Vox synth pads

Hey. One of the things I use Audacity to do is make Soundfont files.

Im wondereing if anyone knows the basics from making vox string synth style sound?

What kind of equalization? and what kind of tone to start out with?

Saw, square, sine, or other?

Any Ideas?


Many of the old analogue style string pad sounds were created using Pulse Width Modulation (PWM).
The easiest way to generate PWM sounds in Audacity is to use “Nyquist” code.

See here about “Nyquist” programming in Audacity: http://audacityteam.org/help/nyquist

Try selecting part of an audio track, then from the “Effect” menu select “Nyquist Prompt”.
Copy and paste the following code into the Nyquist Prompt box, then click “OK”

(mult (pwl 0.1 1.0 0.6 1.0 1.0)
(mult 0.4 (osc-pulse 110 (sum 0.35 (mult 0.4 (hzosc 56.2)))))
(mult 0.3 (osc-pulse 220 (sum 0.35 (mult 0.4 (hzosc 110.5)))))
(mult 0.2 (osc-pulse 440 (sum 0.45 (mult 0.4 (hzosc 221.5)))))

Cool thanks , Ill try it out. :smiley:

K Iv’e noticed the Pulse-width modulation Nyquist code generates it’s own wave. I wonder is there any way to use it as an effect over a sound?
rather than have it generate a wave.

Also could you please tell me what each number changes in the code so I can better understand how it works?

Yes that was a “generator” rather than an “effect”.

For generating a “string pad” type sound you need a lot of overtones/harmonics. You could start with one or more square waves or triangle waves, or saw waves, to produce a rich frequency spectrum (additive synthesis), or you could start with sound generated using “Pulse Width Modulation”. The code that I posted contains 3 PWM generators and a simple envelope shaper.

<sound 1>
<sound 2>
<sound 3>

The “sim” function (simultaneous) combines the three sounds (mixes them).

(osc-pulse 110 (sum 0.35 (mult 0.4 (hzosc 56.2))))

This is the first generator.
It is made from a pulse oscilator (osc-pulse).
The basic way that the pulse oscilator works is that you define the frequency, and the width of the pulse.
(osc-pulse )
So the frequency of this oscilator is 110 Hz.
The “width” parameter (more accurately called the “bias” parameter) is a value between +/- 1
If the bias parameter is zero it will create a square wave - try the following code in the Nyquist Prompt:

(osc-pulse 100 0)

This produces a full-scale square wave with a fundamental frequency of 100 Hz.

It’s easy to scale the amplitude of a sound, simply by multiplying the sound by a number less than 1. So if we want a half height square wave with a fundamental frequency of 440 Hz we could write:

(mult 0.5 (osc-pulse 440 0))

If the pulse width is less than zero, the pulse will be negative more than it is positive, for example:

(mult 0.5 (osc-pulse 440 -0.5))

Here’s some other oscillators:

(mult 0.8 (hzosc 440))

(mult 0.4 (osc-saw 220))

(mult 0.9 (osc-tri 88))

and a generator that is not an oscillator - any guesses what this does? :wink:

(mult 0.5 (noise))

I’ll have to get back to you with the rest of the explanation later in the week as it’s now late and I have to be up early tomorrow.

Sounds like a job for a ring modulator

Alternatively modulate with a more complex waveform by applying Steve’s amplitude modulation code.