Building a Synthesiser - an introductory tutorial for Reaktor v5.

Symple Synth: Low Frequency Oscillator

Next we're going to add some vibrato (low frequency variation in frequency and/or amplitude).
1. First we'll keep things neat and easy to follow by making a container for our LFO. Right click and select Macro>_New 2in2out and open the Structure Window of the new Macro. Delete one of the input ports and add an output port (using Copy/Paste is the quickest way)
2. Use the Properties Dialog to rename the Macro to "Low Frequency Oscillator". The input port is going to carry the signal from the Gate so that the LFO is synchronised with the Oscillators, so rename the Input Port to Sync. The three output ports are going to allow us to route the signal to any (or all) of Oscillator 1 Pitch, Oscillator 2 Pitch and Amplitude. So let's rename them whilst we've got the Properties Dialog to hand.
3. Now for the LFO itself. Right click and select Built-In Module>LFO, Envelope>LFO. As you will see if you check its Properties, this LFO will provide us with three different waveforms at the same time. We're going to put a switch in there so that we just use one at a time. Right click and select Built-In Module>Panel>Switch. Use the Properties Dialog to rename the Switch to "Waveform" and to change MIN NUM PORT GROUPS from 1 to 3. For clarity in the control panel, let's also rename the inputs of the Switch to "Sin", "Tri" and "Pls".

4. We've added a Switch to select which waveform the LFO should use. Now we'll add a switching system to target the LFO's output. We want it to be able to affect any one or two or all three of the Pitch of Oscillators 1 and 2 and the output Amplitude. So we'll need three simple switches, Labelled "Amplitude", "Osc1" and "Osc2". To complete the LFO, Create Controllers for the LFO's inputs (except the Sync, which we've already created) and wire it all up.
5. Before we connect up the LFO, let's tidy up the panel. First we'll unlock it and arrange things to look like the picture on the left. You'll notice that the set of three Switches has a label in the picture - that's a bit of a cheat! I've just right clicked in the Panel and used Insert Built-In Module>Text. Then in the Text's Properties Dialog I've changed "Enter your text here!" to Target, unchecked "Label" on the Visble pane and changed the style from Flat to Transparent.
6. Now let's connect it all up. And we'll add some pitch bend into the bargain. Take an extra output from the Gate to the LFO's "Sync" input.
7. Right click and select Built-In Module>MIDI In>Pitchbend. We'll need to add the Picthbend to NotePitch so Right click and select Built-In Module>Math>Add. In the Properties Dialog of the Add module change MIN NUM PORT GROUPS to 3 (we'll need the third one later) and connect the Notepitch and Pitchbend to the Add module.
8. Our LFO pitch information for each oscillator needs to be added to this incoming Pitch and Pitchbend information. So create two more Add modules and wire them in to the Pitch inputs of the Oscillators
9. Now wire the Notepitch/Pitchbend Add module output to each of the Oscillator Add modules and wire the relevant LFO Osc outputs to the Oscillator Add modules too. I've highlighted the new wiring.
10. Finally, as far as pitch is concerned, cut and paste the Master controls (from the top level) into your Instrument and add the output of the Master Tuning to the spare input of the first Add module we made.
11. Amplitude is a little more complex - we'll have to compensate for levels as we add and multiply things together. Right click and select Built-In Module>Math>Multiply with MIN NUM PORT GROUPS 3 and place it across the output.
12. To convert the Master Level, right click and select Built-In Module>Math>Expon. (A). This converts the logarithmic level values produced by the Master Level to the linear Amplitude values we need. Wire the Master Level output through the Exponentiator to our Multiply module.
13. Create one final Add module, right click one of its input ports and Create a Constant with the value "1". Wire the Amp Output of the LFO into the other input port and wire the output port to the Multiply module.
That's it, we're done with the noise-making part. Let's add a scope so that we can 'see' the wave we're producing