Making a vocoder in ams

Introduction

The entire process of setting up things in linux is more than often a hard one. Newbies have to deal with command lines and learning curves which range from steep roads to climbing mountaintops. Small goals like those presented in this tutorial can help people get confident in using linux as their DAW.

Requirements

  • a sound mind(pardon the pun)
  • jack configured correctly
  • either patchage or knowledge of connecting jack apps to each other
  • AlsaModularSynth
  • Sirlab's(or Achim Settelmeier's) ladspa vocoder plugin
  • vkeybd or any other way of sending midi notes into jack
  • a physical microphone(the day we can emulate that is far from here)

Setting up patchage

Start up patchage, ams and vkeybd. If you get a lot of xruns or crashes from patchage, your jackd daemon isn't started correctly, and the line in ~/.jackdrc should be changed. A last resort for help on getting this right is the linux audio developers channel on irc.freenode.net, #lad. Now, if everything is right, you should be able to connect the apps in patchage as follows:

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There probably are more things on the canvas, but you can ignore them. System capture and playback is what represents your physical microphone and speakers. You can test them by connecting them without going through ams. Blue is audio, green is midi. When you're done, you won't need to mind patchage anymore for this tutorial.

AlsaModularSynth

On ams' canvas you can put all kinds of modules. I will tell you about those necessary for a vocoder. Its goal is to emulate an analogue synth, so learning about one will also help you know the other. Voltage and resistance are replaced by floating point variables, but the emulation is quite accurate, actually.

PCM In/Out

These deal with what goes in and out of the jack connections of ams. This basically means your microphone and your speakers.

MCV

This stands for Midi Controlled Voltage. This is where the signals from vkeybd go to and this can be sent, in parts, to other modules.

Mixer 2 => 1

This one mixes two inputs and turns it into 1 signal. Useful for turning stereo into mono.

VCO

The Voltage Controlled Oscillator is the most important module when it comes to what your voice is going to sound like through the vocoder. The triangle or saw waves are a good place to start. The Frequency input will be linked to the frequency of the MCV, which results in the wave being the same pitch as what you play in vkeybd.

Linear VCA

The Lin. VCA module may not be what you expect of a Voltage Controlled Amplifier if you see the usage in this context. We'll use it to stop signals going through when there is no key pressed in vkeybd.

Vocoder

The cherry on top of the cake. This filters the “sound” of your voice and only the “information” part of your voice remains. The information in your voice gets mixed with the sound of the carrier. Settel can explain this much better than I can.

Here's how you should connect everything in ams:

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It should be pretty straightforward. If you rightclick any module another window opens so you can change some options. Good luck with finding out everything. The vocoder should be set to having 16 bands and you should set all bands to 1. As soon as I find out what every band does I'll put it here. If you do, don't hesitate to put it here.

There you are. You just saved 300 bucks, if not more. Ready for live or studio usage. Have fun!

Dirty bypass for more "formant" signal

You might be disappointed to how clearly you can hear a sentence. In my surroundings people were disappointed on that matter. I solved it doing this:

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Just make sure you mix the bypass accordingly so you don't hear too much of your own, unvocoded, voice. Unless you want that, of course.

Links

wiki/amsvocodertutorial.txt · Last modified: 2013/06/02 15:45 (external edit)