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Learning Subtractive Synthesis

In this tutorial, I am going to focus on explaining subtractive synthesis. The purpose of this article is to actually give you knowledge on basics in synthesis, so that after this tutorial you are able to experiment in your instruments. I didn’t want to create another tutorial on how to make a specific sound, instead I decided to teach you how to make and establish your own signature in music.

Plugin that I am going to use in this tutorial is called Helm. Reason I’ve picked Helm is not only because it’s free, but also very powerful. You can create a wide range of unique sounds and it’s great for experimenting. Also, it’s important to note that you can follow this tutorial in any other subtractive plugin. But once you master the Helm, you will master almost any other plugin that is subtractive synthesizer.

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So let’s start with general knowledge in subtractive synthesis which can be applied to any plugin instrument. How does subtractive synthesis work? In essence, you cut away the part of sounds you don’t want to hear. We will divide it into five basic parts: osciliators, filters, amplifier, modulators and global controls.

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Osciliator, or sound generator, is a source of our sound, it’s the foundation. In Helm, you have two, Massive has three and sylenth has four osciliators. It depends on plugin but the principle stays the same: you pick a waveform you want to shape. Helm includes 10 different waveforms.

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Below it you will find tune and transpose knobs which pitch up or down our sound.

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There is also unison option. Unison is multiplying the signal which is being produced by our osciliator and detunes it, making your sound even bigger and wider.

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You’ve probably noticed the cross modulation knob. This is something unique in this plugin, and it actually modulates (changes) the waveforms you’ve picked, making the sound even more interesting.

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Helm also includes generators or osciliators which are made specifically to add sub or noise. You can also see mixer that can be used to adjust the levels of volume.

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Now let’s move on to filters. This is the part where you cut off the part of frequencies you don’t want to use or hear. Helm offers one filter, which can be applied to all osciliators, but it offers seven filter types.

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Once we choose the filter type we want, we set up cutoff and resonance. With cutoff, we can adjust the filter position, thus cutting the frequencies we don’t want to, while with resonance, we can adjust the frequencies we want to boost.

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So, we’ve picked the waveforms, we have removed the part of the spectrum we don’t want to hear, now we can actually set up our amplitude (or volume) envelope.

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It’s purpose is to shape the varying level of sound over time. It’s broken down in 4 parts: attack, decay, sustain , release. Volume envelope is pretty great for shaping our main characteristics of sound.

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In Helm, attack, decay, sustain and release are marked with beginning letters: A, D, S, R.

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Attack – it’s the part of envelope which represents the time taken for volume to reach it’s maximum level once we press the note.

Decay – represents the reduction in volume once attack phase reached its peak. Volume drops until it reaches sustain part.

Sustain – the period of time in which sound is sustained before it starts to fade out.

Release – final fade in volume once we release the note we were pressing.

To make things more clear, I have made some examples of volume envelopes which are imitating real instruments:

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Here, you can see piano envelope, it has a quick attack, once you’ve pressed key on your piano it almost immediately reaches its maximum volume level. Decay is set on approx. 10 seconds, because when you hold key, level of volume is slowly fading away to a complete silence, which is why a sustain is set to zero. I’ ve set a release to 3 seconds, which means that once we release piano key, volume is still fading slowly to silence.

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This picture shows us envelope of a closed hat (hihat). Attack is set to zero, when you hit the cymbal it immediately reaches its maximum volume peak. There is a little bit of decay and release in it, but zero sustain.

So now that we got this, it’s time to experiment with our effects. Luckily, there are plenty of them in Helm and it’s actually one of the top plugins I have used when it comes to it and they are pretty much self explanatory.

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Now we have foundation, our basic sound. The thing which makes it more interesting and better is modulation. Modulation is a change that is applied to any knob or parameter. We will divide it into modulation envelope and LFO. Modulation envelope is pretty much amplitude envelope, except it isn’t the volume that changes, it’s some parameter you want. Modulation envelope is like having an extra set of fingers to turn your knobs in instrument while playing notes. In Helm, you apply the modulation by left clicking the logo, and then left clicking the paramater you want to change. In this example, I will modulate the filter cutoff.

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Let’s take a look at LFO. LFO is simply an acronym for a low frequency osciliator. It can also affect almost any parameter in instrument,but unlike the modulation envelope, one period of LFO will modulate our parameter continously. Principle of applying it in Helm is same. You can change the amplitude ( how much you want to modulate the sound) and waveform (pattern when modulating sound).

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So now we have covered almost every basic part, except global controls. They affect overall characteristics of sound, like portamento ( glide between notes), pitch bend, and monophonic or polyphonic playback

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Portamento – used to set amount of time that it takes for one note to pitch up or down

Pitch bend – parameter that sets amount of pitch bend on your MIDI keyboard, it’s useless if you don’t have one

Voices – sets how much notes can be played at the same time

There is also a keyboard mod in Helm which is very useful when it comes to adding human effect to our synthesized digital sound.

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There is also arpeggiator included which can be used to play fast and complex notes automatically.

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And that is pretty much it, I have explained every single part of basic subtractive synthesizer plugin. Now that you know everything about it, there is only left to experiment and be creative with it. Play with the synthesizer, process the sound furthermore in your DAW of choice and make your own nice sounding patches. There are infinite possibilities which is the beauty of sound design. I hope that this tutorial has got you little bit familiar with the basis of making your own patches.