Subtractive Synthesis 103 – Modulation and what is an LFO?

Following from the first two post in the series (Part 1 and Part 2) we are going to learn how to turn your synthesizer sounds into fire breathing animals from the future.

So what is Modulation?

So far we’ve used a basic subtractive synthesis to construct a static tone. Which is pretty cool but we want is something AMAZING. This is where modulation comes in. Modulation just means to change. You’ll hear this term anyway from people talking about production, labeled on effect boxes (i.e chorus rate) and more traditional music scoring. Modulating through key changes.

How is it Useful?

Music is time based medium so the tricky part in writing is developing ideas that not only work in three dimension but also hold interest over time. Modulation of synthesis parameters is one of the classic production elements for you can add to your creative tool kit.

Explore Modulation Routing.

Using what we built on in this post on Signal Flow  we know that you can push signal around in anyway you can think of. A flexible synthesis will allow you to do this take one part of synthesis and using it to modulate or manipulate it.

Something like this:


Common Examples:

LFO – Low Frequency Oscillator. One first this that gets used and abused when you start out learning production. Your first track will be riddled when LFO like the new dj who put flanger over everything track.

The low frequency part comes from the rate cycles. Unlike human hearing the LOW FREQ will set below 20 cycles which means that we can’t hear but we can abuse it. By routing the LFO into different parameters we can “modulate” it the same way as if we turn the knob in real time.

Depending on the wave form shape triangle, square, sine etc will determine the way it’s going to modulate.

Straight Sine LFO modulating pitch

Square LFO modulating pitch:

Try this, take our TAl ELECTR7 and using lfo number one set the sine wave, amount full and route it to pan. Now slowly increase the rate and listen to the shift between the speakers, now switch to square and notice how it “jumps”.

Pan Mod Examples.

Square Wave LFO:

Modulate both Pan and Pitch with a Sine wave:

Flexible Routing Systems:

Now that we have the basic idea. We can build on it further with the use of multiple filters or routing different control amounts to different parameters (Pan, Pitch, Volume, ADSR curve, Effect Sends etc). The sky is the limit here.

(If you need a freeware alternative check out this site for some great ones

What if start using two LFOs for modulation of different parameters.

Two Lfo Controlling The Different Parameter At Different Rates:

Two LFO Controlling The Same Parameter At Different Rates:

Try two LFO modulating each other control rate:

Experiment with these and record the stuff you like. Sequence into a musical phrase and BOOM!!!

Share, Subscribe and Stay tuned because in the next post we are going to look at Classic Compression Uses and Abuses:


Enjoying Little Dragon at the moment:


About Braydon Zirkler

Currently based out of Melbourne. I'm dividing my time up between this blog, teaching, a radio show that's in the works and working on a live performance project with physical theatre performers. Get in touch here:
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