Zynaddsubfx

Within the options for modulation, one can select:

Unison is useful in creating the chorus like sound of many simultaneous oscillators

Waveshaping can be done using the Wsh area in the Oscillator editor.

The type of distortion has much influence on how the overtones are being placed. Sometimes, you get a "fat" bass, and sometimes, high frequencies are added, makeing the sound "crystal clear".

An equalizer is a filter effect that applies different volume to different frequencies of the input signal. This can, for example, be used to "filter out" unwanted frequencies. ZynAddSubFX’s implementations follow the "Cookbook formulae for audio EQ" by Robert Bristow-Johnson.

This topic is completely discussed in the Filters section.

We describe all parts of the GUI here. The term passband (or often just "band") refers to the amount of frequencies which are not significantly attenuated by the filter.

In a chorus, many people sing together. Even if each of them sings at exactly the same frequency, all their voices usually sound different. We say they have a different timbre. Timbre is the way we perceive sound and makes us differ between different music instruments. This is, physically, achieved by varying both the amplitude envelope and the frequency spectrum. Multiple sounds with slightly different timbres make a sound more shimmering, or powerful. This is called the chorus effect.

The chorus effect can be achieved by multiple people singing together. In a concert, there are many instruments, resulting in the same effect. When making electronic music, we only have an input wave and need to generate these different timbres by ourselves. ZynAddSubFX therefore simply plays the sound, pitch modulated by an LFO, and adds this to the original sound. This explains the diagram below: The multiple pitches are generated by a delayed version of the input. This version is being pitched by an LFO. More detailled, this pitch is generated by varying the reading speed of the delayed sound; the variation amount is controlled by an LFO.

TODO: Add LFO pointing to delay?

Related effects to Chorus are Flangers. Flangers can be described as Chorus with very short LFO delay and little LFO depth. You can imagine a flanger as two copies of a sound playing at almost the same time. This leeds to interference, which can be clearly heared. It is popular to apply flangers to guitars, giving them more "character".

Distortion means, in general, altering a signal. Natural instruments usually produce sine like waves. A wave is transformed in an unnatural way when distortion is used. The most distorted waves are usually pulse waves. It is typical for distortion to add overtones to a sound. Distortion often increases the power and the loudness of a signal, while the db level is not increased. This is an important topic in the Loudness War.

Distortion can happen in many situations when working with audio. Often, this is not wanted. In classical music, for example, distortion does not occur naturally. However, distortion can also be a wanted effect. It is typical for Rock guitars, but also present in electronic music, mostly in Dubstep and DrumNBass.

The basic components of distortion are mainly

Preamplification changes the volume before the wave is shaped, and is indeed the amount of distortion. For example, if you clip a signal, the louder the input gets, the more distortion you will get. This can have different meanings for different types of distortions, as described below.

This topic is completely discussed in the Oscillator Section. Note that you can use the Oscillator editor in order to find out what your distortion effect does. Also note that while the Oscillator editor’s distortion is limited to some oscillators you can produce in the Oscillator editor, the distortion effect can be used on every wave that you can generate with ZynAddSubFX.

We explain the functionality in a diagram and list the components below.

A dynamic filter is, as the name says, a filter which changes its parameters dynamically, dependent on the input and current time. In ZynAddSubFX, frequency is the only variable parameter. It can be used as an "envelope following filter" (sometimes referenced "Auto Wah" or simply "envelope filter").

Though this filter might look a bit complicated, it is actually easy. We divide the parameters into two classes:

The filter basically works like this: The input signal is passed through a filter which dynamically changes its frequency. The frequency is an additive of:

The amplitude of the input wave is not the current amplitude, but the so called "Root Mean Square (RMS)" value. This means that we build a mean on the current amplitude and the past values. How much the new amplitude takes influence is determined by the Amplitude Smoothness (see below).

The echo effect, also known as delay effect, simulates the natural reflection of a sound. The listener can hear the sound multiple times, usually decreasing in volume. Echos can be useful to fill empty parts of your songs with.

In ZynAddSubFX, the echo is basically implemented as the addition of the current sound and a delayed version of it. The delay is implemented as in the picture below. First, we add the delayed signal to the effect input. Then, they pass an LP1. This shall simulate the effect of dampening, which means that low and especially high frequencies get lost earlier over distance than middle frequencies do. Next, the sound is delayed, and then it will be output and added to the input.

A Reverberation actually expresses the effect of many echoes being played at the same time. This can happen in an enclosed room, where the sound can be reflected in different angles. Also, in nature, thunders approximate reverbs, because the sound is reflected in many different ways, arriving at the listener at different times.

In music, reverbs are popular in many ways. Reverbs with large room size can be used to emulate sounds like in live concerts. This is useful for voices, pads, and hand claps. A small room size can simulate the sound board of string instruments, like guitars or pianos.

As mentioned, a reverb consists of permanent echo. The reverb in ZynAddSubFX is more complex than the echo. After the delaying, comb filters and then allpass filters are being applied. These make the resulting sound more realistic. The parameters for these filters depend on the roomsize. For details, consider the information about Freeverb.

The Phaser is a special dynamic filter. The result is a sweeping sound, which is often used on instruments with a large frequency band, like guitars or strings. This makes it typical for genres like rock or funk, where it is often modulated with a pedal, but also for giving strings a warm, relaxing character.

The audio signal is split into two paths. One path remains unchanged. The other one is sent to a delay line. The delay time (the so called phase) is made dependent on the frequency. Therefore, an all-pass filter is applied to the signal, which preserves the amplitude, but determines the delay time. In the end, both paths are added.

The following picture describes how this works on white noise. Light blue signalises that the frequency is not present at the current time, and dark blue signalises the opposite. The dark blue peaks appear if the delay time is very short, because then, the second path almost equals the first one, which results in duplication of the signal. If the delay line is very long, then it is --- in the case of white noise --- totally at random whether the delayed signal currently duplicates the unchanged path, or whether it cancels it out to zero. This random effect results in white noise between the clear blue structures.

ZynAddSubFX offers different types of phasers:

For the normal phaser, first, the LFO is generated:

Next, the input is being used.

The AlienWah effect is a special, dynamic formant filter (TODO: is this true?). Paul Nasca named it AlienWah because it sounded "a bit like wahwah, but more strange". The result of the filter is a sound varying between the vocals "Ahhhhh" (or "Uhhhhh") and "Eeeeee".

The way that the filter moves between the two vocals is mainly described by an LFO. A bit easified, Paul Nasca has stated the formula (for $i^2=-1; R<1$) as

$fb=R*(\cos(\alpha)+i*\sin(\alpha))$

$y_n=y_{n-delay}*R*(\cos(\alpha)+i*\sin(\alpha))+x_n*(1-R)$.

The input $x_n$ has the real part of the samples from the wavefile and the imaginary part is zero. The output of this effect is the real part of $y_n$. $\alpha$ is the phase.

In order to save a patch, one can either save it from the instruments menu or through the bank window.

With the instrument menu, one can just save the file to any given location with the .xiz extension.

With the banks menu, one can assign a patch to a given slot with a bank. This instrument will remain here for future use until it is deleted. To see the physical location of the .xiz file, one should check the File→Settings→Bank_Root_Dirs window to see the paths for banks.

Have a favorite setting for an envelope, a difficult to reproduce oscillator? Then presets are for you. Presets allow for one to save the settings for any of the components which support copy/paste operations. This is done with preset files (.xpz), which get stored in the folders indicated by File→Settings→Preset_Root_Dirs.

In order to get a copy of the ZynAddSubFX source code, all that needs to be done is:

You should now be in the directory of the source code.

For simple steps on building, please see Appendix B of the manual.

Lets say that development has extended into the creation of a new feature that you want to preview. For the sake of this guide, lets assume that the name of the branch that the feature is on is foo.

Now one should be able to change branches and go into the build directory (as described in Appendix B) and recompile ZynAddSubFX.