The Ultimate Guide To Subharmonic Synthesis

Bass not low enough? Not enough rumble in your track? Can you hear the low-end frequencies pulsating against your ears, but can’t quite seem to give your mix the kick it needs to feel the music?

We’ve all been there, and it sucks when you’re throwing everything you’ve got at the mix with diminishing low-end results.

Fear not – there’s a solution for a lackluster low-end: pumping in some subharmonic synthesis.

And even if you’re not a synthesis expert, there’s a place for this technique in your mixes. You don’t even need to know how to play an instrument to use this one!

What is Subharmonic Synthesis?

Subharmonic frequencies are undertones of a notes fundamental frequency. Most instruments have prevalent overtones that make up their sound, but very few have notable subharmonic content below the fundamental frequency.

To calculate a notes subharmonic frequency, you can use a spectrum analyzer to find the most prevalent note. Once identified, you can use a ratio to determine the undertones of the note. For example:

How to Use a Subharmonic Synthesizer?

Subharmonic synthesis is used to generate undertones, and they’re usually best at creating the ultra low-end frequencies that sit at the bottom of the human hearing range (and slightly below it). The average range of human hearing is 20 Hz – 20 kHz.

Depending on the synthesizer you’re using, you might only get a fixed window of frequencies to work with. Newer synths have become more versatile, with tools like Sub Destroyer performing just as well adding subharmonic content as acting as a standalone bass synth.

Every single tool is going to have a different approach to generating your subharmonic frequencies, but rest assured, the concept is the same regardless of the platform you’re using. Some are just more intuitive than others.

Where to Focus Your Attention

You can’t add endless amounts of low-end frequencies without muddying up your mix, so how do you prep your session for subharmonic synthesis?

First, you should be cleaning your low end up for the bare minimum of required frequency content. For a lot of bands, this is going to limit everything under about 200 Hz is going to be reserved for bass and kick drum. While that’s not a set in stone rule, you’ll want to clear out any of the unnecessary noise floor and “low-end rumble” from your other tracks that don’t have any business taking up that space.

Once you’ve got that under control, make a decision about what you’d think would benefit most from some low-end reinforcement. For me, it’s usually a kick drum or bass guitar.

You can also experiment with extended range guitars and other bass-heavy instruments and get some pretty great results.

Time To Synthesize 

Once you’ve done your housekeeping and your low-end space is relatively cleared out, it’s time to create your subharmonic synth track. For simplicity, we’ll be using Sub Destroyer. Just know that other synths might have slightly different terminology if you’re following these instructions step-by-step:

To get started, create a new Virtual Instrument track in your DAW & load your Sub Destroyer as an Insert.

Once inserted, we’re going to use MIDI to determine when Sub Destroyer gets triggered.

There are multiple approaches for getting the MIDI out of your audio track: some DAWs have the functionality built-in, others use tuning programs like Melodyne to transcribe, and some engineers even prefer to play the melody out themselves or draw it in.

If you’re using a subharmonic synth on your kick drum, the frequency/pitch doesn’t matter since you’re more interested in triggering the synth than playing along with the frequency variations. There’s a good chance you’ll actually end up with a more consistent kick sound this way.

If you’re focused on an instrument that will benefit more from following the notes being played, you’ll want to take all notes in the MIDI performance and lower them accordingly for the undertones you wish to add. For most purposes, down a single octave will usually suffice. If you’re after even more, two octaves down has also come in handy from time to time.

Tying It All Together 

Once you’ve checked your MIDI performance for accuracy, you’ll want to slowly raise its volume to sit under the instrument you’ve transcribed the MIDI from. There is no exact proportion that works best, but the subharmonic synth is there to beef up your sound, not overpower it.

As your subharmonics increase, you should begin to feel the low-end of your song start to flourish. Turn it up loud and the frequencies you were hoping to feel in the mix should be there in all their glory!

Are You Using Subharmonic Synthesis?

So many engineers I talk to about this topic end up knowing more than they think without knowing the technicalities of why it sounds good. Subharmonic synthesis is a tool that benefits technical and non-technical engineers every day.

If you’re using subharmonic synthesis and didn’t even know it, share your experiences with us over on the Joey Sturgis Tones Forum. If you’re new to the concept, come join us anyway and learn how your fellow engineers and producers are using it to increase the quality of their mixes!