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Vocoder - Make your synth sing

You can make your synth ‘sing’. Yes, that’s right! You can create really cool backing vocal parts in your track by using a Vocoder.

There are many techniques you can use in creating a great mix. One of the hidden gems is to use a Vocoder to create ‘backing vocal’ parts. Especially in the modern hip hop & RnB genres.

So, what is a Vocoder?

Simply, vocodor is short for VOice EnCODER. It encodes the characteristics of the voice using a bank of narrow-band filters. The more filters you use, the cleaner the effect. Fewer filters create a more pronounced synthetic ‘artificial/robotic’ quality.

How does it work?

The Vocoder works by breaking up an analysis signal into narrow frequency bands. In the video below I used the lead vocal part as the analysis signal.

The analysis signal is whatever you are using to side chain the Vocoder.

The included Synthesizer is broken up into the same, corresponding narrow frequency bands.

So why does this make it sound like the Synthesizer is singing?

First a little terminology:

Delay is a repeat of the original sound after a given time.

Panning is close, but not quite the same as,a delay that effects sound localization.

Envelope. The envelope is a form of automation built into synthesizers to control the value of a parameter (typically the volume or filter cutoff frequency) over time.

Attack, Decay, Sustain, and Release. (also known as ADSR) are the four basic parameters found on a basic synthesizer envelope generator.

And now, a very basic explanation of how we form words is needed: A human voice produces a number of resonant peaks called formants. These formants all occupy a really narrow frequency band, & the different human vowel sounds are created when a group of these formants combine. As we speak or sing, the formants also change as we change vowels. So, the Vocoder then captures the changing envelopes (see terminology explanation above)

of these formants with their really narrow Frequency bands, and the Envelope Followers apply those envelopes to the synth sound, making the synth ‘produce vowels’, as if it were ‘speaking’ the words of the vocal signal.

If the synth part is playing chords or playing notes, it will seem as if it’s ‘singing’ those words; and there you have it, the “singing synth”!

Ok, granted it is rather robotic; and well, ehrm, ‘synthetic’. But hey, it’s cool!

The consonants (a consonant is a speech sound that is not a vowel) in the analysis signal (remember that vocal in the video) are detected and either passed through, or used to generate a separate noise signal. This lends greater clarity and articulation to the “singing synth”. All of these aspects can be tweaked with the various controls in a Vocoder, so you can dial in a ‘clear’ or more ‘synthetic’, ‘aggressive’ effect.

Here’s how to get the classic Vocoder effect with Logic Pro X EVOC 20 PolySynth.

1. Create a new Software instrument track

2. Insert the vocoder onto the new track

3. On the vocoder synth track; play in or paste some chords from a part of your song or even some melody notes you want the Vocoder synth to play back

4. Use the preset menu on the Logic Pro X EVOC 20 PolySynth to choose a ‘sound’

from. I really like the Vocal heaven Pad from the 02 Vintage vocoder menu option

5. Route the track you want (I used the lead vocal track in the video) to the EVOC’s

Sidechain input.

On the EVOC 20 PolySynth vocoder, the attack and release times can be adjusted to determine the vocoders response to the signal. If you need a more ‘intelligible’ clear effect; then use fast attack times. Keep dialing the knob, until it sounds nice and ‘clean’ or more suited to your track, to you. Also, choose the number of bands you want affected. Just remember that the more bands (wider) you select (up to 20) will result in a ‘cleaner’ version of the effect; and as you lower/narrow the number of bands; so the effect becomes more aggressive, prominent and

‘robotic’. I addition to really tweak and play around with the sound, use The Formant Stretch and Formant Shift controls. You’ll get some really great tonal-shifting special effects, and to if you need to really be intense; start dialing the Resonance control. There are many useful effects and wonderful sonic effects you can come up with the Vocoder.

As a continual professional development practice; I make sure to set aside 3 hours per week to just, well, Play! I’ve found that it’s one of the best ways to get some fresh inspiration.


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