Last month, we took a deeper look at waveshaping and overdrive. This month, we’ll look at alternative uses for bit-crushing. Ableton Live
refers to this effect as “Redux,” and Propellerhead Reason includes it in its Scream device as the “Digital” mode. The bit-crushing sound is based
on down-sampling. By reducing the sample rate of digital audio—without the usual filtering of frequencies that are greater than half the sampling
rate—the result is aliasing: grungy artifacts of the sample rate being too low to accommodate the audio’s upper frequency range. Normally,
you don’t want it. Here, we’ll dare to be different. Scroll to the bottom of this page for audio examples.
Crunchy Top Loops
Sometimes hi-hats and top loop material can have too much
high-end sizzle. EQ is a common way to tame this, but bitcrushing
can accomplish a similar thing while adding a bit
more upper-mid crunch. The secret is to use just a tiny bit.
Here’s Apple Logic’s processor in action.
Example 2: Tuned Aliasing
The aliasing tones created by down-sampling can often be tuned
to the overall key of your mix. So, analyze the dominant pitches in
your mix and tune your effect to reinforce the musicality of your
production. For rhythmic loops, you can transform the part entirely
by adding a gate after the bit-crusher, then adjusting the threshold
until a tighter rhythm is created.
Video Game Explosions
Some bit-crushers, such as Ableton Live’s
Redux, include a “hard” mode for downsampling.
This is often too intense for a
mainstream mix, but it excels at vintage
video game explosion effects. Just run a
noise burst into Redux and twiddle until
you get that “Missile Command” sound.
For Reason users, Thor’s noise oscillator
has a sample-and-hold mode that does
this trick quite nicely.
Example 4: Rises and Falls
In previous columns, we’ve covered the ups and downs of creating
rises and falls. For a tougher version of this production trick, try
automating the down-sampling value of your bit-crusher. Higher
values create lower pitches, and vice versa, so as always, use your
ears as you automate the effect.