Subharmonic OSC Tutorial

Written by Maarten Hoogenboom on Monday the 13th of April, 2009
Did your ever wonder where those enormous rumbles come from whenever spaceships enter our solar system?
The sub basses in movies are often that low and loud that you can really feel them. It is an element of excitement powerful enough to make the public jump out of their seat. This effect is often accomplished by using a Subharmonic Oscillator.

What is it?
A subharmonic oscillator, also called subharmonic synthesizer, is similar to an octaver, but other than the one for your guitar, this one was built to shake the earth. Because an octaver is usually just a type of pitch shifter, the lower frequencies will begin to get messy when things get really deep.

To get nicely pronounced sounds you need a clean waveshape, like a sine. Hence, a subharmonic oscillator adds sine waves to the input signal. These sine waves are subharmonic frequencies, which means they are lower than the fundamental frequency of the input signal in a ratio of 1 / x. Let's say your input signal has a fundamental frequency of 440 Hz, then sub-harmonics include 220 Hz (1/2), 110 Hz (1/4), and so on. So to summarise, one could say that a subharmonic oscillator adds lower frequencies that are in tune with the input signal.

This is how a nice, round and deep bass is added to sounds that don't naturally obtain much presence in the sub range. Audio professionals use it to put bass in all sorts of sounds. Big male voices, knife stabs, bullet impacts - anything that requires that cinematic impact.

Where to get it?
Of course there are various kind of hardware subharmonic synthesizers/oscillators, but these can be expensive. But with a bit of searching on the internet, one can find some sofware equivalents.
Most of these also come with a pricetag, but there is also a free one that does the job, which is the Edge, available for download at codeaudio.com

And look what it does to our sinesweep:
you have to absolutely watch your precious speakers with this.
form_2.jpg

We can clearly see there is another sinewave joining in an octave lower, a very strong (standing) wave.
form.jpg

You can even set the Edge to go as low as 2 octaves.

Now how to get that sub growling.
This will be a send effect, so you can dial in some extra balls when things get heavy.
First we have to control what is going in the Edge. What you probably want is that it only reacts to the strongest and loudest part of your sounds. It does not have a gate built in so it will react to every sound. It has a built in filter but it is important to know exactly what gets through, so better use a reliable filter.
To get more control we first insert a resonant filter. With the filter frequency and resonance you can pinpoint the area that youd like to enhance.
filter.jpg

After that a compressor-gate comes in to get the volume under control. Use long attack and release settings because subbasses are very sensitive to sudden changes in amplitude causing clicks and pops.

gate.jpg

Now turn down the volume of your system by 50% because here comes the Fatass Edge, fiddle around with it until you get the feeling you can control the amount and position of the signal.

edge.jpg

It is immediately clear that certain evil powers woke up in your speaker. To get a hold of all that rumble we insert a limiter directly behind the Edge. We go for loudness here. Just make sure it doenst go past say -6dB to leave some headroom for other sounds.

complimiter.jpg

After that we insert an EQ with visual feedback so you can hear and see what to tweak. Cut a little in the area where the original bass is still active and maybe boost the sweetest spot a little.

eq.jpg

And after that we add just a little reverb to blend everything together.

rev.jpg

Examples we made:

original sound:

with subharmonic oscillator:

original sound:

with subharmonic oscillator:

Resources:

We dont recommend any particular 3rd party software and the plugins used in this tutorial are just preferred tools of the writer(s) of this article. We do however post links to freeware, to ensure you have all the means to follow this tutorial correctly.

WindowsVSTWIN:
Pushtec 5+1A - is a 6-band mid-range and program EQ. A Winamp plugin version is also included.
The Classic Master Limiter
- VST plugin is specially designed to boost the overall level of your final mixes, but can also be used on very dynamic instruments.
Classic Reverb is a nice and smooth reverb that does a good job on almost any instrument.
Mac OS XUniversal BinaryMAC
Rogue Amoeba Mastering Plugin - not tested by yours truly, hence I dont work with mac, but seems to be one of the view free mastering plugins for mac out there!
Slim Slow Slider: Linear Phase Graphical Equalizer 2.1 not tested by yours truly, hence I dont work with mac, but seems to be one of the view free mastering plugins for mac out there!

Now go on and experiment with this to give your effects and beats that extra professional sound quality.

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