Propellerhead Reason tutorials made by Hydlide

Published on Reason Experts

Creating an Analog synthesizer with Thor

Published: 6 months ago

I am Hydlide of In this article, I want to share an idea on how to create an analog synthesizer using Thor inside Propellerhead Reason. While the idea is nothing new (since I have talked about this technique in for instance creating a Moog synthesizer in Reason and while making video presentations like creating an analog synth using subtractors). I am always a fan of perfecting different ideas and this is just one of those moments. Since there is one setting, in particular, I find very useful to emulate the idea of analog style synths. And this would be the setting voice key. The idea I am going for is based on different ideas I did in the past but do something slightly different.

But let's start with the basic context on what are analog synthesizers?

Analog synthesizers vs Digital Synthesizers

To understand what makes an analog synthesizer tick, you will need to know how they are built. Analog synthesizers are based on analog components that change when they become warm. Tubes and transistors are just a few of those components. Due to its nature that these are powered by electricity, they send out signals and voltages. While they should normally transport the exact same amount of voltages, in practice this is not always the case. Due to heat, resistance increases and thus the voltages may vary slightly. Often it is these little changes on which the synthesizer is built on. Because they produce a specific sounding character.

The problem here with emulating analog synthesizers in the digital world is that we have to focus on complex models to make a sound become more analog. Especially if you look at most native stock devices inside reason itself, the waveforms and their oscillators are fixed by nature. While there are waveforms called "analog" for some reason, they do not 100% resemble the analog world as it is in reality. Simply because analog oscillators in reason have a different meaning (since they have a different offset when loading them up, which something else then comparing this to a real analog oscillator). 

While oscillators are one thing, analog filters are another. Because of analog filters (in the analog world) are based on the same physics on which the analog oscillators are built on. Analog components which are heating up and due to resistance their sound output starts to vary slightly. While in the digital realm filters are usually a bit stiffer, they sound much more stepped when moving them around (a thing that analog does not have a problem with). And so on.

Analog oscillators in the digital world

Because of the complex nature of the analog synthesizer, a few basic solutions have been provided just to make it sound a bit more natural. In a device like Thor you can find an oscillator pair called "Analog Oscillator". These oscillators are based on the foundations of what made analog sounds work. Sine, Triangle, Square, and Saw.

This thing with these analog oscillators is what they will do is to set the offset (the starting point of the waveform) always different each time the patch is loaded. When you compare this with a digital waveform (such as the wavetable oscillator in Thor) the start offset will always be the same. Thus they sound a bit stiffer compared to analog oscillators.

A good example would be setting up Thor with 2 times the same exact oscillator. Press a note, and compare an analog pair with a wavetable pair.

Analog oscillator in Thor

The reason why an analog sound will sound like it is phasing in this context is that the start offset is different from oscillator 1 to oscillator 2. While doing the exact same thing with two wavetables they will make the sound louder (because they play the same exact sound twice). 

Making use of the phase offset

To make use of the phase offset we can program thor very simple by looking at the rear of the thor patch and program thor the exact same way.

Analog oscillator true stereo

Oscillator 1 will be going through filter 1 and Oscillator 2 will be going through filter 2.

Thor true stereo patch

In this case, we have routed Oscillator 1 to Filter 1. Oscillator 2 goes through filter 2. The amp section goes to 0. And we have set up the modulation bus matrix so the filter 1 and 2 will go over left vs right.

Download Thor True stereo patch

While this does make things sounding wise a lot more interesting (since we are just creating space over left vs right) there is only one problem with this. Velocity has no effect on this. And if you think about VCA (voltage controlled amplifier) then having some voltage to control the amplitude would be quite essential.

Voice Key, Last Key, and Midi Key

This brings us to a very important section which is often overlooked. Voice key, last key and midi key are 3 different sources you can find inside the modulation bus matrix.

Thor voice key

While they have similar settings (note, velocity and gate) they tend to act differently from one to another. All settings will listen to what is happening on the sequencer (even while "midi key" would suggest otherwise, since it could suggest that it only listens to the midi keyboard). There is barely any difference between the Last Key and Midi key. The only difference is when you start pressing chords. The last key will always respond to the highest key that has been pressed while the midi key sometimes does not. Also the last key and midi key are monophonic. Meaning, the last key that has been pressed will result in a global parameter on all keys assigned to the destination. The voice key, however, is a polyphonic setting. Which means you can adjust a parameter on any polyphony that is played. Unless the destination is a global setting!

The global destinations in Thor would be:

Thor global settings

Portamento, LFO2, the Global envelope, Filter 3, the 2 effects in Thor, the Step sequencer and the CV / Audio outputs. Everything else listens per voice while using the Voice key parameters.

This means we can... if we want to make use of the Amplitude envelope and scale this with Voice Key > Velocity when needed. Inside Thor, there is one section in particular which allows that to happen.

Velocity and true stereo using Thor

It is a similar thing that is shown in the picture of the rear of Thor. But in this case, the Voice Key velocity will now have an influence on how much the amp envelope will be used (thus it controls the volume).

Now if you combine this with an LFO controlling the pitch and filters. You basically have created an oscillator that gets a bit more unstable than normal (thus more leaning more towards an analog synthesizer). 

Analog synthesizer programming

You can download the patch here:

Download analog pulse

Have fun with this one, and till next time!

Published on Reason Experts
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Published on Reason Experts
Published: 6 months ago

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