ReaGate Noise Reduction
Cockos Reaper Tips & Techniques
Technique : Reaper Notes
Reaper’s ReaGate has hidden talents that make it much more than a simple noise‑reduction facility.
Mike Senior
In
my view, a lot of DAW users unduly neglect the humble gate at mixdown,
dismissing it as merely an outmoded noise‑reduction utility. This is
a shame, because ReaGate, in particular, does so much more besides this
that I usually have several instances going on every mix I do. So in
this article I want to give a few examples of this plug‑in’s hidden
talents. There’s not space here to cover the basics of gating, so if
you’re new to it, check out the article back in SOS April 2001: it’s
free to view in the SOS article archive at
www.soundonsound.com/sos/apr01/articles/advanced.asp.
Assuming, then, that you understand how the Threshold, Attack, Release,
Hold and Range controls of a gate can be used to remove noise and spill
in a recording, the only thing to clarify in the first instance is
that, although ReaGate appears to have no Range control, you can still
implement limited‑range gating using its Wet and Dry sliders.
Pre‑open, Hysteresis & Side‑chain Filtering
The
first thing that sets ReaGate apart from many other gates is the
Pre‑open control, which causes ReaGate to respond earlier than it would
normally.
The
secret to ReaGate’s most useful mix applications lies in its ability to
select an external side-chain input, which you can see here. Other
features that make ReaGate stand out from the crowd are the positive
values available on the Hysteresis control and the Pre-open parameter,
which provides a ‘lookahead’ function — great for preserving the attack
of close-miked drums even when there’s lots of unwanted spill.
This is great for reducing spill on snare‑drum close mics, because it
lets you set a high threshold to avoid the spill without the risk of the
gate opening late and clipping off the drum’s initial transient.
The Hysteresis control is also great, because it effectively creates
independent threshold levels for opening and closing the gate.
A negative setting here lowers the closing threshold relative to the
opening threshold, and is a well‑known method of combating sporadic
bursts of opening/closing (often called ‘chattering’) when a signal
hovers around a fast‑attack gate’s threshold level. However, ReaGate is
very unusual in that it offers positive Hysteresis settings too, and if
you max out the Hysteresis slider you effectively turn the gate into
a triggered envelope generator, which can be very useful in certain
scenarios. For example, an old mixing trick is to set up a gate as
a send‑return effect, fed from the kick drum, and then to set it up to
create a little 10‑20 ms ‘blip’. Adding this to the mix increases the
drum’s attack, and you can easily adjust the frequency content of that
attack by EQ’ing the ReaGate channel. However, if your kick drum has any
level variation in it (as live parts certainly will), you’ll get
undesirable variations in the length of the ‘blip’, and therefore the
nature of the added attack. Add positive Hysteresis, however, and the
added attack becomes completely consistent.
What
really gives ReaGate its power, though, is the control it gives you
over the signal that’s sent to its internal level detector (or
‘side‑chain’). For a start, the built‑in filters can quickly remove kick
and hi‑hat spill from the side‑chain when you’re gating a snare
close‑mic recording, improving the triggering reliability. It’s easier
to hear what you’re doing if you click the Preview Filter Output button
to audition the side‑chain on its own. However, if these filters aren’t
man enough for the job, you can use ReaEQ instead.
First
select Auxiliary Input L+R from ReaGate’s Detector Input drop‑down, and
then insert an instance of ReaEQ above ReaGate in the effects window.
Click ReaEQ’s routing button (labelled ‘2 in 2 out’). Now click the
little plus sign in the routing window to increase the number of Track
Channels, and then change the plug‑in’s output setting from 1+2 to 3+4.
You can route a send to ReaGate’s external side‑chain input by sending it to Track Channels 3+4.
Automated Mix Balancing
Nice
though all these things are, the most useful application of ReaGate for
me is in automated mix balancing. Let me explain. Imagine you have
a drum overheads recording where the cymbals are overpowering the snare.
Most people’s first instinct is to rebalance this by using the snare’s
close mic, but that mic usually just goes ‘donk’, rather than sounding
like a real snare drum. A better solution is to boost the level of the
overheads during each snare hit, giving you more of the natural sound of
the snare in the room.
The way to do this is to
insert ReaGate into the overheads channel and then feed its side chain
from the snare close‑mic. Switch ReaGate’s Detector Input to ‘Auxiliary
Input L+R’, and then drag the snare track’s IO button to the overheads
track to create the required send. When the little send controls window
pops up, take the opportunity to do two things:
Change
the ‘=> 1/2’ setting to ‘3/4’, using the ‘New Channels On Receiving
Track’ submenu. This ensures that the snare close‑mic signal is fed
to the ReaGate side‑chain inputs.
Change
the ‘Post‑fader (Post‑pan)’ setting to ‘Pre‑FX’. Although this isn’t
strictly necessary for triggering purposes, it does mean that mix tweaks
to the snare channel won’t make a nonsense of your ReaGate settings.
Now
adjust the ReaGate controls to try to get a reliable burst of overheads
signal occurring on each snare hit. Once you’ve achieved that, pull the
Wet slider right down and set the dry signal to 0dB, so that the gate
is doing precisely nothing. From this starting point, slowly inch up the
Wet slider during playback until you get a better snare level in the
balance. Bear in mind, though, that there’s only so far you can usually
go with this dodge before the gating begins to sound unnatural (above
about 6dB, usually), and you may also need to work a little with the
ReaGate Release control to get the most musical‑sounding snare decay.
Ducking At Mixdown
An
extension of this auto‑balancing idea is made available by the ‘Invert
Gate’ tick box under ReaGate’s Wet slider. What this does is
polarity-invert the wet signal relative to the dry signal, so that they
phase-cancel whenever the gate is open. The practical result is to turn
the gate into a ducker, a processor that is rare in software form but
extremely useful at mixdown.
The
unassuming little ‘Invert Gate’ tick box converts ReaGate into
a ducker, which is another very useful, and frequently underestimated,
mix processor.
The classic application for ducking is clearing
space in a guitar‑heavy mix for the lead vocals; it makes the singing
clearer by turning down the guitars during vocal phrases. You set it up
almost exactly as in the previous snare example:
Insert ReaGate on your guitar submix channel, feed its side‑chain from the lead vocal, and activate the Invert Gate facility.
Set
up reliable triggering from the vocal. To hear what you’re
doing clearly, keep the Wet slider at 0dB and pull the Dry slider all
the way down.
Once the triggering’s sorted
out, pull down the Wet slider and set the Dry slider to 0dB, then play
back your mix and slowly increase the Wet level to subtly introduce the
ducking.
If you want to know how much you’re
ducking, check the Range table. Again, you can usually only push this
effect so far before it sounds unnatural, but that’s not too much of
a bind, as even a decibel or two of ducking can still make
a considerable difference to the vocal sound. 0
MIDI Output
It’s
easy to generate MIDI notes from a drum part using ReaGate’s Send MIDI
On Open/Close option, whereupon you can use the simple ReaSamplOmatic
sample player to trigger a replacement sound.
Although there are now many sophisticated software
drum replacers available, I have to say that I still end up using
ReaGate for this most of the time. All you have to do is tick ‘Send MIDI
on Open/Close’, and the plug‑in will squirt out a user‑specified MIDI
note whenever the gate opens. Follow ReaGate with ReaSamplOmatic5000:
for quick results in ReaSamplOmatic5000, load in a sample (from the
Browse button), select ‘Sample’ in the Mode drop‑down menu, and untick
the ‘Obey Note‑off Messages’ option. Admittedly, ReaGate doesn’t provide
any fancy MIDI velocity options, but I rarely miss those in practice,
and what ReaGate does offer is masses of features aimed at making its
triggering reliable, which I find much more important in
most situations.
Source:
http://www.soundonsound.com/sos/may11/articles/reaper-tech-0511.htm
ReaGate Noise Reduction | Media
Cockos Reaper Tips & Techniques
Technique : Reaper Notes
Using Reaper’s ReaGate Plug-in: Audio Examples
In
May 2011’s edition of Sound On Sound, we looked at using Reaper’s
bundled gating plug-in — ReaGate. Here, Mike has supplied audio examples
to demonstrate the techniques used in the workshop, which can be read
in full by going to
www.soundonsound.com/sos/may11/articles/reaper-tech-0511.htm.
The first set of audio examples show how the
side-chain filtering and Pre-open facilities of Reaper’s ReaGate can be
used to deal with a challenging spill-reduction task.
Snare01_Ungated
Here’s
a live snare-drum close-mic recording. As you can hear, there’s masses
of hi-hat and kick-drum spill, which I want to reduce.
Snare02_Gate
For
this file, I’ve applied ReaGate, using 0ms Attack and 44ms Release
settings so that I can hear the triggering action clearly. (I’ve also
dialled in 3ms of Hold time to reduce gate chattering, in the light of
the fast attack/release times.) I’ve set the Threshold to -27dB, which
is as high as I can get it without losing any of the snare hits, but
despite this both the kick and hi-hat parts are causing the gating to
misfire.
Snare03_Gate_SCFilters
To
improve the triggering, I use ReaGate’s built-in side-chain filtering
options to reduce the levels of kick-drum and hi-hat spill in the
detector signal. Setting the Highpass slider to 674Hz and the Lowpass
slider to 4869Hz does the trick, as you can hear in this example: the
gate now opens only when it should.
Snare04_Gate_FilterListen
In
order to set up ReaGate’s side-chain filters for the
Snare03_Gate_SCFilters example file, I engaged the plug-in’s Preview
Filter Output button so that I could audition the filtered detector
signal directly and refine them by ear. Here’s what the side-chain
signal sounded like by the time I’d finished refining the Highpass and
Lowpass settings. Although it sounds nasty and boxy, it does give the
snare a balance advantage for detection purposes. Compare this with the
Snare01_Ungated file to remind yourself of the original unfiltered spill
levels.
Snare05_Gate_PreOpen
Although
the gate in the Snare03_Gate_SCFilters audio example is now triggering
only on the snare hits, its Threshold has had to be set so high that the
gate is slicing off a little of the initial snare transient, even with a
minimum 0ms Attack setting. ReaGate’s Pre-open facility provides a way
to improve this aspect of the processed sound. In this example I’ve
applied 6ms of Pre-open, which helps the drum onset sound crisper.
Snare06_Gate_Smooth
So
far I’ve deliberately kept ReaGate’s Release setting short and its Dry
slider all the way down so that I could easily hear the finer points of
the gating action. However, in practice a longer release time will give a
more musical-sounding snare decay, and the gating range needn’t be
nearly so extreme: some spill between the mics in a drum kit is usually
beneficial to the sound, so all you really want to do is reduce the
spill on this snare close-mic to a more suitable level. In this audio
example I’ve attended to both these issues, setting the Release to 115ms
and reducing the gating range to 8dB (Wet slider at -4.4dB, Dry slider
at -8dB). Compare this to Snare01_Ungated to hear how far we’ve come
from the original recording.
Kick01_Raw
This
audio example contains a section of the kick-drum close-mic track of a
live drum recording. As you’d expect of a real performer, there is some
inconsistency in the bass-drum levels through the track.
Kick02_ParaGate
One
way to add low-end attack to a kick-drum sound is to set up a fast gate
as a send effect to isolate a little ‘blip’ from each hit, EQ that blip
primarily into the low-frequency region, and then mix it back in with
the unprocessed kick sound. This audio example demonstrates the kind of
sound such a gated send channel would have when fed from the kick-drum
track in the Kick02_Raw audio file. The processing comprises an instance
of ReaGate (Attack: 0ms; Hold: 22ms; Release 6ms) followed by a 940Hz
low-pass filter in ReaEQ. Note that the weight and tone of the blip
changes from hit to hit in response to the inherent level changes in the
live performance.
Kick03_ParaGateMix
This
audio file shows how the gated send in the Kick02_ParaGate example
enhances the raw kick-drum sound of the Kick01_Raw file when they are
mixed together. Again, note the inconsistency of the low-end attack.
Kick04_ParaGateHysteresis
This
file demonstrates how the ‘blip’ in the Kick02_ParaGate example can be
made to sound more consistent when ReaGate’s Hysteresis is increased to
its maximum value of +24dB, effectively transforming the gate into a
triggered envelope generator.
Kick05_ParaGateHysteresisMix
Here
you can listen to the effects of the Kick04_ParaGateHysteresis file’s
improved gated send processing when it is mixed with the unprocessed
kick-drum recording of the
Kick01_Raw file. Compare this with
Kick03_ParaGateMix to hear the difference in consistency at the low end.
Overheads01_NoGate
Here’s
an example of a drum overheads track, recorded from Toontrack’s
Superior 2 virtual instrument, where the cymbals are overpowering the
snare-drum sound.
Overheads02_Gate
Inserting
an instance of ReaGate on the overheads channel and then triggering it
from one of the snare close-mics is able to significantly increase the
snare level in the overheads balance.
Ducking01_NoDuckingFullMix
This section of a full mix contains a lot of overdriven guitar parts, which make it difficult to retain vocal clarity.
Ducking02_NoDuckingGtrsSolo
Here
are the two main guitar parts within the Ducking01_NoDuckingFullMix
file. Note that they are currently pretty consistent in level throughout
this section of the production.
Ducking03_DuckingGtrsSolo
Inserting
ReaGate on the guitar tracks, switching the gate’s operation to ducking
using the plug-in’s Invert Gate tickbox, and then feeding the detection
side-chain from the lead-vocal part results in the following ducked
guitar sound. Notice that the ducking is pretty obvious when heard in
isolation like this.
Ducking04_DuckingFullMix
Here’s
a version of the full mix previously heard in the
Ducking01_NoDuckingFullMix example file, but with the guitars ducked
along the lines audible in the
Ducking03_DuckingGtrSolo demonstration.
Note how the ducking is much less obviously audible within the full-mix
context than when the guitars were soloed, but nonetheless significantly
increases the sense of lead-vocal clarity. 0
Source:
http://www.soundonsound.com/sos/may11/articles/reaperaudio.htm
