Back in the April column, I left you with a lead sound
that faded into harmonics via a controller, and said we were on our way
to emulating classic guitar feedback. Let’s continue with that
exploration. The logical next step is to dirty up the sound a bit—but
not too much—to bring our synth playing closer to the role that
distorted lead guitar has played in music for decades.
These are deep waters we’re entering, and guitar players can
and do go on ad nauseam about the nuances of distortion. I only want to
dip our toes in, so the ground rules for this month are:
We want a subtler addition to our tone. All-out
fuzz and over-the-top grind are cool, but they tend to take over your
sound and playing. Such sounds usually are the product of hard clipping,
where the tops of the waveform have been flattened out severely. It
doesn’t much matter what waveform you feed into these types of sounds,
the distortion itself becomes the tonality, and your sound gives up most
of its character to this effect. Also, it becomes difficult to play
faster lines with any distinction, and forget about playing higher up on
the keyboard, as the aliasing and intermodulation distortion
(especially when pitch-bending) becomes pretty nasty. Check out the
online audio clips to hear what I’m talking about.
Our “dirt” should respond to our playing dynamics. In
guitar terms, overdrive is the even harmonic-based sound of an amp that
clips in a gentle, rounded fashion, called soft clipping. The tops of
the waveform are altered but not completely flattened. When this happens
dynamically, the softer playing is not changed (as much) and the
clipping increases as you feed the effect a stronger signal. This soft
clipping adds some edge to your sound without taking over. For a synth
lead you often don’t want your sound itself to have too much dynamic
range, as you can get lost in the mix while soloing. So we don’t need
the amp or filter to respond significantly to velocity. But by making
your effects respond to velocity you get to control your overdrive dynamically, getting dirtier as you dig in harder.
| Fig. 1. Applied Acoustic Systems’ Ultra Analog offers a variety of filter overdrive types.
Fig. 2. Spectrasonics Omnisphere also provides an abundance of filter types and characteristics.
|Fig. 3. Ableton Live’s Saturator includes a waveshaping mode.
| Fig. 4. Logic’s Distortion plug-in offers basic input and output gain staging, plus a tone control.
Just a Little Edge
Before we go to effects, there are some synthesis-based
ways to give our sound a little attitude. See if your synth has any
controls for boosting the signal going into the filter, or a feedback
loop, or a filter drive parameter. Logic’s ES2, U-he Zebra 2, Applied
Acoustics Ultra Analog (see Figure 1), Reason’s Thor, and many
other software (and hardware) synths have this feature. Other synths may
offer a filter type that already models some amount of saturation or
drive. Figure 2 shows the many choices available in Omnisphere.
Can the parameter be a modulation target? If so, use velocity to
increase the depth or intensity of the effect.
Does your synth have an external audio input? If so, try
routing an output from the synth back into itself. On a hardware synth,
try using the headphone output (this won’t work on synths where plugging
in headphones mutes the main outs and there’s no way to override this
behavior). For a soft synth, you can set up a bus output in your host
software, which you can then feed back into the synth’s input. This is a
classic technique that I first learned from Jan Hammer’s work, where he
connected the low output of his Minimoog back into the external input
and set the level to clip just slightly. This fattened up the sound
nicely, and is now even documented in the manuals for most Moog synths.
Waveshaping can also add some edge to a sound, but you
need to use it very sparingly and find a shape or preset that’s not too
over the top. Some classic hardware synths like Korg’s O1/W and Prophecy
offered it as part of their voice, as do Cakewalk Z3ta+ 2 and Spectrasonics Omnisphere; today’s Korg Kronos, Propellerhead Reason, Ableton Live (see Figure 3),
and many others offer it as an effect type. Whenever possible, set up
velocity to modulate the depth of this drive/waveshaping.
Digging in the Dirt
There are two approaches to adding effects for
overdrive/distortion: using a dedicated effect (including models of
classic effects pedals), or using a complete guitar amp modeling setup
such as a Line 6 Pod or IK Multimedia’s AmpliTube software. While both
can produce wonderful results, I recommend you start with the dedicated
effect for synth leads. Why? Many guitar amp models include
speaker/cabinet emulations, and these roll off frequencies and color the
sound based on the frequency range of a guitar, not the full-range
output of a synthesizer.
To produce overdrive or distortion, the input to an
amplifying device was overloaded, producing additional harmonics and
color. Most effects emulate this by having an input gain control and
another output level control to compensate for the increase in volume
that occurs as you raise the input level. Note that the input control
may be labeled as drive, gain, overdrive, crunch, fuzz, or other things
besides “input gain.” Not to worry. Figure 4 show this in Logic’s
very basic Overdrive effect. The basic idea is: The more you increase
the input gain stage, the more you’ll want to decrease the output stage.
We want more “attitude” for our sound when we kick it in, not more
So look through your synth or soft synth or DAW and find
the category of distortion, or overdrive effects. Pick something as an
insert effect in your synth or DAW. If it has presets, take a tour
through them. As you call up the presets, examine how they’ve set the
controls, paying close attention to the amount of gain or effect being
introduced at the front of the signal chain. This is the critical input
overload stage that we want to set to taste, not going so far as to fuzz
out our playing.
If you find that the effect is drastically changing the
thickness and tonality of your sound, look to see if it includes some
form of speaker simulation and turn that off. If that doesn’t help, you
should set it up on a bus in your DAW, or as a master effect in your
synth, so you can blend the wet/dry mix via the send level to your bus,
or the level of the bus return. This way you can add a little of the
effect’s sizzle without sacrificing all the frequencies of your original
sound. With this routing I can use the most aggressive, high-gain
effect and tame it to my needs, and even accept the results of an
included speaker simulation. Finally, if at all possible, set the master
effect’s wet/dry mix, send, or bus return to be modulated by velocity
so your fingers can interact a bit with the amount of overdrive added.
In a DAW this may need to be done via automation, not just MIDI learn.
As always, experiment and enjoy!