Most people associate various dance genres with their
overall beats per minute and drum stylings, but equally important is the
sound of the bass. What would dubstep be with out its wub-wub bombast? Or electro with its massive sawtooth basses? Or hip-hop with its reliance on sub 60Hz sine waves and TR-808 kicks?
In the April 2014 issue, I covered the new trend of square
wave basses that are cropping up in deep house and techno. Well, that
bass sound now has an even newer offshoot, courtesy of FM
synthesis. Like the square wave bass, this sound emphasizes the odd
harmonics, but with the added punchiness of FM and the snappy
exponential decays that are often associated with its sound. Best of
all, you can also create this sound with more basic FM soft synths, like
Reason's Thor, which includes an FM oscillator option.
Here’s how to do it in both Ableton Live and Propellerhead Reason.
Since this bass sound shares many properties with a
classic square wave—that is, it features prominent odd harmonics—it’s
quite easy to create using only two operators: one modulator and one
carrier. By setting the carrier to the first harmonic (1) and the
modulator to the second harmonic (2), the overall spectrum of the
resulting waveform has that distinctly “hollow” sound associated with
In FM synthesis, the level of the upper harmonics is
determined by the amount of FM applied to the carrier. Higher output
levels from the modulator makes the sound brighter. Lowering that level
functions a little like a low-pass filter, reducing the high frequency
content. Adjust this level to taste, depending on how bright you want
the bass to be in your mix.
Finally, to add impact to this sound, shorten the decay of
the modulator’s envelope so that it's in the 150 to 600-millisecond
range. Again, this is a matter of taste as longer decays allow more of
the “square wave” aspect into the sound, whereas shorter decays give it a
stronger transient punch.
Step 4 (for Reason users)
If you’re a Reason fan, you can create an almost identical effect by
selecting the “FM Pair” oscillator in Thor and choosing a 2:1
modulator/carrier ratio. Then, use Thor’s Mod Envelope (via its
modulation matrix) to control the FM amount parameter, adjusting its
depth and envelope decay in accordance with steps 2 and 3.