly reducing the

chattering effect.

04 LOOK-AHEAD Thelook-ahead function ondynamic plug-ins is one of

the coolest things about working withcomputers, as it enables the plug-in tohave a little look at what’s coming nextand react just before it happens –incredibly handy for preserving sensitive

transients. With this control, you can sethow far ahead the plug-in will look.

05 ATTACK As withcompressors, the attack

defines the speed at which

the gate will open. Depending on what you hope to achieve, you can have it vary fast for things like punchy drums, or slower for instruments with slower attack envelopes, such as bowedinstruments or even voices, where

abrupt bursts of sound would soundincongruous and unnatural.

06 HOLD This is another solution for unwantedchattering. As you might

have guessed, the hold function is theamount of time that elapses after thesignal drops beneath the thresholdbefore the gate closes.

07 RELEASE The releasecontrol determines thespeed at which the gate will

close after the signal drops below the

threshold and the hold period haselapsed. As with compression, it’s very important that you set the attack andrelease correctly for the purpose inhand. For transparent practical uses you

want settings that complement theattack and release portion of your signal’s basic envelope, while moreextreme settings are useful for thecreative side of things.

08 SIDECHAIN As with allsidechains, this enables

you to use a signal other than the original source to trigger the

effect of the gate, but it also allows you

to use an adapted version of the originalsource signal, while the untreated

version is actually processed by thegate. In essence, the incoming signal issplit into two identical versions – one

which will be processed, and another

that will trigger the processing, and which can have other things done to it first. This leads us to the high- and low-cut filters…

09 HIGH-CUT If you’re using

the gate on a snare drummic, for example, there

might well be enough noise-spill from the hi-hats to open the gate atunwanted times, or at least makesetting the threshold and enveloperather tricky. But by rolling off some of

the top-end of the sidechain signal, youcan alleviate this problem whilst leaving

the actual signal being processed free from EQing.

10 LOW-CUT This employsexactly the same principleas the high-cut function, but

is useful for rolling off the bass to stop things like kick drum spill accidentally opening up the gate.

11 MONITOR The monitor

function routes the sidechainsignal to the audio outputs

so you can, for example, actually hear all of the high- and low-cut tweaks that

you’re making.

TUTORIA L MARCH 2006 COMPUTER MUSIC | 061

THE ANATOMY OF A GATE




make music now Gating FX masterclass

062 | COMPUTER MUSIC MARCH 2006 TUTORIAL

Putting gates into action

3Use the second sound to create a rhythmic pattern –

the gate will open each time you press a key and stay

open for as long as you hold it. When used on full tracks and instruments with normally smooth envelopes

(violins, voices, etc), this is creates a great, unrealistic effect.

STEP BY STEP Giving it the chop

1One of the coolest gating tricks is rhythmically choppinga signal. Play some long power chords on a full-fat synth

patch, holding each chord for two beats or more. If youaren’t musical, just start with C, E, G and move your fingers to

the white notes above and/or below each time. >>

2Insert a gate with a sidechain input into the channel

you’ve just created (set it to full gain reduction). Now

create a new channel offering a loud and constantsynth patch with instant attack and release, then mute the

output and send the signal to your gate’s sidechain input. >>

Tips on adding reverb to drums

3Insert a gate on your sine wave channel and send thekick drum signal to the gate’s sidechain. Set any Attack

and Hold controls to zero and hit play . Your bass note

should now be reinforcing your kick. Tweak your gate’sRelease to get rid of any clicking at the end of drum hits.

STEP BY STEP Kicking it

1Start by importing the two audio files Hip-kick loop andHop-hat loop into your sequencer on two different

audio channels. The tempo for them is 102, and you

should get them to loop over the first bar. Now play themback together, so you get a feel for the sound of the kick. >>

2Now create a new instrument channel and load up asoft synth that offers pure sine waves (we’re using

Logic’s EXS24 default No instrument setting). Draw in a

long note covering the whole bar (try somewhere around C1or lower), and set the Attack to zero on your sine wave. >>

3Set the Attack and Release times to quite fast and

make sure that the gate is closing fully. Move the Threshold level until you hear the chattering effect.

Now, by slowly adjusting the Hold time, you can tweak the

chattering until it sounds more like distortion – nice!

STEP BY STEP Roughing things up

1Depending on the gate you’re using, you can get some

quite useable and musical distortion-style effects from the normally undesirable chattering phenomenon

caused by audio levels hovering around the threshold point.

Start by loading the loop Talk talk all day long. >>

2Now insert a gate that enables you to alter attack,

release and hold times. We’re using the one in AbletonLive, set to Flip mode (this reverses the effect of the

threshold so that signals below it pass through while signals

above it are blocked). >>

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make music now

TUTORIAL MARCH 2006 COMPUTER MUSIC | 063

Gating FX masterclass

Gating tips1 Apply a gate to an unruly

bassline and feed your kick

drum channel into the gate’s

sidechain input. This will

ensure your bass notes and kicks

trigger simultaneously for a punchy,

tight, clubby sound. And with slower

attack times, you can delay the sound

of the bass, for a realistic live sound

(people generally play a little behind

the drums).

2 The signal path of your effects

is vital, and gates should

normally go upfront. For

example, if you place EQ

before a gate, any subsequent EQ

changes will alter the level and disrupt

the gate’s activation. And as a

compressor dynamically alters the

signal, it's bound to complicate the

setup of your gate settings.

3Despite what we've just said,

have a go at applying a gate

after any heavily

delayed sound with a fast

attack and use it to accentuate each of

the individual hits. With the gain

reduction setting fixed higher than

usual, you can create a really cool

volume pumping effect each time a

delay sounds. Just use the attack and

release controls to hone the pumping,

and adapt to taste…

4 Just as with compressors, if

you’re gating a stereo signal,

be sure that stereo link is

switched on. This ensures

that any dynamic changes applied to

one side of the stereo split will be

applied to the other – vital if your

source material has a left or right bias.

5 You needn’t just sidechainelements of songs – why not

whole tracks? Sure, you can

always chop up sections of a

track, but nothing beats bashing out a

pattern on your MIDI keyboard and have

it open the gate applied to your whole

track. Just ask Mylo!

6

For an authentic 80s gated

reverb sound, record some

drums in a concrete stairwell

or put them through a phat

reverb patch. Then apply a gate with a

high threshold and fast attack and

release times. You can then extend the

hold parameter, allowing through a

burst of big sound.

If you’re layering a bunch of performances,bring them together and add punch by

applying a gate to each, and then supplying theirsidechains with the audio from the best take.

7

8Gating can have an extremely

strong (and useful) effect on a

signal, but also a destructive

one, so if you do think you

need to apply it to a multitrack

recording session (to eliminate

unwanted hiss or hum, for example) it’s

usually better to get the recording down

dry first and then apply gating at the

mixing stage, where the effects canalways be discarded.

9 You can fatten up kicks by

adding a sine wave or

booming 808 kick sound, but

the envelopes are usually just

messy, so use a gate on each

additional sine wave or low kick sample

to be layered, and trigger their

sidechains with the original kick. Just

make sure you have fast attack times in

place so that the kick layers punch in

nice and quickly.

10 You can create a more punchy sound on some percussion

and bass notes by placing the threshold slightly higher than

it need be to remove noise and setting your attack time as

fast as it goes. The gate will now not open until the high

threshold is reached, and when it is, the sound will explode through the gate.

1Begin by using fast attack and release settings, then tweak the threshold

11

Start out with fast

attack and release

settings so that it’s

clear what'shappening to the signal. Then adjust the

threshold until you find the approximate

level – ie, the point at which the sound

you want comes through, but the sound

you don’t doesn’t. From there you can fine tune the other settings.

7Gates can be very powerful and destructive, so

place them first in the signal path

3

Even this basic MDA

gate can add punch

to your percussion


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