Reaktor Primary - 1. Building a Synth: Absolute Basics

Delving into Reaktor 6's Primary mode allows you to build your own synths and effects. It is a great way of getting into the electronics and theory of synth building without having to worry about soldering and spending money on hundreds of components. This tutorial is going to demonstrate the most basic application of Reaktor's primary mode to build a very basic synth. The only controls on this synth are going to be the oscillator select controls however, in future tutorials, I aim to build off this model and we can build a complex synth together!




Since you are still reading at this point, I will assume at least a basic understanding of synths is present - don't worry if not, following along will help you understand things much better. Step one involves opening Reaktor in your DAW. If you haven't already, I recommend that you open up some of the instruments in the library and have a play about to familiarise yourself with the Reaktor engine. To get to actually building and editing your own synth, we want to look at the top to the EDIT button and make sure that it is selected. You can also hover over the EDIT button to see what the function is (ensure you have the info button enabled if you want details from hovering). As you can see in the image below, a small detail box appears over the mouse. One important thing to note is the shortcut, as this will massively optimise your workflow in Reaktor. The EDIT shortcut is F1.


The next step is to select the down arrow by the REAKTOR logo at the top left corner, select File, then select New Ensemble. An ensemble is essentially the instrument/effect that you can build or load into Reaktor. This will open up a blank slate from which you can create near enough whatever you can think of from scratch.


Once you hit New Ensemble, you are greeted with two inputs and two outputs. This is good for if we are making an effect where we want the sound to come in, get processed and then get sent out. Since we are making a synth though, we don't need to worry about the inputs. You could delete them but it makes no real difference. Again, hover over these modules to see what they are. You will notice that on the right hand side of the in modules is a white dot, same goes for on the left of the outputs. Reaktor signals travel from left to right on the screen. We could, if we wanted to, connect the inputs straight to the outputs, meaning the signal travels through Reaktor unprocessed. Depends if you can handle that much fun in your life.


Now that we've demonstrated the ins and outs of Reaktor (sorry), let's look at how it can be used to make a synth. The heart of a synthesiser is the oscillator, this is a component that creates a waveform which repeats at a controllable frequency. The most basic waveform (sonically) would be a sine wave which contains only one frequency. Let's start with that. To load one in, right click in the main window, anywhere in the space with the inputs and outputs. Select Built in Module, then browse down to Oscillator, and select Sine.


This has loaded a sine oscillator into the middle of the screen. You will be able to tell quickly which oscillator it is because, aside from its name, it has a graphic of a sine wave in it. Let's look at the two inputs, (left hand side). We have one labelled P, and one labelled A. These stand for Pitch and Amplitude. When someone hits a note on the keyboard of a synth, two basic signals are sent: the note, e.g. what pitch is being being played, and also the note status. P will take the MIDI value and assign that to the pitch; A looks at a number of things. For now, we only want the note to be on, when the key is hit, or off when the note is not being played.

To get the information from the keyboard, right click in the main window, as before, and select MIDI In, from here, load up a Note Pitch and Gate module. These are the inputs we need to make the oscillator know what is being played. Gate essentially sends a value of 1 or zero, depending whether the note is being played on or off. When this goes into the A input of the oscillator it will translate to 1=max volume, 0=min/zero volume.


They all connect up fairly intuitively, with the outputs of the oscillator going to each of the two output modules (for stereo left and right). One thing you may notice is that some inputs are orange, and some are white. White is the colour of audio signals which are normally sent at a sample of 44.1kHz; orange is the colour of event signals which run at a much lower sample rate of 400Hz, this is because they don't translate directly to audio and are for internal signalling. As a general rule, orange connects to orange, and whites to whites. They tend not to mix well, but in the case of the Gate A connection it is fine for now (we will modify this in the future anyway).


Take a minute or two to play around with the sound - play notes on your keyboard to make sure everything is working and sound is being outputted. The next stage involves polyphony. You have two types of synth, monophonic (only one note can play at a time), and polyphonic (multiple notes can play simultaneously). Reaktor allows you to do both but by default at the start the sounds are monophonic. To change this, click on the main editing window and select the tick box under the Reaktor logo this is the properties menu, which can also be accessed via F5. Make sure you are looking at the Function tab and look down to Voices. By default, the value will be 1, change this to a larger value. I have set the value to 8 which will be sufficient for most playing styles at the moment. As highlighted in the image below, the wires connecting the oscillator to the outputs are now red. This means there is something bad.


This is because the modules in reaktor are not all capable of handling polyphonic signals. The easiest way to tell is by looking at the musical note symbol on the module itself. Below, you are able to see that the two inputs have a single note and are therefore monophonic, the MIDI in modules on the other hand can send the signals of numerous notes simultaneously. Just like the input modules, the output modules can only take a monophonic signal.


This means that we need to combine the signal into a single sound or voice, so that it may be received by the output module. Easiest way to do this is to find the audio voice combiner. To avoid looking through submenus in Reaktor, its often quicker using the search box. 


Type in "voice" or "combine" into the search box, and you will get options. Select the Audio Voice Combiner. The search box is really handy for modules such as this one, and having seen many users forget its location, its normally quickest going through the search. The other big benefit to the search box is that you can find modules which you don't know the exact name of. Simply type in what it does (e.g "combine") and you will get good options.


You will see the Audio Voice Combiner below with the module title "}" all this does is combine the multiple polyphonic outputs of the oscillator into one signal, which is able to be accepted by the output modules.


At this point, you could argue that we have made the most basic polyphonic synth. It plays sine notes on/off depending whether the keyboard notes are pressed, and nothing else. Let's add a single sound control element to this synth. We want it to be able to select between the basic wave shapes which most synths have. To do this, we follow the steps for loading the sine oscillator (right click, select the oscillators menus, e.t.c), and instead, we an instance of Triangle, Sawtooth, and Pulse. For tidiness arrange them in a column like below - Reaktor gets messy super quick, and so a great way of knowing what you are doing is having basic organisation of each element.


Just like for the Sine oscillator, connect the Pitch in and the Gate inputs, and add an audio voice combiner for each one's output (right click on the middle of the audio voice combiner and select Duplicate to avoid going through the search menus). It should now look something like the image below.


Output modules can only accept one wire going into them at once, so we are not able to connect the audio voice combiners straight to the outputs. We don't actually want to do this anyway because we want a way to select only one oscillator to play at once. This can be done by adding a Switch module. The Switch module can be found under Built in Modules, then Panel, or just find it in the search box.

Connect the top audio voice combiner to the input (you will only see one input just now). Hold the control key and drag the next audio voice combiner's output to just below the first on the switch. A second input should appear. Repeat for each oscillator's signal. Double click on the "In" for each input of the Switch and you have the option of renaming the input. Connect the Switch to the output and you now have a Selectable-Oscillator synth. If you look at the panel view, you will see the faceplate of the synth, where the controls are, and the control switch should be visible. Hear the differences in each waveform as you play through each sound.


At this point, save the ensemble so we can come back to it for future tutorials.

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