GUITAR SOUND EMULATION

What a guitar, harp or piano sound have in common is the short duration of their sound once the key or string is played. The way to achieve a sound like this on reaktor is by using a Hold Envelope whose main function is to shorten the sound.

 

The first components added on the left hand side are the time controls which then are controlled by the Hold Envelope. Then multiplying the sound generator and the Hold Envelope together, would make the sound short which is ideal in order to emulate any string sound.

Now, to make it sound more similar to a guitar sound, the  sound of the oscillator (already shortened) goes attached to an amp/mixer which connects with a simple delay and a low pass filter. All these final steps in order to get a more similar sound to a guitar.

Vocoder With Voice Info Module

The way the vocoder work is to take two signals which are the modulator and the carrier and with this two signals we impose the amplitude of the frequency of the modulator onto the frequency of the carrier. This two signals (our voice as modulator from microphone and the synthesiser as carrier) then running through a series of bandpass filter. 

                                Our synthesiser as Carrier and Microphone input as Modulator

                                           Inside the main Vocoder's macro (Channel L/R)

 So what we actually do is that we take the signal from the modulator sending through a series bandpass filter and each bandpass filter is passed through an envelope follower then multiply the amplitude of each of those filter against the carrier's filter. Again, we do the same thing here with the carrier which is our synthesiser running through the same type of filter and imposing the amplitude of the frequency in the modulator's filter on the frequency on the synthesiser. Base on our research, what we actually found out was that with more bandpass filter more clarity sound could be achieved. So with two pole static bandpass filter in Reaktor that only gives us 4 voices means 4 bandpass filter and also they all set the same frequency. Therefore, we can use them as a number of voices to set the frequency. E.g more voices means more bandpass filter, more bandpass filter means more clarity sound. So, this is where the power of voice info module comes in, the voice info module tell us a maximum number of voices as well as the ID for the current voices. By using voice info module it will let us avoid the need to build a lots of bandpass filter. So we can just use one bandpass filter for the modulator and one for the carrier and then do a bit of math with the voice info module and convert the pitch into frequency then sending through the bandpass filter. This will save a lot of time for us. So, now our vocoder can use a lots of different voices and can achieve more clarity sound.

                                                          Inside the Vocoder Channel

Whole Step and Half Step Vibrato

Base on our researches, the traditional subtractive synthesiser has a whole step vibrato. But in Reaktor what we actually found out was that the amplitude control of the LFO default setting range was 0 to 1.  It is good for the amplitude modulation for tremolo effect with the default setting. But for vibrato 0 to 1 only give us half step vibrato. Because the setting 0 to 1 amplitude is multiply by the +1 to -1 bipolar wave shape so the output is +1 to -1 and that +1 to -1 is added to the notepitch and for example, if we play A above middle C that is note number 69 and that +1 will give up to note 70 and -1 will lower to 68 therefore we will only get half step vibrato with the setting range of 0 to 1. If we will set the LFO's amplitude range from 0 to 2 that mean with 0 there will be no modulation and with 2 that will give us a whole step up and whole step down. We really hope that this will help you as well because this kind of small problem sometime difficult to notice. Below, as you can hear the sample recorded between whole step and half step vibrato. And they were set to the same frequency and played the same note but with the different LFO's amplitude range setting. Half step with range from 0 to 1 and whole step with range from 0 to 2.

 

 

Half step vibrato

 

 

Whole step vibrato

Bipolar and Unipolar Signal Problem

                           Converting bipolar to unipolar signal is a common mistake that we always made in Reaktor. When we want to connect bipolar signal to unipolar signal we need to convert them otherwise it will not sound good because of polarity flapping. For example, when we are building a tremolo effect, we use LFO to modulate the Amplitude of the wave shape by multiply with the Envelope Generator signal so we can use the Envelope Generator to shape the Amplitude of the wave shape as well. But the problem here is that the LFO signal is bipolar -1 to +1 and the Envelope Generator is an unipolar 0 - 1. Therefore, multiply these two signals will not give us a perfect tremolo effect. So to solve this problem we need to convert the bipolar to unipolar signal. All we have to do here is to take the output from LFO that is -1 to +1 then rescale it in half and multiply by 0.5. Now it goes to -0.5 to +0.5 then add on 0.5, so the -0.5 and +0.5 become 0 and the 0.5+0.5 become 1. So we basically take bipolar -1 to +1 signal going into unipolar 0-1 signals. This it the problem that we encountered when we built our tremolo effect and it took us a while to understand it and solved the problem. Also as you can hear the samples that we recorded below. It used sine wave and the frequency rate was set to 1Hz. The one without converting bipolar to unipolar never gave us a perfect 1 Hz oscillation. Other one with converting bipolar to unipolar gave us a perfect tremolo effect. Obviously, if you compare two of them, you will definitely hear the different between them.

                                                    With Converting bipolar to unipolar

Without Converting bipolar to unipolar