LAST MONTH WE STARTED EXPLORING FILTER TYPES AND DOING BASIC SWEEPS.
I expect that you listened to the online examples and got an aural “sense” of what
each filter type sounds like. Now, we can get into further expressive tips for using
filters in live performance. - JERRY KOVARSKY
|Fig. 1. A dual-filter configuration on the Korg Kronos. Filter B is highpass, and lets all frequencies through by default. With an assigned MIDI control, I can raise its cutoff “floor” slightly to sharpen my sound.
There’s a world of possibilities in sweeping a lowpass
filter with differing amounts of resonance.
Let’s expand on that and add some more character
to your sweeps. The trick is to add an additional
filter type into your signal chain, which
will only be heard when you sweep it with a different
controller than whatever you normally use
for cutoff and resonance.
How to set this up will vary depending on
your synth and on whether you’re tweaking
an existing preset or making your own. Some
synths offer a dual-filter design, with a choice
of running them in parallel (the pre-filter
signal goes through both filters at the same
time—sometimes using one filter per stereo
side) or serial (the output of one filter feeds
the next). Note that I’m talking about having
two completely independent filters, each
with their own cutoff and resonance controls.
Certain synths offer configurations that combine
two filter types in a preset chain, under
the control of a single cutoff, but we can’t use
those for our purposes here.
Assuming a true dual, independent filter design,
you want the serial routing. Your first filter
would be the usual lowpass, set to your favorite
values for cutoff and resonance. The second filter
will be a different type—let’s try a highpass.
(See Figure 1 above.) It’s important that the
highpass cutoff be set to the lowest value, so it’s
letting all the frequencies pass through. Set like
this, you won’t initially hear any eff ect from the
highpass—it’s just in the signal path awaiting
further “instructions.” Sweeping your usual cutoff
controller (knob, mod wheel, etc.) will only
affect the lowpass filter.
Now, you want to set another controller to
fully modulate the lowpass cutoff while slightly
modulating the highpass cutoff . This could be
an unused knob or slider, a ribbon or vector
joystick—your choice. I like the effect to be
subtle for the highpass, just adding some cool
timbre-shaping at the end of my controller gesture.
So I’d use a low positive value for that
filter modulation assignment, maybe 15 to 45
percent. (See Figure 2 below). This way your
highpass cutoff starts at zero, or wide open.
As you move your controller, you’re slightly
raising that frequency “floor,” which removes
some low end from your sound. Go too high
and your sound will “thin out” too quickly,
likely not cutting through the mix well enough.
When it’s just right, though, the effect can
actually spotlight the mids and highs.
|Fig. 2. Here, the same knob (MIDI CC 17), raises the lowpass filter’s cutoff
a lot (intensity set to +92) as it also raises the highpass cutoff more subtly (intensity at +44). This gesture can further accent my sound even though the lowpass filter might be all the way open.
If it’s offered, you can also add a little resonance
to your highpass filter to help accentuate
its effects. Now, you can do your traditional filter
sweep from the usual controller, or go to your
second controller for a sweep that has a little
more character. Alternately, you could dedicate
the second controller only to highpass sweeps
and interact with both as desired.
After experimenting with this, try changing
the highpass to a band-reject (a.k.a. notch)
filter type, and using more modulation depth/
intensity for how the controller changes its
cutoff frequency—around 80 percent works
well for me. This adds very cool aural interest
to the mid and upper parts of the sweep,
precisely when the lowpass filter is fully open
and thus has nothing more to add. Setting up a
dedicated modulator for a band-reject filter is
also fun, as it adds a kind of manual flanger to
Effect Slot as Filter
How do you do the above when you’re using an
emulation of a classic synth that didn’t offer dual
filters? That could be a Minimoog clone, a simple
virtual analog design, or a DSP-based synth that’s
using all of its available filter horsepower to emulate
a 24dB-per-octave filter. (Many of my Korg
synths do this, for example.) Effects to the rescue!
Since we’re focusing on lead synth playing, I’m
assuming most of your sounds are monophonic
or that you’re playing one note at a time. So using
a filter effect from your synth’s effects section,
or a separate filter plug-in on top of a soft synth,
will work fine even though it doesn’t represent a
true per-voice filter design. On a synth, all of your
sound normally goes through the filter, so use an
insert or total/master effect here to do the same.
Putting the filter effect on an aux send bus is not
desirable, since we want no dry signal mixed in,
which would weaken your sweeps. As far as performance
control goes, we have the same options
as earlier, as virtually all software hosts and hardware
keyboards let you map effects parameters to
Start exploring this, and next month we’ll go
even further into other types of effects that will
enhance your filter sweeps. Enjoy!
Here’s a partial list of synths and
software that give you the tools
to set up the serial filter routing
from this column.
Hardware synths: Korg M3, M50,
and Kronos (Stereo Multi Mode
Filter); Roland Jupiter-80 (Super
Filter) and V-Synth GT; Yamaha
Motif series (Dynamic Filter).
DAWs: Ableton Live (Auto Filter)
Apple Logic and MainStage
(Auto Filter); Avid Pro Tools
(AIR Vintage Filter); Cakewalk
Sonar (ModFilter); MOTU Digital
Performer (Multimode Filter);
PreSonus Studio One (Auto Filter).
Third party plug-ins: Audio
Damage FilterStation; Camel
Audio CamelPhat; FabFilter Simplon,
Micro, and Volcano; Roger
Linn AdrenaLinn Sync; SoundToys
FilterFreak; U-he Filterscape;